Journal articles: 'Agnes Banks'

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Harner, Christie. "Animal and Social Ecologies in Anne Brontë's Agnes Grey." Victorian Literature and Culture 48, no. 3 (2020): 577–99. http://dx.doi.org/10.1017/s1060150319000147.

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In Anne Brontë's Agnes Grey (1847), the eponymous narrator uses a range of ecological metaphors to make sense of her interactions with others. She likens governessing to domestic horticulture and envisions how her task of educating children will be “to train the tender plants, and watch their buds unfolding day by day.” Rather than voice her unfulfilled romantic feelings for Weston or consciously work through her self-doubts about physical appearance, she visualizes them both as insects: she is the “humble glow-worm” who, without a “power of giving light” (i.e., beauty), “the roving fly might pass her . . . a thousand times, and never light beside her” (123). Even the reader, in the opening sentence, assumes the role of active participant: a nucivorous beast hunting for whatever “dry, shriveled kernel” of narrative meaning might be found by “cracking the nut” (5). As character, the budding naturalist “botanize[s] and entomologize[s] along the green banks and budding hedges”; as narrator, she projects herself and those around her into complex ecosystems (95). Her choice of metaphors captures a matrix of exchanges in which species of all kinds interact with one another and their environments in unpredictable ways. Agnes assigns the life cycles of flora and fauna to characters, populating the novel with human and nonhuman animals in ways that draw heavily on early nineteenth-century science even as they also prefigure some of the concerns of contemporary animal studies and ecocriticism.

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Periyasami, Govindasami, Selvakumar Palaniappan, Ponmurugan Karuppiah, Mostafizur Rahaman, Perumal Karthikeyan, Ali Aldalbahi, and Naif Abdullah Al-Dhabi. "Biogenic Silver Nanoparticles Fabricated by Euphorbia granulata Forssk’s Extract: Investigating the Antimicrobial, Radical Scavenging, and Catalytic Activities." Journal of Nanomaterials 2022 (April 11, 2022): 1–13. http://dx.doi.org/10.1155/2022/3864758.

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The plants of Euphorbiaceae have high medicinal values and their phytochemical composition plays a major role in metal ion reduction. In this research, Euphorbia granulata (EG) the “spurge family” plant extract was used to reduce silver ions to silver nanoparticles (AgNPs). This nanoparticle formation was observed by UV-VIS spectrophotometric analysis at different times and temperatures to achieve the most optimal conditions. The synthesized biogenic silver nanoparticles (EG-AgNPs) were subjected to FTIR studies. The obtained low-intensity bands of fingerprint region bands (612 cm-1) and aromatic OH bands (3385 cm-1) are identified that the reduction of silver ions (Ag+) into metallic silver (Ag0) nanoparticles. Further, the charge, size, and morphology of the synthesized EG-AgNPs were studied using various spectroscopic methods including powder X-ray diffraction (XRD), high-resolution scanning electron microscope (HRSEM), FESEM-EDX elemental mapping, and high-resolution transmission electron microscope (HRTEM). The notable efficacy of the EG-AgNPs in antimicrobial activity including minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) suggested the EG-AgNPs are noteworthy material for biomedical applications. EG-AgNPs exhibited an efficient photocatalytic activity by degrading environmental pollutants, methylene blue (MB), and methyl orange (MO) dyes. The antioxidant property by radical scavenging (DPPH) assay of synthesized AgNPs was studied. Furthermore, the studied antioxidant behavior of EG-AgNPs by DPPH assay strongly supports that the EG-AgNPs are highly suitable materials for anticancer agents.

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Ma, Liang, Shuting Lv, Jianxin Tang, Jianxin Liu, Wen Li, Jing Deng, Yan Deng, Jingjing Du, Xueying Liu, and Xiaoxi Zeng. "Study on bioactive molecules involved in extracellular biosynthesis of silver nanoparticles by Penicillium aculeatum Su1." Materials Express 9, no. 5 (August 1, 2019): 475–83. http://dx.doi.org/10.1166/mex.2019.1508.

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In this paper, the biosynthesis of high-stable and biocompatible silver nanoparticles (AgNPs) was implemented by employing cell-free filtrate of Penicillium aculeatum Su1. The compositions analysis of reducing biomolecules in reaction system before and after AgNPs synthesis suggested that proteins were mainly involved in the biosynthesis process of AgNPs. Polyacrylamide gel electrophoresis (SDS-PAGE) analysis displayed that two main protein bands with molecular weights ranging from 66.2 to 116 KDa and 35 to 45 KDa were capped on the surface of AgNPs. The further identification of these protein bands by liquid chromatography-mass spectrometry (LC-MS/MS) analysis indicated that actin as a major protein component was responsible for stabilization of prepared AgNPs. The activity of nitrate reductase secreted by P. aculeatum Su1 was 73.73 ± 3.89 μg/(g · h). Furthermore, the dialysis assay showed that small molecular components had significant impacts on yield and particle size of biosynthesized AgNPs. Reduced nicotinamide adenine dinucleotide or reduced nicotinamide adenine dinucleotide phosphate (NADH or NADPH)-dependent nitrate reductases and other types of reductases or non-enzymatic bioactive molecules (≥ 3.5 KDa) might simultaneously participate in the biosynthesis process of AgNPs mediated by P. aculeatum Su1.

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Soliman, Magda I., Nada S. Mohammed, Ghada EL-Sherbeny, Fatmah Ahmed Safhi, Salha Mesfer ALshamrani, Amal A. Alyamani, Badr Alharthi, et al. "Antibacterial, Antioxidant Activities, GC-Mass Characterization, and Cyto/Genotoxicity Effect of Green Synthesis of Silver Nanoparticles Using Latex of Cynanchum acutum L." Plants 12, no. 1 (December 30, 2022): 172. http://dx.doi.org/10.3390/plants12010172.

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Green synthesis of nanoparticles is receiving more attention these days since it is simple to use and prepare, uses fewer harsh chemicals and chemical reactions, and is environmentally benign. A novel strategy aims to recycle poisonous plant chemicals and use them as natural stabilizing capping agents for nanoparticles. In this investigation, silver nanoparticles loaded with latex from Cynanchum acutum L. (Cy-AgNPs) were examined using a transmission electron microscope, FT-IR spectroscopy, and UV-visible spectroscopy. Additionally, using Vicia faba as a model test plant, the genotoxicity and cytotoxicity effects of crude latex and various concentrations of Cy-AgNPs were studied. The majority of the particles were spherical in shape. The highest antioxidant activity using DPPH was illustrated for CAgNPs (25 mg/L) (70.26 ± 1.32%) and decreased with increased concentrations of Cy-AGNPs. Antibacterial activity for all treatments was determined showing that the highest antibacterial activity was for Cy-AgNPs (50 mg/L) with inhibition zone 24 ± 0.014 mm against Bacillus subtilis, 19 ± 0.12 mm against Escherichia coli, and 23 ± 0.015 against Staphylococcus aureus. For phytochemical analysis, the highest levels of secondary metabolites from phenolic content, flavonoids, tannins, and alkaloids, were found in Cy-AgNPs (25 mg/L). Vicia faba treated with Cy-AgNPs- (25 mg/L) displayed the highest mitotic index (MI%) value of 9.08% compared to other Cy-AgNP concentrations (50–100 mg/L) and C. acutum crude latex concentrations (3%). To detect cytotoxicity, a variety of chromosomal abnormalities were used, including micronuclei at interphase, disturbed at metaphase and anaphase, chromosomal stickiness, bridges, and laggards. The concentration of Cy-AgNPs (25 mg/L) had the lowest level of chromosomal aberrations, with a value of 23.41% versus 20.81% for the control. Proteins from seeds treated with V. faba produced sixteen bands on SDS-PAGE, comprising ten monomorphic bands and six polymorphic bands, for a total percentage of polymorphism of 37.5%. Eight ISSR primers were employed to generate a total of 79 bands, 56 of which were polymorphic and 23 of which were common. Primer ISSR 14 has the highest level of polymorphism (92.86%), according to the data. Using biochemical SDS-PAGE and ISSR molecular markers, Cy-AgNPs (25 mg/L) showed the highest percentage of genomic template stability (GTS%), with values of 80% and 51.28%, respectively. The findings of this work suggest employing CyAgNPs (25 mg/L) in pharmaceutical purposes due to its highest content of bioactive compounds and lowest concentration of chromosomal abnormalities.

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Shakir Basha S, Ashok Thulluru, Naresh Babu C, Chithra Shekar C, Jagadeesh P, Mohammed Idress N S, Praveena R, Sravan Kumar C, and Anil A. "Synthesis, Characterization And Assessment of Anti Microbial Behaviour of Goat Faecal Mediated Silver Nanoparticles- Fed on Tirumala Hills." International Journal of Research in Pharmaceutical Sciences 11, no. 4 (December 21, 2020): 8016–25. http://dx.doi.org/10.26452/ijrps.v11i4.4752.

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To synthesize, characterize, and to assess the anti-microbial activity of silver nanoparticles (AgNPs) induced by goat fecal matter. The AgNPs were processed by the microwave heating method and the characterization was accomplished by employing various spectroscopic approaches such as UV-Visible, FTIR spectroscopy, XRD, Particle size, and Zeta potential analysis. The lmax for both extracts were found at 426& 438nm. The wideband corresponded to O-H stretching vibrations at 3384.0 cm-1, 3273.9 cm-1 and 3366.2 cm-1, bands at 2918.5 cm-1, 2922.5 cm-1, 2853.2 cm-1, and 2850.2 cm-1 corresponded to the N–H and C–H stretching. The bands at 1638.1 cm-1, 1651.9, and 1686.5 cm-1 corresponded to the C=C stretch. Bands of 1460.3 cm-1, 1450.4 cm-1, 1409.2 cm-1 and 1376.3 cm-1 corresponded to C-N, C-C bond stretching vibrations. The stretch of C-O indicates bands at 1159.7 cm-1, 1033.2 cm-1, and 1032.8 cm-1. The synthesized AgNPsdemonstrated good anti-microbial activity on gram +Ve (S.aureus) and gram -Ve (E.coli) bacteria. Bio/Green synthesized AgNPs have shown improved biological performance, this tends to minimize production cost, pollution-free, less chemical usage, and stable generation of nanoparticles.

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Shakir Basha S, Ashok Thulluru, Naresh Babu C, Chithra Shekar C, Jagadeesh P, Mohammed Idress N S, Praveena R, Sravan Kumar C, and Anil A. "Synthesis, Characterization And Assessment of Anti Microbial Behaviour of Goat Faecal Mediated Silver Nanoparticles- Fed on Tirumala Hills." International Journal of Research in Pharmaceutical Sciences 12, no. 2 (June 30, 2021): 1223–32. http://dx.doi.org/10.26452/ijrps.v12i2.4752.

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To synthesize, characterize, and to assess the anti-microbial activity of silver nanoparticles (AgNPs) induced by goat fecal matter. The AgNPs were processed by the microwave heating method and the characterization was accomplished by employing various spectroscopic approaches such as UV-Visible, FTIR spectroscopy, XRD, Particle size, and Zeta potential analysis. The lmax for both extracts were found at 426& 438nm. The wideband corresponded to O-H stretching vibrations at 3384.0 cm-1, 3273.9 cm-1 and 3366.2 cm-1, bands at 2918.5 cm-1, 2922.5 cm-1, 2853.2 cm-1, and 2850.2 cm-1 corresponded to the N–H and C–H stretching. The bands at 1638.1 cm-1, 1651.9, and 1686.5 cm-1 corresponded to the C=C stretch. Bands of 1460.3 cm-1, 1450.4 cm-1, 1409.2 cm-1 and 1376.3 cm-1 corresponded to C-N, C-C bond stretching vibrations. The stretch of C-O indicates bands at 1159.7 cm-1, 1033.2 cm-1, and 1032.8 cm-1. The synthesized AgNPsdemonstrated good anti-microbial activity on gram +Ve (S.aureus) and gram -Ve (E.coli) bacteria. Bio/Green synthesized AgNPs have shown improved biological performance, this tends to minimize production cost, pollution-free, less chemical usage, and stable generation of nanoparticles.

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7

Singh, Dattu, Vandana Rathod, Shivaraj Ninganagouda, Jyothi Hiremath, Ashish Kumar Singh, and Jasmine Mathew. "Optimization and Characterization of Silver Nanoparticle by Endophytic FungiPenicilliumsp. Isolated fromCurcuma longa(Turmeric) and Application Studies against MDRE. coliandS. aureus." Bioinorganic Chemistry and Applications 2014 (2014): 1–8. http://dx.doi.org/10.1155/2014/408021.

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Development of ecofriendly and reliable processes for the synthesis of nanoparticles has attracted considerable interest in nanotechnology because of its tremendous impetus in modulating metals into nanosize to their potential use for human benefits. In this study an endophytic fungus,Penicilliumsp., isolated from healthy leaves ofCurcuma longa(turmeric) was subjected to extracellular biosynthesis of silver nanoparticles (AgNps) and their activity against MDRE. coliandS. aureus. The biosynthesized AgNps optimization was studied and characterized by UV-visible spectroscopy, Fourier transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM). Then produced AgNps were tested against MDRE. coliandS. aureus. The endophytic fungusPenicilliumsp. from healthy leaves ofC. longa(turmeric) was found to be a good producer of AgNps. Parametric optimization showed maximum absorbance of 420–425 nm at pH-7, 25°C with 1 mM AgNO3concentration and 15–20 g of wet biomass. Further TEM revealed the formation of spherical, well-dispersed nanoparticles with size ranging between 25 and 30 nm and FTIR shows the bands at 1644 and 1538 cm−1corresponding to the binding vibrations of amide I and II bands of proteins, respectively. Antibacterial activity against MDRE. coliandS. aureusshowed good results showing maximum zone of inhibition of 17 mm and 16 mm, respectively, at 80 µL of AgNps.

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Fuloria, S., O. J. Hong, C. B. Kim, B. Y. S. Ting, S. Karupiah, N. Paliwal, U. Kumari, K. Sathasivam, S. Vetriselvan, and N. K. Fuloria. "Synthesis of Silver Nanoparticles of Corn Silk Agrowaste and Their Bioactivities." Asian Journal of Chemistry 32, no. 6 (2020): 1497–504. http://dx.doi.org/10.14233/ajchem.2020.22625.

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Present study was intended to synthesize silver nanoparticles (AgNPs) using corn silk aqueous extract (CSAE) and evaluate for antimicrobial and antiurolithiatic potential. The aqueous decoction of corn silk offered light yellow CSAE. Treatment of AgNO3 with CSAE offered AgNPs with absorbance 430 nm. Optimization study established 5 mM silver nitrate, 2.5:7.5 extract to AgNO3 ratio, pH 8, and 24 h time as parametric requirement for synthesis of AgNPs using CSAE. Stability study supported the AgNPs stability based on retention of SPR signal between 428 to 450 nm. The synthesis of AgNPs was confirmed on broad and shifted FTIR bands; XRD signals at 2θ values of 32.27º, 40.72º, 46.20º, 65.69º, 69.31º and 76.49º indexed to 111, 200, 220 and 311 planes, respectively; particle size range from 22.05-36.69 nm in FESEM; and elemental silver content of 62.17% as per EDX spectrum. The synthesized AgNPs exhibited high antibacterial and antiurolithiatic potential. Present study recommends that synthesis of AgNPs using CSAE is a facile and eco-friendly method

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Rashid, Mohd, and Suhail Sabir. "Biosynthesis of Self-Dispersed Silver Colloidal Particles Using the Aqueous Extract of P. peruviana for Sensing dl-Alanine." ISRN Nanotechnology 2014 (February 2, 2014): 1–7. http://dx.doi.org/10.1155/2014/670780.

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We report the biosynthesis of silver nanoparticles (AgNPs) in a single step using edible fruit aqueous extract of P. peruviana that essentially involved the concept of green chemistry. Yellowish-brown color appeared upon adding the broth of P. peruviana to aqueous solution of 1 mM AgNO3 which indicates the formation of AgNPs. The maximum synthesis of these nanoparticles was being achieved in nearly 2 hrs at 28°C. The synthesis of AgNPs was followed by AgNPs UV-visible spectroscopy. Particle size and morphology of AgNPs were studied by transmission electron microscopy (TEM) and scanning electron microscopy (SEM), respectively. These studies revealed that the AgNPs characterized were spherical in shape with diameter ranging from 31 to 52 nm. The energy dispersive X-ray spectroscopy showed that the AgNPs present are approximately 63.42 percent by weight in the colloidal dispersion. The absorption spectra of the AgNPs in absence and presence of dl-alanine show a distinguish shift in surface plasmon resonance (SPR) bands. Thus, these nanoparticles may be used as a chemical sensor for dl-alanine present in the human blood.

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Hamdiani, Saprini, and Yeng-Fong Shih. "A Green Method for Synthesis of Silver-Nanoparticles-Diatomite (AgNPs-D) Composite from Pineapple (Ananas comosus) Leaf Extract." Indonesian Journal of Chemistry 21, no. 3 (May 5, 2021): 740. http://dx.doi.org/10.22146/ijc.63573.

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This study aims to develop a green method to load silver nanoparticles (AgNPs) into the diatomite (D) pores to produce AgNPs-D composite material. The AgNPs were synthesized by pineapple leaf extract at the temperature of 70 °C for 30 min. The composite formation was characterized by UV-Vis, FTIR, TGA, particle sizes analysis, gravimetric, and color observation. The appearance of surface plasmon bands in 440–460 nm confirms the AgNPs formation. The percentage of the AgNO3 which converted to AgNPs was 99.8%. The smallest particle size of AgNPs was 30 nm, obtained in an AgNO3 concentration of 1 mM with a stirring time of 24 h at 70 °C. The colloidal AgNPs were stable for up to 7 days. The adsorption process of AgNPs was marked by the appearance of –C=O and –C–O– groups peak at 1740 and 1366 cm–1 on the FTIR spectrum. By adsorption and gravimetric technique, as much as 1 wt.% of AgNPs were loaded into D pores. The color of diatomite material changes from white to reddish-brown. The TGA analysis showed that the remaining D and AgNPs-D at 580 °C are 98.22% and 95.74%, respectively. The AgNPs loading through the green technology technique was expected to increase diatomite application in the biomedical field.

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Do, Thi-Nga, Godfrey Gumbs, Danhong Huang, Bui D. Hoi, and Po-Hsin Shih. "Role Played by Edge-Defects in the Optical Properties of Armchair Graphene Nanoribbons." Nanomaterials 11, no. 12 (November 28, 2021): 3229. http://dx.doi.org/10.3390/nano11123229.

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We explore the implementation of specific optical properties of armchair graphene nanoribbons (AGNRs) through edge-defect manipulation. This technique employs the tight-binding model in conjunction with the calculated absorption spectral function. Modification of the edge states gives rise to the diverse electronic structures with striking changes in the band gap and special flat bands at low energy. The optical-absorption spectra exhibit unique excitation peaks, and they strongly depend on the type and period of the edge extension. Remarkably, there exist the unusual transition channels associated with the flat bands for selected edge-modified systems. We discovered the special rule governing how the edge-defect influences the electronic and optical properties in AGNRs. Our theoretical prediction demonstrates an efficient way to manipulate the optical properties of AGNRs. This might be of importance in the search for suitable materials designed to have possible technology applications in nano-optical, plasmonic and optoelectronic devices.

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Dhimdhime, A. D., R. S. Talegaonkar, A. K. Wanjari, A. R. Somwanshi, and R. D. Ghodil. "PLANT MEDIATED GREEN AND FACILE SYNTHESIS OF SILVER NANOPARTICLES AND THEIR POSSIBLE APPLICATION AS ANTIMICROBIAL AGENTS." Rasayan Journal of Chemistry 15, no. 01 (2022): 504–8. http://dx.doi.org/10.31788/rjc.2022.1516818.

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In recent year green and eco-friendly synthesis of metal nanoparticles plays an important role in nanotechnology, medical science, industries, ceramics etc. The manuscript focuses on the green and facile synthesis of AgNPs from aqueous solution of leaf of Cassia fistula. UV-Visible spectra confirm the bio-formation of AgNPs at 412 nm with the witness of change in colour. Synthesized silver nanoparticle characterized further by FTIR, SEM, EDX and XRD spectroscopic technique. The shape of AgNPs is observed to be like oval, triangular and cylindrical respectively. EDX analysis confirmed the elemental percentage of silver 93.02%. FTIR shows shifting in bands from lower side to upside.The biosynthesized AgNPs shows antibacterial activity against E. coli and B. subtilis pathogens and it was found that AgNPs were more effective against E. coli and B. subtilis bacteria. The method used in this study for the biosynthesis of AgNPs from aqueous extracts of Cassia Fistula was green, reduce harmful chemical with no environmental hazards.

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Ibrahim, Essam H., Ali Alshehri, Hamed A. Ghramh, Mona Kilany, Kareem Morsy, Attalla F. El-Kott, and Mahmoud A. Sayed. "Rosemary Extract and Its Biogenic Silver Nanoparticles Induce Apoptosis and Arrest Cell Cycle in HT-29 Colon Cancer Cells." Science of Advanced Materials 13, no. 1 (January 1, 2021): 36–49. http://dx.doi.org/10.1166/sam.2021.3893.

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Colorectal malignancy is a significant reason of morbidity and mortality. Rosmarinus officinalis is a medicinal plant and used as diet. Metal nanoparticles are utilized in various fields. This study aimed to investigate if R. officinalis leaves acetone extract (ROLAExt) can kill the abnormally fast dividing cells (cancer) and not normal fast diving cells (proliferation-activated) aided by nanoparticles. Silver nanoparticles (AgNPs) were prepared using ROLAExt and characterized with UV/Vis spectrophotometry, XRD and SEM. Functional groups found in the ROLAExt and ROLAExt containing AgNPs (ROLAExt + AgNPs) were explored using FTIR. Sugars, ROS and proteins in ROLAExt were investigated. Biological properties of ROLAExt and ROLAExt + AgNPs including cell cycle arrest, antibacterial, induction of p53 protein, and apoptotic capacity properties were tested. Results demonstrated that AgNPs are of 75 nm in diameter. There is active biomolecules, minute amount of sugars, no protein bands, and 175.2 pg/mL ROS in ROLAExt. AgNPs increased the antibacterial activity, p53 expression, apoptosis, arrestment of HT-29 cells at G2/M phase and did not affect the fast dividing cells. ROLAExt and ROLAExt + AgNPs were safe to the vital organs. In conclusion, R. officinalis acetone extract showed excellent effects on HT-29 cancer cells, but in the presence of AgNPs killed cancer cells and stimulated splenic cells.

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Silva, Mário R. P. da, Robert S. Matos, Michael D. S. Monteiro, Samuel B. Santos, Henrique D. F. Filho, George R. S. Andrade, Marco Salerno, and Luís E. Almeida. "Exploiting the Physicochemical and Antimicrobial Properties of PHB/PEG and PHB/PEG/ALG-e Blends Loaded with Ag Nanoparticles." Materials 15, no. 21 (October 27, 2022): 7544. http://dx.doi.org/10.3390/ma15217544.

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Poly(3-hydroxybutyrate) (PHB)-based films containing Poly(ethylene glycol) (PEG), esterified sodium alginate (ALG-e) and polymeric additives loaded with Ag nanoparticles (AgNPs) were obtained by a conventional casting method. AgNPs were produced in aqueous suspension and added to polymeric gels using a phase exchange technique. Composite formation was confirmed by finding the Ag peak in the XRD pattern of PHB. The morphological analysis showed that the inclusion of PEG polymer caused the occurrence of pores over the film surface, which were overshadowed by the addition of ALG-e polymer. The PHB functional groups were dominating the FTIR spectrum, whose bands associated with the crystalline and amorphous regions increased after the addition of PEG and ALG-e polymers. Thermal analysis of the films revealed a decrease in the degradation temperature of PHB containing PEG/AgNPs and PEG/ALG-e/AgNPs, suggesting a catalytic effect. The PHB/PEG/ALG-e/AgNPs film combined the best properties of water vapor permeability and hydrophilicity of the different polymers used. All samples showed good antimicrobial activity in vitro, with the greater inhibitory halo observed for the PEG/PEG/AgNPs against Gram positive S. aureus microorganisms. Thus, the PHB/PEG/ALG-e/AgNPs composite demonstrated here is a promising candidate for skin wound healing treatment.

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Ghramh, Hamed A., Essam H. Ibrahim, and Mona Kilnay. "Majra Honey Abrogated the Normal and Cancer Cells Proliferation Inhibition by Juniperus procera Extract and Extract/Honey Generated AgNPs." Anti-Cancer Agents in Medicinal Chemistry 20, no. 8 (July 24, 2020): 970–81. http://dx.doi.org/10.2174/1871520620666200213104224.

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Background: Juniperus procera and Majra honey are well-known as a folk medicine in many countries. Objectives: This work aimed to study the immunomodulatory effects after mixing Majra honey, J. procera water leaves extract and silver Nanoparticles (AgNPs) on immune or cancer cells. Methods: Juniperus procera water leaves extract and 20% Majra honey were prepared. Both the extract and honey were used separately to synthesize AgNPs. AgNPs were characterized using UV/Vis spectrophotometry and electron microscopy. Bioactive molecules in honey and the extract were explored using Fourier Transform Infrared (FT-IR) spectroscopy. Protein profile of honey was explored using Sodium Dodecyl Sulfate- Polyacrylamide Gel Electrophoresis (SDS-PAGE) and honey sugar content was determined using High- Performance Liquid Chromatography (HPLC). Biological activities of honey and the extract were tested. Results: The results demonstrated the ability of the extract/honey to produce AgNPs in a spherical shape. The extract/honey contained many functional groups. SDS-PAGE of Majra honey showed many protein bands. HPLC revealed honey is of good quality and no external additives are added to it. The extract and extract+ AgNPs inhibited the growth of normal rat splenic cells while honey stimulated it. The extract+honey turned stimulatory to the splenic cells’ growth and significantly diminished the inhibitory potential of the extract containing AgNPs. Both the extract and honey have antimicrobial activities, this potential increased in the presence of AgNPs. Honey and Honey+AgNPs inhibited HepG2 cancer cell proliferation while Hela cell growth inhibited only with honey+AgNPs. Conclusion: Both honey and the extract have antibacterial and immunomodulatory potentials as well as the power to produce AgNPs. Majra honey alone showed anticancer activity against HepGe2 cells, but not against Hela cells, and when contained AgNPs had anticancer activity on both cell lines. Mixing of Majra honey with J. procera extract showed characterized immunomodulatory potentials that can be described as immunostimulant.

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Osei, Eric Boateng, Liliia Paniushkina, Konrad Wilhelm, Jürgen Popp, Irina Nazarenko, and Christoph Krafft. "Surface-Enhanced Raman Spectroscopy to Characterize Different Fractions of Extracellular Vesicles from Control and Prostate Cancer Patients." Biomedicines 9, no. 5 (May 20, 2021): 580. http://dx.doi.org/10.3390/biomedicines9050580.

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Extracellular vesicles (EVs) are membrane-enclosed structures ranging in size from about 60 to 800 nm that are released by the cells into the extracellular space; they have attracted interest as easily available biomarkers for cancer diagnostics. In this study, EVs from plasma of control and prostate cancer patients were fractionated by differential centrifugation at 5000× g, 12,000× g and 120,000× g. The remaining supernatants were purified by ultrafiltration to produce EV-depleted free-circulating (fc) fractions. Spontaneous Raman and surface-enhanced Raman spectroscopy (SERS) at 785 nm excitation using silver nanoparticles (AgNPs) were employed as label-free techniques to collect fingerprint spectra and identify the fractions that best discriminate between control and cancer patients. SERS spectra from 10 µL droplets showed an enhanced Raman signature of EV-enriched fractions that were much more intense for cancer patients than controls. The Raman spectra of dehydrated pellets of EV-enriched fractions without AgNPs were dominated by spectral contributions of proteins and showed variations in S-S stretch, tryptophan and protein secondary structure bands between control and cancer fractions. We conclude that the AgNPs-mediated SERS effect strongly enhances Raman bands in EV-enriched fractions, and the fractions, EV12 and EV120 provide the best separation of cancer and control patients by Raman and SERS spectra.

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Brycki, Bogumił, Adrianna Szulc, and Mariia Babkova. "Synthesis of Silver Nanoparticles with Gemini Surfactants as Efficient Capping and Stabilizing Agents." Applied Sciences 11, no. 1 (December 26, 2020): 154. http://dx.doi.org/10.3390/app11010154.

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The scientific community has paid special attention to silver nanoparticles (AgNPs) in recent years due to their huge technological capacities, particularly in biomedical applications, such as antimicrobials, drug-delivery carriers, device coatings, imaging probes, diagnostic, and optoelectronic platforms. The most popular method of obtaining silver nanoparticles as a colloidal dispersion in aqueous solution is chemical reduction. The choice of the capping agent is particularly important in order to obtain the desired size distribution, shape, and dispersion rate of AgNPs. Gemini alkylammonium salts are named as multifunctional surfactants, and possess a wide variety of applications, which include their use as capping agents for metal nanoparticles synthesis. Because of the high antimicrobial activity of gemini surfactants, AgNPs stabilized by this kind of surfactant may possess unique and strengthened biocidal properties. The present paper presents the synthesis of AgNPs stabilized by gemini surfactants with hexadecyl substituent and variable structure of spacer, obtained via ecofriendly synthesis. UV-Vis spectroscopy and dynamic light scattering were used as analyzing tools in order to confirm physicochemical characterization of the AgNPs (characteristic UV-Vis bands, hydrodynamic diameter of NPs, polydispersity index (PDI)).

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Morita, Reinaldo Yoshio, Mariane Schnitzler, Karen Wohnrath, Jarem Garcia, Ronilson Vasconcelos Barbosa, Bianca Iodice, and Juliana Regina Kloss. "Montmorillonite Silver Nanoparticles for Applications in Polymeric Materials." Materials Science Forum 805 (September 2014): 627–31. http://dx.doi.org/10.4028/www.scientific.net/msf.805.627.

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This work presents the preparation of silver nanoparticles (AgNPs) with montmorillonite to produce a nanomaterial with bactericidal properties. The modified montmorillonite was characterized through the techniques of Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy and X-ray diffraction (XRD). The FTIR and Raman spectrum’s showed specific bands of involving stretching silver. In the XRD analyses was observed the occurrence of the following crystallographic planes (111), (200) e (220) silver related. The nanocomposites of polyethylene with AgNPs did not show loss in mechanical properties, this fact was important and indicate that the nanomaterial can be inserted in this polymer matrix with considerable technological interest.

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SEVİNDİK, Emre, Serkan CANER, and Mahmut COŞKUN. "Molecular Characterization of Vitex agnus-castus L. (Verbenaceae) Populations Grown in Aydin, Turkey." Notulae Scientia Biologicae 11, no. 2 (June 28, 2019): 218–21. http://dx.doi.org/10.15835/nsb11210418.

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In this study, we performed a genetic diversity analysis using RAPD markers for some Vitex agnus-castus populations grown in Aydin, Turkey. Total genomic DNA isolation from the leaves of Vitex agnus-castus was performed using a commercial kit. Seven RAPD primers (OPA-02, OPA-05, OPA-13, OPA-15, OPA-16, OPA-18, OPA-20) were used to determine genetic diversity among populations. Polymerase Chain Reaction (PCR) was performed with all genomic DNA samples and primers. PCR products were run in agarose gel electrophoresis and visualized under UV light. The amplified products were scored as bands (1) and no bands (0) for all gel images and their matrix files were generated. A total of 36 characters were obtained from the primers. Phylogenetic relationships and genetic distances between the cultivars were calculated by using the PAUP* (Phylogenetic Analysis Using Parsimony and other methods) program. According to PAUP analysis, the closest genetic distances were between Çine pink flower and Çakmar purple flower, and Çakmar pink flower and Çakmar purple flower populations with a value of 0.05556; and the greatest genetic distance was between Çakmar pink flower and Köşk purple flower populations with a value of 0.36111. In the phylogenetic analysis obtained using UPGMA algorithms, the phylogenetic tree consisted of four groups. The results suggest that RAPD markers are useful tools for determining genetic relationships among Vitex agnus-castus genotypes.

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Ahmed, Anees, Abdur Rauf, Hassan A. Hemeg, Muhammad Nasimullah Qureshi, Rohit Sharma, Abdullah S. M. Aljohani, Fahad A. Alhumaydhi, Ibrahim Khan, Amir Alam, and Md Mominur Rahman. "Green Synthesis of Gold and Silver Nanoparticles Using Opuntia dillenii Aqueous Extracts: Characterization and Their Antimicrobial Assessment." Journal of Nanomaterials 2022 (March 26, 2022): 1–17. http://dx.doi.org/10.1155/2022/4804116.

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In the present study, gold (Au) and silver (Ag) nanoparticles (NPs) were synthesized from aqueous extracts of Opuntia dillenii, characterized by various advanced techniques and investigated for antibacterial and antifungal potential. Phytochemical screening of O. dillenii showed the presence of alkaloids, betacyanin, saponins, tannins, flavonoids, and phlobatannins. The characterizations of the synthesized metal NPs were performed such as UV-visible spectrophotometer, FTIR (Fourier transform infrared) spectrophotometer, SEM (scanning electron microscopy) and EDX (energy-dispersive X-ray). Through the application of such advance techniques, the UV-visible spectrophotometer showed the bands of absorbance for AgNPs and AuNPs at 420 nm and 525 nm range, respectively. The FTIR spectra for both and AgNPs also appeared in the range of 4000-400 cm-1. SEM was performed for the textural and morphological characteristics of the NPs such as shape, size distribution, and surface structure. Elemental analysis was recorded for the synthesis of Au and AgNPs, which confirmed its purity. The O. dillenii extract and their synthesized Au and AgNPs showed a clear zone of inhibition against the E. coli, S. aureus, K. pneumonia, and P. aeruginosa bacteria and T. viride, C. albicans, C. krusei, and A. niger fungal species.

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Foerster, J., and WA Milne-Home. "Application of AGNPS to model nutrient generation rates under different farming management practices at the Gunnedah Research Centre catchment." Australian Journal of Experimental Agriculture 35, no. 7 (1995): 961. http://dx.doi.org/10.1071/ea9950961.

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Data collected at a conservation tillage trial site operational between 1971 and 1986 were used to assess the performance of the Agricultural Non-Point Source model (AGNPS). Eight trial plots, each of about 1 ha (average slope of 3.8%), were established on the black earths of paddock 2 at the Gunnedah Research Centre, New South Wales. The plots were subjected in pairs to stubble-burning, stubble incorporation, stubble-mulching, and no-tillage treatments. Runoff and peak flow rate from the plots, resulting from 5 rainfall events between 1982 and 1986, were used to calibrate the hydrology module of AGNPS. Hydrologic simulations for each plot and associated tillage treatment performed after calibration showed that conservation farming practices could effectively reduce runoff and peak flow rate. AGNPS was also used to simulate nutrient generation rates, defined as the transport of soluble and sediment-adsorbed nitrogen and phosphorus in runoff and sediment discharge, for the whole catchment for a number of rainfall events. The model predicted that nutrient movement could be reduced using best management practices, including the implementation of contour banks, contour cultivation, and no tillage. Additional information related to soil chemical properties and pore/surface water nutrient content could improve model performance.

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Hieu, H. N., D. T. H. Trang, V. T. T. Hien, N. V. Nghia, N. T. Lam, and T. M. D. Nguyen. "Microorganism-mediated green synthesis of silver nanoparticles using Aspergillus niger and Bacillus megaterium." Digest Journal of Nanomaterials and Biostructures 17, no. 1 (January 2022): 359–67. http://dx.doi.org/10.15251/djnb.2022.171.359.

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Research in the field of nanotechnologies, the development of reliable and environmentally friendly processes for the synthesis of metallic nanoparticles constitutes an important element in this field. In this study, biosynthesis of silver nanoparticles using Bacillus megaterium and Aspergillus niger is reported. The results show that the characteristic UV-vis absorbance peak of AgNPs synthesized using Aspergillus niger was observed in the 433 - 448 nm range and around 475 nm with Bacillus megaterium. Most of the particles were spherical in shape and within a size range of 1 to 10.5 nm using Aspergillus niger and 3 to 15 nm with Bacillus megaterium. The FTIR analysis of AgNPs showed five absorbance bands at 3446, 1645, 1373, 1080, and 790 cm−1 . These AgNPs have potential antibacterial activity against Escherichia coli. The results of our study could help to improve the silver nanoparticle synthesis since our method makes them small, stable, and with a high antibacterial efficiency.

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BATTILOSSI, STEFANO. "Financial innovation and the golden ages of international banking: 1890–1931 and 1958–81." Financial History Review 7, no. 2 (October 2000): 141–75. http://dx.doi.org/10.1017/s0968565000000093.

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Stefano Battilossi, Financial innovation and the golden ages of international banking: 1890–1931 and 1958–81Throughout the twentieth century, the internationalisation of banking was both a factor for, and an ensuing aspect of, rising globalisation. During the period 1890–1931, commercial banks of industrialised countries promoted organisational and process innovations that successfully challenged the dominance of merchant banks in international financial intermediation. International banking re-emerged from interwar nationalistic retrenchment during the late 1950s, when banks exploited regulatory asymmetries to foster the emergence of Eurocurrency markets. Eurobanks provided not only global liquidity redistribution but also portfolio transformation services to corporate and sovereign customers. Financial innovations related to Eurobanking mark a secular discontinuity as they proved to be vehicles of a banking revolution, based on competition, deregulation and wholesale-market funding.

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Khalil, Muhammad Saqib, Muhammad Shakeel, Naila Gulfam, Syed Umair Ahmad, Aamir Aziz, Junaid Ahmad, Shabana Bibi, et al. "Fabrication of Silver Nanoparticles from Ziziphus nummularia Fruit Extract: Effect on Hair Growth Rate and Activity against Selected Bacterial and Fungal Strains." Journal of Nanomaterials 2022 (June 25, 2022): 1–14. http://dx.doi.org/10.1155/2022/3164951.

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Nanoparticles are extensively used in biomedical and biotechnological research. Their large surface area, excellent physical properties, high permeability, and retention effect make them ideal for biomedical applications including diagnosis and treatment. Silver nanoparticles proved to be the safest for therapeutic uses. In the present study, silver nanoparticles (AgNPs) were prepared using various ratios of Ziziphus nummularia fruit extract and silver nitrate solution. The nanoparticles were investigated for hair growth and antibacterial and antifungal activities. Characterization of AgNPs was done by using UV-spectrophotometer, scanning electron microscope (SEM), X-ray diffractometer (XRD), thermogravimeter (TG), energy dispersive X-ray (EDX), Fourier transform infrared spectroscopy (FTIR), and master sizer. UV-spectrophotometer results showed the best ratio 10 : 10 of Z. nummularia fruit aqueous extract to silver solution for nanoparticle production at 400 to 430 nm wavelength. The size of AgNPs was 40 nm as measured by SEM. Characterization of AgNPs through EDX resulted in a silver peak at 3 keV. In contrast, differential scanning calorimetry (DSC) spectra show that the AgNPs are stable up to 160°C. The XED spectra gave 12 nm size of crystallite at 2 theta degree angle. FTIR bands for the metal oxides were recorded at 665 cm-1. Weight loss of the prepared nanoparticles was observed due to moisture loss when subjected to TGA, whereas particle size distribution 0.1 μm to 0.17 μm was recorded by the master seizer. The Z. nummularia fruit aqueous extract-mediated AgNPs were noted highly effective against Gram-positive bacteria compared to ethanolic, methanolic, chloroform, and ethyl acetate extracts of Z. nummularia fruit. The Gram-negative bacteria fungal species showed less sensitivity to AgNPs. The hair growth activity was observed to be higher for AgNPs followed by minoxidil than ethanolic and methanolic extracts of Z. nummularia fruit. These findings have concluded that Z. nummularia-AgNPs have an effective hair growth activity and exhibit several applications in distinctive biomedical and pharmaceutical industries.

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Ciptasari, Nurhayati Indah, Murni Handayani, Caesart Leonardo Kaharudin, Afif Akmal Afkauni, Adhi Dwi Hatmanto, Isa Anshori, Ahmad Maksum, Rini Riastuti, and Johny Wahyuadi Soedarsono. "Synthesis of nanocomposites reduced graphene oxide-silver nanoparticles prepared by hydrothermal technique using sodium borohydride as a reductor for photocatalytic degradation of Pb ions in aqueous solution." Eastern-European Journal of Enterprise Technologies 6, no. 5 (120) (December 30, 2022): 54–62. http://dx.doi.org/10.15587/1729-4061.2022.269844.

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Heavy metals are pollutants that are harmful to living things and the environment can be degraded by microbes or understood by other living things so that they can cause health problems. One of the heavy metals that is often found in wastewater is lead. Lead is widely used in the manufacture of batteries, metal products such as ammunition, cable coatings, Polyvinyl Chloride (PVC) tubing, solder, chemicals and dyes This use causes humans to be exposed to large amounts of lead. One method to deal with lead pollution is to use photocatalysts. Photocatalysts react with heavy metals and reduce them so that the level of toxicity becomes lower than before through photocatalytic reactions. In this study, synthesis of reduced graphene oxide/silver nanoparticle nanoparticles was performed by facile hydrothermal methods for photocatalytic degradation of Pb ion. The characterization results indicate that the synthesis has been successfully carried out. The successful result of rGO/AgNPs nanocomposites synthesis was proved by several techniques such as X-ray diffraction analysis, Raman, UV-Vis spectroscopy, Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray analysis (EDX). This indicates the presence of these groups in the graphene oxide and rGO/AgNPs samples, respectively. The resulting rGO/AgNPs nanocomposite has an absorbance peak at a wavelength of 267 nm. The diffraction peaks for nanocomposites rGO/AgNPs and their Miller indices were 38.08° (111), 44.16° (200), 64.44° (220), and 77.44° (311). The Raman spectra of rGO/AgNPs exhibits D bands at 1334,13 with intensity of 630,60 cm−1 and G band at 1594,61 with intensity of 477,29 cm−1. The ID/IG ratio rGO/AgNPs-NaBH4 is ~1,32. Furthermore, the photocatalytic activity test results showed that the rGO/AgNPs nanocomposite was able to reduce Pb2+ to Pb with a maximum exposure time of 1.5 hours

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Lite, Mihaela Cristina, Rodica Roxana Constantinescu, Elena Cornelia Tănăsescu, Andrei Kuncser, Cosmin Romanițan, Ioana Lăcătuşu, and Nicoleta Badea. "Design of Green Silver Nanoparticles Based on Primula officinalis Extract for Textile Preservation." Materials 15, no. 21 (November 1, 2022): 7695. http://dx.doi.org/10.3390/ma15217695.

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The present study aims to bring an addition to biomass resources valorization for environmental-friendly synthesis of nanoparticles. Thus, the green synthesis of silver nanoparticles (AgNPs) was performed, using a novel and effective reducing agent, Primula officinalis extract. The synthesis was optimized by monitoring the characteristic absorption bands, using UV–Vis spectroscopy, and by evaluating the size and physical stability. The phenolic consumption was established using Folin-Ciocâlteu method (1.40 ± 0.42 mg, representing ~5% from the total amount of poly--phenols) and the antioxidant activity was evaluated using chemiluminescence and TEAC methods. The optimum ratio extract to Ag ions was 1:3, for which the AgNPs presented a zeta potential value of −29.3 ± 1.2 mV and particles size of 5-30 nm. For characterization, EDS and XRD techniques were used, along with microscopy techniques (TEM). The AgNPs dispersions were applied on natural textile samples (cotton and wool), as a novel antimicrobial treatment for textile preservation. The treated fabrics were further characterized in terms of chromatic parameters and antimicrobial effect against Escherichia coli, Staphylococcus aureus, Bacillus subtilis, and Penicillium hirsutum strains. The high percentages of bacterial reduction, >99%, revealed that the AgNPs produced are a good candidate for textiles preservation against microbial degradation.

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Diniz, Flavia Resende, Romerito Cesar A. P. Maia, Lucas Rannier Andrade, Luciana Nalone Andrade, Marco Vinicius Chaud, Classius Ferreira da Silva, Cristiane Bani Corrêa, et al. "Silver Nanoparticles-Composing Alginate/Gelatine Hydrogel Improves Wound Healing In Vivo." Nanomaterials 10, no. 2 (February 23, 2020): 390. http://dx.doi.org/10.3390/nano10020390.

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Polymer hydrogels have been suggested as dressing materials for the treatment of cutaneous wounds and tissue revitalization. In this work, we report the development of a hydrogel composed of natural polymers (sodium alginate and gelatin) and silver nanoparticles (AgNPs) with recognized antimicrobial activity for healing cutaneous lesions. For the development of the hydrogel, different ratios of sodium alginate and gelatin have been tested, while different concentrations of AgNO3 precursor (1.0, 2.0, and 4.0 mM) were assayed for the production of AgNPs. The obtained AgNPs exhibited a characteristic peak between 430–450 nm in the ultraviolet-visible (UV–Vis) spectrum suggesting a spheroidal form, which was confirmed by Transmission Electron Microscopy (TEM). Fourier Transform Infra-red (FT–IR) analysis suggested the formation of strong intermolecular interactions as hydrogen bonds and electrostatic attractions between polymers, showing bands at 2920, 2852, 1500, and 1640 cm−1. Significant bactericidal activity was observed for the hydrogel, with a Minimum Inhibitory Concentration (MIC) of 0.50 µg/mL against Pseudomonas aeruginosa and 53.0 µg/mL against Staphylococcus aureus. AgNPs were shown to be non-cytotoxic against fibroblast cells. The in vivo studies in female Wister rats confirmed the capacity of the AgNP-loaded hydrogels to reduce the wound size compared to uncoated injuries promoting histological changes in the healing tissue over the time course of wound healing, as in earlier development and maturation of granulation tissue. The developed hydrogel with AgNPs has healing potential for clinical applications.

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Wypij, Magdalena, Tomasz Jędrzejewski, Maciej Ostrowski, Joanna Trzcińska, Mahendra Rai, and Patrycja Golińska. "Biogenic Silver Nanoparticles: Assessment of Their Cytotoxicity, Genotoxicity and Study of Capping Proteins." Molecules 25, no. 13 (July 2, 2020): 3022. http://dx.doi.org/10.3390/molecules25133022.

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The development of nanotechnology in the last two decades has led to the use of silver nanoparticles (AgNPs) in various biomedical applications, including antimicrobial, anti-inflammatory, and anticancer therapies. However, the potential of the medical application of AgNPs depends on the safety of their use. In this work, we assessed the in vitro cytotoxicity and genotoxicity of silver nanoparticles and identified biomolecules covering AgNPs synthesized from actinobacterial strain SH11. The cytotoxicity of AgNPs against MCF-7 human breast cancer cell line and murine macrophage cell line RAW 264.7 was studied by MTT assay, cell LDH (lactate dehydrogenase) release, and the measurement of ROS (reactive oxygen species) level while genotoxicity in Salmonella typhimurium cells was testing using the Ames test. The in vitro analysis showed that the tested nanoparticles demonstrated dose-dependent cytotoxicity against RAW 264.6 macrophages and MCF-7 breast cancer cells. Moreover, biosynthesized AgNPs did not show a mutagenic effect of S. typhimurium. The analyses and identification of biomolecules present on the surface of silver nanoparticles showed that they were associated with proteins. The SDS-PAGE (sodium dodecyl sulfate–polyacrylamide gel electrophoresis) analysis revealed the presence of 34 and 43 kDa protein bands. The identification of proteins performed by using LC-MS/MS (liquid chromatography with tandem mass spectrometry) demonstrated their highest homology to bacterial porins. Capping biomolecules of natural origin may be involved in the synthesis process of AgNPs or may be responsible for their stabilization. Moreover, the presence of natural proteins on the surface of bionanoparticles eliminates the postproduction steps of capping which is necessary for chemical synthesis to obtain the stable nanostructures required for application in medicine.

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Pal, Sudipto, Rossella Nisi, and Antonio Licciulli. "Antibacterial Activity of In Situ Generated Silver Nanoparticles in Hybrid Silica Films." Photochem 2, no. 3 (June 23, 2022): 479–88. http://dx.doi.org/10.3390/photochem2030033.

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Herein we present silver nanoparticles (AgNPs)-doped inorganic–organic hybrid silica films on glass and polypropylene substrates. A hybrid inorganic–organic silica sol in alcoholic medium was prepared at room temperature using TEOS, GLYMO, and APTES. Silver nanoparticles were generated in situ within the hybrid silica sol. AgNPs-SiO2 film was obtained by dip coating method following drying at 80 °C. FTIR spectra shows several vibrational bands of the hybrid silica network and amine functionalization. AgNPs formation was observed from the XRD spectra of the dried film. UV–Visible spectra show sharp surface plasmon resonance (SPR) band centered at 412 nm arising from the evenly distributed silver nanoparticle inside the silica film that was supported by morphological characterization. Both the coated films showed good antibacterial activity against E. coli bacterial strain by forming a zone of inhibition in the agar diffusion test. The antibacterial efficiency for coated glass and polypropylene was 72.5% and 83.75%. This coating approach provides a straight-forward solution to prepare antibacterial coatings on various substrates especially on plastics, where low temperature processing is necessary.

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Haider, Md Kaiser, Azeem Ullah, Muhammad Nauman Sarwar, Takumi Yamaguchi, Qianyu Wang, Sana Ullah, Soyoung Park, and Ick Soo Kim. "Fabricating Antibacterial and Antioxidant Electrospun Hydrophilic Polyacrylonitrile Nanofibers Loaded with AgNPs by Lignin-Induced In-Situ Method." Polymers 13, no. 5 (February 28, 2021): 748. http://dx.doi.org/10.3390/polym13050748.

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Concerning the environmental hazards owing to the chemical-based synthesis of silver nanoparticles (AgNPs), this study aimed to investigate the possibility of synthesizing AgNPs on the surface of polyacrylonitrile (PAN) nanofibers utilizing biomacromolecule lignin. SEM observations revealed that the average diameters of the produced nanofibers were slightly increased from ~512 nm to ~673 nm due to several factors like-swellings that happened during the salt treatment process, surface-bound lignin, and the presence of AgNPs. The presence of AgNPs was validated by transmission electron microscope (TEM) and X-ray photoelectron spectroscopy (XPS) analysis. The amount of synthesized AgNPs on PAN nanofibers was found to be dependent on both precursor silver salt and reductant lignin concentration. Fourier transform infrared-attenuated total reflectance (FTIR-ATR) spectra confirm the presence of lignin on PAN nanofibers. Although the X-ray diffraction pattern did not show any AgNPs band, the reduced intensity of the stabilized PAN characteristics bands at 2θ = 17.28° and 29.38° demonstrated some misalignment of PAN polymeric chains. The water contact angle (WCA) of hydrophobic PAN nanofibers was reduced from 112.6 ± 4.16° to 21.4 ± 5.03° for the maximum AgNPs coated specimen. The prepared membranes exhibited low thermal stability and good swelling capacity up to 20.1 ± 0.92 g/g and 18.05 ± 0.68 g/g in distilled water and 0.9 wt% NaCl solution, respectively. Coated lignin imparts antioxidant activity up to 78.37 ± 0.12% at 12 h of incubation. The resultant nanofibrous membranes showed a proportional increase in antibacterial efficacy with the rise in AgNPs loading against both Gram-positive S. aureus and Gram-negative E. coli bacterial strains by disc diffusion test (AATCC 147-1998). Halos for maximum AgNPs loading was calculated to 18.89 ± 0.15 mm for S. aureus and 21.38 ± 0.17 mm for E. coli. An initial burst release of silver elements within 24 h was observed in the inductively coupled plasma-atomic emission spectrometry (ICP-AES) test, and the release amounts were proportionally expansive with the increase in Ag contents. Our results demonstrated that such types of composite nanofibers have a strong potential to be used in biomedicine.

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Ahmad, Nisar, Fozia, Musarrat Jabeen, Zia Ul Haq, Ijaz Ahmad, Abdul Wahab, Zia Ul Islam, et al. "Green Fabrication of Silver Nanoparticles using Euphorbia serpens Kunth Aqueous Extract, Their Characterization, and Investigation of Its In Vitro Antioxidative, Antimicrobial, Insecticidal, and Cytotoxic Activities." BioMed Research International 2022 (January 10, 2022): 1–11. http://dx.doi.org/10.1155/2022/5562849.

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The silver nanoparticles (AgNPs) were synthesized via green synthesis approach using Euporbia serpens Kunth aqueous extract. The synthesized AgNPs were characterized by UV-visible spectroscopy and Furrier Transformer Infra-Red spectroscopy to justify the reduction and stabilization of AgNPs from its precursors. AgNPs characteristic absorption peak was observed at 420 nm in the UV-visible spectrum. The SEM and TEM analysis demonstrated the spherical shape of the synthesized nanoparticles with particle sizes ranging from 30 nm to 80 nm. FTIR transmission bands at 2920 cm-1, 1639 cm-1, 1410 cm-1, 3290 cm-1, and 1085 cm-1 were attributed to C-H, C=O, C-C, N-H, and C-N functional groups, respectively. XRD peaks could be attributed to (111), (200), (220), and (311) crystalline plane of the faced-centered cube (FCC) crystalline structure of the metallic silver nanoparticles. The AgNPs showed good antibacterial activity against all the tested bacteria at each concentration. The particles were found to be more active against Escherichia coli (E. coli) with 20 ± 06 mm and Salmonella typhi (S. typhi) with 18 ± 0.5 mm zone of inhibition in reference to standard antibiotic amoxicillin with 23 ± 0.3 mm and 20 ± 0.4 mm zone of inhibition, respectively. Moderate antifungal activities were observed against Candida albicans (C. albicans) and Alternaria alternata (A. alternata) with zone of inhibitions 16.5 mm and 15 mm, respectively, compared to the standard with 23 mm of inhibition. Insignificant antifungal inhibition of 7.5 mm was observed against Fusarium gramium (F. gramium). All the tested concentrations of AgNPs showed comparable % RSA with the standard reference ascorbic acid in the range sixty percent to seventy five percent. The percent motility at 3 hours postincubation showed quick response and most Tetramorium caespitum were found deceased or paralyzed. Similarly, the percent mortality showed a linear response at concentration and time. It was observed that 1 μg/mL to 2 μg/mL concentration of AgNPs displayed a significant cytotoxic activity against Artemia salina with LD50 of 5.37 and 5.82, respectively.

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Brezeștean, Ioana Andreea, Ana Maria Raluca Gherman, Alia Colniță, Nicoleta Elena Dina, Csilla Müller Molnár, Daniel Marconi, Vasile Chiș, Ioan-Leontin David, and Simona Cîntă-Pînzaru. "Detection and Characterization of Nodularin by Using Label-Free Surface-Enhanced Spectroscopic Techniques." International Journal of Molecular Sciences 23, no. 24 (December 12, 2022): 15741. http://dx.doi.org/10.3390/ijms232415741.

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Nodularin (NOD) is a potent toxin produced by Nodularia spumigena cyanobacteria. Usually, NOD co-exists with other microcystins in environmental waters, a class of cyanotoxins secreted by certain cyanobacteria species, which makes identification difficult in the case of mixed toxins. Herein we report a complete theoretical DFT-vibrational Raman characterization of NOD along with the experimental drop-coating deposition Raman (DCDR) technique. In addition, we used the vibrational characterization to probe SERS analysis of NOD using colloidal silver nanoparticles (AgNPs), commercial nanopatterned substrates with periodic inverted pyramids (KlariteTM substrate), hydrophobic Tienta® SpecTrimTM slides, and in-house fabricated periodic nanotrenches by nanoimprint lithography (NIL). The 532 nm excitation source provided more well-defined bands even at LOD levels, as well as the best performance in terms of SERS intensity. This was reflected by the results obtained with the KlariteTM substrate and the silver-based colloidal system, which were the most promising detection approaches, providing the lowest limits of detection. A detection limit of 8.4 × 10−8 M was achieved for NOD in solution by using AgNPs. Theoretical computation of the complex vibrational modes of NOD was used for the first time to unambiguously assign all the specific vibrational Raman bands.

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MECHCATIE, ELIZABETH. "FDA Panel Backs Shingles Vaccine for Ages 60 Plus." Skin & Allergy News 37, no. 2 (February 2006): 13. http://dx.doi.org/10.1016/s0037-6337(06)71015-4.

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Kyomuhimbo, Hilda Dinah, Immaculate Nyambura Michira, Emmanuel Iheanyichukwu Iwuoha, and Usisipho Feleni. "Electroconductive Polyaniline–Ag-ZnO Green Nanocomposite Material." Processes 10, no. 3 (February 24, 2022): 457. http://dx.doi.org/10.3390/pr10030457.

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Metal-conducting polyaniline (PANI)-based nanocomposite materials have attracted attention in various applications due to their synergism of electrical, mechanical, and optical properties of the initial components. Herein, metal-PANI nanocomposites, including silver nanoparticle-polyaniline (AgNP-PANI), zinc oxide nanoparticle-polyaniline (ZnONP-PANI), and silver-zinc oxide nanoparticle-polyaniline (Ag–ZnONP-PANI), were prepared using the two processes. Nanocomposite-based electrode platforms were prepared by depositing AgNPs, ZnONPs, or Ag–ZnONPs on a PANI modified glass carbon electrode (GCE) in the presence of 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide/N-Hydroxysuccinimide (EDC/NHS, 1:2) as coupling agents. The incorporation of AgNPs, ZnONPs, and Ag–ZnONPs onto PANI was confirmed by UV-Vis spectrophotometry, which showed five absorbance bands at 216 nm, 412 nm, 464 nm, 550 nm, and 831 nm (i.e., transition of π-π*, π-polaron band transition, polaron-π* electronic transition, and AgNPs). The FTIR characteristic signatures of the nanocomposite materials exhibited stretching arising from C–H aromatic, C–O, and C–N stretching mode for benzenoid rings, and =C–H plane bending vibration formed during protonation. The CV voltammograms of the nanocomposite materials showed a quasi-reversible behavior with increased redox current response. Notably, AgNP–PANI–GCE electrode showed the highest conductivity, which was attributed the high conductivity of silver. The increase in peak currents exhibited by the composites shows that AgNPs and ZnONPs improve the electrical properties of PANI, and they could be potential candidates for electrochemical applications.

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Fang, Hui, Fei-Peng Zhang, Zhi-Nian Jiang, Jin-Yun Peng, and Ru-Zhi Wang. "Strain-induced asymmetric modulation of band gap in narrow armchair-edge graphene nanoribbon." Modern Physics Letters B 29, no. 34 (December 20, 2015): 1550224. http://dx.doi.org/10.1142/s0217984915502243.

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We investigate the band structure of narrow armchair-edge graphene nanoribbons (AGNRs) under tensile strain by means of an extension of the Extended Hückel method. The strain-induced band gap modulation presents asymmetric behavior. The asymmetric modulation of band gap is derived from the different changes of conduction and valence bands near Fermi level under tensile strain. Further analysis suggests that the asymmetric variation of band structure near Fermi level only appear in narrow armchair-edge graphene nanoribbons.

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Moore, Michael E. Hoenicke. "Books, Banks, Buttons, and Other Inventions from the Middle Ages. Chiara Frugoni , William McCuaig." Speculum 80, no. 1 (January 2005): 225–26. http://dx.doi.org/10.1017/s0038713400006990.

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Devaraj, Preetha, Prachi Kumari, Chirom Aarti, and Arun Renganathan. "Synthesis and Characterization of Silver Nanoparticles Using Cannonball Leaves and Their Cytotoxic Activity against MCF-7 Cell Line." Journal of Nanotechnology 2013 (2013): 1–5. http://dx.doi.org/10.1155/2013/598328.

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Cannonball (Couroupita guianensis) is a tree belonging to the family Lecythidaceae. Various parts of the tree have been reported to contain oils, keto steroids, glycosides, couroupitine, indirubin, isatin, and phenolic substances. We report here the synthesis of silver nanoparticles (AgNPs) using cannonball leaves. Green synthesized nanoparticles have been characterized by UV-Vis spectroscopy, SEM, TEM, and FTIR. Cannonball leaf broth as a reducing agent converts silver ions to AgNPs in a rapid and ecofriendly manner. The UV-Vis spectra gave surface plasmon resonance peak at 434 nm. TEM image shows well-dispersed silver nanoparticles with an average particle size of 28.4 nm. FTIR showed the structure and respective bands of the synthesized nanoparticles and the stretch of bonds. Green synthesized silver nanoparticles by cannonball leaf extract show cytotoxicity to human breast cancer cell line (MCF-7). Overall, this environmentally friendly method of biological silver nanoparticles production provides rates of synthesis faster than or comparable to those of chemical methods and can potentially be used in various human contacting areas such as cosmetics, foods, and medical applications.

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Burratti, Luca, Eleonora Bolli, Mauro Casalboni, Fabio de Matteis, Federico Mochi, Roberto Francini, Stefano Casciardi, and Paolo Prosposito. "Synthesis of Fluorescent Ag Nanoclusters for Sensing and Imaging Applications." Materials Science Forum 941 (December 2018): 2243–48. http://dx.doi.org/10.4028/www.scientific.net/msf.941.2243.

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Metal nanoparticles have attracted more and more attention in the last years due to their unique chemical and physical properties which are very different from the metal bulk material. In particular, when the size of nanoparticles decreases below two nm, nanoparticles can be described as nanoclusters (NCs), and they present peculiar optical properties. The excited electrons in addition to specific absorption bands show also a bright luminescence related to the quantum size effect which produce discrete energy levels. Optical properties (absorption and fluorescence) of these NCs are widely used in many different applications in science and engineering, such as chemical sensors, fluorescent probes for bio imaging or in environmental issues. In the present study, we report on the synthesis of silver nanoclusters (AgNCs) in aqueous phase using silver nitrate as precursor salt and L-Glutathione (GSH) as stabilizer. AgNCs were characterized using absorption and fluorescence spectroscopy, and transmission electron microscopy (TEM). The strong absorption and luminescence shown by these NCs are very promising for a possible exploitation both as label for bioimaging and for optical sensors for heavy metal ions.

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Lindenthal, Sebastian, Nicolas Frederic Zorn, Simon Settele, and Jana Zaumseil. "Absorption and Emission of Chemically and Electrochemically Doped Graphene Nanoribbons." ECS Meeting Abstracts MA2022-01, no. 12 (July 7, 2022): 870. http://dx.doi.org/10.1149/ma2022-0112870mtgabs.

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Graphene nanoribbons (GNRs) are narrow stripes of graphene that exhibit unique optical and electronic properties depending on their width and edge type. Recent advances in the bottom-up synthesis of GNRs have enabled precise control over their structure and thus their bandgap. However, the systematic optical and electrical characterization of GNRs obtained from solution-mediated reactions has so far been prevented by the poor stability and processability of GNR dispersions. Here we employ liquid cascade centrifugation (LCC) to obtain size-selected and stable dispersions of bottom-up synthesized 9-aGNRs in toluene and tetrahydrofuran and investigate their intrinsic optical properties. Dispersions and films of these 9-aGNRs show well-defined absorption and photoluminescence bands between 800 and 1000 nm, with relative intensities depending on the LCC-fraction. The best GNR dispersions show photoluminescence quantum yields of up to 70 %. Trions are charged excitons with red-shifted emission that can be created in doped low-dimensional semiconductors, such as carbon nanotubes. Theoretical studies predict large trion binding energies (> 300 meV) in graphene nanoribbons (depending on their width). Hence their optical properties upon doping and possible new features are of interest. Chemical doping of our 9-aGNR dispersions with the strong molecular p-dopant F4-TCNQ and electrochemical doping of GNR thin films in ambipolar electrolyte-gated field-effect transistors results in the expected bleaching of the main absorption bands but also the emergence of new redshifted, charge-induced absorption peaks that may indicate the existence of trions in GNRs.

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Jiang, D. R., Xinwu Cao, and J. F. Zhou. "The VLBI core in Radio Loud AGNs." Symposium - International Astronomical Union 205 (2001): 148–49. http://dx.doi.org/10.1017/s0074180900220792.

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We present statistical results on VLBI cores from large VLBI samples at C, L and S/X bands. Most of the results are consistent with the inhomogeneous jet model. The magnetic field distribution and particle density in the inhomogeneous jet model were estimated. We also found that the flux densities and luminosities of the cores at 5 GHz were correlated with those at optical band in the rest-frame.

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Neacsu, Ionela Andreea, Sorina-Alexandra Leau, Stefania Marin, Alina Maria Holban, Bogdan-Stefan Vasile, Adrian-Ionut Nicoara, Vladimir Lucian Ene, Coralia Bleotu, Mădălina Georgiana Albu Kaya, and Anton Ficai. "Collagen-Carboxymethylcellulose Biocomposite Wound-Dressings with Antimicrobial Activity." Materials 14, no. 5 (March 1, 2021): 1153. http://dx.doi.org/10.3390/ma14051153.

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Microbial infections associated with skin diseases are frequently investigated since they impact on the progress of pathology and healing. The present work proposes the development of freeze-dried, glutaraldehyde cross-linked, and non-cross-linked biocomposite dressings with a porous structure, which may assist the reepithelization process through the presence of collagen and carboxymethylcellulose, along with a therapeutic antimicrobial effect, due to silver nanoparticles (AgNPs) addition. Phisyco-chemical characterization revealed the porous morphology of the obtained freeze-dried composites, the presence of high crystalline silver nanoparticles with truncated triangular and polyhedral morphologies, as well as the characteristic absorption bands of collagen, silver, and carboxymethylcellulose. In vitro tests also assessed the stability, functionality, and the degradability rate of the obtained wound-dressings. Antimicrobial assay performed on Gram-negative (Escherichia coli), Gram-positive (Staphyloccocus aureus) bacteria, and yeast (Candida albicans) models demonstrated that composite wound dressings based on collagen, carboxymethylcellulose, and AgNPs are suitable for skin lesions because they prevent the risk of infection and have prospective wound healing capacity. Moreover, the cell toxicity studies proved that the obtained materials can be used in long time treatments, with no cytotoxic effects.

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Stefanik, Kay C., and William J. Mitsch. "Structural and functional vegetation development in created and restored wetland mitigation banks of different ages." Ecological Engineering 39 (February 2012): 104–12. http://dx.doi.org/10.1016/j.ecoleng.2011.11.016.

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Churazov, E., M. Gilfanov, A. Finoguenov, R. Sunyaev, M. Chernyakova, Yu Apalkov, S. Grebenev, et al. "Review of GRANAT Observations of AGNs." Symposium - International Astronomical Union 159 (1994): 63–72. http://dx.doi.org/10.1017/s0074180900174856.

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Brief review of AGNs observations in the X-ray / soft gamma-ray bands with the orbital observatory GRANAT is presented.For three well known bright objects (3C273, NGC4151 and Cen A) broad band (3 keV–few hundreds keV) spectra have been obtained. Imaging capabilities allowed accurate (several arcminutes) identification of these objects with sources of hard X-rays.The spectrum of NGC4151 above ≈ 50 keV was found to be much steeper than that in most of the previous observations, while in standard X-ray band the spectrum agrees with observed previously. The comparison of the observed spectra with that of the X-Ray Background (XRB) indicates that sources similar to NGC4151 could reproduce the shape of XRB spectrum in 3–60 keV band.Cen A was observed in the very low state during most of observations in 1990–1993, except for two observations in 1991. The variability of the hard X-ray flux has been detected on the time scales of several days.

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Ghisellini, Gabriele, and Francesco Haardt. "Thermal Or Non–Thermal X–Rays From AGNs?" Symposium - International Astronomical Union 159 (1994): 33–36. http://dx.doi.org/10.1017/s0074180900174819.

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Recent data from OSSE on CGRO and SIGMA on GRANAT challenge the non-thermal interpretation of the origin of the high energy emission of AGNs, showing that the hard X-ray spectra of several Seyfert AGN are steep like those of Galactic black hole candidates. Thermal models are therefore favoured. Two–phase models, in which a hot corona is placed above a relatively cold accretion disk can account for the observed X–ray spectra and the correlated variability in the UV and X–ray bands. Cold matter, both in the vicinity of the nucleous, and located further away in the torus surrounding the nucleous, may modify substantially the spectrum with important consequences on the expected variability and spectral shape.

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Dike, MC, and LC Nwosu. "Variations in soil seed banks of abandoned farmlands of various ages in Umukabia Umuagbom, Abia State, Nigeria." International Journal of Biological and Chemical Sciences 7, no. 1 (July 9, 2013): 338. http://dx.doi.org/10.4314/ijbcs.v7i1.29.

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Bacic, Ivan Luiz Zilli, David G. Rossiter, and Christiaan Mathias Mannaerts. "Applicability of a distributed watershed pollution model in a data-poor environment in Santa Catarina State, Brazil." Revista Brasileira de Ciência do Solo 32, no. 4 (August 2008): 1699–712. http://dx.doi.org/10.1590/s0100-06832008000400035.

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Intensification of agricultural production without a sound management and regulations can lead to severe environmental problems, as in Western Santa Catarina State, Brazil, where intensive swine production has caused large accumulations of manure and consequently water pollution. Natural resource scientists are asked by decision-makers for advice on management and regulatory decisions. Distributed environmental models are useful tools, since they can be used to explore consequences of various management practices. However, in many areas of the world, quantitative data for model calibration and validation are lacking. The data-intensive distributed environmental model AgNPS was applied in a data-poor environment, the upper catchment (2,520 ha) of the Ariranhazinho River, near the city of Seara, in Santa Catarina State. Steps included data preparation, cell size selection, sensitivity analysis, model calibration and application to different management scenarios. The model was calibrated based on a best guess for model parameters and on a pragmatic sensitivity analysis. The parameters were adjusted to match model outputs (runoff volume, peak runoff rate and sediment concentration) closely with the sparse observed data. A modelling grid cell resolution of 150 m adduced appropriate and computer-fit results. The rainfall runoff response of the AgNPS model was calibrated using three separate rainfall ranges (< 25, 25-60, > 60 mm). Predicted sediment concentrations were consistently six to ten times higher than observed, probably due to sediment trapping along vegetated channel banks. Predicted N and P concentrations in stream water ranged from just below to well above regulatory norms. Expert knowledge of the area, in addition to experience reported in the literature, was able to compensate in part for limited calibration data. Several scenarios (actual, recommended and excessive manure applications, and point source pollution from swine operations) could be compared by the model, using a relative ranking rather than quantitative predictions.

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Yuan, Q., J. Wu, and K. Huang. "Luminosity Correlation of the X-ray Selected Radio-Loud AGNs." Symposium - International Astronomical Union 194 (1999): 306–10. http://dx.doi.org/10.1017/s0074180900162151.

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This paper presents a test of the luminosity correlation of the X-ray selected radio-loud Active Galactic Nuclei (AGNs), based on a large sample constructed by combining our cross-identification of southern sky sources with the radio-loud sources in the northern hemisphere given by Brinkmann et al. (1995). All sources were detected both by the ROSAT All-Sky Survey and the radio surveys at 4.85 GHz. The broad band energy distribution confirms the presence of strong correlations between luminosities in the radio, optical, and X-ray bands which differ for quasars, seyferts, BL Lacs, and radio galaxies. The tight correlations between spectral indices αox and monochromatic luminosities at 5500 Å and 4.85 GHz are also shown.

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Ueda, Yoshihiro, Masayuki Akiyama, Günther Hasinger, Takamitsu Miyaji, and Michael G. Watson. "Cosmological Evolution of X-ray Selected AGNs and Synthesis of the X-ray Background." Proceedings of the International Astronomical Union 9, S304 (October 2013): 125–31. http://dx.doi.org/10.1017/s1743921314003536.

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AbstractX-ray surveys provide us with one of the least biased samples of Active Galactic Nuclei (AGNs) against obscuration. Here we present the most up-to-date AGN X-ray luminosity function (XLF) and absorption function over the redshift range from 0 to 5, using the largest, highly complete sample ever available obtained from surveys of various depth, depth, and energy bands. We utilize a maximum likelihood method to reproduce the count-rate versus redshift distribution for each survey, by taking into account the evolution of the absorbed fraction, contribution from Compton-thick AGNs, and AGN broad band X-ray spectra including reflection components from tori based on the luminosity and redshift dependent unified scheme. We find that the shape of the XLF at z ~ 1–3 is significantly different from that in the local universe, for which the luminosity dependent density evolution (LDDE) model gives the best description. These results establish the standard population synthesis model of the X-Ray Background (XRB), which well reproduces the source counts in both soft and hard bands, the observed fractions of Compton-thick AGNs, and the spectrum of the XRB.

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Souter, David W., Ann M. Cameron, and R. Endean. "Implications of sublethal predation, autotomy and regeneration: pigment bands on their spines can not be used to determine the ages of adult specimens of the corallivore Acanthaster planci." Marine and Freshwater Research 48, no. 4 (1997): 321. http://dx.doi.org/10.1071/mf96060.

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Attempts to determine the ages of five adult specimens of Acanthaster planci from the pigment bands on the aboral spine ossicles were unsuccessful because there was little coincidence in the number and arrangement of the bands on different spines obtained from the same starfish. Hence, different spines often yielded markedly different putative ages. Spines along the midline of an arm usually possessed more bands than did those from the edge; the further from the central disc the location of an arm spine, the fewer bands it carried; and the numbers of bands on spines from the regenerating portions of arms were always significantly fewer than those on spines from intact portions of arms. Spines from intact portions of different arms from the same starfish yielded different putative ages, and the mean putative age of arm spines was greater than, similar to, or less than that of spines from the central disc. It was concluded that the putative age derived from the banding patterns on the aboral spines of a starfish bears no relationship to the actual age of the starfish but reflects its recent history of spine autotomy, sublethal predation and regeneration.

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De Souza, Michele Lemos, Samuel Valdivia, Juan Carlos Otero, and Isabel López-Tocón. "Sensing Bisphenol A by Means of Surface-Enhanced Raman Spectroscopy and DFT Calculations to Elucidate the Enhancement Mechanism That Dominates the Spectrum." Chemosensors 11, no. 2 (January 20, 2023): 78. http://dx.doi.org/10.3390/chemosensors11020078.

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Surface-Enhanced Raman Spectroscopy (SERS) was employed as a spectroscopic tool to detect Bisphenol A (BPA), a building block in polycarbonate and epoxy resins or an additive in other polymer plastics like PVC, which has an endocrine disruptor effect. Silver nanoparticles (AgNPs) synthesized by using different reducing agents such as hydroxylamine (Ag@HX), citrate (Ag@Cit), borohydride (Ag@BH), and β-cyclodextrin (Ag@βCD) were employed, aiming to select the best standard SERS substrate. The lowest limit of quantification was reached at a concentration of 0.01 mM (2.3 μg/mL) of a sonicated aqueous solution by using Ag@Cit NPs and identifying two enhanced bands recorded at about 350 and 460 cm−1. In order to gain insight into the nature of the enhanced bands, and therefore into which mechanism governs the SERS signal, electrochemical spectra recorded at different electrode potentials were acquired and TD-DFT calculations were applied to a neutral silver complex of BPA, Ag2-BPA, and to its monohydroxylated chemical specie, Ag2-BPA(OH), which is present in sonicated solution. The calculated electronic structure and the resonance Raman spectra point out that a surface plasmon-like resonance inside the silver cluster dominates the SERS spectrum corresponding to the physisorbed BPA(OH) species, a charge transfer enhancement mechanism or an intramolecular resonance transition localized in the phenolic framework was then discarded.

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Journal articles on the topic 'Agnes Banks'

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