Anti-HSV Activity of Metallic Nanoparticles Functionalized with Sulfonates vs. Polyphenols

Metallic nanoparticles exhibit broad-spectrum activity against bacteria, fungi, and viruses. The antiviral activity of nanoparticles results from the multivalent interactions of nanoparticles with viral surface components, which result from the nanometer size of the material and the presence of functional compounds adsorbed on the nanomaterial surface. A critical step in the virus infection process is docking and entry of the virus into the host cell. This stage of the infection can be influenced by functional nanomaterials that exhibit high affinity to the virus surface and hence can disrupt the infection process. The affinity of the virus to the nanomaterial surface can be tuned by the specific surface functionalization of the nanomaterial. The main purpose of this work was to determine the influence of the ligand type present on nanomaterial on the antiviral properties against herpes simplex virus type 1 and 2. We investigated the metallic nanoparticles (gold and silver) with different sizes (5 nm and 30 nm), coated either with polyphenol (tannic acid) or sulfonates (ligands with terminated sulfonate groups). We found that the antiviral activity of nano-conjugates depends significantly on the ligand type present on the nanoparticle surface.     

The Multivalent Effect in Glycosidase Inhibition: Probing the Influence of Valency,Peripheral Ligand Structure,and Topology with Cyclodextrin‐Based Iminosugar Click Clusters

In view of recent reports of a strong multivalent effect in glycosidase inhibition, a library of β‐CD‐based multivalent iminosugars has been efficiently synthesized by way of Cu^I‐catalyzed azide–alkyne cycloaddition (CuAAC). In combination with the first application of isothermal titration calorimetry (ITC) experiments to the study of multivalent iminosugar–enzyme interactions, the inhibition properties of these click clusters were evaluated on a panel of glycosidases. The structural parameters that were varied include valency, peripheral ligand structure, and topology. The inhibition results obtained with the iminosugar clusters further highlight the importance of multivalency in the inhibition of α‐mannosidase. Generally, the evaluated multivalent iminosugars displayed comparable thermodynamic signatures of binding towards α‐mannosidase (Jack bean): that is, large negative enthalpies of complexation coupled with small entropies of either sign. In addition, the enthalpy–entropy compensation observed in all tested cases may be attributed to a common mechanism of dissociation for the enzyme–multivalent iminosugar interactions. The measured binding stoichiometries indicated that each iminosugar cluster interacts with no more than one protein molecule.     

Chitosan/MCM‐41 nanocomposites for efficient beryllium separation

Chitosan nanoparticles (Ch NPs) with individual particles 10–30 nm in size and average aggregate sizes of 240 nm were prepared via ionic gelation. Ordered mesoporous Mobil Composition of Matter No. 41 (MCM‐41) with a surface area of 1590 m²/g was prepared via a sol–gel method. The nanocomposites were prepared via the in situ dispersion of MCM‐41 in chitosan followed by ionic gelation with a multivalent anion to produce MCM‐41‐impregnated Ch NPs or via the mixture of dispersed MCM‐41 with preprepared Ch NPs to produce Ch NPs supported on MCM‐41. The beryllium‐uptake efficiency was studied with different pH values, contact times, and initial Be(II) concentrations. The maximum achieved uptake efficiencies of the nanocomposites (95% and 96%) were superior to that of MCM‐41 (38%) and higher than that of Ch NPs (90%). The nanocomposite formulas facilitated post‐treatment separation while maintaining a high beryllium‐uptake efficiency. The Be(II)‐uptake process for all of the materials followed the pseudo‐second‐order kinetic model and both the Langmuir and Freundlich isotherms. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46040.     

Removal of arsenic from aqueous solutions by an adsorption process with titania–silica binary oxide nanoparticle loaded polyacrylonitrile polymer

A new and simple method was developed to produce gelatin nanoparticles of ～ 30–40 nm for use as carriers for drug release applications. The nanoparticles were uniform in size and well dispersed. An anticancer drug, 5‐fluorouracil, was encapsulated with an efficiency as high as 85%. The nanoparticles showed sustained release of 5‐fluorouracil, and release rates varied with amount of crosslinking in the nanoparticles. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.     

Effects of multi‐walled carbon nanotube functionalization on the morphological and mechanical properties of nanocomposite foams based on poly(vinyl chloride)/(wood flour)/ (multi‐walled carbon nanotubes)

Experimental results are presented for nanocomposite foams based on unplasticized poly(vinyl chloride)/(wood flour)/(multi‐wall carbon nanotubes) (PVC/WF/MWCNTs). The nanocomposite samples were prepared in an internal mixer and foamed via a batch processing method using compression molding. Nanoparticles were functionalized by sodium hypochlorite solution, and the functionalization process was monitored by Fourier‐transform infrared spectroscopy. The effects of MWCNTs (both neat and functionalized) and blowing agent concentration on the morphological properties (cell size and cell density) and mechanical properties (tensile and flexural strength) of the foam samples were studied. The results revealed that foam cell sizes decreased and cell densities increased with addition of MWCNTs. The dispersion of nanoparticles in the PVC medium was increased by functionalization, and the morphological properties of the foams containing functionalized nanoparticles were improved. Density of nanocomposite foams decreased more with functionalized MWCNTs as compared to other samples. Chemical blowing agent concentration had no significant effect on sample density. Mechanical properties of the samples were improved by using functionalized MWCNTs in comparison with those of foams without this component. J. VINYL ADDIT. TECHNOL., 18:161–167, 2012. © 2012 Society of Plastics Engineers     

Understanding the Interaction of an Intense Laser Pulse with Nanoparticles: Application to the Quantification of Single Particle Mass Spectrometry

Understanding the characteristic behavior of ions produced from the interaction of a high energy laser pulse with nanoparticles is essential for quantitative determination of composition and size of nanoparticles from single particle mass spectrometry (SPMS). We employed a one-dimensional hydrodynamic model, where the laser field is coupled to the non-equilibrium time-dependent plasma hydrodynamics of the heated particles. We focus on regimes of laser width from 0.01 ns to 10 ns (532 nm wavelength, 100 mJ/pulse) and particle size (20–400 nm in diameter) most relevant to commonly used SPMS, and determine the properties of ions generated during the interaction with a strong laser pulse. We compare the simulation results with experiments conducted on aluminum nanoparticles.

The laser-particle interaction is separated into a “soft heating” regime followed by a hydrodynamic expansion. Simulation results showed that the ablation/ionization is effectively complete well before the laser ever reaches its peak intensity. As the pulse width decreased for a given pulse energy, the kinetic energy of ions increased, suggesting that too short a pulse laser (i.e., high laser intensity) would be undesirable because higher energetic ions lead to lower detection efficiency in the SPMS. Results also show that for particle sizes in the range of 100 nm ～ 400 nm, as particle size increased, the kinetic energy of ions produced from the particle increased with a power law relationship, consistent with experiment. Lastly our simulations indicated that ions from the surface of the particle are of higher energy, and therefore have lower detection efficiency.     

Effect of degree of substitution and molecular weight of carboxymethyl chitosan nanoparticles on doxorubicin delivery

The aim of this study was to evaluate the potential of carboxymethyl chitosan (CM‐chitosan) nanoparticles as carriers for the anticancer drug, doxorubicin (DOX). Different kinds of CM‐chitosan with various molecular weight (MW) and degree of substitution (DS) were employed to prepare nanoparticles through ionical gelification with calcium ions. Factors affecting nanoparticles formation in relation to MW and DS of CM‐chitosan were discussed. By the way of dynamic light scattering (DLS), TEM, and atomic force microscopy (AFM), nanoparticles were shown to be around 200–300 nm and in a narrow distribution. FTIR revealed strong electrostatic interactions between carboxyl groups of CM‐chitosan and calcium ions. DOX delivery was affected by the molecular structure of CM‐chitosan. Increasing MWs of CM‐chitosan from 4.50 to 38.9 kDa, DOX entrapment efficiency was enhanced from 10 to 40% and higher DS slightly improved the load of DOX. In vitro release studies showed an initial burst followed by an extended slow release. The DOX release rate was hindered by CM‐chitosan with high MW and DS. These preliminary studies showed the feasibility of CM‐chitosan nanoparticles to entrap DOX and the potential to deliver it as controlled release nanoparticles. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4689–4696, 2006     

Preparation of temperature‐ and pH‐sensitive,stimuli‐responsive poly(N‐isopropylacrylamide‐co‐methacrylic acid) nanoparticles

The effects of the monomer ratio, surfactant, and crosslinker contents on the particle size and phase‐transition behavior of the copolymer poly(N‐isopropylacrylamide‐co‐methacrylic acid) (PNIPAAm–MAA) were investigated with Fourier transform infrared, differential scanning calorimetry, and dynamic laser scattering techniques. In addition to the thermoresponsive property of poly(N‐isopropylacrylamide), ionized methacrylic acid groups brought pH sensitivity to the PNIPAAm–MAA copolymer particles. The polymer particle size varied with the amounts of the monomer ratio, surfactant, and crosslinker. As the monomer ratio and crosslinker content increased and the amount of the surfactants decreased, the particle size increased. The influence of the crosslinker content on the particle size was less significant than the effect of the monomer ratio and surfactants. When the temperature increased, the particles tended to shrink and decreased in size to near or below 100 nm. Particle sizes at 20°C decreased to less than 100 nm with increased surfactant content. The control of the particle size within the 100‐nm range makes PNIPAAm–MAA copolymer particles useful for biomedical and heavy‐metal‐ion adsorption applications. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Encapsulation and release of cladribine from chitosan nanoparticles

This study shows the potential of chitosan (CH) nanoparticles as both an oral and IV drug delivery system using the anticancer drug cladribine as a model drug. Smooth, spherical nanoparticles were prepared by the ionotropic gelation of CH with sodium tripolyphosphate. Nanoparticle size depended on degree of hydration, drug loading, and crosslinking conditions, with the smallest nanoparticles in the size range of 212 ± 51 nm. Cladribine was entrapped in the CH matrix with an entrapment efficiency of up to 62%, depending on the initial loading. The release of cladribine followed a near‐Fickian diffusion rate over the first several hours and then reached a plateau. A second release phase began after 30–40 h of incubation in the release medium, and proceeded until ～100 h. Loaded CH nanoparticles that were crosslinked with genipin showed a delayed release profile, with only 40% of loaded drug being released after 100 h. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Preparation and adsorption properties of chitosan–poly(acrylic acid) nanoparticles for the removal of nickel ions

Chitosan (CS) nanoparticles with different mean sizes ranging from 100 to 195 nm were prepared by ionic gelation of CS and poly(acrylic acid) (PAA). Variations in the final solution pH value and CS : PAA volume ratio were examined systematically for their effects on nanoparticle size, intensity of surface charge, and tendency toward particle aggregation. The sorption capacity and sorption isotherms of the CS–PAA nanoparticles for nickel ions were evaluated. The parameters for the adsorption of nickel ions by the CS–PAA nanoparticles were also investigated. The CS–PAA nanoparticles could sorb nickel ions effectively. The sorption rate for nickel ions was affected significantly by the initial concentration of the solution, sorbent amount, particle size, and pH value of the solution. The samples of nanoparticles were well correlated with Langmuir's isotherm model, and the adsorption kinetics of nickel correlated well with the pseudo‐second‐order model. The maximum capacity for nickel sorption deduced from the use of the Langmuir isotherm equation was 435 mg/g, which was significantly higher than that of the micrometer‐sized CS. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

Preparation and drug‐release behavior of 5‐fluorouracil‐loaded poly(lactic acid–4‐hydroxyproline–polyethylene glycol) amphipathic copolymer nanoparticles

Poly(lactic acid–4‐hydroxyproline–polyethylene glycol) (PLA–Hpr–PEG) was synthesized via melt copolymerization with stannous chloride as a catalyst activated by a proton acid. Copolymers with different poly(ethylene glycol) (PEG) concentrations (0.1, 0.5, 1, and 5 wt %) were synthesized and exhibited moderate molecular weights (weight‐average molecular weight = 9705–13,600 g/mol) and reasonable molecular weight distributions (weight‐average molecular weight/number‐average molecular weight = 1.35– 1.66). The structure of the polymers was verified with infrared spectroscopy and proton nuclear magnetic resonance spectroscopy. The nanoparticles were made by the nanoprecipitation method with PLA–Hpr–PEG. The size and size distribution of the nanoparticles were investigated with laser light scattering, and the surface morphology of the nanoparticles was investigated with transmission electron microscopy. The drug encapsulation efficiency and drug loading content were measured with ultraviolet absorption spectroscopy. The effects of various formulation parameters were evaluated. The prepared nanoparticles were spherical and greater than 100 nm in size. The drug loading content and encapsulation efficiency were greatly influenced by the amount of the copolymer and the volume of the solvent. The PEG content in the polymer could affect the release of drugs from the PLA–Hpr–PEG nanoparticles. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2654–2659, 2007     

Aqueous Colloidal Stability Evaluated by Zeta Potential Measurement and Resultant TiO2 for Superior Photovoltaic Performance

Controlling the morphological structure of titanium dioxide (TiO₂) is crucial for obtaining superior power conversion efficiency for dye‐sensitized solar cells. Although the sol–gel‐based process has been developed for this purpose, there has been limited success in resisting the aggregation of nanostructured TiO₂, which could act as an obstacle for mass production. Herein, we report a simple approach to improve the efficiency of dye‐sensitized solar cells (DSSC) by controlling the degree of aggregation and particle surface charge through zeta potential analysis. We found that different aqueous colloidal conditions, i.e., potential of hydrogen (pH), water/titanium alkoxide (titanium isopropoxide) ratio, and surface charge, obviously led to different particle sizes in the range of 10–500 nm. We have also shown that particles prepared under acidic conditions are more effective for DSSC application regarding the modification of surface charges to improve dye loading and electron injection rate properties. Power conversion efficiency of 6.54%, open‐circuit voltage of 0.73 V, short‐circuit current density of 15.32 mA/cm², and fill factor of 0.73 were obtained using anatase TiO₂ optimized to 10–20 nm in size, as well as by the use of a compact TiO₂ blocking layer.     

Formulation of Highly Functionalizable DNA Nanoparticles Based on 1,2‐Dithiolane Derivatives

We describe the formulation of synthetic virus models based on ionic compounds bearing the polymerizable 1,2‐dithiolane moiety. First, cationic amphiphiles containing the polymeric inducer were prepared and used to efficiently condense a DNA plasmid (pDNA) into a highly monodisperse population of small polymeric cationic DNA nanoparticles (NPs; D_h～100 nm). These nonspecific cationic particles were then functionalized with anionic PEGylated conjugates, also based on the 1,2‐dithiolane motifs, in order to produce stable and fully dispersible stealth DNA nanoparticles. Our results show that both ionic interactions and polymerization based on the 1,2‐dithiolane pattern occur and that they produce highly functionalizable nonviral DNA NPs.     

Functionalization of manganite nanoparticles and their interaction with biologically relevant small ligands: picosecond time-resolved FRET studies

We report molecular functionalization of the promising manganite nanoparticles La0.67Sr0.33MnO3 (LSMO) for their solubilization in aqueous environments. The functionalization of individual NPs with the biocompatible citrate ligand, as confirmed by Fourier transform infrared (FTIR) spectroscopy, reveals that citrates are covalently attached to the surface of the NPs. UV-VIS spectroscopic studies on the citrate functionalized NPs reveals an optical band in the visible region. Uniform size selectivity (2.6 nm) of the functionalization process is confirmed from high resolution transmission electron microscope (HRTEM). In the present study we have used the optical band of the functionalized NPs to monitor their interaction with other biologically important ligands. F?rster resonance energy transfer (FRET) of a covalently attached probe 4-nitrophenylanthranilate (NPA) with the capped NPs confirm the attachment of the NPA ligands to the surface functional group (-OH) of the citrate ligand. The FRET of a DNA base mimic, 2-aminopurine (2AP), with the NPs confirms the surface adsorption of 2AP. Our study may find relevance in the study of the interaction of individual manganite NPs with drug/ligand molecules.     

Globotriose-functionalized gold nanoparticles as multivalent probes for Shiga-like toxin

Compared to monovalent carbohydrates, multivalent carbohydrate ligands exhibit significantly enhanced binding affinities to their interacting proteins. Here, we report globotriose (P(k) ligand)-functionalized gold nanoparticle (AuNP) probes for the investigation of multivalent interactions with the B(5) subunit of Shiga-like toxin I (B-Slt). Six P(k)-ligand-encapsulated AuNPs (P(k)-AuNPs) of varying particle size and linker length were synthesized and evaluated for their potential as multivalent affinity probes by using a surface plasmon resonance competition assay. The affinity of these probes for the interacting proteins was greatly affected by nanoparticle size, linker length, and ligand density on nanoparticle surface. For example, the 20-nm 20-P(k)-l-AuNP, which had a relatively long linker showed a >10(8)-fold increase in affinity compared with the mono P(k) ligand. This intrinsic high-affinity AuNP probe specifically captured the recombinant B-Slt from Escherichia coli lysate, and the resulting purity of the B-Slt was >95 %. We also developed a robust P(k)-AuNP-based detection method for Slt-I by combining the technique with silver enhancement.     

Polystyrene latex particles bearing primary amine groups via soap‐free emulsion polymerization

Polystyrene latexes were prepared in the presence of an amino‐containing functional comonomer, N‐(3‐aminopropyl)methacrylamide hydrochloride (APMH), via soap‐free batch emulsion polymerization initiated by the cationic initiator 2,2′‐azobis(2‐amidinopropane) dihydrochloride. These latexes were characterized by studying the influence of the ionic comonomers on the polymerization kinetics, particle size, surface charge density and colloidal properties. The synthesized latexes were monodisperse with a final size between 100 and 600 nm depending on the APMH concentration. The initial polymerization rate and the particle number increased in accordance with the Smith–Ewart theory for soap‐free styrene emulsion polymerization with a hydrophilic functional comonomer. The final functionalization rate of the particles has been particularly studied with the intention of fitting the prepared latexes to be used in the immobilization of biological molecules for biological sample preparation and diagnostic applications. © 2020 Society of Chemical Industry     

Nylon 11/silica nanocomposite coatings applied by the HVOF process. I. Microstructure and morphology

Nylon 11 coatings filled with nanosized silica and carbon black have been produced using the high velocity oxy‐fuel (HVOF) combustion spray process. The physical properties and microstructure of coatings produced from nylon 11 powders with starting particle sizes of 30 and 60 μm have been evaluated as a function of the filler content, filler chemistry, and processing conditions. The nominal filler content was varied from 5 to 20 vol %. Co‐milling of the nano‐sized fillers with the polymer powders produced an embedded 4–8 μm thick filler layer on the surfaces of the polymer particles. Optimization of the HVOF processing parameters based on an assessment of the degree of splatting of polymer particles was accomplished by varying the jet temperature (via hydrogen/oxygen ratio). Gas mixtures with low hydrogen contents minimized polymer particle degradation. The filler was found to be agglomerated at the splat boundaries in the final coating microstructures. Aggregates of silanated silica and carbon black were of the order of 50 nm in size, whereas the aggregates of untreated silica and hydrophilic silica were of the order of 100 nm. The morphology of the polymer and the microstructure of the coatings depended on the filler surface chemistry and the volume fraction of the filler, as well as the initial nylon 11 particle size. Although all filled coatings had higher crystallinities than pure nylon 11 coatings, coatings produced from a smaller starting polymer particle size exhibited improved spatial distribution of the silica in the matrix and lower crystallinity. In addition, coatings prepared from smaller polymer particles had a higher density and lower porosity. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1684–1699, 2000     

Preparation of poly(DL‐lactide‐co‐glycolide) nanoparticles without surfactant

The preparation of poly(DL ‐lactide‐co‐glycolide) (PLGA) nanoparticles was performed by a dialysis method without surfactant or emulsifiers. The size of the PLGA nanoparticles prepared from dimethylacetamide (DMAc) as an initial solvent was smaller than that from acetone. The sizes of the PLGA nanoparticles from DMAc and acetone were 200.4 ± 133.0 and 642.3 ± 131.1 nm, respectively. The effects of the initial solvent selected to dissolve the copolymer and the lactide:glycolide ratio were investigated. The PLGA nanoparticles were spherical as revealed by the results of scanning electron microscopy and transmission electron microscopy observations. From these results it was shown that PLGA nanoparticles could be formed by the dialysis method without surfactant. The drug‐loading contents and efficiency were also dependent on the lactide:glycolide ratio and initial feeding amount of the drug. A higher lactide ratio resulted in higher drug loading and higher loading efficiency. However, a higher initial feeding amount of the drug resulted in higher drug loading and lower loading efficiency. Clonazepam was released for at least 2 days and the release rate was slower with a higher lactide:glycolide ratio and a larger amount of drug‐loading nanoparticles than that with a lower lactide:glycolide ratio and a smaller amount of drug‐loading nanoparticles. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2228–2236, 2001     

Effect of acrylic core–shell rubber particles on the particulate flow and toughening of PVC

Different types of acrylic core–shell rubber particles with a poly(butyl acrylate) (PBA) core and a grafted poly(methyl methacrylate) (PMMA) shell were synthesized. The average size of acrylic core–shell latex particles ranged from 100 to 170 nm in diameter, having the core gel content in the range of 35–80%. The melt blending behavior of the poly(vinyl chloride) (PVC) and the acrylic core–shell rubber materials having different average particle sizes and gel contents was investigated in a batch mixing process. Although the torque curves showed that the particulate flow of the PVC in the blends was dominant, some differences were observed when the size and gel content of the particles varied. This behavior can be attributed to differences in the plasticizing effect and dispersion state of various types of core–shell rubber particles, which can vary the gelatin process of the PVC in the mixing tool. On the other hand, the highest toughening efficiency was obtained using core–shell rubber particles with the smallest particle size (i.e., 100 nm). The results showed that increasing the gel content of the core–shell impact modifiers with the same particle size improved the particle dispersion state in the PVC matrix. The toughening efficiency decreased for the blends containing 100 and 170 nm rubber particles as the gel content increased. Nevertheless, unexpected behavior was observed for the blends containing 140 nm rubber particles. It was found that a high level of toughness could be achieved if the acrylic core–shell rubber particles as small as 100 nm had a lower gel content. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009