Silver Salt Solution Research Articles

Biocomposite Materials Derived from Andropogon halepensis: Eco-Design and Biophysical Evaluation.

This research work presents a "green" strategy of weed valorization for developing silver nanoparticles (AgNPs) with promising interesting applications. Two types of AgNPs were phyto-synthesized using an aqueous leaf extract of the weed Andropogon halepensis L. Phyto-manufacturing of AgNPs was achieved by two bio-reactions, in which the volume ratio of (phyto-extract)/(silver salt solution) was varied. The size and physical stability of Andropogon-AgNPs were evaluated by means of DLS and zeta potential measurements, respectively. The phyto-developed nanoparticles presented good free radicals-scavenging properties (investigated via a chemiluminescence technique) and also urease inhibitory activity (evaluated using the conductometric method). Andropogon-AgNPs could be promising candidates for various bio-applications, such as acting as an antioxidant coating for the development of multifunctional materials. Thus, the Andropogon-derived samples were used to treat spider silk from the spider Pholcus phalangioides, and then, the obtained "green" materials were characterized by spectral (UV-Vis absorption, FTIR ATR, and EDX) and morphological (SEM) analyses. These results could be exploited to design novel bioactive materials with applications in the biomedical field.

Hydrocortisone을 담지한 Chitosan silver nanoparticles의 약물흡수 및 방출

The final goal of this research was to improve a treatment for allergy rhinitis using chitosan-hydrocortisone silver nanoparticles based on hydrocortisone-deposited chitosan. The nanoparticles were produced by depositing hydrocortisone in chitosan, generating a reaction with highly reactive silver, and placing the nanoparticles into the nasal mucosa. Silver nanoparticles were manufactured after chitosan deposition and the optimal hydrocortisone concentration supporting the highest drug delivery efficiency was identified. For efficient DDS(Drug Delivery Systems applications, an adsorption experiment was performed before silver nanoparticle production according to the hydrocortisone concentration. In addition, a release experiment with different amounts of silver salt was performed to determine the optimal hydrocortisone and silver salt concentrations for producing chitosan-hydrocortisone silver nanoparticles. The amount released was investigated as a parameter of time. When the hydrocortisone concentration was 0.05g, the chitosan adsorption rate was highest at 48%. A release experiment was conducted at 36℃ in PBS, which is similar to the human body condition, while changing the silver salt amount. At approximately 60 hours, the absorbance was constant, indicating that hydrocortisone was emitted from the chitosan particles. In the cases of the 50㎕ reaction and 100㎕ reaction, the release rate was 14.17% and 12.92%, respectively. Otherwise, in the case of using 10㎕ silver salt solution for the reaction, 99.6% of the amount absorbed was released, showing the highest efficiency as a drug delivery agent.

Anticandidal activity of green synthesised silver nanoparticles and extract loaded chitosan nanoparticles of Euphorbia prostata

This study aimed to synthesize the silver nanoparticles (SNPs) and loaded chitosan nanoparticles (LCNPs) using Euphorbia prostata based on their anticandidal activity. Antioxidant capacity and the total phenolic and total flavonoid content of plant samples and synthesized nanoparticles (NPs) were also evaluated. SNPs and LCNPs were prepared, respectively using chemical reduction of silver salt solution and ionotropic gelation method. The anticandidal activity was assessed by broth micro-dilution method and the antioxidant activity was determined using free-radical scavenging assays. The synthesized NPs after the optimization process were found to be spherical with sizes ranging from 12 to 100 nm. Spectroscopic analysis of NPs showed the appearance of peaks in prescribed wavelength ranging between 402 and 493 nm. The synthesized NPs showed potent anticandidal activity compared to the free extract. The SNPs formulations NpEPM 7.5 and NpEPMR 7.5, showed significantly low MIC values ranging between 2 and 128 µg/mL. In the case of LCNPs, NpEPM (4:1) and NpEPME (4:1) also showed lower MIC values ranging from 32 to 256 µg/mL. The plant samples as well as NPs showed antioxidant potential. In addition, plant extracts and NPs possess the potent biological potential and can be further investigated through in vivo experiments.

Морфофункціональні зміни гіпоталамо-адреналової системи щурів під дією наночастинок срібла при ожирінні

The aim of this study was to compare the effect of silver salt and silver nanoparticles on the morphofunctional state of the hypothalamic-adrenal system in obese rats. The experiment was carried out on 24 male rats at the age of 6 months. The rats of the control group received standard food. In other groups of animals, obesity was induced using a diet-induced model of metabolic disorders. The rats, modeled for obesity, were divided into several groups. Animals of different groups received NaCl solution, silver nitrate solution and silver nanoparticle solution for 10 days, respectively. After the end of the experiment, the hypothalamic nuclei and adrenal glands, prepared according to the appropriate histological methods, were taken from the animals. In the paraventricular nucleus of the hypothalamus, a small-cell area of neurons was examined. In the adrenal glands of rats, cells of three zones of the cortex were examined: glomerular, fascicular, and reticular. The results of the study showed that obesity led to the increase of functional activity in the nuclei of neurons in the small-cell region of the PVN of the rat hypothalamus. The cells of the glomerular zone of the adrenal cortex had the maximum increase in functional activity, the fascicular zone – a moderate increase in functional activity, and no significant changes were recorded in the reticular zone. It was shown that the silver salt solution caused the increase in the functional activity of PVN neurons in the hypothalamus of obese rats. In the glomerular zone, the parameters of the functional activity of cells increased significantly, in the fascicular zone, the parameters of cell nuclei decreased to the greater extent, in the reticular zone, mainly the parameters of the nuclei increased. It was investigated that the solution of silver nanoparticles caused the intensification of PVN cells in the hypothalamus of obese rats. In the glomerular zone of the adrenal cortex, a significant increase in cell parameters was observed, in the fascicular zone – the increase in the cytoplasm parameters, in the reticular zone – the decrease mainly in the parameters of cell nuclei. In general, the administration of the solution of silver nanoparticles led to more pronounced activation of PVN cells of the hypothalamus and adrenal cortex in obese rats than the silver salt.

Identification of the most stable silver cluster ions produced under plasma solution conditions

For several decades, silver nanoparticles have been grown from a solution of silver salts under electrode-free plasma conditions. Yet, details of the atom-by-atom growth from 1Ag+ to iAgm n+ (cluster of m atoms with n charge) is not known. Here, we report with theoretical calculations the thermodynamically driven growth of silver clusters up to m = 5 and n = 4 in water. These pathways are elucidated from high quality DFT energies of reaction and formation with a continuum solvation model, and all possible isomers for each cluster size are considered. We find that (i) all steps are favourable, and (ii) the most stable pathway involves neither neutral clusters nor those with high positive charges, but rather those with relatively low charged states. The most stable pathway can be understood based on the extra stability associated with clusters that are sigma-aromatic, however, clusters with higher charges violate this rule. The results for the most favoured species, (1Ag2 0 and 1Ag4 2+) are in agreement with experimental findings, and we postulate that 1Ag3 + and 2Ag5 2+ should also be present in appreciable quantities for future spectroscopic confirmation. We use time-dependent density functional theory to predict optical spectra of the most important clusters as a guide to future experiments.

A facile and green approach for the fabrication of nano-biocomposites by reducing silver salt solution into silver nanoparticles using modified carboxymethyl cellulose for antimicrobial potential

Biopolymers represent an excellent alternative to their synthetic analogues for use as natural stabilizers in the development of unique metal nanoparticles, owing to their attractive properties including low cost, environmentally friendly nature, renewability, biodegradability and biocompatibility. Herein, a new, straightforward chemical approach was investigated to synthesize Ag nanoparticle-decorated sulfonated carboxymethyl cellulose (AgNPs/S-CMC) nano-biocomposite materials with strong antimicrobial properties. Sodium carboxymethyl cellulose (CMC) was firstly chemically modified into sulfonated CMC (S-CMC), which was used as an environmentally friendly stabilizer and a nonhazardous reducing agent towards the fabrication of AgNPs in aqueous solution. Four types of AgNPs/S-CMC nano-biocomposites were fabricated to investigate the effect of the concentration of the S-CMC stabilizing/reducing agent on the fabrication of AgNPs, the physiochemical properties and the antimicrobial activity performance. The fabrication of AgNPs was investigated by UV-Vis spectra through characteristic surface plasmon resonance peak analysis, and the chemical structures were characterized by FTIR, FE-SEM, EDAX and XRD analyses. The synthesized AgNPs/S-CMC nano-biocomposites were tested as a potential antimicrobial agent, confirmed by the agar diffusion method, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) analysis against Gram-positive B. subtilis and Gram-negative E. coli bacterial strains. The obtained results confirm that the proposed nano-biocomposites exhibit excellent antimicrobial activity against both Gram-positive and Gram-negative bacterial strains.

Facile and Fast Transformation of Nonluminescent to Highly Luminescent Metal-Organic Frameworks: Acetone Sensing for Diabetes Diagnosis and Lead Capture from Polluted Water.

Metal-organic frameworks (MOFs) stand as one of the most promising materials for the development of advanced technologies owing to their unique combination of properties. The conventional synthesis of MOFs involves a direct reaction of the organic linkers and metal salts; however, their postsynthetic modification is a sophisticated route to produce new materials or to confer novel properties that cannot be attained through the traditional methods. This work describes the postsynthetic MOF-to-MOF transformation of a nonluminescent MOF (Zn-based Oxford University-1 material [Zn-BDC, where BDC = 1,4-benzene dicarboxylate] (OX-1)) into a highly luminescent framework (Ag-based Oxford University-2 material [Ag-BDC] (OX-2)) by a simple immersion of the former in a silver salt solution. The conversion mechanism exploits the uncoordinated oxygen atoms of terephthalate linkers found in OX-1, instead of the unsaturated metal sites commonly employed, making the reaction much faster. The materials derived from the OX-1 to OX-2 transformation are highly luminescent and exhibit a selective response to acetone, turning them into a promising candidate for manufacturing fluorometric sensors for the diagnosis and monitoring of diabetes mellitus. Our methodology can be extended to other metals such as lead (Pb). The fabrication of a polymer mixed-matrix membrane containing OX-1 is used as a proof-of-concept for capturing Pb ions (as pollutants) from water. This research instigates the exploration of alternative methodologies to confer MOFs with special aptitudes for photochemical sensing or for environmental applications such as water purification.

Photo-assisted bio-fabrication of silver nanoparticles using Annona muricata leaf extract: exploring the antioxidant, anti-diabetic, antimicrobial, and cytotoxic activities

Green synthesis of metal nanoparticles is reputed to have a robust range of biomedical applications. Silver nanoparticles (AgNPs) bio-fabricated using aqueous leaf extract of Annona muricata were characterized and evaluated for in-vitro antioxidant, lipid peroxidation inhibition, anti-diabetic and antimicrobial activities as well as cytotoxicity in human keratinocyte cells (HaCaT).The extract induced colour change of silver salt solution which absorbed at 420 nm and confirmed the formation of AgNPs. FTIR showed that free amide and hydroxyl groups were responsible for the synthesized nanoparticles. Both XRD and SAED confirmed the crystalline nature of the particles with face centered cubic (FCC) phase. The zeta potential revealed -27.2 mV potential and average distribution size of 35 nm. DLS indicated that the majority of the particles were 86.78 nm size and with a polydispersity index (PDI) of 0.329.AgNPs displayed strong activities against DPPH (IC50 = 51.80 μg/ml), ABTS (IC50 = 30.78 μg/ml), α-amylase (IC50 = 0.90 μg/ml) and α-glucosidase (IC50 = 3.32 μg/ml). The particles exhibited a dose-dependent inhibition of Fe2+-induced lipid peroxidation with effective antimicrobial activity against a battery of bacterial strains and cytotoxicity in HaCaT cell line. These findings revealed the potential biomedical applications of the particles and further work will be required to establish its molecular mechanism of action.

Modeling the Process of Synthesis of Nanoparticles into Fibrous Materials by the Method of Chemical Reduction

Silk fibers served as a matrix for the reduction of nanoparticles from a silver salt solution. A mathematical model describing the dependence of the total content of reduced silver on a fiber Y on the input parameters X1, X2, X3, X4 (silver concentration in the treatment solution, concentration of reducing agent, temperature and duration of the reduction process, respectively) is constructed. A chemically substantiated nonlinear regression model and a two-layer perceptron are proposed, which make it possible to obtain mathematical expressions for the dependence of the silver content on silk fibers on the input parameters. Both models adequately reflect the experimental data – the error of the regression model is 0.16, the error of the two-layer perceptron is 0.14.

Facile and eco-benign fabrication of Ag/Fe2O3 nanocomposite using Algaia Monozyga leaves extract and its' efficient biocidal and photocatalytic applications.

Noble metal/metal oxide nanocomposites are pet and spellbound candidates in biomedical and catalytic fields because of their awestruck properties. This report put forward the facile and environmentally friendly fabrication of Ag/Fe2O3 nanocomposite using the eqeous extract of Algaia Monozyga leaves. The Ag/ Fe2O3 bimetallic nanocomposite was prepared using AgNO3, FeCl3 (anhydrous) and plant leaves extract as a natural source for reduction and stabilization of this nanocomposite. We prepared a separate solution of Silver and Iron salts and upon addition of this solution to the plant extract, the conversion of colour to brown appears within 10 min at constant stirring at 350 rpm. To confirm the synthesis of nanocomposite, UV-vis spectroscopy, Scanning electron microscopy (SEM), EDX and X-ray diffraction spectroscopy were used. The as prepared nanocomposite was used for photocatalytic activity in degradation of Methylene Blue (MB) in the presence of light which shows effective photocatalytic activity. The antimicrobial activities were also determined for nanocomposite which were found to be efficient against human pathogenic multidrug resistant bacteria. The Ag/Fe2O3 nanocomposite significantly preventing the growth of Staphylococcus aureus, E.coli QH4 and Pseudomonas putida with zones of inhibition 23 (±0.5), 21 (±0.4) and 19 (±0.4) mm, respectively.The eco-benignly synthesized Ag/Fe2O3 nanocomposite could be a desired material for efficient remediation of toxic organic pollutants and microbes.

Antibacterial properties and in vivo studies of tannic acid-stabilized silver–halloysite nanomaterials

AbstractTannic acid-stabilized silver nanoparticles were synthesized in situ on halloysite clay nanotubes. The synthesis strategy included simple steps of tannic acid adsorption on clay nanotubes and further particle formation from silver salt solution. Pristine halloysite nanotubes as well as amino-modified clays were used for silver stabilization in water or ethanol. The materials were tested for antibacterial performance using three different methods. All of the materials produced showed antimicrobial activity. The pristine halloysite-based material with ~5 nm particles produced using ethanol as the solvent and tannic acid as the reducing agent showed the greatest antibacterial activity against Serratia marcescens. The materials were tested in vivo on Caenorhabditis elegans nematodes to ensure their safety, and they showed no negative effects on nematode growth and life expectancy.

One-pot phytosynthesis of nano-silver from Mentha longifolia L.: their characterization and evaluation of photodynamic potential

The present study deals with the ecofriendly one-pot synthesis and stabilization of silver nanoparticles (AgNPs) by using aqueous extract of Mentha longifolia branches. Spectrophotometric analysis of different ratios of reactants revealed that a 1 to 9 ratio of plant extract and silver salt solution respectively is the most suitable proportion for synthesis. Synthesis of AgNPs was confirmed initially by the observation of change in the color of the reaction mixture which was carried out at 60 °C by using 3 mM of silver salt and the pH of the reaction medium was maintained at 5.22. A characteristic surface plasmon resonance (SPR) band was observed at 495 nm of light wavelength. SEM images revealed that the nanoparticles are in ∼20–80 nm and are anisotropic and nearly spherical while EDX analysis showed the presence of elemental Ag with ∼90% signal intensity. Size distribution analysis of AgNPs was performed by dynamic light scattering technique and AgNPs were found in the range of ∼8–30 nm. ROS quantification revealed that the AgNPs have a quantum yield of 0.09 Φ which provides them the ability to proteolytically treat cancer and other microbial pathogenic cells. AgNPs did not report any photothermal activity to be used as photodynamic agents. These findings explain the redox potential of M. longifolia to bio-fabricate AgNPs and their abilities to generate ROS may help to curb dreading diseases.

Preparation, characterization and application of polymeric thin films containing silver and copper nanoparticles with bactericidal activity

The aim of this work was to prepare and characterize self-assembled thin films (SATFs) of poly(allylamine hydrochloride) and poly(acrylic acid) containing silver (AgNPs) and copper nanoparticles (CuNPs) for their subsequent application in the disinfection of an industrial wastewater. The AgNPs and CuNPs were synthesized by direct irradiation of SATFs with ultraviolet light after immersion in silver and copper (II) salt solutions. At the end of the self-assembly procedure, the SATFs were thoroughly characterized by different instrumental techniques, including glow discharge optical emission spectroscopy (GD-OES), atomic force microscopy (AFM), field emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS), inductively coupled plasma optical emission spectrometry (ICP-OES), and transmission electron microscopy (TEM). In general, the GD-OES spectra confirmed the incorporation/formation of AgNPs and CuNPs/copper (II) oxide in the SATFs. Moreover, it was observed through the FESEM and TEM analyses that a change in the salt concentration promoted a variation in the nanoparticle size incorporated into the SATFs (10−250 nm for AgNPs, and 10−170 nm for CuNPs). The disinfection process of the industrial wastewater with the SATFs reduced the total count of coliforms by 91 and 100 % compared to the raw industrial wastewater (untreated), being the SATF prepared with a concentration of 0.1098 mmol Ag+ L−1 the most efficient material. Finally, the SATFs developed in this work present great potential for a possible application in the tertiary treatment of industrial wastewater due to ease of application, reduced environmental impact, and satisfactory inhibitory action.

МОРФОФУНКЦІОНАЛЬНИЙ СТАН ВІСЦЕРАЛЬНОЇ БІЛОЇ ЖИРОВОЇ ТКАНИНИ ЩУРІВ ЗА УМОВ РОЗВИТКУ ОЖИРІННЯ ТА ПРИ ВВЕДЕННІ НАНОЧАСТИНОК СРІБЛА

There was studied the morphofunctional state of the visceral white adipose tissue of rats with obesity and after introduction of silver salt solution and silver nanoparticles solution. In particular, we analyzed the morphofunctional changes in the visceral white adipose tissue of rats on a high-calorie diet, as well as the effects of the silver nitrate solution and the silver nanoparticles solution at a dose of 1 mg / 1 kg body weight and 0.5 mg / 1 kg body weight on the morphofunctional state of the visceral white adipose tissue of rats on a high-calorie diet. There were established morphofunctional changes in cells of the rats white adipose tissue on the high-calorie diet and with the introduction of silver preparations in different concentrations. The condition of the adipose tissue was evaluated on the basis of the following parameters: the relative mass of the visceral fat, the cross-sectional area of adipocytes, the relative number of adipocytes per unit area. There were compared effects of administration to animals with obesity of the silver nitrate solution at a dose of 1 mg / 1 kg body weight and 0.5 mg / 1 kg body weight, as well as a of the silver nanoparticles solution at a dose 1 mg / 1 kg body weight and 0.5 mg / 1 kg of body weight. All the above silver preparations reduced the manifestations of obesity in animals which were maintained in a high-calorie diet. In addition to the form of the silver preparation (silver nitrate solution or silver nanoparticle solution), its concentration is important. The highest efficiency was shown after the administration of the silver nanoparticles solution at a dose 0.5 mg / 1 kg of body weight. In rats of this experimental group, the studied parameters not only reached the control values, but they also exceeded them, which indicates expressed influence of the drug on the obesity manifestations. In addition, the rats showed signs of fat depletion.

Femtosecond laser fabrication of silver nanostructures on glass for surface enhanced Raman spectroscopy

We report on an optimized fabrication protocol for obtaining silver nanoparticles on fused silica substrates via laser photoreduction of a silver salt solution. We find that multiple scans of the laser over the surface leads to a more uniform coverage of densely packed silver nanoparticles of approximately 50 nm diameter on the fused silica surface. Our substrates yield Raman enhancement factors of the order of 1011 of the signal detected from crystal violet. We use a theoretical model based on scanning electron microscope (SEM) images of our substrates to explain our experimental results. We also demonstrate how our technique can be extended to embedding silver nanoparticles in buried microfluidic channels in glass. The in situ laser inscription of silver nanoparticles on a laser machined, sub-surface, microfluidic channel wall within bulk glass paves the way for developing 3D, monolithic, fused silica surface enhance Raman spectroscopy (SERS) microfluidic sensing devices.

Ag2O-Ag/CAC/SiO2 composite for visible light photocatalytic degradation of cumene hydroperoxide in water

A visible light-active composite, Ag2O-Ag/CAC/SiO2, was produced by loading an aqueous silver salt solution onto the layer of hydrated calcium aluminate cement coating on porous SiO2 sphere. The mild cement hydration condition induced the formation of in situ Ag2O precipitates on the cement surface which were partially decomposed to metallic Ag after drying and appropriate heat treatment at 200°C to enhance both decomposition and crystallinity of Ag2O. The coexistence of Ag2O and Ag in the composite was clearly confirmed by XRD and XPS, and the mechanisms for the formation of Ag2O particles on the hydrated cement layer and for the photocatalytic degradation of CHP were also suggested. The photocatalytic activity of Ag2O-Ag/CAC/SiO2 composite (calcined at 200°C), evaluated under UV and visible lights irradiation through the photodecomposition of CHP in water quantified by HPLC, was two times higher than that of Ag2O-Ag/CAC/SiO2 composite (dried at 45°C), and able to completely decompose CHP in 5h. Additionally, the photostability of Ag2O-Ag/CAC/SiO2 photocatalyst remained unchanged for 5 recycling tests.

Oligodynamic Boons of Daptomycin and Noble Metal Nanoparticles Packaged in an Anti-MRSA Topical Gel Formulation.

Daptomycin is a popular anti-MRSA antibiotic, especially for surgical wound infections. The side-effects of Daptomycin dosage through intravenous administration have prompted the experimental use of topical Daptomycin. Also, combinatorial drug therapy involving noble metal nanoparticles and conventional antibiotics have proved beneficial in the past. The synergistic oligodynamic effect of Daptomycin with nanoparticles for topical application was attempted for the first time in this work. The present study was focused on topical gel formulation containing Daptomycin combined with mycogenic gold, silver and bimetallic gold and silver nanoparticles and evaluation of their synergistic antibacterial effect against an MRSA strain. An efficient approach for fungal growth was discussed wherein the biomass was cultivated under non-limiting conditions, followed by the addition of gold salt, silver salt and bimetallic (Gold and silver) solution. The metal salt reduction efficacy was evaluated using Cyclic Voltammetry. Formation of nanoparticles was observed by visual color changes and confirmed by UV-visible characteristic peaks. The mycosynthesized metallic and bimetallic nanoparticles were characterized by various advanced analytical methods. Further, Daptomycin was combined with nanoparticles in a topical gel formulation. The properties of the topical gels were evaluated and their antimicrobial activity was investigated against an MRSA strain associated with burn infections though disc diffusion method. Formation of nanoparticles was observed by visual color changes and confirmed by UVvisible characteristic peaks. XRD spectra revealed the crystalline nature of nanoparticles whereas TEM confirmed the presence of spherical nanoparticles. The bio fabricated nanoparticles were characterized using ICP-MS, XRD and TEM. The UV-Visible spectrum of the gold, silver, bimetallic nanoparticles showed a characteristic peak at 550 nm, 450 nm, and 480 nm, respectively. ICP-MS of the residual salt concentration depicted more than 75% bioconversion of metal salt to metal nanoparticles. TEM showed the formation of uniform, spherical monometallic nanoparticles. XRD results were in sync with the dynamic light scattering experiments which determined that the gold, silver, bimetallic nanoparticles ranged between 10-20 nm, 5-30 nm, and 20-40 nm respectively and were crystalline in nature with the face centered cubic symmetry. Topical gels combining Daptomycin and nanoparticles were formulated and characterized. The in-vitro drug release studies indicated controlled release of antibiotic from bimetallic nanoparticles and Daptomycin combination in topical gel formulation. The MIC values reduced for the combinatorial drug and the average synergistic antimicrobial effect was 37% and the increase in efficacy of Daptomycin due to the synergistic effect with bimetallic nanoparticles was 43%. Topical gels were formulated using the biologically synthesized gold, silver and bimetallic gold-silver nanoparticles and modern-day antibiotic Daptomycin to combat burn infections. The topical gel formulations showed enhanced antimicrobial activity against methicillin-resistant Staphylococcus aureus at lower MIC values as compared to individual nanoparticle or antibiotic. The best results were obtained with bimetallic nanoparticles in topical gel formulation as it assisted in controlled drug release up to 94.6% and improved antimicrobial effect i.e. 43%.

Improvement of Dyeing and Antimicrobial Properties of Cotton Fabrics Through Pre-treatment with Silver Nanoparticles

Silver nanoparticles have been synthesized by chemical reduction of silver salt solution, characterized by its surface plasmon resonance peak in absorption spectra at 425 nm. The studies were carried out by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDX) and Fourier transform infrared spectroscopy (FTIR). The size and size distribution of these nanoparticles have also been examined using particle size analyzer, the average size of the particles is found to lie between 5 nm and 50 indicated the presence of micrometer-size conglomerates composed of much smaller particles. Chemical analysis performed with the use of EDX revealed that the powder contains about 72% of silver. The findings support the size and shape of the synthesized nano silver particles. These nanoparticles have been applied to cotton, by usual exhaustion process and manifested the improved microbial resistance. The dyeing behavior of the treated fabrics with reactive yellow 2 has been studied and the build-up of dye, measured as color strength in terms of K/S values. The higher K/S values are obtained when the Ag nano is anchored in the fiber matrix. Improved color strength with good wash and light fastness is also obtained after treatment of fabrics with nanoparticles.

Hygienic coatings with bioactive nano-additives from Senna occidentalis-mediated green synthesis

Nowadays urban populations spend 90% of their time in buildings where microbial growth lead to hazardous environments which produce health problems characterized by irritation of the respiratory tract, infections, allergies and asthma. Some research lines seek to obtain antimicrobial materials to prevent such health problems. Green synthesis of different nanoparticles was carried out to explore their antimicrobial potential. Solutions of silver, copper, cerium, lanthanum and zinc salts were used as source of metal ions for the synthesis process. Aqueous plant extract from Senna occidentalis, a small shrub, was used, for the first time, as reducing and stabilizing agent to obtain additives to bioactive coatings. The stable synthesis products were evaluated by UV–vis spectroscopy and their antimicrobial properties were assessed. Other characterizations by transmission electron microscopy and Fourier transformed infrared spectroscopy were also performed. Silver and copper nanoparticles were stable over time. However, only silver nanoparticles showed antibacterial and antifungal activity and were used for obtaining antimicrobial waterborne acrylic paints. The formulation with 25 mg/100 g resulted in efficient inhibition of the fungal and bacterial biofilm.

Microwave-enhanced silver nanoparticle synthesis using chitosan biopolymer: optimization of the process conditions and evaluation of their characteristics

AbstractA facile and green synthesis of silver nanoparticles (AgNPs) by aqueous chitosan solution and microwave irradiation is proposed as a cost effective and environmentally benevolent alternative to chemical and physical methods. With this aim, different amounts of chitosan solution (3–9 ml) with several concentration (4–6% w/v) and 3 ml of the silver salt solution (0.5% w/v) were mixed and microwave irradiated for 100 s. Response surface methodology (RSM) was used to evaluate the effects of the amount and concentration of chitosan solution on the particle size and concentration of the synthesized AgNPs. The optimum AgNPs synthesis process was obtained using 9 ml of 0.4% (w/v) chitosan solution. The spherical and more stable AgNPs synthesized at optimum conditions had particle size, concentration, polydispersity index (PDI) and zeta potential values of 37 nm, 69 ppm, 0.557 and +50 mV, respectively. The synthesized AgNPs indicated strong antifungal activity towardAspergillus flavusand high antibacterial activity against both Gram-positive (Staphylococcus aureus) and Gram-negative bacteria (Escherichia coli).