Journal articles: 'NP aggregation'

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Wu, Xinghuo, Zhiwei Liao, Kun Wang, Wenbin Hua, Xianzhe Liu, Yu Song, Yukun Zhang, Shuhua Yang, and Cao Yang. "Targeting the IL-1β/IL-1Ra pathways for the aggregation of human islet amyloid polypeptide in an ex vivo organ culture system of the intervertebral disc." Experimental & Molecular Medicine 51, no. 9 (September 2019): 1–16. http://dx.doi.org/10.1038/s12276-019-0310-7.

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Abstract Intervertebral disc degeneration (IDD) is characterized by excessive apoptosis of nucleus pulposus (NP) cells and hyperactive extracellular matrix (ECM) catabolism. Our previous studies revealed the relationship between human islet amyloid polypeptide (hIAPP) and NP cell apoptosis. However, the role of hIAPP aggregates in IDD has not yet been investigated. This study aimed to determine whether the accumulation of hIAPP aggregates promotes IDD progression. The aggregation of hIAPP increased in human NP tissues during IDD. The deposition of hIAPP aggravated the compression-induced IDD that promoted NP cell apoptosis and ECM degradation via IL-1β/IL-1Ra signaling in an ex vivo rat disc model. Moreover, neutralizing IL-1β augmented the protective effects of hIAPP overexpression by decreasing hIAPP aggregation in human NP cells. These results suggest that the aggregation of hIAPP promotes NP cell apoptosis and ECM degradation ex vivo and in vitro by disrupting the balance of IL-1β/IL-1Ra signaling.

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Aminfar, Habib, Nayyer Razmara, and Mousa Mohammadpourfard. "Molecular Dynamics Study of Aggregation in Nanofluid Flow: Effects of Liquid–Nanoparticle Interaction Strength and Particles Volume Fraction." International Journal of Applied Mechanics 07, no. 01 (February 2015): 1550010. http://dx.doi.org/10.1142/s1758825115400104.

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Molecular dynamics simulations (MDSs) are carried on to examine the effects of liquid–nanoparticle (NP) interaction strength, size and number of nanoparticles on the aggregation process in liquid-based nanofluid flowing inside nanochannel. The results show that the increase in liquid–NP interaction strength leads to the reduction of aggregation rate. In addition, the increase in the size and number of NPs leads to more aggregation rate. Predicted results for aggregation trend are in good agreement with experimental data. Likewise, variations of velocity profile and density distribution of liquid particles inside nanochannel are explored.

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Helman, Paul. "A family of NP-complete data aggregation problems." Acta Informatica 26, no. 5 (March 1989): 485–99. http://dx.doi.org/10.1007/bf00289148.

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Kataoka, Keita, Kazuhiro Nakabayashi, Chen-Tsyr Lo, and Hideharu Mori. "Threonine-Based Stimuli-Responsive Nanoparticles with Aggregation-Induced Emission-Type Fixed Cores for Detection of Amines in Aqueous Solutions." Polymers 14, no. 7 (March 27, 2022): 1362. http://dx.doi.org/10.3390/polym14071362.

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Stimuli-responsive polymeric nanoparticles (NPs) exhibit reversible changes in the dispersion or aggregation state in response to external stimuli. In this context, we designed and synthesized core-shell NPs with threonine-containing weak polyelectrolyte shells and fluorescent cross-linked cores, which are applicable for the detection of pH changes and amine compounds in aqueous solution. Stable and uniform NP(dTh) and NP(Fl), consisting of fluorescent symmetric diphenyl dithiophene (dTh) and diphenyl fluorene (Fl) cross-linked cores, were prepared by site-selective Suzuki coupling reactions in self-assembled block copolymer. NP(Fl) with the Fl unit in the core showed a high fluorescence intensity in different solvents, which is regarded as an aggregation-induced emission-type NP showing strong emission in aggregated states in the cross-linked core. Unimodal NPs were observed in water at different pH values, and the diameter of NP(Fl) changed from 122 (pH = 2) to 220 nm (pH = 11). Furthermore, pH-dependent changes of the fluorescence peak positions and intensities were detected, which may be due to the core aggregation derived from the deprotonation of the threonine-based shell fragment. Specific interactions between the threonine-based shell of NP(Fl) and amine compounds (triethylamine and p-phenylenediamine) resulted in fluorescence quenching, suggesting the feasibility of fluorescent amine detection.

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Nestele, Jeremy A., Anne-Katrin Rohlfing, Valerie Dicenta, Alexander Bild, Daniela Eißler, Frederic Emschermann, Marcel Kremser, et al. "Characterization of GPVI- or GPVI-CD39-Coated Nanoparticles and Their Impact on In Vitro Thrombus Formation." International Journal of Molecular Sciences 23, no. 1 (December 21, 2021): 11. http://dx.doi.org/10.3390/ijms23010011.

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Traditional antithrombotic agents commonly share a therapy-limiting side effect, as they increase the overall systemic bleeding risk. A novel approach for targeted antithrombotic therapy is nanoparticles. In other therapeutic fields, nanoparticles have enabled site-specific delivery with low levels of toxicity and side effects. Here, we paired nanotechnology with an established dimeric glycoprotein VI-Fc (GPVI-Fc) and a GPVI-CD39 fusion protein, thereby combining site-specific delivery and new antithrombotic drugs. Poly(lactic-co-glycolic acid) (PLGA) nanoparticles, NP-BSA, NP-GPVI and NP-GPVI-CD39 were characterized through electron microscopy, atomic force measurements and flow cytometry. Light transmission aggregometry enabled analysis of platelet aggregation. Thrombus formation was observed through flow chamber experiments. NP-GPVI and NP-GPVI-CD39 displayed a characteristic surface coating pattern. Fluorescence properties were identical amongst all samples. NP-GPVI and NP-GPVI-CD39 significantly impaired platelet aggregation. Thrombus formation was significantly impaired by NP-GPVI and was particularly impaired by NP-GPVI-CD39. The receptor-coated nanoparticles NP-GPVI and the bifunctional molecule NP-GPVI-CD39 demonstrated significant inhibition of in vitro thrombus formation. Consequently, the nanoparticle-mediated antithrombotic effect of GPVI-Fc, as well as GPVI-CD39, and an additive impact of CD39 was confirmed. In conclusion, NP-GPVI and NP-GPVI-CD39 may serve as a promising foundation for a novel therapeutic approach regarding targeted antithrombotic therapy.

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Domingos, Dayane Gonzaga, Rosana Oliveira Henriques, Jéssica Antunes Xavier, Nelson Libardi Junior, and Rejane Helena Ribeiro da Costa. "Increasing activated sludge aggregation by magnetite nanoparticles addition." Water Science and Technology 79, no. 5 (February 11, 2019): 993–99. http://dx.doi.org/10.2166/wst.2019.055.

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Abstract The behavior of mixed samples (activated sludge and wastewater) was investigated after the addition of magnetite nanoparticles (NP-magnetite) in jar tests, with objective to increase the aggregation of sludge and improve its settleability, aiming for future application in granular sequencing batch reactors. The NP-magnetite was synthesized by the method of ion co-precipitation of Fe2+ and Fe3+ and characterized. The process of sludge sedimentation was evaluated for two different experimental strategies, with NP-magnetite concentrations between 25 and 150 mg L−1. The concentration of 75 mg L−1 was the most favorable to process, as evidenced by sludge volumetric index and density. The results presented indicate that the addition of nanoparticles has the potential to improve aerobic granular systems, increasing the settleability of seed sludge.

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Robinson, D. A., J. Duay, A. M. Kondajji, and K. J. Stevenson. "Mechanistic aspects of hydrazine-induced Pt colloid instability and monitoring aggregation kinetics with nanoparticle impact electroanalysis." Faraday Discussions 193 (2016): 293–312. http://dx.doi.org/10.1039/c6fd00121a.

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Here we investigate the mechanistic aspects of Pt nanoparticle (NP) aggregation in solutions typically used for detecting NP/electrode impacts by electrocatalytic amplification (ECA). We previously proposed a general mechanism for Pt colloid destabilization that involved the participation of both the hydrazine redox probe and the pH buffer species as coagulants. Herein the Pt NP coagulation and aggregation mechanisms were further investigated with microscopic kinetic NP concentration monitoring and zeta potential measurements using nanoparticle tracking analysis (NTA), as well as open circuit potential experiments with a citrate-treated polycrystalline Pt surface to assess electrical double layer potential. After considering the combined results of these experiments we propose that the colloidal stability of citrate-capped platinum nanoparticles involves much more than the typical physicochemical interactions predicted by DLVO theory. A structure based on intermolecular H-bonding in the citrate capping layer is the most plausible explanation for the exceptional stability of large Pt NPs in high ionic strength buffers. Thus, the mechanism of Pt NP aggregation includes specific reactive contributions from hydrazine. The catalytic decomposition of hydrazine, in particular, is thought to occur to some extent at the citrate-coated Pt surface while the citrate remains adsorbed. Evolved gases such as ammonia and possible surface bound intermediates from Pt-catalyzed decomposition of hydrazine may disrupt the stability of the citrate layer, causing colloidal instability and thus promoting Pt NP coagulation. In the closing section, we demonstrate nanoparticle impact electroanalysis by ECA detection as a method to quantify Pt NP concentration with adequate time resolution for monitoring the kinetics of Pt NP coagulation.

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Broumi, Said, Irfan Deli, and Florentin Smarandache. "Neutrosophic Parametrized Soft Set Theory and its Decision Making." International Frontier Science Letters 1 (July 2014): 1–10. http://dx.doi.org/10.18052/www.scipress.com/ifsl.1.1.

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In this work, we present definition of neutrosophic parameterized (NP) soft set and its operations. Then we define NP-aggregation operator to form NP-soft decision making method which allows constructing more efficient decision processes. We also dive an example which shows that they can be successfully applied to problem that contain indeterminacy.

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Schroer, Martin A., Po-Sheng Hu, Natalia Tomasovicova, Marianna Batkova, Katarina Zakutanska, Po-Yi Wu, and Peter Kopcansky. "Dependence of the Nanoscale Composite Morphology of Fe3O4 Nanoparticle-Infused Lysozyme Amyloid Fibrils on Timing of Infusion: A Combined SAXS and AFM Study." Molecules 26, no. 16 (August 11, 2021): 4864. http://dx.doi.org/10.3390/molecules26164864.

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Understanding the formation process and the spatial distribution of nanoparticle (NP) clusters on amyloid fibrils is an essential step for the development of NP-based methods to inhibit aggregation of amyloidal proteins or reverse the assembling trend of the proto-fibrillary complexes that prompts pathogenesis of neuro degeneration. For this, a detailed structural determination of the diverse hybrid assemblies that are forming is needed, which can be achieved by advanced X-ray scattering techniques. Using a combined solution small angle X-ray scattering (SAXS) and atomic force microscopy (AFM) approach, this study investigates the intrinsic trends of the interaction between lysozyme amyloid fibrils (LAFs) and Fe3O4 NPs before and after fibrillization at nanometer resolution. AFM images reveal that the number of NP clusters interacting with the lysozyme fibers does not increase significantly with NP volume concentration, suggesting a saturation in NP aggregation on the fibrillary surface. The data indicate that the number of non-adsorbed Fe3O4 NPs is highly dependent on the timing of NP infusion within the synthesis process. SAXS data yield access to the spatial distribution, aggregation manner and density of NP clusters on the fibrillary surfaces. Employing modern data analysis approaches, the shape and internal structural morphology of the so formed nanocomposites are revealed. The combined experimental approach suggests that while Fe3O4 NPs infusion does not prevent the fibril-formation, the variation of NP concentration and size at different stages of the fibrillization process can impose a pronounced impact on the superficial and internal structural morphologies of these nanocomposites. These findings may be applicable in devising advanced therapeutic treatments for neurodegenerative diseases and designing novel bio-inorganic magnetic devices. Our results further demonstrate that modern X-ray methods give access to the structure of—and insight into the formation process of—biological–inorganic hybrid structures in solution.

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DICKINSON, Natalie T., Elliott K. JANG, and Richard J. HASLAM. "Activation of cGMP-stimulated phosphodiesterase by nitroprusside limits cAMP accumulation in human platelets: effects on platelet aggregation." Biochemical Journal 323, no. 2 (April 15, 1997): 371–77. http://dx.doi.org/10.1042/bj3230371.

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cGMP enhances cAMP accumulation in platelets via cGMP-inhibited phosphodiesterase (PDE3) [Maurice and Haslam (1990) Mol. Pharmacol. 37, 671–681]. However, cGMP might also limit cAMP accumulation by activating cGMP-stimulated phosphodiesterase (PDE2). We therefore evaluated the role of PDE2 in human platelets by using erythro-9-(2-hydroxy-3-nonyl)adenine (EHNA) to inhibit this enzyme selectively. IC50 values for the inhibition of platelet PDE2 by EHNA, with 10 μM cAMP as substrate in the absence and in the presence of 1 μM cGMP, were 15 and 3 μM respectively. Changes in platelet cyclic [3H]nucleotides were measured after prelabelling with [3H]adenine and [3H]guanine. Nitroprusside (NP) caused concentration-dependent increases in [3H]cGMP and a biphasic increase in [3H]cAMP, which was maximal at 10 μM (49±6%) and smaller at 100 μM (32±6%) (means±S.E.). In the presence of EHNA (20 μM), which had no effects alone, NP caused much larger increases in platelet [3H]cAMP (125±14% at 100 μM). EHNA also enhanced [3H]cGMP accumulation at high NP concentrations. In accord with these results, EHNA markedly potentiated the inhibition of thrombin-induced platelet aggregation by NP. The roles of cAMP and cGMP in this effect were investigated by using 2´,5´-dideoxyadenosine to inhibit adenylate cyclase. This compound decreased the accumulation of [3H]cAMP but not that of [3H]cGMP, and diminished the inhibition of platelet aggregation by NP with EHNA. We conclude that much of the effect of NP with EHNA is mediated by cAMP. Lixazinone (1 μM), a selective inhibitor of PDE3, increased platelet [3H]cAMP by 177±15%. This increase in [3H]cAMP was markedly inhibited by NP; EHNA blocked this effect of NP. Parallel studies showed that NP suppressed the inhibition of platelet aggregation by lixazinone. EHNA enhanced the large increases in [3H]cAMP seen with 20 nM prostacyclin (PGI2), but had no effect with 1 nM PGI2. NP and 1 nM PGI2 acted synergistically to increase [3H]cAMP, an effect attributable to the inhibition of PDE3 by cGMP; EHNA greatly potentiated this synergism. In contrast, NP decreased the [3H]cAMP accumulation seen with 20 nM PGI2, an effect that was blocked by EHNA. The results show that, provided that cGMP is present, PDE2 plays a major role in the hydrolysis of low cAMP concentrations and restricts any increases in cAMP concentration and decreases in platelet aggregation caused by the inhibition of PDE3. At high cAMP, PDE2 plays the major role in cAMP breakdown, whether cGMP is present or not.

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Liu, Fei, Dan Wu, and Ken Chen. "The Cooperative Effect Analysis when Nanoparticles Enter a Biological Cell." Nano 14, no. 04 (April 2019): 1950039. http://dx.doi.org/10.1142/s1793292019500395.

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The nanoparticle (NP) is one of the most used nanostructures in biomedicine. The Np–biomembrane interface plays an important role in delivering NPs into a living biological cell. While most researchers focus on the interaction between a single Np and a cell membrane, we pay attention to the NP–biomembrane interaction when a cluster of NPs are put into a biological cell together, and analyze the cooperative effect of these NPs. We find that the NPs would not enter the cell individually, but have a trend to form an aggregation to reduce the repel force from the cell membrane. The dissipative particle dynamics simulation shows that the NP aggregation may have three interactive states with the membrane: adhere on the surface of the cell, uptaken by the membrane and enter the cell. We propose to use catalytic (CA) particles which are not sensitive to the membrane to reduce the driving force required in NP delivery. Energy analysis demonstrates that the introduced (CA) particles can decrease the free energy gap between the inside and the outside of the membrane, and increase the success rate of NPs entering the cell.

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Amirian, Mohammad Mahdi, and Saeed Shiry Ghidary. "Xeggora: Exploiting Immune-to-Evidence Symmetries with Full Aggregation in Statistical Relational Models." Journal of Artificial Intelligence Research 66 (September 3, 2019): 33–56. http://dx.doi.org/10.1613/jair.1.11322.

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We present improvements in maximum a-posteriori inference for Markov Logic, a widely used SRL formalism. Inferring the most probable world for Markov Logic is NP-hard in general. Several approaches, including Cutting Plane Aggregation (CPA), perform inference through translation to Integer Linear Programs. Aggregation exploits context-specific symmetries independently of evidence and reduces the size of the program. We illustrate much more symmetries occurring in long ground clauses that are ignored by CPA and can be exploited by higher-order aggregations. We propose Full-Constraint-Aggregation, a superior algorithm to CPA which exploits the ignored symmetries via a lifted translation method and some constraint relaxations. RDBMS and heuristic techniques are involved to improve the overall performance. We introduce Xeggora as an evolutionary extension of RockIt, the query engine that uses CPA. Xeggora evaluation on real-world benchmarks shows progress in efficiency compared to RockIt especially for models with long formulas.

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Sikder, Mithun, Jingjing Wang, Brett A. Poulin, Malak M. Tfaily, and Mohammed Baalousha. "Nanoparticle size and natural organic matter composition determine aggregation behavior of polyvinylpyrrolidone coated platinum nanoparticles." Environmental Science: Nano 7, no. 11 (2020): 3318–32. http://dx.doi.org/10.1039/d0en00659a.

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Singh, Vidyadhar, Cathal Cassidy, Murtaza Bohra, Antony Galea, Zafer Hawash, and Mukhles Sowwan. "Surface Morphology of Films Grown by Size-Selected Ta Nanoparticles." Advanced Materials Research 647 (January 2013): 732–37. http://dx.doi.org/10.4028/www.scientific.net/amr.647.732.

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Tantalum nanoparticle (NP) films have been deposited on silicon substrates, using sputter deposition with gas aggregation. The resultant NP films have been characterized using high resolution atomic force microscopy and X-ray fluorescence spectroscopy. The films remain stable and the NPs maintain a spherical structure on annealing up to 600 °C. In addition to characterization, these NP films have been locally patterned by atomic force microscope scanning of the surface in contact mode.

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Xu, Dong, and Nazrul I. Shaikh. "A Heuristic Approach for Ranking Items Based on Inputs from Multiple Experts." International Journal of Information Systems and Social Change 9, no. 3 (July 2018): 1–22. http://dx.doi.org/10.4018/ijissc.2018070101.

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This article describes how rank aggregation focuses on synthesizing a single ranked list based on rankings supplied by multiple judges. Such aggregations are widely applied in the areas of information retrieval, web search, and data mining. The problem of rank aggregation has been shown to be NP-hard and this article presents a heuristic approach to create an aggregated ranking score for all items on the lists. The proposed heuristic is scalable and performs. A computational study, as well as a real-life study involving the ranking of 147 engineering colleges in the US is presented to elucidate the performance. The authors' key finding is that the quality of the solution is sensitive to (a) the number of judges available to rank, (b) how the items are assigned to judges, and (c) how consistent/inconsistent the judges are. All these factors are generally considered exogenous in most of the rank aggregation algorithms in extant literature.

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Zhu, Shuze, Jason Galginaitis, and Teng Li. "Critical Dispersion Distance of Silicon Nanoparticles Intercalated between Graphene Layers." Journal of Nanomaterials 2012 (2012): 1–4. http://dx.doi.org/10.1155/2012/375289.

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Nanocomposites of silicon nanoparticles (Si NPs) dispersed in between graphene layers emerge as potential anode materials of high-charge capacity for lithium-ion batteries. A key design requirement is to keep Si NPs dispersed without aggregation. Experimental design of the Si NP dispersion in graphene layers has remained largely empirical. Through extensive molecular dynamics simulations, we determine a critical NP dispersion distance as the function of NP size, below which Si NPs in between graphene layers evolve to bundle together. These results offer crucial and quantitative guidance for designing NP-graphene nanocomposite anode materials with high charge capacity.

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Babakhani, Peyman, Jonathan Bridge, Tanapon Phenrat, Ruey-an Doong, and Karl R. Whittle. "Aggregation and sedimentation of shattered graphene oxide nanoparticles in dynamic environments: a solid-body rotational approach." Environmental Science: Nano 5, no. 8 (2018): 1859–72. http://dx.doi.org/10.1039/c8en00443a.

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Khan, Rizwan, Muhammad Inam, Sarfaraz Khan, Andrea Jiménez, Du Park, and Ick Yeom. "The Influence of Ionic and Nonionic Surfactants on the Colloidal Stability and Removal of CuO Nanoparticles from Water by Chemical Coagulation." International Journal of Environmental Research and Public Health 16, no. 7 (April 9, 2019): 1260. http://dx.doi.org/10.3390/ijerph16071260.

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The widespread use of copper oxide nanoparticles (CuO NPs) and surfactants in various consumer products makes it likely that they coexist in aqueous environments, making it important to study the effects of surfactants on the fate and transport behavior of CuO NPs. The present study aims to investigate the influence of anionic sodium lauryl sulfate (SLS) and nonionic nonylphenol ethoxylate (NPEO, Tergitol NP-9), on CuO NPs adsorption, aggregation, and removal from water by the coagulation process. The result of the sorption study indicates that both surfactants could be adsorbed on the surface of CuO NPs, and that SLS remarkably decreases the ζ potential as well as the hydrodynamic diameter (HDD) of CuO as compared to NP-9. The kinetic aggregation study showed that both SLS and NP-9 reduced the HDD of CuO NPs and retarded the settling rates at surfactant concentrations above 0.015% (w:v) over a 24 h-period. Moreover, enhanced aggregation of CuO NPs was observed in two environmental waters as compared to pure water, which could be related to their high ionic strength. The addition of surfactants in natural waters has been shown to reduce the aggregation and sedimentation of CuO; however, the reductive effect of SLS was more pronounced than that of NP-9. Finally, the coagulation results showed that the removal efficiencies of CuO, Cu2+, and the surfactant in all tested waters at optimum ferric chloride dosage reached around 98, 95, and 85%, respectively. Furthermore, the coagulation mechanism revealed that the combination of charge neutralization and adsorptive micellar flocculation (AMF) might be involved in the removal of both pollutants. The results of the present study provide new insight into the environmental behavior of coexisting NPs and surfactants in wastewater treatment processes.

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Brancolini, Giorgia, Maria Celeste Maschio, Cristina Cantarutti, Alessandra Corazza, Federico Fogolari, Vittorio Bellotti, Stefano Corni, and Gennaro Esposito. "Citrate stabilized gold nanoparticles interfere with amyloid fibril formation: D76N and ΔN6 β2-microglobulin variants." Nanoscale 10, no. 10 (2018): 4793–806. http://dx.doi.org/10.1039/c7nr06808e.

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Peng, Cheng, Hong Tong, Peng Yuan, Lijuan Sun, Lei Jiang, and Jiyan Shi. "Aggregation, Sedimentation, and Dissolution of Copper Oxide Nanoparticles: Influence of Low-Molecular-Weight Organic Acids from Root Exudates." Nanomaterials 9, no. 6 (June 1, 2019): 841. http://dx.doi.org/10.3390/nano9060841.

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The rhizosphere is an essential pathway for the uptake of metal-based nanoparticles (MNPs) by plant roots. However, the interaction between root exudates and MNPs is still unclear. In this study, we initially identified the major low-molecular-weight organic acids (LMWOAs) in the rice root exudates using hydroponics. Then, the individual LMWOAs were added to CuO nanoparticle suspensions to investigate their effects on the environmental behavior of the MNPs. The results showed that both the variety and the concentration of LMWOAs impacted the aggregation, sedimentation, and dissolution of CuO nanoparticles (NPs). Almost all LMWOAs except succinic acid inhibited the aggregation of CuO NPs by enhancing the electrostatic repulsive force between NPs. The presence of citric and oxalic acids rather than lactic acid greatly improved the stability of CuO NP suspensions, but other acids showed a low promoting and high inhibiting effect on NP sedimentation. Moreover, all the LMWOAs from root exudates facilitated the dissolution of CuO NPs with a positive dose-dependent correlation, especially formic acid. Notably, citric acid, as the most abundant LMWOAs in rice root exudates, largely determined the aggregation, sedimentation, and dissolution of CuO NPs. This study provides a better understanding on NP–plant interactions in the rhizosphere.

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Morozova, Olga V., Olga N. Volosneva, Olga A. Levchenko, Nikolay A. Barinov, and Dmitry V. Klinov. "Protein Corona on Gold and Silver Nanoparticles." Materials Science Forum 936 (October 2018): 42–46. http://dx.doi.org/10.4028/www.scientific.net/msf.936.42.

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Gold or silver nanoparticles (NP) were covered with protein corona by: 1) direct binding with a number of proteins; 2) nanoprecipitation of proteins from their solutions in fluoroalcohols; 3) physisorption of proteins on the NP surface treated with poly (allylamine) s; 4) encapsulation of Ag or Au NP into SiO2 envelope and functionalization with organosilanes. Adsorption of proteins on surfaces of metal NP is reversible and up to 70% of the attached proteins can be eluted. Ag NP possess high affinity for binding with immunoglobulins and fibrinogens but not with any protein. Nanoprecipitation of Ag and Au NP with proteins resulted in combined NP with metal core and protein shell with ligand-binding and enzymatic activities. SiO2 layer on surfaces of metal NP is suitable for silanization and covalent immobilization of any protein. Protein corona prevents Ag and Au NP from oxidation, dissolution and aggregation. Proteins attached to metal NP reduce their antimicrobial activity and cytotoxicity for eukaryotic cells. The developed methods of fabrication of Ag/Au NP with protein shells permit to attach any protein at different distances from metal core to avoid possible inactivation of proteins, to reduce fluorescence fading and to stabilize the nanoconjugates.

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Lee, Eun-Hye, Mi-Kyung Lee, and Soo-Jeong Lim. "Enhanced Stability of Indocyanine Green by Encapsulation in Zein-Phosphatidylcholine Hybrid Nanoparticles for Use in the Phototherapy of Cancer." Pharmaceutics 13, no. 3 (February 26, 2021): 305. http://dx.doi.org/10.3390/pharmaceutics13030305.

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Indocyanine green (ICG) is a clinically approved near-infrared dye that has shown promise as a photosensitizer for the phototherapy of cancer. However, its chemical instability in an aqueous solution has limited its clinical application. Encapsulating ICG in liposomes, phosphatidylcholine nanoparticles (PC-NP), has shown partial effectiveness in stabilizing it. Prompted by our recent finding that the zein-phosphatidylcholine hybrid nanoparticles (Z/PC-NP) provide an advanced drug carrier compared to PC-NP, we herein investigated the potential of Z/PC-NP as an improved ICG formulation. Dynamic light scattering analysis, transmission electron microscopy, and Fourier-transform infrared spectroscopy studies showed that ICG was encapsulated in Z/PC-NP without hampering the high colloidal stability of the Z/PC-NP. During storage, the Z/PC-NP almost completely inhibited the ICG aggregation, whereas the PC-NP did so partially. The Z/PC-NP also more effectively blocked the ICG degradation compared to the PC-NP. The phototoxicity of ICG encapsulated in Z/PC-NP on cancer cells was twofold higher than that in the PC-NP. The ICG encapsulated in Z/PC-NP, but not in PC-NP, maintained its photocytotoxicity after four-day storage. These findings highlight the promising potential of Z/PC-NP as an ICG formulation that provides a higher stabilization effect than PC-NP.

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D’Addato, Sergio, Daniele Pinotti, Maria Chiara Spadaro, Guido Paolicelli, Vincenzo Grillo, Sergio Valeri, Luca Pasquali, Luca Bergamini, and Stefano Corni. "Influence of size, shape and core–shell interface on surface plasmon resonance in Ag and Ag@MgO nanoparticle films deposited on Si/SiO x." Beilstein Journal of Nanotechnology 6 (February 9, 2015): 404–13. http://dx.doi.org/10.3762/bjnano.6.40.

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Ag and Ag@MgO core–shell nanoparticles (NPs) with a diameter of d = 3–10 nm were obtained by physical synthesis methods and deposited on Si with its native ultrathin oxide layer SiO x (Si/SiO x ). Scanning electron microscopy and transmission electron microscopy (TEM) images of bare Ag NPs revealed the presence of small NP aggregates caused by diffusion on the surface and agglomeration. Atomic resolution TEM gave evidence of the presence of crystalline multidomains in the NPs, which were due to aggregation and multitwinning occurring during NP growth in the nanocluster source. Co-deposition of Ag NPs and Mg atoms in an oxygen atmosphere gave rise to formation of a MgO shell matrix surrounding the Ag NPs. The behaviour of the surface plasmon resonance (SPR) excitation in surface differential reflectivity (SDR) spectra with p-polarised light was investigated for bare Ag and Ag@MgO NPs. It was shown that the presence of MgO around the Ag NPs caused a red shift of the plasmon excitation, and served to preserve its existence after prolonged (five months) exposure to air, realizing the possibility of technological applications in plasmonic devices. The Ag NP and Ag@MgO NP film features in the SDR spectra could be reproduced by classical electrodynamics simulations by treating the NP-containing layer as an effective Maxwell Garnett medium. The simulations gave results in agreement with the experiments when accounting for the experimentally observed aggregation.

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Caleffi, Matteo, Paolo Mariani, Giovanni Bertoni, Guido Paolicelli, Luca Pasquali, Antonio Agresti, Sara Pescetelli, Aldo Di Carlo, Valentina De Renzi, and Sergio D’Addato. "Ag/MgO Nanoparticles via Gas Aggregation Nanocluster Source for Perovskite Solar Cell Engineering." Materials 14, no. 19 (September 23, 2021): 5507. http://dx.doi.org/10.3390/ma14195507.

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Nanocluster aggregation sources based on magnetron-sputtering represent precise and versatile means to deposit a controlled quantity of metal nanoparticles at selected interfaces. In this work, we exploit this methodology to produce Ag/MgO nanoparticles (NPs) and deposit them on a glass/FTO/TiO2 substrate, which constitutes the mesoscopic front electrode of a monolithic perovskite-based solar cell (PSC). Herein, the Ag NP growth through magnetron sputtering and gas aggregation, subsequently covered with MgO ultrathin layers, is fully characterized in terms of structural and morphological properties while thermal stability and endurance against air-induced oxidation are demonstrated in accordance with PSC manufacturing processes. Finally, once the NP coverage is optimized, the Ag/MgO engineered PSCs demonstrate an overall increase of 5% in terms of device power conversion efficiencies (up to 17.8%).

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Farner, Jeffrey M., Jacopo De Tommaso, Heather Mantel, Rachel S. Cheong, and Nathalie Tufenkji. "Effect of freeze/thaw on aggregation and transport of nano-TiO2 in saturated porous media." Environmental Science: Nano 7, no. 6 (2020): 1781–93. http://dx.doi.org/10.1039/d0en00008f.

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Research has focused on nanoparticle (NP) aggregation and transport behavior in saturated granular porous media, but few studies have looked at the effect that temperature variability associated with winter conditions will have on engineered NPs.

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Therezien, Mathieu, Antoine Thill, and Mark R. Wiesner. "Importance of heterogeneous aggregation for NP fate in natural and engineered systems." Science of The Total Environment 485-486 (July 2014): 309–18. http://dx.doi.org/10.1016/j.scitotenv.2014.03.020.

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Hudry, Olivier. "NP-hardness results for the aggregation of linear orders into median orders." Annals of Operations Research 163, no. 1 (May 29, 2008): 63–88. http://dx.doi.org/10.1007/s10479-008-0353-y.

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Gericke, Martin, Katja Geitel, Cornelia Jörke, Joachim H. Clement, and Thomas Heinze. "Reactive Nanoparticles Derived from Polysaccharide Phenyl Carbonates." Molecules 26, no. 13 (July 1, 2021): 4026. http://dx.doi.org/10.3390/molecules26134026.

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Polysaccharide (PS) based nanoparticles (NP) are of great interest for biomedical applications. A key challenge in this regard is the functionalization of these nanomaterials. The aim of the present work was the development of reactive PS-NP that can be coupled with an amino group containing compounds under mild aqueous conditions. A series of cellulose phenyl carbonates (CPC) and xylan phenyl carbonates (XPC) with variable degrees of substitution (DS) was obtained by homogeneous synthesis. The preparation of PS-NP by self-assembling of these hydrophobic derivatives was studied comprehensively. While CPC mostly formed macroscopic aggregates, XPC formed well-defined spherical NP with diameters around 100 to 200 nm that showed a pronounced long-term stability in water against both particle aggregation as well as cleavage of phenyl carbonate moieties. Using an amino group functionalized dye it was demonstrated that the novel XPC-NP are reactive towards amines. A simple coupling procedure was established that enables direct functionalization of the reactive NP in an aqueous dispersion. Finally, it was demonstrated that dye functionalized XPC-NP are non-cytotoxic and can be employed in advanced biomedical applications.

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Woitassek, Dennis, Swantje Lerch, Wulv Jiang, Meital Shviro, Stefan Roitsch, Thomas Strassner, and Christoph Janiak. "The Facile Deposition of Pt Nanoparticles on Reduced Graphite Oxide in Tunable Aryl Alkyl Ionic Liquids for ORR Catalysts." Molecules 27, no. 3 (February 2, 2022): 1018. http://dx.doi.org/10.3390/molecules27031018.

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In this study, we present the facile formation of platinum nanoparticles (Pt-NPs) on reduced graphite oxide (rGO) (Pt-NP@rGO) by microwave-induced heating of the organometallic precursor ((MeCp)PtMe3 in different tunable aryl alkyl ionic liquids (TAAIL). In the absence of rGO, transmission electron microscopy (TEM) reveals the formation of dense aggregates of Pt-NPs, with primary particle sizes of 2 to 6 nm. In contrast, in the Pt-NP@rGO samples, Pt-NPs are homogeneously distributed on the rGO, without any aggregation. Pt-NP@rGO samples are used as electrode materials for oxygen reduction reaction (ORR), which was assessed by cyclic voltammetry (CV) and linear sweep voltammetry (LSV). The electrochemical surface area (ECSA) and mass-specific activity (MA) increase up to twofold, compared with standard Pt/C 60%, making Pt-NP@rGO a competitive material for ORR.

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Luo, Hongyong, Changwei Gu, Weihua Zheng, Fei Dai, Xinling Wang, and Zhen Zheng. "Facile synthesis of novel size-controlled antibacterial hybrid spheres using silver nanoparticles loaded with poly-dopamine spheres." RSC Advances 5, no. 18 (2015): 13470–77. http://dx.doi.org/10.1039/c4ra16469e.

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Sub-micrometer hybrid spheres with a poly-dopamine core and loaded with silver nanoparticles (NPs) were fabricated by a facile method. The new hybrid spheres show a strong antibacterial activity due to their special structure, effectively preventing silver NP aggregation.

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Rossi, Andrea, Massimiliano Cuccioloni, Lisa Rita Magnaghi, Raffaela Biesuz, Marco Zannotti, Laura Petetta, Mauro Angeletti, and Rita Giovannetti. "Optimizing the Heavy Metal Ion Sensing Properties of Functionalized Silver Nanoparticles: The Role of Surface Coating Density." Chemosensors 10, no. 11 (November 15, 2022): 483. http://dx.doi.org/10.3390/chemosensors10110483.

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We present a colorimetric sensor based on functionalized silver nanoparticles for the detection of metal ions in aqueous solutions. The interaction between the target metal ion and the functionalizing agent triggers the aggregation of these nanoparticles, and the consequent change in optical properties allows the detection/quantification of the analyte. In detail, this work describes the synthesis of AgNPs by a chemical reduction method, and the production of mercaptoundecanoic acid functionalized NPs with different surface densities (multi-, full-, and two partial layers). UV-Vis spectroscopy was used to monitor the functionalization processes, and to investigate the aggregation behavior of each AgNPs@11MUA sensor upon titration with the metal ions of interest, namely Ni2+, Zn2+, Co2+, Cd2+, Mn2+, and Cu2+. The resulting UV-Vis raw data obtained for each layer density were submitted to principal component analysis to dissect the role of the metal ions in NP aggregation and in establishing the sensitivity and selectivity of the AgNPs@11MUA sensor. Interestingly, we observed an increase in sensor sensitivity and selectivity at a lower density of the functionalizing agent on the AgNPs’ surface, which results in characteristic colors of the NP suspension upon titration with each metal ion.

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Zielińska, Katarzyna. "Solid phase microextraction speciation analysis of triclosan in aqueous media containing sorbing nanoparticles." Environmental Chemistry 11, no. 1 (2014): 72. http://dx.doi.org/10.1071/en13167.

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Environmental context Speciation analysis of organic compounds in aquatic media is often performed using solid phase microextraction with the assumption that only the free organic form is accumulated. We show that in the presence of silica nanoparticles, this interpretation is confounded by partitioning of nanoparticulate-bound compounds between water and the solid phase, as well as their aggregation at solid–bulk medium interfaces. Equilibrium measurement of the target analyte is feasible if the solid phase is protected by a suitable membrane. Abstract Solid phase microextraction (SPME) is applied in the speciation analysis of the hydrophobic compound triclosan in an aqueous medium containing sorbing SiO2 nanoparticles (NPs). It is found that these NPs, as well as their complexes with triclosan, partition between the bulk medium and the solid phase poly(dimethylsiloxane) (PDMS). Furthermore, they appear to aggregate at the PDMS–water interface. The total triclosan concentration in the solid phase thus includes both the free and the NP-bound forms. Proper computation of the analyte concentration in the sample medium requires (i) consideration of the speciation of triclosan inside the solid phase and (ii) elimination of the effects of aggregation of NP complexes at the solid phase–bulk medium interface. Possible solutions include application of a protective membrane with pore size smaller than the NP diameter. This allows measurement of the free triclosan concentration, albeit at the cost of longer accumulation times and loss of kinetic information on the triclosan–NP complex.

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Takagiwa, Shota, Osamu Kanasugi, Kentaro Nakamura, and Masahito Kushida. "Synthesis of Vertically-Aligned Carbon Nanotubes from Langmuir-Blodgett Films Deposited Fe Nanoparticles on Al2O3/Al/SiO2/Si Substrate." Journal of Nanoscience and Nanotechnology 16, no. 4 (April 1, 2016): 3289–94. http://dx.doi.org/10.1166/jnn.2016.12312.

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In order to apply vertically-aligned carbon nanotubes (VA-CNTs) to a new Pt supporting material of polymer electrolyte fuel cell (PEFC), number density and outer diameter of CNTs must be controlled independently. So, we employed Langmuir-Blodgett (LB) technique for depositing CNT growth catalysts. A Fe nanoparticle (NP) was used as a CNT growth catalyst. In this study, we tried to thicken VA-CNT carpet height and inhibit thermal aggregation of Fe NPs by using Al2O3/Al/SiO2/Si substrate. Fe NP LB films were deposited on three typed of substrates, SiO2/Si, as-deposited Al2O3/Al/SiO2/Si and annealed Al2O3/Al/SiO2/Si at 923 K in Ar atmosphere of 16 Pa. It is known that Al2O3/Al catalyzes hydrocarbon reforming, inhibits thermal aggregation of CNT growth catalysts and reduces CNT growth catalysts. It was found that annealed Al2O3/Al/SiO2/Si exerted three effects more strongly than as-deposited Al2O3/Al/SiO2/Si. VA-CNTs were synthesized from Fe NPs-C16 LB films by thermal chemical vapor deposition (CVD) method. As a result, at the distance between two nearest CNTs 28 nm or less, VA-CNT carpet height on annealed Al2O3/Al/SiO2/Si was about twice and ten times thicker than that on SiO2/Si and that on as-deposited Al2O3/Al/SiO2/Si, respectively. Moreover, distribution of CNT outer diameter on annealed Al2O3/Al/SiO2/Si was inhibited compared to that on SiO2/Si. These results suggest that since thermal aggregation of Fe NPs is inhibited, catalyst activity increases and distribution of Fe NP size is inhibited.

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Bai, Jie, Bin Geng, Xingwen Wang, Shenghong Wang, and Yayi Xia. "Analysis of Potential Hub Genes for Neuropathic Pain Based on Differential Expression in Rat Models." Pain Research and Management 2022 (March 3, 2022): 1–14. http://dx.doi.org/10.1155/2022/6571987.

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Objective. Neuropathic pain (NP) is a type of intractable chronic pain with complicated etiology. The exact molecular mechanism underlying NP remains unclear. In this study, we searched for molecular biomarkers of NP. Methods. Differentially expressed genes (DEGs) were predicted by analyzing three NP-related microarray datasets in Gene Expression Omnibus with robust rank aggregation. A weighted gene coexpression network analysis was conducted to construct a network of differentially expressed genes, followed by the evaluation of correlations between gene sets and the determination of hub genes. The candidate genes from the key module were identified using a gene set enrichment analysis. Results. In total, 353 upregulated and 383 downregulated genes were obtained, among which five hub genes were determined to be related to pain phenotypes. Reverse transcription-quantitative polymerase chain reaction was performed to verify the expression of these hub genes in the dorsal root ganglia of rats with spared nerve injury, which revealed the decreased expression of EMC4. Hence, EMC4 was defined as a biomarker for NP development. Conclusions. The results of this study form a basis for further research into the mechanism of NP development and are expected to aid in the development of novel therapeutic strategies.

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Yin, Dan, and Hong Gao. "A flexible aggregation framework on large-scale heterogeneous information networks." Journal of Information Science 43, no. 2 (July 10, 2016): 186–203. http://dx.doi.org/10.1177/0165551516630237.

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OLAP (On-line Analytical Processing) can provide users with aggregate results from different perspectives and granularities. With the advent of heterogeneous information networks that consist of multi-type, interconnected nodes, such as bibliographic networks and knowledge graphs, it is important to study flexible aggregation in such networks. The aggregation results by existing work are limited to one type of node, which cannot be applied to aggregation on multi-type nodes, and relations in large-scale heterogeneous information networks. In this paper, we investigate the flexible aggregation problem on large-scale heterogeneous information networks, which is defined on multi-type nodes and relations. Moreover, by considering both attributes and structures, we propose a novel function based on graph entropy to measure the similarities of nodes. Further, we prove that the aggregation problem based on the function is NP-hard. Therefore, we develop an efficient heuristic algorithm for aggregation in two phases: informational aggregation and structural aggregation. The algorithm has linear time and space complexity. Extensive experiments on real-world datasets demonstrate the effectiveness and efficiency of the proposed algorithm.

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Minigalieva, I. А., T. V. Bushueva, V. G. Panov, A. N. Varaksin, V. Ya Shur, E. V. Shishkina, V. B. Gurviсh, and B. A. Katsnelson. "Some aspects of metal oxide nanoparticles toxicity assessment on cell cultures as exemplified by NiO and Mn3O4." Toxicological Review, no. 5 (October 28, 2017): 35–43. http://dx.doi.org/10.36946/0869-7922-2017-5-35-43.

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Comparative and combined damaging actions of NiO and Mn3O4 anoparticles were estimated on cultures of different established human cell lines. It was found out that the addition of the fetal bovine serum (FBS) to the culture media ,used in the investigation, renders NiO-NPs and, to even a greater extent, Mn3O4-NPs exponentially soluble while without FBS their dissolution was extremely low. Along with it, sedimentation of those MeO-NPs caused by their aggregation noticeably slowed down in the presence of the same FBS. The dependence of cell damage on the MeO-NPs concentration was found out, at a higher cytotoxicity of Mn3O4-NP as compared to NiO-NP. Thus, comparative assessment of NPs non-specific toxicity previously obtained in animal experiments was reproduced in the «in vitro» tests. However, with respect to manganese-specific brain damage «in vivo» discovered previously in sub-chronic intoxication with the same MeO-NPs, the present «in vitro» experiment on neurons only showed a certain enhancing effect of Mn3O4-NP on the action of NiO-NP, but the role of NiO-NP in the combination prevailed.

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Kaleeswaran, Palanichamy, Thanasekaran Nandhini, and Kasi Pitchumani. "Naked eye sensing of melamine: aggregation induced recognition by sodium d-gluconate stabilised silver nanoparticles." New Journal of Chemistry 40, no. 4 (2016): 3869–74. http://dx.doi.org/10.1039/c5nj03083h.

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Cao, Xue-Zheng, Holger Merlitz, Chen-Xu Wu, Goran Ungar, and Jens-Uwe Sommer. "A theoretical study of dispersion-to-aggregation of nanoparticles in adsorbing polymers using molecular dynamics simulations." Nanoscale 8, no. 13 (2016): 6964–68. http://dx.doi.org/10.1039/c5nr08576d.

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BRANDENBURG, FRANZ J., ANDREAS GLEIßNER, and ANDREAS HOFMEIER. "COMPARING AND AGGREGATING PARTIAL ORDERS WITH KENDALL TAU DISTANCES." Discrete Mathematics, Algorithms and Applications 05, no. 02 (June 2013): 1360003. http://dx.doi.org/10.1142/s1793830913600033.

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Comparing and ranking information is an important topic in social and information sciences, and in particular on the web. Its objective is to measure the difference of the preferences of voters on a set of candidates and to compute a consensus ranking. Commonly, each voter provides a total order or a bucket order of all candidates, where bucket orders allow ties. In this work we consider the generalization of total and bucket orders to partial orders and compare them by the nearest neighbor and the Hausdorff Kendall tau distances. For total and bucket orders these distances can be computed in [Formula: see text] time. We show that the computation of the nearest neighbor Kendall tau distance is NP-hard, 2-approximable and fixed-parameter tractable for a total and a partial order. The computation of the Hausdorff Kendall tau distance for a total and a partial order is shown to be coNP-hard. The rank aggregation problem is known to be NP-complete for total and bucket orders, even for four voters and solvable in [Formula: see text] time for two voters. We show that it is NP-complete for two partial orders and the nearest neighbor Kendall tau distance. For the Hausdorff Kendall tau distance it is in [Formula: see text], but not in NP or coNP unless NP = coNP, even for four voters.

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Losonczy, G., I. Mucha, J. DiPirro, J. Sweeney, G. Brown, J. Brentjens, and R. Venuto. "The effect of pregnancy on the response to the TxA2/PGH2 analogue U-46619 in rabbits." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 265, no. 4 (October 1, 1993): R772—R780. http://dx.doi.org/10.1152/ajpregu.1993.265.4.r772.

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We compared the hemodynamic actions of U-46619, a stable thromboxane A2 (TxA2) prostaglandin H2 (PGH2) analogue, in nonpregnant (NP) rabbits with those observed in late pregnant (P) rabbits. An intravenous injection of U-46619 (10 micrograms) to each of eight NP chronically instrumented rabbits (mean body weight 3.4 kg) induced an immediate (1 min) and reversible fall of cardiac output (CO, 66%) and mean arterial pressure (MAP, 41%, both P < 0.01). P rabbits (n = 6, mean body weight 3.8 kg), however, responded with an elevation of MAP (5%, P < 0.02) upon intravenous injection of the drug (10 micrograms), while CO remained unchanged. The fall of CO in NP rabbits was associated with the temporary disappearance of a fraction of circulating platelets between the superior vena cava and the aortic arch. The number of platelets at 30 and 60 s after U-46619 was reduced (P < 0.05) by 14 and 20% respectively in the aortic blood, whereas caval platelet counts were unchanged until 90 s (-6%, P < 0.05). In contrast, intraaortic administration of this drug (10 micrograms) to NP rabbits resulted in neither thrombocytopenia nor hypotension. U-46619 (10-30 micrograms i.v.) caused no decrease in platelet count in the aorta of P rabbits. In vitro, U-46619-induced aggregation of platelets harvested from P rabbits was also blunted (P < 0.001). This could not be attributed to reduced affinity or number of platelet thromboxane receptors. The data indicate that U-46619 induces a fall of arterial pressure simultaneous with intravascular platelet aggregation.(ABSTRACT TRUNCATED AT 250 WORDS)

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Morgalev, Sergey Yu, Tamara G. Morgaleva, Yuri N. Morgalev, and Irina A. Gosteva. "Stability of Disperse Systems during Bioassay of Nanoecotoxicity with Use of Aquatic Organisms." Advanced Materials Research 1085 (February 2015): 424–29. http://dx.doi.org/10.4028/www.scientific.net/amr.1085.424.

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The paper is devoted to studying the stability of of dispersed systems (DS) of nanoparticles (NP) of nickel (nNi), platinum (nPt), titanium dioxide (nTiO2), zinc oxide, multicomponent nanopowder (MNP) and multi-walled carbon nanotubes (MWCNT), formed basing on the growth media used in bioassay with application of aquatics: bacterial test-cultures Ecolum, Photobacterium phosphoreum and Escherihia coli, unicellular algae Chlorella vulgaris Beijer, infusoria Paramecium caudatum, cladocera Daphnia magna Straus and Ceriodaphnia affinis, fish Danio rerio. In the process of establishing a test-system the increase in the initial nanosubstance concentration of more than 5 mg/l results in the increase in the speed of aggregation of NP into DS and the decrease in their final concentration. We suggest the variants of estimation of effective concentration of NP in long-term biotesting.

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Corti, Roberta, Alysia Cox, Valeria Cassina, Luca Nardo, Domenico Salerno, Claudia Adriana Marrano, Natalia Missana, et al. "The Clustering of mApoE Anti-Amyloidogenic Peptide on Nanoparticle Surface Does Not Alter Its Performance in Controlling Beta-Amyloid Aggregation." International Journal of Molecular Sciences 21, no. 3 (February 5, 2020): 1066. http://dx.doi.org/10.3390/ijms21031066.

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The deposition of amyloid-β (Aβ) plaques in the brain is a significant pathological signature of Alzheimer’s disease, correlating with synaptic dysfunction and neurodegeneration. Several compounds, peptides, or drugs have been designed to redirect or stop Aβ aggregation. Among them, the trideca-peptide CWG-LRKLRKRLLR (mApoE), which is derived from the receptor binding sequence of apolipoprotein E, is effectively able to inhibit Aβ aggregation and to promote fibril disaggregation. Taking advantage of Atomic Force Microscopy (AFM) imaging and fluorescence techniques, we investigate if the clustering of mApoE on gold nanoparticles (AuNP) surface may affect its performance in controlling Aβ aggregation/disaggregation processes. The results showed that the ability of free mApoE to destroy preformed Aβ fibrils or to hinder the Aβ aggregation process is preserved after its clustering on AuNP. This allows the possibility to design multifunctional drug delivery systems with clustering of anti-amyloidogenic molecules on any NP surface without affecting their performance in controlling Aβ aggregation processes.

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Baalousha, Mohammed, Mithun Sikder, Ashwini Prasad, Jamie Lead, Ruth Merrifield, and G. Thomas Chandler. "The concentration-dependent behaviour of nanoparticles." Environmental Chemistry 13, no. 1 (2016): 1. http://dx.doi.org/10.1071/en15142.

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Environmental context Studies of manufactured nanoparticles (NPs) in the environment have been performed almost exclusively at high NP concentrations. These data lead to misunderstandings related to NP fate and effects at relevant environmental concentrations, which are expected to be low. A better understanding of the concentration-dependent behaviour of NPs will improve our understanding of their fate and effects under environmentally realistic conditions. Abstract This rapid communication highlights the importance of nanoparticle concentration in determining their environmental fate and behaviour. Notably, two fate processes have been considered: dissolution and aggregation. The decrease in nanoparticle concentration results in increased dissolution and decreased aggregate sizes, inferring higher potential for environmental transport of nanoparticles.

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Nesterenko, Y. O. "ELECTROLYTIC AGGREGATION IN SOLUTIONS WITH QUANTUM DOTS AND GOLD NANOPARTICLES MODIFIED WITH OLIGONUCLEOTIDES." Biotechnologia Acta 15, no. 4 (August 31, 2022): 22–26. http://dx.doi.org/10.15407/biotech15.04.022.

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Aim. To investigate electrolytic aggregation of different nano-objects in solutions with quantum dots (QDs) and Au nanoparticles (NPs) modified by oligonucleotides as well as the effect of aggregates on the photoluminescence (PL) of QDs. Methods. Au NPs and AgInS2/ZnS QDs were modified by oligonucleotides. Two types of QDs that differ in size and stabilizing ligand were used. PL and optical absorption of nano-objects in water and SSC buffer solutions were studied. Results. The transfer of modified by oligonucleotides QDs from water to a buffer solution and the addition of Au NP modified by oligonucleotides to the solution caused quenching of the QD PL intensity. The PL quenching was observed for the QDs of two types and increased during the incubation of solutions, but didn’t depend on its multiplicity. An aggregation of Au-DP occurred only in buffer solutions with QDs of one type and increased with multiplicity of the buffer solution. Conclusion. It is found that the electrolytic aggregation of Au NPs modified by oligonucleotides in buffer solutions with QDs depends on the QD type and didn’t affect the quenching of the PL intensity of the QDs.

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S., Vimal, and Srivatsa S K. "A Reliable Peer-to-Peer Platform for Adding New Node Using Trust Based Model." International Journal of Electrical and Computer Engineering (IJECE) 7, no. 6 (December 1, 2017): 3515. http://dx.doi.org/10.11591/ijece.v7i6.pp3515-3520.

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In order to evaluate the trustworthiness of participating peers in unstructured peer-to-peer networks, Reputation aggregation methods are used in this method. Each and every peer of the network will collect the local scores of each transaction and will compute global scores by aggregating all the local scores with the help of global scores, each individual peer can interact with its suitable peers. But the existing method will not consider the score of the new peer. In this condition, requests are handled by existing peers who leads to failure in downloading process. To rectify this, NP-TRUST model is used to distribute the request to all peers including the newly joined peers. The proposed method is compared with gossip and DFR-TRUST model in Transaction Success rate and variation in file request.

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Ritthidej, Garnpimol C., W. Pichayakorn, Chulalongkorn Kusonwiriyawong, and V. Lipipun. "Preparation of Chitosan Nanoparticles for Protein Delivery by w/o/w Emulsion Solvent Evaporation and Simple Ionotropic Gelation Techniques." Solid State Phenomena 121-123 (March 2007): 751–54. http://dx.doi.org/10.4028/www.scientific.net/ssp.121-123.751.

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The purpose of this study was to prepare chitosan nanoparticles (CS NP) for controlled protein delivery. Two techniques, simple ionotropic gelation (method [I]) and w/o/w emulsion solvent evaporation containing ionotropic gelation (method [II]), were used to prepare CS NP. Tripolyphosphate (TPP) and Eudragit L100-55 (Eud) were used as anionic agents to form complex with cationic chitosan. Bovine serum albumin (BSA) was encapsulated into NP. The morphological characteristics, particle size and size distribution, protein entrapment efficiency, zeta potential, in vitro release, protein secondary structure and its integrity were investigated. The results showed that CS NP could be prepared by appropriate cationic and anionic ratios in both methods. Excess anionic agents resulted in particle aggregation of micron size. The median sizes of particles were between 0.127-0.273 mcm with method [I] provided the smallest size. The 0.02-0.10% BSA loaded preparations showed the same particle sizes and size distributions as blank preparations. SEM photomicrographs revealed that the obtained NP were spherical. Protein entrapment efficiency was between 47-84% and increased when decreasing the percentage of drug loading. The method [II] with TPP exhibited the highest protein entrapment efficiency, following by the method [II] with Eud and method [I] with TPP, respectively. The zeta potentials were positive. Prolonged in vitro protein release profiles were observed from all preparations of CS NP. After 10 days, the release was between 53-72%. Circular dichroism and SDS-polyaceylamide gel electrophoresis techniques confirmed that these processes did not have any destructive effect on the protein structure. Therefore these preparation techniques could be used to encapsulate water-soluble drugs, proteins, DNA, or antigens into CS NP as effective delivery carriers.

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Shellaiah, Muthaiah, and Kien-Wen Sun. "Review on Anti-Aggregation-Enabled Colorimetric Sensing Applications of Gold and Silver Nanoparticles." Chemosensors 10, no. 12 (December 16, 2022): 536. http://dx.doi.org/10.3390/chemosensors10120536.

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Gold- and silver nanoparticles (Au NPs and Ag NPs)-based colorimetric detection of specific analytes has attracted intense research interest and is still in great demand. The majority of Au NPs- and Ag NPs-based sensory reports have revealed that, during the analyte recognition, dispersed NPs typically aggregated and displayed color changes from wine-red to blue/purple and yellow to orange/brown, respectively. On the other hand, only a few reports demonstrated that the aggregated Au NPs and Ag NPs underwent anti-aggregation in the presence of certain analytes, which displayed reversed color changes from blue/purple to wine-red and orange/brown to yellow, correspondingly. There are some examples of anti-aggregation phenomena mentioned in a vast number of studies on Au NPs- and Ag NPs-based colorimetric sensors via NP aggregation. However, a review targeting the anti-aggregation-enabled Au NPs- and Ag NPs-based colorimetric sensing of diverse analytes is not yet available. In this review, anti-aggregation-facilitated Au NPs- and Ag NPs-based colorimetric detection of metal ions, anions, bio-analytes, pesticides, and herbicides is delivered with detailed underlying mechanisms. Moreover, the probe design, sensory requirement, merits, limitations, and future scope of anti-aggregation-enabled Au NPs- and Ag NPs-based colorimetric sensors are discussed.

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Duprat, Anne-Marie, Paulette Kan, Françoise Foulquier, and Michel Weber. "In vitro differentiation of neuronal precursor cells from amphibian late gastrulae: morphological, immunocytochemical studies, biosynthesis, accumulation and uptake of neurotransmitters." Development 86, no. 1 (April 1, 1985): 71–87. http://dx.doi.org/10.1242/dev.86.1.71.

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Neuronal differentiation has been studied in dissociated cell cultures from early neurulae of Pleurodeles waltl and Ambystoma mexicanum. Cocultures were prepared from the neural primordium and underlying chordamesoderm. NP and NF cultures were prepared from isolated neural plate and neural folds, respectively. Neuronal precursors in NP and NF cultures had distinctive aggregation properties already evident after 1–2 days in culture. After 10–15 days, mature neurones and synapses were observed by electron microscopy in the three culture types. The expression of neurofilament polypeptides and tetanus-toxin-binding sites was also present in these cultures. A small percentage of neurones contained cytochemically detectable catecholamine. Many neurones took up tritiated dopamine with a high affinity. Quantitative measurement of [3H]acetylcholine synthesis and storage from [3H]choline were negative at the early neurula stage and in 5 to 15-day-old NF cultures, and remained low in 5 to 15-day-old NP cultures. Acetylcholine production in cocultures increased linearly with time and was always much higher than in NP cultures. These results suggest that, at the early neurula stage, some neuronal precursors have acquired the capacity to express a high degree of morphological and biochemical differentiation even in the absence of further chordamesoderm influence. However, the chordamesodermal cells in the cultures increased acetylcholine synthesis.

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Son, Han Am, and Taehun Lee. "Enhanced Oil Recovery with Size-Dependent Interactions of Nanoparticles Surface-Modified by Zwitterionic Surfactants." Applied Sciences 11, no. 16 (August 4, 2021): 7184. http://dx.doi.org/10.3390/app11167184.

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This study reports the size-dependent interactions of silica nanoparticle (NP) dispersions with oil, which facilitate oil recovery from sandstone rock. Herein, we studied various 7–22 nm sized colloidal silica NPs (CSNPs; the colloidal state when dispersed in aqueous solutions) and fumed silica nanoparticles (FSNPs; the dry powder state). Interfacial tension at the oil-nanofluids interface declined with decreasing NP size in a range from 7 to 22 nm. This is because NP spatial density at the interface increased with smaller particle size, thereby, the interface area per NP decreased to approximately 1/30, and interfacial energy had reduced enough. In addition, smaller NPs more strongly were adsorbed to the rock because of improved diffusion in suspension and increased adsorption density. This caused creating a wedge film between oil and rock, which changed the oil contact angle. Due to this effect, core flooding experiments indicated that oil recovery increased with decreasing particle size. However, FSNP dispersions exhibited low recovery factor because of particle aggregation. This phenomenon may facilitate massive permeability reduction, thus causing oil trapping inside rock pore. We found that both the sizes and types of CSNPs and FSNP affected the Interfacial tension at oil-water interface and rock surface wettability, which influenced ultimate oil recovery.

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Mainali, Badri P., and Francis P. Zamborini. "Chemical Detection by Analyte-Induced Change in Electrophoretic Deposition of Gold Nanoparticles." Journal of The Electrochemical Society 169, no. 1 (January 1, 2022): 016504. http://dx.doi.org/10.1149/1945-7111/ac418c.

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Abstract:

The electrophoretic deposition (EPD) of citrate-stabilized Au nanoparticles (cit-Au NPs) occurs on indium tin oxide (ITO)-coated glass electrodes upon electrochemical oxidation of hydroquinone (HQ) due to the release of hydronium ions. Anodic stripping voltammetry (ASV) for Au oxidation allows the determination of the amount of Au NP deposition under a specific EPD potential and time. The binding of Cr3+ to the cit-Au NPs inhibits the EPD by inducing aggregation and/or reducing the negative charge, which could lower the effective NP concentration of the cit-Au NPs and/or lower the electrophoretic mobility. This lowers the Au oxidation charge in the ASV, which acts as an indirect signal for Cr3+. The binding of melamine to cit-Au NPs similarly leads to aggregation and/or lowers the negative charge, also resulting in reduction of the ASV Au oxidation peak. The decrease in Au oxidation charge measured by ASV increases linearly with increasing Cr3+ and melamine concentration. The limit of detection (LOD) for Cr3+ is 21.1 ppb and 16.0 ppb for 15.1 and 4.1 nm diameter cit-Au NPs, respectively. Improving the sensing conditions allows for as low as 1 ppb detection of Cr3+. The LOD for melamine is 45.7 ppb for 4.1 nm Au NPs.

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Journal articles on the topic 'NP aggregation'

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