Surface Modification Of Silver Nanoparticles Research Articles

Surface-Modified Silver Nanoparticles and Their Encapsulation in Liposomes Can Treat MCF-7 Breast Cancer Cells.

Silver nanoparticles (AgNPs) have emerged as a promising tool for cancer treatment due to their unique physicochemical and biological properties. However, their clinical applications are limited by their potential cytotoxicity caused due to oxidation stress and non-specific cellular uptake pathways. To overcome these barriers, surface modifications of AgNPs have been proposed as an effective strategy to enhance their biocompatibility and specificity toward cancer cells. In this study, AgNPs were synthesised using the chemical reduction method and subsequently conjugated with various capping agents such as Polyvinylpyrrolidone (PVP) and Bovine Serum Albumin (BSA). Further, this study involves the synthesis of liposomes by using dipalmitoyl phosphatidylcholine lipid (DPPC) and cholesterol to increase the biocompatibility and bioavailability of AgNPs to MCF-7 breast cancer cells. In vitro, cytotoxicity studies were performed to determine which surface modification method exhibited the highest cytotoxic effect on the MCF-7 breast cancer cells, which was determined through the MTT assay. The AgNPs conjugated with BSA exhibited the highest cytotoxicity at the lowest dosage, with an IC50 of 2.5 μL/mL. The BSA-AgNPs induced a dose-dependent rise in cytotoxicity through the enhancement of nucleophilic dissolution of the AgNPs in cancer cells. In comparison, the unmodified AgNPs had an IC50 value of 3.0 μL/mL, while the PVP-modified AgNPs had an IC50 of 4.24 μL/mL. AgNPs encapsulated in liposomes had an IC50 value of 5.08 μL/mL, which shows that the encapsulation of AgNPs in liposomes controls their entry into cancer cells. The findings of this research have provided insights into the potential use of surface-modified AgNPs and liposomal encapsulated AgNPs as novel therapeutic tools to overcome the conventional treatment limitations of breast cancer cells.

High performance antibiofouling hollow fiber polyethersulfone nanocomposite membranes incorporated with novel surface-modified silver nanoparticles suitable for membrane bioreactor application

Surface-modified silver nanoparticles with amine, thiol, carboxyl, and the thiol-polyvinylpyrroldidone (PVP) functional groups were synthesized as functional filler for nanocomposite membranes for membrane bioreactor (MBR), with the aims to enhance antimicrobial effect of silver, while immobilizing silver nanoparticles inside the matrix of the membrane. Analyses by fourier transform infrared (FTIR), field emission scanning electron microscopy (FESEM), and dynamic light scattering (DLS) proved successful surface modification for each type of nanoparticles, with average particle sizes of 69, 20, 33, and 34 nm for amine, carboxyl, thiol and thiol-PVP modified silver nanoparticles, respectively. Polyethersulfone (PES) based nanocomposite hollow fiber membranes showed different morphology and performance in ultrafiltration and MBR experiments. The surface modifications were able to immobilize silver nanoparticles inside the membrane by providing proper interactions between the nanoparticles and polymer, reducing silver release compared to the unmodified nanoparticles. Modified nanoparticles changed the phase inversion, resulting in different morphology and average pore size in the range of 7.6–28.0 nm. The surface-modified nanoparticles with enhanced antimicrobial activity improved antifouling properties of the nanocomposite membranes, leading to interesting MBR performance improvements, with 122 % increase of flux, 23 % increase of chemical oxygen demand (COD) removal and flux recovery by over 30 %.

Fabrication and characterization of inner selective antibiofouling forward osmosis hollow fiber membranes for simultaneous wastewater treatment and desalination

Forward osmosis (FO) hollow-fiber membranes were prepared by in situ thin layer assembly of polyethyleneimine (PEI) on antifouling PES-based porous nanocomposite membranes during membrane formation by spinning and phase inversion, via incorporation of surface-modified silver nanoparticles (NPs) in the dope solution and addition of PEI in the bore liquid; after cross-linking with glutaraldehyde the FO selective layer was obtained at the lumen surface while the shell surface had ultrafilter (UF) properties. This design enabled the utilization of the FO membranes in active layer facing draw solution (DS) orientation to employ maximum effective osmotic pressure, while the UF layer in combination with the antibacterial NPs was supposed to reduce fouling by the wastewater used as feed solution (FS). The quality of the active layer assembly was characterized using atomic force microscopy and scanning electron microscopy analyses, as well as salt rejection, structural parameter (S), and molecular weight cut-off (MWCO) measurements. The separation performance of these membranes was evaluated in an osmotic membrane bioreactor (OMBR) system, showing for the best FO nanocomposite membranes less than 10% fouling and flux reduction over 5 cycles of operation over a total period of 5 days. The best-suited membrane showed promising separation performance in the OMBR system by providing 43.4 LMH water flux and only around 0.2 g/l specific reverse salt flux (SRSF) with 1 M NaCl and DI water serving as DS and feed, respectively. This study focused also on distinctive performance criteria in combined FO and OMBR systems, such as the membrane’s potential in a pretreatment step of brine streams (used as DS) to provide proper feed composition for RO units and introduced a new specific performance index (SPI) for better characterization of FO membranes which summarizes all essential characteristics of the membrane application, instead of using existing structural parameter equations for membrane characterization. The best-suited FO membrane offered an SPI of 778.2 gl−1 m−2 h−1, meaning 778.2 g/l reduction of TDS in DS per unit membrane surface area per hour.

Synthesis and Characterization of Indium Tin Oxide Nanowires with Surface Modification of Silver Nanoparticles by Electrochemical Method.

In this study, indium tin oxide nanowires (ITO NWs) with high density and crystallinity were synthesized by chemical vapor deposition (CVD) via a vapor–liquid–solid (VLS) route; the NWs were decorated with 1 at% and 3 at% silver nanoparticles on the surface by a unique electrochemical method. The ITO NWs possessed great morphologies with lengths of 5~10 μm and an average diameter of 58.1 nm. Characterization was conducted through transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and X-ray photoelectron spectroscope (XPS) to identify the structure and composition of the ITO NWs. The room temperature photoluminescence (PL) studies show that the ITO NWs were of visible light-emitting properties, and there were a large number of oxygen vacancies on the surface. The successful modification of Ag was confirmed by TEM, XRD and XPS. PL analysis reveals that there was an extra Ag signal at around 1.895 eV, indicating the potential application of Ag-ITO NWs as nanoscale optical materials. Electrical measurements show that more Ag nanoparticles on the surface of ITO NWs contributed to higher resistivity, demonstrating the change in the electron transmission channel of the Ag-ITO NWs. ITO NWs and Ag-ITO NWs are expected to enhance the performance of electronic and optoelectronic devices.

Synergetic effect of piezoelectricity and Ag deposition on photocatalytic performance of barium titanate perovskite

Modifying traditional photocatalysts has always been the focus of scientists’ efforts. Using piezoelectric potential to assist photocatalysis can improve catalytic efficiency. The catalytic performance of BaTiO3 was further enhanced by surface modification of silver nanoparticles deposited by a simple photoreduction method. The synergism among piezo-, photo-catalysis and the LSPR effect greatly enhanced the catalytic efficiency (more than 240%). The involved free radicals generated in the catalytic system and the cycle stability of the catalysts were examined. Based on the experimental results, an enhanced synergistic catalytic mechanism of BaTiO3 modified with Ag was proposed. The strategy presented here provides ideas for realizing the development of high-efficient catalysts for practical applications.

The Optoelectronic Nose.

How does one tell the difference between one molecule or mixture of molecules from another? Chemical sensing seeks to probe physical or chemical properties of molecular or ionic species (i.e., analytes) and transform that information into a useful and distinguishable output. The olfactory system of animals is the prototype of chemical sensing. Even for human beings (who are generally more visual than olfactory creatures), the sense of smell is one of our most basic capabilities, and we can discriminate among many thousands, and possibly even billions, of different odors. The chemical specificity of the olfactory system does not come from specific receptors for specific analytes (i.e., the traditional lock-and-key model of enzyme-substrate interactions), but rather olfaction uses pattern recognition of the combined responses of several hundred olfactory receptors.In analogy to olfaction, colorimetric sensor arrays provide high dimensional data from the color changes of chemically responsive colorants as they are exposed to analytes. These colorants include pH responsive dyes, Lewis acid/base indicators, redox dyes, vapochromics, and surface-modified silver nanoparticles. The color difference maps so created provide chemical sensing with high sensitivity (often down to ppb levels), impressive discrimination among very similar analytes, and exquisite fingerprinting of extremely similar mixtures over a wide range of analyte types, both in the gas and liquid phases. Such colorimetric arrays probe a wide range of the chemical reactivity of analytes, rather than the limited dimensionality of physical properties (e.g., mass) or physisorption (e.g., traditional electronic noses). Our sensor arrays are disposable and simple to produce by either inkjet or robotic dip-pen printing onto the surface of porous polymer membranes or even paper.Design of both sensor arrays and optical readers for their analysis has advanced to a fully self-contained pocket-sized instrument, the optoelectronic nose. Quantitative analysis requires appropriate chemometric methods for pattern recognition of data with inherently high dimensionality, e.g., hierarchical cluster analysis and support vector machines. A wide range of applications for the colorimetric sensor arrays has been developed, including personal dosimetry of toxic industrial chemicals, detection of explosives or fire accelerants, monitoring pollutants for artwork and cultural heritage preservation, quality control of foods and beverages, rapid identification of bacteria and fungi, and detection of disease biomarkers in breath or urine. The development of portable, high-accuracy instrumentation using standard imaging devices with the capability of onboard, real-time analysis has had substantial progress and increasingly meets the expectations for real-world use.

Polymeric membrane ion-selective electrodes with anti-biofouling properties by surface modification of silver nanoparticles

Polymeric membrane ion-selective electrodes (ISEs) have been widely applied in environmental analysis. In many cases of practical relevance, however, when these sensors are applied in complex samples, they could suffer from problems of biofouling (related to microorganisms and biofilms) which may shorten the sensors’ lifetimes and cause the measurement errors. Herein, we describe a robust and effective method to endow the ISE membranes with anti-biofouling properties based on surface modification of silver nanoparticles (Ag NPs). The ISE membrane is modified with the hydrophilic polydopamine (PDA) followed by in-situ formation of Ag NPs. The PDA modification enhances anti-adhesive properties of the ISE membrane by increasing the surface hydrophilicity, while Ag NPs impart strong anti-microbial properties to the membrane. A classical polymeric membrane K+-ISE has been chosen as a model. Compared to the unmodified K+-ISE, the Ag NPs modified K+-ISE exhibits significantly improved anti-biofouling properties in terms of the low viability and adhesion rates of bacteria while retaining its original potentiometric ion response properties. Moreover, Ag NPs on the sensor surface show an excellent long-term stability. We believe that the proposed approach can be extended to improve the anti-fouling abilities of other polymeric membrane-based electrochemical sensors for detection in complex environmental samples.

Surface‐enhanced Raman scattering as a tool to study cationic surfactants exhibiting low critical micelle concentration

AbstractThe collection of surface‐enhanced Raman scattering (SERS) by silver nanocolloids was used to identify the critical micelle concentration (CMC) of three cationic surfactants in 0.5‐M NaCl solutions: hexadecyltrimethylammonium bromide, dodecyltrimethylammonium bromide, and benzalkonium chloride. Despite structural similarity between the three test surfactans, differences of the shape and size of the respective micelles affected the corresponding SERS signals. The CMC values determined by this method agreed with the respective values measured by conventional methods, including fluorescence probing and electrical conductivity measurements. The potential for the application of SERS technique for low CMC determination without surface modification of silver nanoparticles by a Raman‐active molecule was also demonstrated.

Selective colorimetric detection of HgII using silver nanoparticles modified with Apple and Nigella Sativa seed extracts and β-Cyclodextrin

The surface modification of silver nanoparticles (AgNPs) with natural products could be environmentally friendly method of manufacturing provided that their inherent properties could be substantiated. Therefore, AgNPs were synthesized from AgNO3 using β-Cyclodextrin and seed extracts from Apple (Ap-AgNPs) and Nigella Sativa species (N-AgNPs). AgNPs thus prepared were incorporated as a colorimetric sensor for determining HgII ions and proved to be both selective and adequately sensitive in detecting mercuric ions. These nanoparticles are found to show a limit of detection (LOD) of 29.0 nM and 58.0 nM for Ap-AgNPs and N-AgNPs, respectively. The results demonstrate the higher sensitivity of Ap-AgNPs over N-AgNPs with maximum absorption causing a color shift to blue due to HgII ions and the resulted color change from yellow to pale yellow, even colorless upon addition of HgII in AgNPs solutions. The results validate the applicability of nanoparticles as a sensor with the potential for rapid and on-site detection of HgII ions.

Nano-formulations for Diagnostics and Therapeutics of Foot-and-Mouth Disease in Animals

Background:Foot and mouth disease (FMD) is caused by a virus of the genus Aphthovirus, family Picornaviridae which includes several members of medical importance, Multiple subtypes or antigenic variants within each serotype, which make the vaccine from one serotype does not confer protection against the other serotype.Methods:Green synthesized silver nanoparticles were functionalized with FMDV antigen /antibody. The functionalized silver nanoparticles were characterized by UV -Visible spectrophotometer, Fluorescence Spectrophotometer etc. Immunomodulation study, efficacy and toxicity tests on the final product were carried out.Results:The protein profile after immunoprecipitation with AntiFMD antibody analysed on a 12.5% SDS-PAGE which corresponded to the viral proteins. The western blot analysis confirmed the same pattern. When the infected mice were treated with functionalised silver nanoparticles, all mice were recovered from the disease within 12 hrs. The field trial of these nanoformulations showed 100% recovery of the animals with minimum neutralizing antibody without any other physiological problems.Conclusion:Surface modification of silver nanoparticles can create multifunctional materials with potential applications. Nanoformulations developed by functionalizing whole FMD viral protein /antibody with that of silver nanoparticles, elicite an optimal immuno-protective response and as diagnostic agent against foot and mouth disease causing virus The easy method of preparation of nanoparticle, the flexibility of functionalization techniques, long shelf life without cold chain protection and minimum single low dosage reveals the feasibility of this nanoformulation applications ranging from prophylactic vaccines, diagnostics, therapy for all infections leading to autoimmune diseases.

Improved mechanical and antibacterial properties of thermoplastic polyurethanes by efficient double functionalization of silver nanoparticles

ABSTRACTWhen making nanocomposites, there is a big challenge to obtain both functional and mechanical enhancement. In this study, a new in situ polymerization methodology for the incorporation of surface modified silver nanoparticles (AgNPs) in a thermoplastic polyurethane matrix was developed. AgNPs with contents ranging from 0 to 1.5 wt % were used. A double functionalization of the nanoparticles with oleic acid was performed, which lead to a reaction of carboxylic acid groups in the nanoparticle's surface with isocyanate groups of the 4,4′‐methylene diphenyl diisocyanate monomer as corroborated from the Raman results. The successful incorporation of the nanoparticles was verified with EDS, TGA, and Raman measurements. Thermal properties of nanocomposites were investigated by DSC. AgNPs made positive impact in two ways: first, increased more than twice the elastic modulus, as studied via nanoindentation measurements and second, based on the inhibition zone method, great bactericidal effectiveness for nanocomposites containing 1.5 wt % AgNPs was observed for Escherichia coli. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46180.

Effect of Surface Modification of Silver Nanoparticles on the Proliferation of Human Lung Squamous Cell Carcinoma (HTB182) and Bronchial Epithelial (HBE) Cells In Vitro

Effect of Surface Modification of Silver Nanoparticles on the Proliferation of Human Lung Squamous Cell Carcinoma (HTB182) and Bronchial Epithelial (HBE) Cells<i> In Vitro</i>

The effect of sol–gel surface modified silver nanoparticles on the protective properties of the epoxy coating

In this study, the effect of surface modified silver nanoparticles on the corrosion protection of an epoxy coating on mild steel was studied.

Chiral supramolecular nanoparticles: The study of chiral surface modification of silver nanoparticles by cysteine and its derivatives

Many studies dealing with modified nanoparticles are based on the assumption that organic molecules form single-layer structure on their surface. In this work, we suggest a novel approach to study the important phenomenon of supramolecular chirality at metal nanoparticle surfaces. Self-assembly layers of several ligands, namely l-cysteine, l-penicillamine and α-methyl-l-cysteine, on different silver nanoparticles were studied by means of absorption and electronic circular dichroism spectroscopy in UV–vis range and surface enhanced Raman scattering spectroscopy. The amount of ligands bonded to the surface of nanoparticles was quantified by absorption spectroscopy. Quantification was performed indirectly by measuring concentration of free ligands in solution after incubation with absorption labels 4-toluenesulfonyl chloride or 1-fluoro-2,4-dinitrobenzene. Data were obtained for ligands at concentration levels from 10−6 to 10−3 mol L−1. The results showed the significantly lower adsorbed molecules of methyl derivatives of cysteine than for cysteine themselves. This fact could explain the unexpected behavior of silver nanoparticles that provide ECD bands in the presence of cysteine and not in the presence of its derivatives.

Synthesis and characterization of cysteine functionalized silver nanoparticles for biomolecule immobilization.

A facile method for the aqueous phase synthesis of cysteine-functionalized silver nanoparticles by potato extract has been reported in the present work. These functionalized nanoparticles were then used for the covalent immobilization of a biomolecule, alkaline phosphatase, on its surface through carbodiimide coupling. Different reaction parameters such as cysteine concentration, reducing agent concentration, temperature, pH and reaction time were varied during the nanoparticles' formation, and their effects on plasmon resonance were studied using Ultraviolet-visible spectroscopy. Fourier transform infrared spectroscopy was used to confirm the surface modification of silver nanoparticles by cysteine and the particle size analysis was done using particle size analyzer, which showed the average nanoparticles' size of 61 nm for bare silver nanoparticles and 201 nm for the enzyme-immobilized nanoparticles. The synthesized nanoparticles were found to be highly efficient for the covalent immobilization of alkaline phosphatase on its surface and retained 67% of its initial enzyme activity (9.44 U/mg), with 75% binding efficiency. The shelf life of the enzyme-nanoparticle bioconjugates was found to be 60 days, with a 12% loss in the initial enzyme activity. With a simple synthesis strategy, high immobilization efficiency and enhanced stability, these enzyme-coated nanoparticles have the potential for further integration into the biosensor technology.

Surface modification of silver nanoparticles with dopamine dithiocarbamate for selective colorimetric sensing of mancozeb in environmental samples

We report the use of dopamine dithiocarbamate functionalized silver nanoparticles (DDTC-Ag NPs) as a colorimetric probe for sensing of mancozeb in environmental water and fruit juice samples. The DDTC-Ag NPs were characterized by UV–visible spectrometry, FT-IR, 1H NMR, dynamic light scattering (DLS) and transmission electron microscopy (TEM), respectively. It is observed that the mancozeb induces the aggregation of DDTC-Ag NPs via Michael addition and enamine formation between DDTC-Ag NPs and mancozeb, leading to a color change from brownish orange to bluish, which can be seen with naked eyes, and measured by UV–visible spectrometry, TEM and DLS. The response is linearly dependent on the concentration of mancozeb in the range from 5×10−5 to 3×10−4M, and the limit of detection is 21.1×10−6M. The present method is very close to the gas chromatography (GC) for the analysis of mancozeb in apple juice sample. The proposed method provided a very fast and efficient procedure to detect mancozeb from various environmental water (tap, canal and river) and fruit juice (apple, grape, and tomato) samples with minimized sample preparations.

Synthesis of PPy–silver nanocomposites via in situ oxidative polymerization

Silver nanoparticles were synthesized by chemical reduction method. The surface of silver nanoparticles (SNPs) was modified using polyvinylpyrrolidone to make them more compatible with pyrrole. Surface-modified SNPs were dispersed in pyrrole and polymerized via in situ oxidative polymerization technique. The molar ratio of monomer unit to initiator and dopant was 1:1:1 and the weight percent of SNPs in polymer matrix was varied from 1 to 10. The properties of polypyrrole–silver nanocomposites have been characterized using Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscope, transmission electron microscope, thermo-gravimetric analysis and four-probe resistivity meter. All these characterizations indicate that the polypyrrole–silver nanocomposite is successfully synthesized via in situ oxidative polymerization and electrical extent shows suitable conductivity.

Surface Immobilization of Engineered Nanomaterials for in Situ Study of their Environmental Transformations and Fate

The transformation and environmental fate of engineered nanomaterials (ENMs) is the focus of intense research due to concerns about their potential impacts in the environment as a result of their uniquely engineered properties. Many approaches are being applied to investigate the complex interactions and transformation processes ENMs may undergo in aqueous and terrestrial environments. However, major challenges remain due to the difficulties in detecting, separating, and analyzing ENMs from environmental matrices. In this work, a novel technique capable of in situ study of ENMs is presented. By exploiting the functional interactions between surface modified silver nanoparticles (AgNPs) and plasma-deposited polymer films, AgNPs were immobilized on to solid supports that can be deployed in the field and retrieved for analysis. Either negatively charged citrate or polyethylene glycol, or positively charged polyethyleneimine were used to cap the AgNPs, which were deployed in two field sites (lake and marina), two standard ecotoxicity media, and in primary sewage sludge for a period of up to 48 h. The chemical and physical transformations of AgNPs after exposure to different environments were analyzed by a combination of XAS and SEM/EDX, taken directly from the substrates. Cystine- or glutathione-bound Ag were found to be the dominant forms of Ag in transformed ENMs, but different extents of transformation were observed across different exposure conditions and surface charges. These results successfully demonstrate the feasibility of using immobilized ENMs to examine their likely transformations in situ in real environments and provide further insight into the short-term fate of AgNPs in the environment. Both the advantages and the limitations of this approach are discussed.

Surface Modification of Silver Nanoparticles in Phase Change Materials for Building Energy Application

In this report, we propose a direct silica-coating technique to enhance the stability of silver nanoparticles as a doping additive to enhance the thermal conductivity phase change materials (PCM). Our experimental results show that a thin layer of silica can protect silver nanoparticles and help retain its intrinsic metallic properties, when subjected to harsh corrosive environments found in PCM media. Furthermore, PCM materials can be effectively used to cool the ambient temperature of a building room by up to ~1.2 degree Celsius. Our preliminary results demonstrate a real opportunity in air-conditioning energy-savings for buildings using enhanced PCM.

Encapsulation of Silver Nanoparticles in a Polystyrene Matrix by Miniemulsion Polymerization and Its Antimicrobial Activity

Surface-modified silver nanoparticles (NAg) were encapsulated into a polystyrene (PS) matrix by in situ miniemulsion polymerization. Silver nanoparticles were modified with 3-aminopropyltrimethoxysilane (APTMS) that acts as a coupling agent and costabilizer in the polymerization reaction. The PS-Nag nanocomposites synthesized via miniemulsion polymerization were made at two different concentrations of the initiator (0.7 and 2.5 g/L in H2O); at higher concentration of the initiator the conversion and efficiency of encapsulation increases, and the average particle size decreases. The PS-NAg composites showed excellent antimicrobial performance toward bacteria such as Escherichia coli and Staphylococcus aureus.