Journal articles: 'Gold nanoparticles'

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Murei, A., K. Pillay, and A. Samie. "Syntheses, Characterization, and Antibacterial Evaluation of P. grandiflora Extracts Conjugated with Gold Nanoparticles." Journal of Nanotechnology 2021 (December 24, 2021): 1–10. http://dx.doi.org/10.1155/2021/8687627.

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Background. With the recent increase in antibiotic resistance to conventional antibiotics, gold nanoparticles, and medicinal plants, extracts present an interesting alternative. Objectives. This study aimed to synthesize, characterize, and evaluate Pyrenacantha grandiflora Baill extracts and gold nanoparticle conjugates against pathogenic bacteria. Methods. We synthesized gold nanoparticles by chemical and biological methods. The nanoparticles were characterized by the use of UV-visible spectrophotometry, followed by transmission electron microscopy (TEM) and energy-dispersive X-ray analysis (EDX). Gold nanoparticles were conjugated to plant extracts and analyzed with a Fourier-transform infrared spectroscope (FTIR). We determined the antimicrobial activity of the conjugates using well diffusion and the microdilution assays. Results. The UV–visible spectra of gold nanoparticles showed a synthesis peak at 530 nm. FTIR analysis indicated functional biomolecules that were associated with plant extract conjugated gold nanoparticles; the formation of C–H group and carbonyl (C=O) groups, –OH carbonyl, and C≡C groups were also observed. Biologically synthesized nanoparticles were star-shaped when observed by TEM with an average size of 11 nm. Gold nanoparticles synthesized with P. grandiflora water extracts showed the largest zone of inhibition (22 mm). When the gold nanoparticles synthesized by the biological method were conjugated with acetone extracts of P. grandiflora, MIC as low as 0.0063 mg/mL was observed against beta-lactamase producing K. pneumonia. The activity of acetone extracts was improved with chemically synthesized gold nanoparticles particularly when beta-lactamase producing E. coli and MRSA were used as test organisms. A synergistic effect was observed against all tested bacteria, except for MRSA when gold nanoparticles were conjugated with acetone extract. Conclusion. Overall, P. grandiflora tuber extracts conjugated with gold nanoparticles showed a very good antibacterial activity that improved both plant extract and gold nanoparticle’s individual activity.

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Mat Isa, Siti Zaleha, Rafidah Zainon, and Mahbubunnabi Tamal. "State of the Art in Gold Nanoparticle Synthesisation via Pulsed Laser Ablation in Liquid and Its Characterisation for Molecular Imaging: A Review." Materials 15, no. 3 (January 24, 2022): 875. http://dx.doi.org/10.3390/ma15030875.

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With recent advances in nanotechnology, various nanomaterials have been used as drug carriers in molecular imaging for the treatment of cancer. The unique physiochemical properties and biocompatibility of gold nanoparticles have developed a breakthrough in molecular imaging, which allows exploration of gold nanoparticles in drug delivery for diagnostic purpose. The conventional gold nanoparticles synthetisation methods have limitations with chemical contaminations during the synthesisation process and the use of higher energy. Thus, various innovative approaches in gold nanoparticles synthetisation are under development. Recently, studies have been focused on the development of eco-friendly, non-toxic, cost-effective and simple gold nanoparticle synthesisation. The pulsed laser ablation in liquid (PLAL) technique is a versatile synthetic and convincing technique due to its high efficiency, eco-friendly and facile method to produce gold nanoparticle. Therefore, this study aimed to review the eco-friendly gold nanoparticle synthesisation method via the PLAL method and to characterise the gold nanoparticles properties for molecular imaging. This review paper provides new insight to understand the PLAL technique in producing gold nanoparticles and the PLAL parameters that affect gold nanoparticle properties to meet the desired needs in molecular imaging.

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RAJASULOCHANA, P., R. DHAMOTHARAN, P. MURUGAKOOTHAN, S. MURUGESAN, and P. KRISHNAMOORTHY. "BIOSYNTHESIS AND CHARACTERIZATION OF GOLD NANOPARTICLES USING THE ALGA Kappaphycus alvarezii." International Journal of Nanoscience 09, no. 05 (October 2010): 511–16. http://dx.doi.org/10.1142/s0219581x10007149.

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As a part of our ongoing investigation into the use of algae for gold nanoparticle synthesis, we screened the marine alga Kappaphycus alvarezii, to investigate its efficiency to reduce gold ions as well as the formation of gold nanoparticles. In the present work, we report the reaction condition of the alga K. alvarezii with aqueous gold ions for gold nanoparticle synthesis within the biomass extracellularly. The formation of gold nanoparticles was characterized by UV–Vis spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD) method. Moreover, we have found that the reaction of gold ions with the K. alvarezii biomass under stationary conditions results in the rapid extracellular formation of gold nanoparticles of spherical morphology. The gold nanoparticles are not toxic to the cells that continued to grow after the biosynthesis of the gold nanoparticles.

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Yuan, Juan, Qing Quan Guo, Xiang Zhu He, and Yan Ping Liu. "Researching on the Adsorption of Protein on Gold Nanoparticles." Advanced Materials Research 194-196 (February 2011): 462–66. http://dx.doi.org/10.4028/www.scientific.net/amr.194-196.462.

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Because of their unique properties, gold nanoparticles(NPs) show a wide range of applications such as surface-enhanced raman characteristics, biological sensing, biomedical and other fields. Different initial concentrations of Bull Serum Albumin(BSA) and egg white lysozyme respectively react with different size of gold nanoparticles. The condition of adsorption is determined by spectrometry method, then the area of protein with different molecular mass on the surface of a gold nanoparticle is calculated. The results show that the larger particle size of a gold nanoparticle is, the more protein the surface a gold nanoparticle adsorbs; the smaller the molecular mass of protein is, the more protein is adsorbed by gold nanoparticles surface.

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Yuan, Qunying, Manjula Bomma, and Zhigang Xiao. "Enhanced Extracellular Synthesis of Gold Nanoparticles by Soluble Extracts from Escherichia coli Transformed with Rhizobium tropici Phytochelatin Synthase Gene." Metals 11, no. 3 (March 12, 2021): 472. http://dx.doi.org/10.3390/met11030472.

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Phytochelatins, the enzymatic products of phytochelatin synthase, play a principal role in protecting the plants from heavy metal and metalloid toxicity due to their ability to scavenge metal ions. In the present study, we investigated the capacity of soluble intracellular extracts from E. coli cells expressing R. tropici phytochelatin synthase to synthesize gold nanoparticle. We discovered that the reaction mediated by soluble extracts from the recombinant E. coli cells had a higher yield of gold nanoparticles, compared to that from the control cells. The compositional and morphological properties of the gold nanoparticles synthesized by the intracellular extracts from recombinant cells and control cells were similar. In addition, this extracellular nanoparticle synthesis method produced purer gold nanoparticles, avoiding the isolation of nanoparticles from cellular debris when whole cells are used to synthesize nanoparticles. Our results suggested that phytochelatins can improve the efficiency of gold nanoparticle synthesis mediated by bacterial soluble intracellular extracts, and the potential of extracellular nanoparticle synthesis platform for the production of nanoparticles in large quantity and pure form is worth further investigation.

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Compostella, Federica, Olimpia Pitirollo, Alessandro Silvestri, and Laura Polito. "Glyco-gold nanoparticles: synthesis and applications." Beilstein Journal of Organic Chemistry 13 (May 24, 2017): 1008–21. http://dx.doi.org/10.3762/bjoc.13.100.

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Glyco-gold nanoparticles combine in a single entity the peculiar properties of gold nanoparticles with the biological activity of carbohydrates. The result is an exciting nanosystem, able to mimic the natural multivalent presentation of saccharide moieties and to exploit the peculiar optical properties of the metallic core. In this review, we present recent advances on glyco-gold nanoparticle applications in different biological fields, highlighting the key parameters which inspire the glyco nanoparticle design.

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Devi, S., B. Singh, A. K. Paul, and S. Tyagi. "Highly sensitive and selective detection of trinitrotoluene using cysteine-capped gold nanoparticles." Analytical Methods 8, no. 22 (2016): 4398–405. http://dx.doi.org/10.1039/c6ay01036a.

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(A) A schematic representation of the formation of cysteine capped gold nanoparticles and their interaction at pH 5 and 9.3. (B) A schematic representation of the formation of a Meisenheimer complex between cysteine modified gold nanoparticles and TNT, and possible cross-linking between gold nanoparticles bound to the Meisenheimer complex with gold nanoparticle bound cysteine.

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Tsalsabila, A., Y. Herbani, and Y. W. Sari. "Study of Lysine and Asparagine as Capping Agent for Gold Nanoparticles." Journal of Physics: Conference Series 2243, no. 1 (June 1, 2022): 012102. http://dx.doi.org/10.1088/1742-6596/2243/1/012102.

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Abstract The wide application of gold nanoparticles has attracted much attention to the development of research in gold nanoparticles. In this study, the gold nanoparticles were prepared by chemical reduction method using potassium tetrachloroaurate as the gold source and sodium borohydride as reducer agent. The formation of gold nanoparticles was confirmed by surface plasmon spectra in ultraviolet-visible spectroscopy at wavelength 507 nm. The capping process of gold nanoparticles was studied using two different charges of amino acids. The asparagine had used as uncharge amino acid and lysine as a positive charge amino acid. The redshift in surface plasmon spectra showed the aggregation of the gold nanoparticles after being capped with amino acids that indicates the surface modification. The amine and carboxylate group was present on the gold nanoparticle surface after being capped with amino acids. The zeta potential results indicate the lysine capped gold nanoparticles have slightly higher stability than the asparagine capped gold nanoparticles. These stability and surface modification of gold nanoparticles are expected to increase their utilization on biological and medical applications.

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Huang, Jian-Yuan, Min-Hua Chen, and Feng-Huei Lin. "The Synthesis and Characterization of PEG-SH-Modified Gold Nanoparticle in One-Pot Synthesis by Stenotrophomonas maltophilia." Journal of Nanoscience and Nanotechnology 19, no. 11 (November 1, 2019): 7278–84. http://dx.doi.org/10.1166/jnn.2019.16625.

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Colloidal gold nanoparticles have been researched and utilized in many technical applications. However, the conventionalmethods to produce polyethyleneglycol (PEG) immobilized gold nanoparticles have to take several steps, including residual solvent removing. In the study, we propose an idea green route to synthesize gold nanoparticles by using Stenotrophomonas maltophilia in a one-pot reaction. The relationship between Au precursor and S. maltophilia was evaluated systematically. After PEG-SH addition, the bacterial cell wall was broken down and the synthetic nanoparticles could be released into culture medium. Furthermore, we identified that the crystal structure of synthetic gold nanoparticle was face-center cubic and PEG-SH was immobilized on synthetic gold nanoparticle ideally. The size of Au-PEG-SH was smaller than 30 nm. These findings suggest that gold nanoparticle with PEG-SH modification could be prepared in an eco-friendly one-pot reaction through the metabolic activity of S. maltophilia.

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& MAHMOOD, HAMID. "THE SYNERGISTIC EFFECT OF GOLD NANOPARTICLE LOADED WITH CEFTAZIDIUM ANTIBIOTIC AGAINST MULTIDRUG ERSISTANCE PSEUDOMONAS AERUGINOSA." IRAQI JOURNAL OF AGRICULTURAL SCIENCES 52, no. 4 (August 22, 2021): 828–35. http://dx.doi.org/10.36103/ijas.v52i4.1391.

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This study was aimed to evaluate the antimicrobial activity of gold nanoparticles that was synthesized by biological method using Aloe Vera extract. The Surface morphology of the synthesized gold nanoparticles was confirmed by Atomic force microscope (AFM) while the nature of functional groups present in gold nanoparticles was determined by FT-IR analysis. The antibacterial activity of gold nanoparticle was tested against multidrug resistance (MDR)pseudomonas aeruginosa, the results showed a significant effect against MDR isolates. Gold nanoparticle was loaded with ceftazidium antibiotic in order to improve the antibacterial activity and drug delivery efficiency. The synergistic effects of biosynthesize gold loaded with ceftazidium antibiotic at different concentration against MDR bacteria were also investigated. The result showed that ceftazidium-loaded nanoparticles have superior effectiveness compared to native ceftazidium against pseudomonas aeruginosa.

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Manzila, Ifa, Tri Puji Priyatno, and Fikri Hidayatullah. "Konjugat Poliklonal Antibodi Nanopartikel Emas untuk Deteksi Potato Virus Y." Jurnal Fitopatologi Indonesia 16, no. 2 (December 2, 2020): 87–93. http://dx.doi.org/10.14692/jfi.16.2.87-93.

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Polyclonal Antibodi-Gold Nanoparticles for Potato Virus Y Detection Gold nanoparticles are stable colloidal solutions with dimensions of 1-100 nm having surface plasmon resonance with six free electrons. The existing of six free electrons on the surface of a plasmon causes gold nanoparticles to bind easily to various types of bioreseptors including polyclonal antibodies. Polyclonal potato virus Y (PVP) antibodi been successfully conjugate with gold nanoparticles in order to develop a rapid detection for PVY infection in potato plants. The gold nanoparticles was synthetized by the reduction of gold (III) chloride trihydrate (HAuCl4) with 1% sodium citrate. Subsequently, the nanoparticles were used to make gold nanoparticle-antiobody PVY-conjugate. PVY detection was carried out with dot blot method on the nitrocellulose membrane. The results showed that the PVY virus on the membrane can be detected 10-30 minutes after incubation, depend on the concentration of the conjugate and the concentration of the virus in the sampel. The use of gold nanoparticle conjugates can increase the efficiency of the immunodot blot method in about 1 hour, and this method can be developed to be a lateral flow system for field detection of PVY.

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Clarke, Christian, Deming Liu, Fan Wang, Yongtao Liu, Chaohao Chen, Cuong Ton-That, Xiaoxue Xu, and Dayong Jin. "Large-scale dewetting assembly of gold nanoparticles for plasmonic enhanced upconversion nanoparticles." Nanoscale 10, no. 14 (2018): 6270–76. http://dx.doi.org/10.1039/c7nr08979a.

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13

Jauregui-Gomez, Daniel, Oscar M. Bermejo-Gallardo, Edgar D. Moreno-Medrano, M. Guadalupe Perez-Garcia, Israel Ceja, Victor Soto, Francisco Carvajal-Ramos, and Alberto Gutierrez-Becerra. "Freeze-drying storage method based on pectin for gold nanoparticles." Nanomaterials and Nanotechnology 7 (January 1, 2017): 184798041769732. http://dx.doi.org/10.1177/1847980417697328.

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A cheap, reproducible, environmentally friendly, and biocompatible method for stabilizing and storing gold nanoparticles for prolonged time is presented. Adding a diluted pectin solution immediately after the synthesis of gold nanoparticles increases the stability of the aqueous nanoparticle dispersion, avoiding agglomeration and further precipitation, regardless of the initial size and shape of the nanoparticles. When the gold nanoparticles–pectin solution is freeze-dried, a sponge-like solid is obtained, improving significantly the pectin capacity to stabilize gold nanoparticles. Because the gold nanoparticles are immobilized into the freeze-dried pectin matrix, the size, size distribution, and shape remain unchanged, regardless of how long the solid is stored. The solid can be redispersed in water to obtain a solution that is able to maintain the stability of the gold nanoparticles, even for more than 20 weeks. This solution can be freeze-dried again, with no changes in the gold nanoparticles size. The proposed method is an alternative for stabilizing nanoparticles with no toxic agents, increasing significantly the storage time.

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Zhang, Liangmin. "Optical Conduction Resonance in Self-Assembled Metal Nanoparticle Array-Dielectric Thin Films." Journal of Nanomaterials 2018 (December 10, 2018): 1–9. http://dx.doi.org/10.1155/2018/8540805.

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Optical conduction resonance- (OCR-) enhanced third-order optical nonlinearity of two dimensional (2D) periodic gold nanoparticle array-dielectric thin films has been investigated. The third-order optical susceptibility of periodic gold nanoparticle array embedded in silica thin film shows ~104 enhancement comparing to gold nanoparticle colloids. The 2D gold nanoparticle arrays were synthesized by using the electrostatic self-assembly (ESA) technique. During the fabrication process, the positively or negatively functionalized gold nanoparticles are automatically self-aligned to establish a 2D array with a very small interparticle spacing due to the polymer shell on the metal particles. Then, a monolayer of silica can be coated on the top of the 2D metal nanoparticle array. This type of 2D gold nanoparticle array-dielectric thin films has high volume fraction of gold nanoparticles. According to the extended Maxwell-Garnett theory, this kind of films can exhibit OCR. The OCR frequency can be tuned from visible to mid-infrared by controlling the gold nanoparticle volume fraction. During OCR, the real part of the composite dielectric constant is zero to make the induced electromagnetic waves in gold nanoparticles to couple effectively within the film. The open-aperture z-scan technique is used to measure the nonlinear optical properties of the ESA films.

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Ibrayev, N. Kh. "TRANSIENT ABSORPTION OF GOLD NANOPARTICLES OF VARIOUS DIAMETERS." Eurasian Physical Technical Journal 19, no. 4 (December 26, 2022): 73–77. http://dx.doi.org/10.31489/2022no4/73-77.

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excitation by nanosecond laser pulses has been studied. It was shown that the maximum of stationary absorption exhibits as a wide structureless band with a maximum at about 520–540 nm. The transient absorption band of gold nanoparticles with a maximum at about 430 nm has a fine structure with a frequency of maxima of 6–8 nm and it does not depend on the size of the nanoparticles. The absorption duration decreases with a decrease in the average size of nanoparticles. The lifetime of transient absorption is equal to 23±2 and 19.5±2 ns for large and small particles, respectively. The nanosecond lifetime of the transient absorption of Au nanoparticles is the result of a prolonged relaxation process in the “interface of Au nanoparticle–solvent molecule” system as a manifestation of hindered heat exchange with the environment.

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Poonthiyil, Vivek, Thisbe K. Lindhorst, Vladimir B. Golovko, and Antony J. Fairbanks. "Recent applications of click chemistry for the functionalization of gold nanoparticles and their conversion to glyco-gold nanoparticles." Beilstein Journal of Organic Chemistry 14 (January 3, 2018): 11–24. http://dx.doi.org/10.3762/bjoc.14.2.

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Glycoscience, despite its myriad of challenges, promises to unravel the causes of, potential new detection methods for, and novel therapeutic strategies against, many disease states. In the last two decades, glyco-gold nanoparticles have emerged as one of several potential new tools for glycoscientists. Glyco-gold nanoparticles consist of the unique structural combination of a gold nanoparticle core and an outer-shell comprising multivalent presentation of carbohydrates. The combination of the distinctive physicochemical properties of the gold core and the biological function/activity of the carbohydrates makes glyco-gold nanoparticles a valuable tool in glycoscience. In this review we present recent advances made in the use of one type of click chemistry, namely the azide–alkyne Huisgen cycloaddition, for the functionalization of gold nanoparticles and their conversion to glyco-gold nanoparticles.

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Wu, Nianqiang. "(Invited) Distinguishing Roles of Gold Nanoparticles in Photocatalysis." ECS Meeting Abstracts MA2018-01, no. 31 (April 13, 2018): 1859. http://dx.doi.org/10.1149/ma2018-01/31/1859.

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The addition of gold nanoparticles into the semiconductors has significant effect of on the photocatalysis of the semiconductors. Gold nanoparticles can passivate the semiconductor surface, change the charge dynamics via the Fermi level equilibration, serve as the plasmonic photosensitizers and acts the surface co-catalyst. The gold nanoparticle could play more than two roles simultaneously. This presentation will discuss how to separate each role of the gold nanoparticles.

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Dozie-Nwachukwu, S. O., J. D. Obayemi, Y. Danyo, G. Etuk-Udo, N. Anuku, O. S. Odusanya, Karen Malatesta, C. Chi, and W. O. Soboyejo. "Biosynthesis of Gold Nanoparticles with Serratia marcescens Bacteria." Advanced Materials Research 1132 (December 2015): 19–35. http://dx.doi.org/10.4028/www.scientific.net/amr.1132.19.

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This paper presents the biosynthesis of gold nanoparticles from the bacteria, Serratia marcescens.The intra-and extra-cellular synthesis of gold nanoparticles is shown to occur over a range of pH and incubation times in cell-free exracts and biomass ofserratia marcescensthat were reacted with 2.5mM Tetrachloroauric acid (HAuCl4). The formation of gold nanoparticles was identified initially via color changes from yellow auro-chloride to shades of red or purple in gold nanoparticle solutions. UV-Visible spectroscopy (UV-Vis), Transmission Electron Microscopy (TEM) and Energy Dispersive X-ray spectroscopy (EDS), Helium Ion Microscopy (HIM) and Dynamic Light Scattering (DLS) were also used to characterize gold nanoparticles produced within a range of pH conditions. The results show clearly that the production of gold nanoparticles from cell-free extracts require shorter times than the production of gold nanoparticles from the biomass.

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Bozich, Jared S., Samuel E. Lohse, Marco D. Torelli, Catherine J. Murphy, Robert J. Hamers, and Rebecca D. Klaper. "Surface chemistry, charge and ligand type impact the toxicity of gold nanoparticles to Daphnia magna." Environ. Sci.: Nano 1, no. 3 (2014): 260–70. http://dx.doi.org/10.1039/c4en00006d.

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Abad, José M., Sara Puertas, Daniel Pérez, and Christian Sánchez-Espinel. "Design and Development of Antibody Functionalized Gold Nanoparticles for Biomedical Applications." Journal of Nanoscience and Nanotechnology 21, no. 5 (May 1, 2021): 2834–40. http://dx.doi.org/10.1166/jnn.2021.19057.

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Antibody-functionalized gold nanoparticle constitutes a powerful interface biosystem for biomedical applications where the properties of gold nanoparticles and the specificity of antibody–antigen interactions are combined. This study provides insight into the key factors for the development of antibody functionalized gold nanoparticles focusing on the immobilization of the antibody. Here, we address an oriented antibody immobilization procedure on gold nanoparticles. It comprises chelatemodified gold nanoparticles that are designed for oriented immobilization of IgG antibodies (end on spatial orientation) through the metal-chelation to histidine-rich metal binding site in the heavy chain (Fc) of the antibody.

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Motamedi, Hossein, Samaneh Khademi Mazdeh, Azim Akbarzadeh Khiavi, and Mohammad Reza Mehrabi. "Optimization of Gold Nanoparticle Biosynthesis by Escherichia coli DH5α and its Conjugation with Gentamicin." Journal of Nano Research 32 (May 2015): 93–105. http://dx.doi.org/10.4028/www.scientific.net/jnanor.32.93.

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Metal nanoparticles are one option for targeted drug delivery. In order to increase antibiotic efficiency and decrease its side effects, antibiotic conjugated nanoparticles have been known as a suitable approach. The aim of this study was optimization of gold nanoparticle biosynthesis byEscherichia coliDH5α and its conjugation with gentamicin. For this purpose gold nanoparticles were biosynthesized from HAuCl4and confirmed by Uv/ Vis, XRD, DLS and SEM. Then the effects of different parameters on optimum conditions for gold nanoparticles production were investigated. The MIC and MBC of gentamicin and its conjugate were investigated againstE. coli,Clostridium perfringensandClostridium botulinum. The results revealed that among different treatments, centrifuge (10000 rpm, 10 min) and sonication are the optimum conditions for gold nanoparticle production with less than 10 nm sizes. Filtration was also the best method for purifying nanoparticles. The conjugated nanoparticles significantly reduced the MIC of gentamicin againstE. coliand also overcame the natural resistance of tested anaerobic bacteria. In conclusion, the optimized method is an effective, inexpensive and environmental friendly method for biosynthesis of gold nanoparticles. Overcoming natural resistance of anaerobic bacteria using antibiotic conjugates with nanoparticles provides hopes for further experiments and in vivo studies.

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Burkitt, Sean, Mana Mehraein, Ramunas K. Stanciauskas, Jos Campbell, Scott Fraser, and Cristina Zavaleta. "Label-Free Visualization and Tracking of Gold Nanoparticles in Vasculature Using Multiphoton Luminescence." Nanomaterials 10, no. 11 (November 12, 2020): 2239. http://dx.doi.org/10.3390/nano10112239.

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Gold nanoparticles continue to generate interest for use in several biomedical applications. Recently, researchers have been focusing on exploiting their dual diagnostic/therapeutic theranostic capabilities. Before clinical translation can occur, regulatory agencies will require a greater understanding of their biodistribution and safety profiles post administration. Previously, the real-time identification and tracking of gold nanoparticles in free-flowing vasculature had not been possible without extrinsic labels such as fluorophores. Here, we present a label-free imaging approach to examine gold nanoparticle (AuNP) activity within the vasculature by utilizing multiphoton intravital microscopy. This method employs a commercially available multiphoton microscopy system to visualize the intrinsic luminescent signal produced by a multiphoton absorption-induced luminescence effect observed in single gold nanoparticles at frame rates necessary for capturing real-time blood flow. This is the first demonstration of visualizing unlabeled gold nanoparticles in an unperturbed vascular environment with frame rates fast enough to achieve particle tracking. Nanoparticle blood concentration curves were also evaluated by the tracking of gold nanoparticle flow in vasculature and verified against known pre-injection concentrations. Half-lives of these gold nanoparticle injections ranged between 67 and 140 s. This label-free imaging approach could provide important structural and functional information in real time to aid in the development and effective analysis of new metallic nanoparticles for various clinical applications in an unperturbed environment, while providing further insight into their complex uptake and clearance pathways.

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Yao, Cuiping, Luwei Zhang, Jing Wang, Yulu He, Jing Xin, Sijia Wang, Hao Xu, and Zhenxi Zhang. "Gold Nanoparticle Mediated Phototherapy for Cancer." Journal of Nanomaterials 2016 (2016): 1–29. http://dx.doi.org/10.1155/2016/5497136.

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Gold nanoparticles exhibit very unique physiochemical and optical properties, which now are extensively studied in range of medical diagnostic and therapeutic applications. In particular, gold nanoparticles show promise in the advancement of cancer treatments. This review will provide insights into the four different cancer treatments such as photothermal therapy, gold nanoparticle-aided photodynamic therapy, gold nanoparticle-aided radiation therapy, and their use as drug carrier. We also discuss the mechanism of every method and the adverse effects and its limitations.

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Romanovskaia, Elena, Peter Slovenský, S. Marzieh Kalantarian, Lila Laundry-Mottiar, Valentin Romanovski, Maroš Halama, Michael Auinger, and Yolanda S. Hedberg. "Electrochemical Estimations of the Gold Nanoparticle Size Effect on Cysteine-Gold Oxidation." Journal of The Electrochemical Society 169, no. 2 (February 1, 2022): 021501. http://dx.doi.org/10.1149/1945-7111/ac4bf8.

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Gold nanoparticles are interesting for nanobiomedical applications, such as for drug delivery and as diagnostic imaging contrast agents. However, their stability and reactivity in-vivo are influenced by their surface properties and size. Here, we investigate the electrochemical oxidation of differently sized citrate-coated gold nanoparticles in the presence and absence of L-cysteine, a thiol-containing amino acid with high binding affinity to gold. We found that smaller sized (5, 10 nm) gold nanoparticles were significantly more susceptible to electrochemical L-cysteine interactions and/or L-cysteine-facilitated gold oxidation than larger (20, 50 nm) sized gold nanoparticles, both for the same mass and nominal surface area, under the conditions investigated (pH 7.4, room temperature, stagnant solutions, and scan rates of 0.5 to 450 mV s−1). The electrochemical measurements of drop-casted gold nanoparticle suspensions on paraffin-impregnated graphite electrodes were susceptible to the quality of the electrode. Increased cycling resulted in irreversible oxidation and detachment/oxidation of gold into solution. Our results suggest that L-cysteine-gold interactions are stronger for smaller nanoparticles.

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Maghoul, Amir, Ali Rostami, Samiyeh Matloub, and Amin Pourrezaei. "Design Considerations Influencing Optical Response in Gold Spherical Nanoparticles." Journal of Nano Research 46 (March 2017): 1–11. http://dx.doi.org/10.4028/www.scientific.net/jnanor.46.1.

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In this article, the relations between extinction cross section and Gold nanoparticle's parameters such as dimensions have been investigated. In this work, the extinction cross section of the core-shell nanoparticles is analyzed by changing the shell material and its thickness. By this, the interesting results such as shifting resonant peak in optical response are obtained. Moreover, a new model of nanostructure is proposed in which the resonant peak of extinction cross section can be controlled by adding silicon nanoparticles and impurity in the shell. This method can be used for tuning of the scattering properties of the core-shell nanoparticle. In the following, we demonstrate that the effective epsilon properties can be used for tuning of the desired optical response in the combinational structure of the spherical nanoparticles. At the end, the effective relative epsilon is also calculated for the selected structures. The operational frequency band is selected from 300 (THz) to 900 (THz).

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António, Maria, Tânia Lima, Rui Vitorino, and Ana L. Daniel-da-Silva. "Interaction of Colloidal Gold Nanoparticles with Urine and Saliva Biofluids: An Exploratory Study." Nanomaterials 12, no. 24 (December 13, 2022): 4434. http://dx.doi.org/10.3390/nano12244434.

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The use of gold nanoparticles for drug delivery, photothermal or photodynamic therapy, and biosensing enhances the demand for knowledge about the protein corona formed on the surface of nanoparticles. In this study, gold nanospheres (AuNSs), gold nanorods (AuNRs), and gold nanoflowers (AuNFs) were incubated with saliva or urine. After the interaction, the surface of gold nanoparticles was investigated using UV-VIS spectroscopy, zeta potential, and dynamic light scattering. The shifting of the localized surface plasmon resonance (LSPR) band, the increase in hydrodynamic diameter, and the changes in the surface charge of nanoparticles indicated the presence of biomolecules on the surface of AuNSs, AuNRs, and AuNFs. The incubation of AuNFs with saliva led to nanoparticle aggregation and minimal protein adsorption. AuNSs and AuNRs incubated in saliva were analyzed through liquid chromatography with tandem mass spectrometry (LC-MS/MS) to identify the 96 proteins adsorbed on the surface of the gold nanoparticles. Among the 20 most abundant proteins identified, 14 proteins were common in both AuNSs and AuNRs. We hypothesize that the adsorption of these proteins was due to their high sulfur content, allowing for their interaction with gold nanoparticles via the Au-S bond. The presence of distinct proteins on the surface of AuNSs or AuNRs was also investigated and possibly related to the competition between proteins present on the external layers of corona and gold nanoparticle morphology.

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Paul, Saurav, Bimal B. Chakraborty, Kuheli Deb, and Sudip Choudhury. "FUSED RING HETEROCYCLE FUNCTIONALIZED GOLD NANOPARTICLES: SYNTHESIS AND SELF-ASSEMBLY." Chemical Problems 21, no. 2 (2023): 188–96. http://dx.doi.org/10.32737/2221-8688-2023-2-188-196.

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Self-assembled nanoparticles are an area of great research prospect as they offer switchable element for designing and creating micro-scale constructs. Self-assembly of nano-hybrids through some noncovalent interactions such as electrostatic, π-π and van der Waal interactions in different classes of composite materials provide a great prospect of utilization of these functional properties in tailor-made device applications. In this work gold nanoparticle functionalized with coumarin based fused-ring heterocyclic thiol exhibiting self-assembly is reported. The present work has been designed giving prior to pi-stacking mediated self-aggregation of nanoparticles resulting formation of larger superstructures. The work reports the coumarin-based heterocyclic fused ring having a thiol anchoring group grafted to the gold nanoparticle surface for easier electron flow between the metal nanoparticle and the aromatic ligand and study their self-assembly nature.

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Do, Hoa Quang, Nghiem Thi Ha Lien, Vu Duong, Nguyen Thanh Thuy, and Do Quang Hoa. "A Short Pulse, Narrow Band Distributed Feedback Dye Laser Using Nanoparticle-doped Dye Solution Active Medium." Communications in Physics 24, no. 3S2 (September 24, 2014): 141–45. http://dx.doi.org/10.15625/0868-3166/24/3s2/5015.

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Spherical gold nanoparticles doped dye solution was used for laser active medium. Fluorescence and absorption spectral shapes of laser dye molecules were modified by the resonance energy transfer between gold nanoparticles due to localized surface plasmon effect. Laser pulse width and tuning range of a distributed feedback dye laser can be controlled by using various gold nanoparticle concentrations. The gold nanoparticles can be considered as a quenching element inside laser cavity to remove relaxation oscillation pulses at high pumping rate above threshold.

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Thanh, Ngo Vo Ke, Nguyen Dang Giang, Lam Quang Vinh, and Huynh Thanh Dat. "A low Cost Microwave Synthesis Method for Preparation of Gold Nanoparticles." Communications in Physics 24, no. 2 (July 23, 2014): 146. http://dx.doi.org/10.15625/0868-3166/24/2/3809.

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Gold nanoparticles are being used in various biomedical applications due to their small size to volume ratio, extensive thermal stability, less toxic… Many different techniques e.g. chemical, photochemical reduction and electrochemical, gamma have been applied to preparing this nanoparticle. In this paper, we are developing a low-cost technique by using a common microwave system with medium power for synthesizing gold nanoparticles with using sodium citrate (Na3Ct) reduction in chloroauric acid (HAuCl4.3H2O). It was found that the comparing with normal thermal method, the reaction by the microwave irradiation was much faster. Besides, the effects the sodium citrate concentration and optical properties of gold nanoparticles were studied. The optical properties of gold nanoparticles suspension were characterized by using transmission electron microscopy (TEM), X-ray diffraction (XRD), and UV-VIS absorption spectroscopy (UV-Vis). Maximum absorbance wavelengths ( λmax ) for gold nanoparticles are ~ 518-524 nm with the size of 12-25 nm. The size of gold nanoparticles decreases with increasing concentration of sodium citrate. Besides, the morphology of gold nanoparticles have a spherical shape with face-centered-cubic (fcc) crystalline structure.

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Fukushima, Shunta, Hirofumi Hidai, Sho Itoh, and Souta Matsusaka. "Local control of optical absorption properties of glass using precipitation of gold nanoparticles via gold sphere movement driven by laser." Nanotechnology 33, no. 45 (August 23, 2022): 455202. http://dx.doi.org/10.1088/1361-6528/ac8556.

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Abstract Glass embedded with metal nanoparticles is a promising material necessary for optical devices because of its absorption properties associated with the surface plasmon resonance (SPR) of metal nanoparticles. We demonstrated that continuous-wave laser illumination of the metal sphere in glass migrates the metal sphere and dopes the migration trajectory. In this study, we have attempted to locally control the absorption properties of borosilicate glass via gold nanoparticle precipitation using gold sphere migration. The gold sphere was moved in the glass via laser illumination, and the gold nanoparticles were precipitated in the movement trajectory. The trajectory was colored in red and purple gradations because of the SPR of gold nanoparticles. The particle size of the precipitated gold nanoparticles and the absorption peak wavelength increased with increasing velocity of the gold sphere. The absorption properties of the trajectory depend on the velocity of the gold sphere migration, which enabled local control of the absorption properties of the glass.

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Sotiriou, Georgios A., Gion Diego Etterlin, Anastasia Spyrogianni, Frank Krumeich, Jean-Christophe Leroux, and Sotiris E. Pratsinis. "Plasmonic biocompatible silver–gold alloyed nanoparticles." Chem. Commun. 50, no. 88 (2014): 13559–62. http://dx.doi.org/10.1039/c4cc05297h.

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Huynh, Ngoc Han, and James C. L. Chow. "DNA Dosimetry with Gold Nanoparticle Irradiated by Proton Beams: A Monte Carlo Study on Dose Enhancement." Applied Sciences 11, no. 22 (November 17, 2021): 10856. http://dx.doi.org/10.3390/app112210856.

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Heavy atom nanoparticles, such as gold nanoparticles, are proven effective radiosensitizers in radiotherapy to enhance the dose delivery for cancer treatment. This study investigated the effectiveness of cancer cell killing, involving gold nanoparticle in proton radiation, by changing the nanoparticle size, proton beam energy, and distance between the nanoparticle and DNA. Monte Carlo (MC) simulation (Geant4-DNA code) was used to determine the dose enhancement in terms of dose enhancement ratio (DER), when a gold nanoparticle is present with the DNA. With varying nanoparticle size (radius = 15–50 nm), distance between the gold nanoparticle and DNA (30–130 nm), as well as proton beam energy (0.5–25 MeV) based on the simulation model, our results showed that the DER value increases with a decrease of distance between the gold nanoparticle and DNA and a decrease of proton beam energy. The maximum DER (1.83) is achieved with a 25 nm-radius gold nanoparticle, irradiated by a 0.5 MeV proton beam and 30 nm away from the DNA.

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Chen, Li Ping. "In Situ Reducing Synthesis of (CTAB+C₁₈NH₂)-Modified Hydrophobic Gold Nanoparticles at Room Temperature." Applied Mechanics and Materials 618 (August 2014): 203–7. http://dx.doi.org/10.4028/www.scientific.net/amm.618.203.

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The hydrophobic gold nanoparticles with monodispersity are synthesized by using n-butanol reduction in situ under the condition of alkali promotion in cetyltrimethylammonium bromide (CTAB)/n-butanol/n-heptane/HAuCl4/NaOH(aq) W/O microemulsion at 30°C. The CTAB-stabilized gold nanoparticles are characterized by UV-vis, TEM , XRD and so on. The replacement of simple surfactant (CTAB ) with mixed surfactant CTAB/ octadecylamine can weaken the direction of CTAB to the growth of gold nanopartices and increase the monodispersity of gold nanoparticles. The effects of components of the microemulsion system on the shape, size and monodispersity of gold nanoparticles are also explored. The results show that the size of gold particles is changed by the amount of CTAB and C18NH2.

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Niidome, Takuro. "Gold nanoparticles." Drug Delivery System 31, no. 5 (2016): 477–79. http://dx.doi.org/10.2745/dds.31.477.

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Slepička, Petr, Nikola Slepičková Kasálková, Jakub Siegel, Zdeňka Kolská, and Václav Švorčík. "Methods of Gold and Silver Nanoparticles Preparation." Materials 13, no. 1 (December 18, 2019): 1. http://dx.doi.org/10.3390/ma13010001.

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The versatile family of nanoparticles is considered to have a huge impact on the different fields of materials research, mostly nanoelectronics, catalytic chemistry and in study of cytocompatibility, targeted drug delivery and tissue engineering. Different approaches for nanoparticle preparation have been developed, not only based on “bottom up” and “top down” techniques, but also several procedures of effective nanoparticle modifications have been successfully used. This paper is focused on different techniques of nanoparticles’ preparation, with primary focus on metal nanoparticles. Dispergation methods such as laser ablation and vacuum sputtering are introduced. Condensation methods such as reduction with sodium citrate, the Brust–Schiffrin method and approaches based on ultraviolet light or biosynthesis of silver and gold are also discussed. Basic properties of colloidal solutions are described. Also a historical overview of nanoparticles are briefly introduced together with short introduction to specific properties of nanoparticles and their solutions.

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Beynik, T. G. "Synthesis and characterization of branched gold nanoparticles." Functional materials 23, no. 4 (March 24, 2017): 021–25. http://dx.doi.org/10.15407/fm24.01.021.

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Mugade, Megha, Shrutika Patila, Meera Deshmukh, and Pranati Tilaka. "Biomedical applications of gold & silver nanoparticles." International Journal of Research Publication and Reviews 5, no. 4 (April 11, 2024): 3257–66. http://dx.doi.org/10.55248/gengpi.5.0424.1011.

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Chang, Chia-Chen, Chie-Pein Chen, Tzu-Heng Wu, Ching-Hsu Yang, Chii-Wann Lin, and Chen-Yu Chen. "Gold Nanoparticle-Based Colorimetric Strategies for Chemical and Biological Sensing Applications." Nanomaterials 9, no. 6 (June 6, 2019): 861. http://dx.doi.org/10.3390/nano9060861.

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Gold nanoparticles are popularly used in biological and chemical sensors and their applications owing to their fascinating chemical, optical, and catalytic properties. Particularly, the use of gold nanoparticles is widespread in colorimetric assays because of their simple, cost-effective fabrication, and ease of use. More importantly, the gold nanoparticle sensor response is a visual change in color, which allows easy interpretation of results. Therefore, many studies of gold nanoparticle-based colorimetric methods have been reported, and some review articles published over the past years. Most reviews focus exclusively on a single gold nanoparticle-based colorimetric technique for one analyte of interest. In this review, we focus on the current developments in different colorimetric assay designs for the sensing of various chemical and biological samples. We summarize and classify the sensing strategies and mechanism analyses of gold nanoparticle-based detection. Additionally, typical examples of recently developed gold nanoparticle-based colorimetric methods and their applications in the detection of various analytes are presented and discussed comprehensively.

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Lien, Nghiem Thi Ha, Vu Xuan Hoa, Vu Thi Thuy Duong, Nguyen Van Tinh, and Tran Hong Nhung. "Synthesis and Optical Properties of Colloidal Gold Nanoparticles for Biomedical Applications." Communications in Physics 21, no. 1 (March 31, 2011): 63. http://dx.doi.org/10.15625/0868-3166/21/1/96.

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The gold nanoparticle solutions are well known as an extremely sensitive biomedical analytical tool due to the strong dependence of their absorption in the visible range on the environment. In this work, the colloidal nano golds were synthesized from metal precursor chloroauric acid (HAuCl4) using trisodium citrate dehydrate (C6H5O7Na3) as reducing and stabilizing agents. The optical characterization - absorption of colloidal gold solution have been investigated under the different synthetic conditions such as: reducing agent concentration, concentration of auric ion, pH, duration of reaction and aging time. The results show that the absorption and the stability of the colloidal gold nanoparticles depend robustly on the synthetic conditions and pH of environment.

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Harlaftis, Filippos, Dean Kos, Qianqi Lin, Kevin T. P. Lim, Calvin Dumesnil, and Jeremy J. Baumberg. "Trapping plasmonic nanoparticles with MHz electric fields." Applied Physics Letters 120, no. 20 (May 16, 2022): 203303. http://dx.doi.org/10.1063/5.0091763.

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Dielectrophoresis drives the motion of nanoparticles through the interaction of their induced dipoles with a non-uniform electric field. We experimentally observe rf dielectrophoresis on 100 nm diameter gold nanoparticles in a solution and show that for MHz frequencies, the nanoparticles can reversibly aggregate at electrode gaps. A frequency resonance is observed at which reversible trapping of gold nanoparticle “clouds” occurs in the gap center, producing almost a 1000-fold increase in density. Through accounting for gold cores surrounded by a conducting double layer ion shell, a simple model accounts for this reversibility. This suggests that substantial control over nanoparticle separation is possible, enabling the formation of equilibrium nanoarchitectures in specific locations.

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Peshkova, Alexandra, Inga Zinicovscaia, Liliana Cepoi, Ludmila Rudi, Tatiana Chiriac, Nikita Yushin, Tran Tuan Anh, Ho Manh Dung, and Serghei Corcimaru. "Effects of Gold Nanoparticles on Mentha spicata L., Soil Microbiota, and Human Health Risks: Impact of Exposure Routes." Nanomaterials 14, no. 11 (May 29, 2024): 955. http://dx.doi.org/10.3390/nano14110955.

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Nanoparticles, due to their extensive production and application, can have significant consequences for the environment, including soil and plant pollution. Therefore, it is very important to assess how nanoparticles will affect plants depending on the exposure pathways. The effect of gold nanoparticles in a concentration range of 1–100 mg/L on Mentha spicata L. during a 28-day experiment was investigated. Two routes of nanoparticles exposure were applied: root and foliar. Transmission electron microscopy was used to characterize nanoparticles and their effect on plant leaves’ ultrastructure. Gold content in soil and plant segments was determined using k0-neutron activation analysis. For root exposure, gold was mainly accumulated in soil (15.2–1769 mg/kg) followed by root systems (2.99–454 mg/kg). The maximum accumulation of gold in leaves (5.49 mg/kg) was attained at a nanoparticle concentration of 100 mg/L. Foliar exposure resulted in the maximum uptake of gold in leaves (552 mg/kg) and stems (18.4 mg/kg) at the highest applied nanoparticle concentration. The effect of nanoparticles on the Mentha spicata L. leaves’ biochemical composition was assessed. Nanoparticles affected the content of chlorophyll and carotenoids and led to an increase in antioxidant activity. Root exposure to gold nanoparticles resulted in an increase in the number of starch grains in chloroplasts and also suppressed the activity of the soil microbiota. Gold extraction from mint leaves into herbal infusion varied from 2 to 90% depending on the concentration of nanoparticles in the solution and the exposure route. The health risk as a result of gold exposure via herbal tea intake was assessed through estimated daily intake. The hazard quotient values were found to be less than the cutoff, indicating that a cup of tea infusion should not cause a serious impact to human health.

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Ha, Chu Viet, J. C. Brochon, and Tran Hong Nhung. "Influence of Surface Plasmon Resonance on Fluorescence Emission of Dye-doped Nanoparticles." Communications in Physics 24, no. 3S2 (April 20, 2016): 121–29. http://dx.doi.org/10.15625/0868-3166/24/3s2/5057.

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The influence of the surface plasmon of gold nanoparticles on the optical properties of the fluorescent nanoparticles in aqueous solution have been investigated. The fluorescence of nanoparticles can be enhanced or quenched in the presence of gold nanoparticles depending on the domination of energy transfer mechanisms: radiating surface plasmon coupling emission or F\"{o}rster energy transfer from fluorescent particles to gold particles, which exciting absorbing plasmon. The fluorescence enhancement or quenching is attributed to the increase or decrease of radiative recombination rates, respectively. The parameters of the energy transfer between fluorescent nanoparticles (dye molecules encapsulated in silica nanoparticles) and nano golds have been estimated. The results show that the interactions between nanoparticles depend on the size of both fluorophores (as donors) and gold nanoparticles (as acceptors).

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Gülderen, Abdurrahman Taha, and Yasemin Oztekin. "Investigation of the Shape Effects of Green Synthesized Gold Nanoparticles on Electrochemical Detection of Dopamine." Journal of Nano Research 64 (November 2020): 105–14. http://dx.doi.org/10.4028/www.scientific.net/jnanor.64.105.

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Herein, this study shows three different synthesis of gold nanoparticles with various nano-shapes and an investigation of the correlation between nano-shapes and electrochemical effects on dopamine oxidation. To synthesize nano-shaped gold nanoparticles green reducing sources such as rose extract, glucose, and pomegranate juice were used. Thereby, three different gold nanoparticles were synthesized. In order to examine nanoparticle shapes microscopic and spectroscopic characterizations of nanoparticles were carried out. Subsequently the effects of shapes on electrochemical probes and dopamine were accomplished. As a result, it was confirmed that the shapes of the same metal nanoparticles had different effects on electrochemical experiments.

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You, Guangning, Shuping Xu, Xingfei Yao, Huanhuan Wu, and Yingying Shi. "Preparation of AuNPs/SF Nanofibers and Its Ability to Inhibit Tumor Growth in Breast Cancer-Bearing Animal Models." Journal of Nanoscience and Nanotechnology 21, no. 2 (February 1, 2021): 921–27. http://dx.doi.org/10.1166/jnn.2021.18640.

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Silk fibroin was used as a stabilizer for gold nanoparticles, and a direct silk fibroin-gold nanoparticle composite system was prepared by a direct compounding method in this paper. The stability of Au NPs/SF in phosphate buffer solution with different pH and KCl concentration was studied. The Au NPs/SF system was characterized by UV-visible light spectrum, transmission electron microscope and infrared spectrum. The silk fibroin-gold nanoparticle composite system was prepared by in situ reduction of chloroauric acid with silk fibroin, according to the change of solution color and the change of ultraviolet absorption peak. The effects of exogenous factors on the stability of the silk fibroin-gold nanoparticle in situ composite system were initially discussed, and its inhibition in breast cancer-bearing animal models was studied. In vivo experiments show that in situ injection of Au NPs/SF nanofibers and treatment with light can effectively control tumor growth. Compared with monodisperse gold nanoparticles, silk fibroin-gold nanoparticles can kill tumor cells and inhibit tumor tissue growth more effectively.

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Wang, Fei, Hui Xu, Ying Wei Wang, Jing Yue Fang, Wei Chen, and Xue Ao Zhang. "Self-Assembly of Gold Nanoparticle Arrays with Anodic Aluminum Oxide Template." Advanced Materials Research 1004-1005 (August 2014): 55–58. http://dx.doi.org/10.4028/www.scientific.net/amr.1004-1005.55.

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Nanoparticles and their ordered arrays have many important applications in fields such as electronic, optical, memory storage devices and sensors. Herein, a simple method was used for fabricating three-dimensional ordered gold nanoparticle arrays with template technique. Gold films were deposited onto anodic aluminum oxide by using electron beam evaporation. After thermal annealing, interestingly, order arrays of gold nanoparticles were obtained by a thermodynamically driven self-assembled process. The spectrum taken by UV-Vis spectrophotometer demonstrates clear surface plasmon resonance at around 500 nm, which appears blue-shift compared with usual gold nanoparticles.

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Anbu, Periasamy, Subash CB Gopinath, and S. Jayanthi. "Synthesis of gold nanoparticles using Platycodon grandiflorum extract and its antipathogenic activity under optimal conditions." Nanomaterials and Nanotechnology 10 (January 1, 2020): 184798042096169. http://dx.doi.org/10.1177/1847980420961697.

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Gold nanoparticles have many applications in the biomedical field, mainly for drug delivery, cancer therapy, and detection of pathogenic microorganisms. In this study, gold nanoparticles synthesized using Platycodon grandiflorum (Balloon flower plant) extracts were evaluated for their antibacterial potential. Gold nanoparticles were synthesized at 20–50°C using different volumes of the leaf extract. Biosynthesis of gold nanoparticles was confirmed by ultraviolet–visible spectral absorption at 545 nm by surface plasmon resonance. The morphology and size of the P. grandiflorum gold nanoparticles were further characterized as spherical in shape with an average size of 15 nm in diameter by scanning electron microscopy and transmission electron microscopy. Energy-dispersive X-ray analysis clearly displayed the presence of gold particles. The structural analysis results with face central cubic crystalline nature and elemental composition, including gold, were confirmed by X-ray diffraction and X-ray photoelectron spectroscopy, respectively. In addition, Fourier transform infrared results identified the functional group in P. grandiflorum that is involved in the reduction of metal ions to gold nanoparticles. The synthesized P. grandiflorum gold nanoparticles exhibited efficient antibacterial activity against Escherichia coli (16 mm) and Bacillus subtilis (11 mm). This report confirms the synthesis of gold nanoparticle from balloon flower plant extracts, which can be used as a reducing and stabilizing agent and demonstrates its antibacterial applications.

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Kodiha, Mohamed, Hicham Mahboubi, Dusica Maysinger, and Ursula Stochaj. "Gold Nanoparticles Impinge on Nucleoli and the Stress Response in MCF7 Breast Cancer Cells." Nanobiomedicine 3 (January 1, 2016): 3. http://dx.doi.org/10.5772/62337.

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Cancer cells can take up gold nanoparticles of different morphologies. These particles interact with the plasma membrane and often travel to intracellular organelles. Among organelles, the nucleus is especially susceptible to the damage that is inflicted by gold nanoparticles. Located inside the nucleus, nucleoli are specialized compartments that transcribe ribosomal RNA genes, produce ribosomes and function as cellular stress sensors. Nucleoli are particularly prone to gold nanoparticle-induced injury. As such, small spherical gold nanoparticles and gold nanoflowers interfere with the transcription of ribosomal DNA. However, the underlying mechanisms are not fully understood. In this study, we examined the effects of gold nanoparticles on nucleolar proteins that are critical to ribosome biogenesis and other cellular functions. We show that B23/nucleophosmin, a nucleolar protein that is tightly linked to cancer, is significantly affected by gold nanoparticles. Furthermore, gold nanoparticles impinge on the cellular stress response, as they reduce the abundance of the molecular chaperone hsp70 and O-GlcNAc modified proteins in the nucleus and nucleoli. Together, our studies set the stage for the development of nanomedicines that target the nucleolus to eradicate proliferating cancer cells.

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Zhou, He, Hongwei Yang, Guangke Wang, Aijun Gao, and Zhiqin Yuan. "Recent Advances of Plasmonic Gold Nanoparticles in Optical Sensing and Therapy." Current Pharmaceutical Design 25, no. 46 (January 10, 2020): 4861–76. http://dx.doi.org/10.2174/1381612826666191219130033.

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: Gold nanoparticles with special surface plasmon resonance have been widely used in sensing and therapy because of their easy preparation, unique optical properties, excellent biocompatibility, etc. The applications of gold nanoparticles in chemo/biosensing, imaging, and therapy reported in 2016-2019, are summarized in this review. Regarding the gold nanoparticle-based sensing or imaging, sensing mechanisms and strategies are provided to illustrate the concepts for designing sensitive and selective detection platforms. Gold nanoparticlemediated therapy is introduced by surface plasmon resonance-based therapy and delivery-based therapy. Beyond the sole therapeutic system, platforms through synergistic therapy are also discussed. In the end, discussion of the challenges and future trends of gold nanoparticle-based sensing and therapy systems is described.

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Zambre, Ajit, Nripen Chanda, Sudhirdas Prayaga, Rosana Almudhafar, Raghuraman Kannan, Anandhi Upendran, and Zahra Afrasiabi. "Gold Nanoparticle Based Immunostrip Assay Method for Detection of Protein-A." Applied Mechanics and Materials 229-231 (November 2012): 260–66. http://dx.doi.org/10.4028/www.scientific.net/amm.229-231.260.

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We have successfully developed gold nanoparticle based immunostrip assay to detect protein-A (PA). Rabbit polyclonal antibody IGg (αPA) that has affinity to PA was conjugated to gold nanoparticles (GNPs) and the gold nanoconjugate (αPA-GNP) was used to detect protein-A by simple immunostrip assay method. ELISA experiments were used to confirm the retention of binding affinity of antibody towards protein-A after conjugation with gold nanoparticles.

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Yusoff, Muhamad Shakir, Subash C. B. Gopinath, M. N. A. Uda, Thangavel Lakshmipriya, Ahmad Radi Wan Yaakub, and Periasamy Anbu. "Conjugation of Silver and Gold Nanoparticles for Enhancing Antimicrobial Activity." INNOSC Theranostics and Pharmacological Sciences 4, no. 2 (April 22, 2022): 38–47. http://dx.doi.org/10.36922/itps.v4i2.70.

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Silver and gold nanoparticles are promising agents that can enhance the antibacterial activity of conjugated/capped extract of plant compounds. The aim of our study is to synthesize silver nanoparticles from Gymnema sylvestre plant extract. In this study, the antimicrobial activity of conjugated silver which was green synthesized and gold nanoparticle that was obtained from a commercial source was evaluated using disk-diffusion method against Escherichia coli and Aspergillus niger. Transmission electron microscopy, scanning electron microscopy, ultraviolet-visible spectroscopy, and Fourier transform infrared spectroscopy analyses were also carried out to characterize the conjugated silver and gold nanoparticles. The conjugation of silver and gold nanoparticles was performed chemically using 16-mercaptodecanoic acid. Our results revealed that conjugated silver and gold nanoparticle both showing larger inhibition zones against E. coli and A. niger. The minimum inhibitory concentration (MIC) of the above metallic conjugation was found to be stable with MIC was reported to be 1 mM. When comparing the sample analysis on conjugation of gold and silver nanoparticles against E. coli and A. niger, the antimicrobial activity recorded was 2.0 ± 0.01 and 2.32 ± 0.04 cm, respectively, with no significance difference was found (P = 0.85). In conclusion, the combination of two different nanoparticles is efficient for microbial inhibition and can be useful for studying antimicrobial activities with the combination of different nanomaterials in future.

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Journal articles on the topic 'Gold nanoparticles'

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