Size Of AgNPs Research Articles

UV-mediated photochemical synthesis and investigation of the antiviral properties of Silver nanoparticle-polyvinyl butyral nanocomposite coatings as a novel antiviral material with high stability and activity

Effectively developing new antimicrobial surfaces for viral diseases requires considerable research, money, and time. Moreover, new species of microorganisms and pathogens are constantly appearing or entering from other regions, which can cause epidemics or pandemics. The ongoing presence of SARS-CoV-2 underscores the need to develop new antimicrobial materials. In this context, a novel UV-irradiated photochemical in-situ synthesis method is introduced for producing durable, long-lasting antiviral silver-polymer (AgNP-PVB) nanocomposite coatings. These coatings are intended to mitigate infectious disease transmission across various frequently touched surfaces, such as door handles, keypads, bank encoders, telephone locks, lift buttons, etc. Additionally, the significance of the size and concentration of AgNP in influencing the physical and antiviral properties of these nanocomposite coatings is illustrated. Detailed studies of AgNP-PVB coatings were conducted using X-ray diffraction, Raman spectroscopy, atomic force microscopy (AFM), and ultraviolet-visible-near-infrared spectroscopy, and contact angle measurements. The antiviral properties of the coatings were evaluated by a one-step reverse transcription real-time polymerase chain reaction (one-step qRT‒PCR) using synthetic SARS-CoV-2 RNA. Raman spectra signatures confirm AgNPs in the PVB matrix by matching identified peaks in X-ray diffractograms. AFM analysis revealed a reduction in AgNP size in the nanocomposite with an increase in the irradiation duration from 5 to 30 min. Spectroscopic results corresponding to AFM measurements highlighted specific wavelengths related to different AgNP size ranges. Contact angle measurements suggest that antiviral activity can be predicted by calculating the surface free energy (SFE) of the sample. As the SFE value increases, antiviral activity decreases. Nanocomposite coatings (with concentrations of 150, 200, 500, and 1000 ppm AgNP) are effective in reducing the activity of SARS-CoV-2, indicating their potential as long-acting preventive agents against viral infections. A methodology incorporating a specialized algorithm was devised for the application of the investigated coatings, which also integrates 3D scanning and printing techniques for fabricating complex geometry flexible protective cover. Subsequently, this coating was applied to produce a protective cover for the widely utilized public object, the door handle, employing 3D printing technology. As a result of the work, a long-term, durable antiviral AgNP-PVB nanocomposite coating with varying AgNP sizes (ranging from 15 to 118 nm) and concentrations (150, 200, 500, and 1000 ppm) was successfully developed.

Size-dependent antibacterial efficacy of silver nanoparticles from a green synthesis method: Effects of extract quantity and origin

BackgroundSilver nanoparticles (AgNPs) are known for their antibacterial characteristics. The green synthesis method, in which plant extracts are used for AgNP preparation, has attracted attention recently since it provides an eco-friendly approach. However, there are many operating conditions for this green synthesis method, and a correlation between the antibacterial efficiency and AgNP characteristics is needed to maximize the bactericidal efficacy. MethodsAgNPs were synthesized via green synthesis methods from green tea leaf (GT) and Cassia seed (CS) extracts at 9:1, 1:1, and 1:9 precursor-to-extract v/v ratios. The resulting AgNPs were tested for antibacterial activity against S. aureus and the antioxidant level. Significant findingsThis study revealed a robust quantitative correlation between antibacterial activity and AgNP size, with an R2 value of 0.92. Green-synthesized AgNPs with an average particle size of 25 nm (GT) and 12 nm (CS) had a minimum inhibitory concentration (MIC) of 25 µg mL−1 and 5 µg mL−1, respectively. The enhanced antibacterial activity of AgCS is attributed to its smaller particle size. Additionally, we propose the use of a silver precursor to extract-dry-weight ratio (in mole g−1) to represent an operating parameter for the green synthesis method. The resulting AgNP sizes showed a weak negative relationship with this ratio.

Green synthesis of silver nanoparticles for their antifungal activity against anthracnose disease causing Colletotrichumcapsici

Anthracnose disease caused by Colletotrichum capsici, is a major fungal issue in chilies (Capsicum annuum L.) worldwide, leading to a reduction in global production. It can be controlled by using synthetic fungicides, but these fungicides can hamper the environmental and ecological balance. As a result, alternative approaches are needed to control this important fungal disease. In this study, economically feasible silver nanoparticles (AgNPs) were manufactured and demonstrated antifungal activity against anthracnose disease causing Colletotrichum capsici. AgNPs were synthesized from Colchicum luteum leaf extract. Physico-chemical characterization confirmed the synthesis, average size, and shape of AgNPs. The AgNPs were spherical in shape, with an average size of 11.75 nm. The isolated fungal pathogen causing anthracnose in chili was identified as C. capsici. The antifungal activity of AgNPs, AgNO3, and a fungicide was evaluated, with AgNPs showing the strongest inhibitory impact on the mycelial growth of C. capsici. In an in vitro leaflet assay, AgNPs demonstrated significant efficacy in inhibiting fungal proliferation on chili leaves. The results highlight the ability of AgNPs as antifungal agents against C. capsici, surpassing the effectiveness of both AgNO3 and conventional fungicide treatments. These findings advocate for continued investigation into the practical application of AgNPs as a promising alternative strategy for managing fungal diseases in agricultural settings.

Green synthesis of Superparamagnetic Iron Oxide and Silver Nanoparticles in Satureja hortensis Leave Extract: Evaluation of Antifungal Effects on Botryosphaeriaceae Species.

In recent years, green synthesis methods of metallic nanoparticles (MNPs) have been attractive because of the more facile, cheaper, and appropriate features associated with biomolecules in MNPs biosynthesis. This research represented an easy, fast, and environmentally friendly method to biosynthesis of superparamagnetic iron oxide nanoparticles (SPIONPs) and silver nanoparticles (AgNPs) by the Satureja hortensis leaf extract as stabilizer and reducer. The SPIONPs synthesized in co-precipitation method. The biosynthesized SPIONPs and AgNPs were studied their antifungal effects against three Botryosphaeriaceae plant pathogens, Botryosphaeria dothidea, Diplodia seriata, and Neofusicoccum parvum. UV-visible spectra (UV-Vis), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), field emission scanning electron microscopy (Fe-SEM), energy-dispersive X-ray spectroscopy (EDX), and vibrating-sample magnetometer (VSM) analyses were used to evaluate the physicochemical properties and verify the formation of green synthesized SPIONPs and AgNPs. UV-Vis spectra revealed absorption peaks at 243 and 448 nm for SPIONs and 436 nm for AgNPs, respectively. Microscopic and XRD analysis showed that SPIONPs and AgNPs was found spherical in shape with an average particle size of SPIONPs and AgNPs 10 and 12 nm, respectively. The antifungal test against Botryosphaeriaceae species showed that SPIONPs and AgNPs possessantifungal properties against B. dothidea, D. seriata, and N. parvum. However, AgNPs exhibits greaterantifungal activity than SPIONPs. Theresultsof thecytotoxicitytests of SPIONs and AgNPs on the MCF-7 cell line showed that AgNPs was significantly more cytotoxictowardsthe MCF-7 cell line, whereas nosignificant cytotoxiceffect was recorded by SPIONs. Therefore, these biosynthesized MNPs could be substituted for toxic fungicides that are extensively applied in agriculture and contribute to environmental health and food safety.

Pharmacological Effect of In Vitro Antioxidant Property and Green Synthesis of Silver Nanoparticles (AgNPs) Utilizing Murraya koenigii Antibacterial Application

ABSTRACT Background: Nonessential heavy metals pose a significant threat to human health due to their toxicity. Mercury, in particular, is identified as a hazardous metal. The study aims to detect mercury using colorimetric analysis with Murraya koenigii, emphasizing the eco-friendliness of the method. Aims and Objectives: The primary objective is to detect mercury using a colorimetric analysis method employing Murraya koenigii. Additionally, the study aims to investigate the eco-friendliness of this detection method. Materials and Methods: Colorimetric analysis was conducted using Murraya koenigii to detect mercury. Ultraviolet-visible (UV-vis) spectroscopy was employed to detect the formation of silver nanoparticles (AgNPs), with a characteristic surface plasmon resonance (SPR) band observed. X-ray diffraction (XRD) data analysis was performed to determine the crystalline nature and size of AgNPs. Scanning electron microscopy (SEM) was utilized to visualize the morphology of AgNPs. Fourier transform infrared (FTIR) spectroscopy was employed to identify functional groups involved in reducing silver ions. Antibacterial properties of synthesized AgNPs were tested against various microorganisms, including Escherichia coli, Staphylococcus aureus, Streptococcus mutans, and Enterococcus faecalis. Results: Mercury was successfully detected using colorimetric analysis with Murraya koenigii. Formation of AgNPs was confirmed by UV-vis spectroscopy, with a characteristic SPR band at 418 nm. AgNPs were found to be crystalline with an average size of 5.20 nm, as determined by XRD analysis. SEM images revealed spherical and polycrystalline AgNPs. FTIR spectra indicated the involvement of the -OH group of compounds in the extract in reducing silver ions. Synthesized AgNPs exhibited antibacterial properties against various microorganisms. Conclusion: A sustainable and eco-friendly method for synthesizing AgNPs using Murraya koenigii extract was successfully developed. This method not only detected mercury but also demonstrated antibacterial properties against various microorganisms. The study underscores the health implications of nonessential heavy metals, emphasizing the importance of eco-friendly detection and mitigation methods.

Viability and Proliferation Assessment of Gingival Fibroblasts Cultured on Silver Nanoparticle-Doped Ti-6Al-4V Surfaces.

To investigate the biocompatibility of silver nanoparticle (AgNP)-doped Ti-6Al-4V surfaces by evaluating the viability and proliferation rate of human gingival fibroblasts (HGFs)-as the dominant cells of peri-implant soft tissues-seeded on the modified surfaces. AgNPs (sizes 8 nm and 30 nm) were incorporated onto Ti-6Al-4V specimen surfaces via electrochemical deposition, using colloid silver dispersions with increasing AgNP concentrations of 100 ppm, 200 ppm, and 300 ppm. One control and six experimental groups were included in the study: (1) control (Ti-6Al-4V), (2) 8 nm/100 ppm, (3) 8 nm/200 ppm, (4) 8 nm/300 ppm, (5) 30 nm/100 ppm, (6) 30 nm/200 ppm, and (7) 30 nm/300 ppm. HGF cell primary cultures were isolated from periodontally healthy donor patients and cultured in direct contact with the group specimens for 24 and 72 hours. The cytotoxicity of AgNP-doped Ti-6Al-4V specimens toward HGF was assessed by the MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) and BrdU (5-bromo-2'-deoxyuridine) assay tests. Calcein AM and ethidium homodimer (EthD-1) fluorescent stains were used to determine the live and dead cells. The morphology and attachment properties of the HGFs were determined via scanning electron microscopy (SEM). Energy dispersive x-ray (EDX) analysis confirmed the presence of AgNPs on the specimens. The MTT test revealed that AgNPs of both sizes and all concentrations presented a decreased cellular metabolic activity compared to the control discs. All concentrations of both sizes of AgNPs affected the cell proliferation rate compared to the control group, as revealed by the BrdU assay. Overall, cytotoxicity of the modified Ti-6Al-4V surfaces depended on cell exposure time. Observation via confocal microscopy confirmed the results of the MTT and BrdU assay tests. Specifically, most cells remained alive throughout the 72-hour culture period. SEM images revealed that adjacent cells form bonds with each other, creating confluent layers of conjugated cells. The findings of the present study indicate that Ti-6Al-4V surfaces modified with 8 nm and 30 nm AgNPs at concentrations of 100 ppm, 200 ppm, and 300 ppm do not produce any serious cytotoxicity toward HGFs. The initial arrest of the HGF proliferation rate recovered at 72 hours. These results on the antibacterial activity against common periodontal pathogens, in combination with the results found in a previous study by the same research group, suggest that AgNP-doped Ti-6Al-4V surfaces are potential candidates for use in implant abutments for preventing peri-implant diseases.

Characterization of Tridax procumbens amines with a potential to synthesize silver nanoparticles

Our previous findings showed that amines from Tridax procumbens (Family: Asteraceae) were responsible for the synthesis of silver nanoparticles. T. procumbens is a weed plant with rich source of medicinal compounds. In the current work, we studied the initial characterization of bioactive compounds by LC-MS, an essential tool for the characterization and identification of low molecular compounds. Further the isolated compounds were investigated for silver nanoparticle synthesis. The leaf extracts examined revealed many novel amine derivative compounds reported for the first time mainly belonging to the group of free amines: n-Pentylhydrazine hydrochloride, 2-Nitrobenzenesulfonyl chloride, 1,7-Dichlorooctamethyltetrasiloxane, 5-Chloro-1,2,4-trihydroxybenzene, 3-Chloro-2-hydroxy-5-(trifluoromethyl)pyridine and 2-(Diphenylphosphino) ethyltriethoxysilane and conjugated amines: 5-Methoxy-diisopropyltryptamine, 4-Chlorophenoxyacetic acid, Diphenhydramine, Erucamide, n(4-((2-(2,5-dimethoxybenzylidene)hydrazino)carbonyl)ph)-4-me-benzenesulfonamide and 1,3,5-Trithia-2,4,6-tristannacyclohexane, 2,2,4,4,6,6-hexamethyl. Characterization by UV-Vis spectra, XRD, EDX and TEM revealed well separated spherical shaped AgNPs size ranging 8-50 nm. These findings suggest that further work could be extended to isolate and elucidate the structures of the identified molecules using powerful instruments such as HPLC-MS, HPLC-NMR and high resolution-MS (HR-MS). Further biotechnological approaches towards synthesis of novel metals will be enhanced to promote green chemistry technology for the synthesis of nanoparticles.

Biosynthesis, characterization and study of the application of silver nanoparticle for 4-nitrophenol reduction, and antimicrobial activities

Silver nanoparticles (AgNPs) were synthesized from Vigna unguiculata (L) Walp extracted leaves, and characterized. The UV–Visible spectrum showed a peak between 411 and 415 nm at the Plasmon absorbance of the AgNPs. TEM showed that the size of AgNPs ranged from 5 to 13 nm. It was spherical with an average size of 11.08 nm. The size of AgNPs was 7 ± 6 nm and disperse in water. The AgNPs effectively reduced 4-Nitrophenol (4-NP) to 4-aminophenol (4-AP) in the presence of NaBH4. The AgNPs exhibited a strong antioxidant and antibacterial activity against Gram-negative bacteria: Escherichia coli (E. coli) and Klebsiella pneumonia and Gram-positive: Bacillus pumilus and Staphylococcus aureus. The average zones of inhibition of AgNPs were: 29 mm for Staphylococcus aureus, 23 mm for Bacillus pumilus, 17 mm for Klebsiella pneumonia and 15 mm for Escherichia coli (E. coli). Thus, AgNPs has exhibted good antibacterial activity compared to antibiotics drug and 4-NP reduction.

The effects of biological and chemical silver nanoparticles along with aerobic and anaerobic training protocols on tissues: Morphological and histopathological evaluation.

Nanotechnology and its byproducts are used increasingly considering its global nanotechnology market size and many applications in the health field. The aim of the present study was to investigate the effect of aerobic and anaerobic exercises on cellular uptake of nanoparticles in body tissues. Fusarium oxysporum was used to synthesize biological AgNPs in silver nitrate solution and UV-vis spectrophotometer; XRD and TEM were used to confirm production of nanoparticles. Moreover, 45 male Wistar rats were purchased and randomly divided into 9 equal groups including healthy control groups, aerobic preparation, anaerobic preparation, biological AgNPs, chemical AgNPs, biological AgNPs+aerobic preparation, biological AgNPs+anaerobic preparation, chemical AgNPs+ aerobic preparation, chemical AgNPs+anaerobic preparation. In order to induce aerobic and anaerobic preparation and to create tissue adaptations, male rats completed two types of aerobic and anaerobic protocols three sessions per week for 10 weeks. At the end of the study, sampling was done for histopathology study. The size and shape of AgNPs was 20-30 nm and spherical to polygonal, respectively. The results showed that anaerobic exercise was significantly effective in weight loss. The chemical nanoparticle group led to more intensive tissue degradation in all variables and there were no significant tissue changes in the aerobic, anaerobic, the biological nanoparticles + aerobic and anaerobic groups. It seems that biological AgNPs are more effective than chemical AgNPs on body tissues and chemical AgNPs lead to more tissue damage in most variables. RESEARCH HIGHLIGHTS: There were severe degradative histological effects in the chemical AgNPs groups compare biological AgNPs groups, in terms of most variables.

Green synthesis of lichenan-decorated silver nanoparticles for catalytic hydrogenation of organic dyes and bacterial disinfection

Developing an eco-friendly and efficient homogeneous catalyst for treating complex wastewater containing toxic organic pollutants and bacteria is in significant demand. Herein, ultra-small Ag nanoparticles (NPs)-loaded random coil lichenan nanocomposite (L-AgNP) was prepared through a low-cost and green one-step in-situ reduction strategy using lichenan as the reducing agent. The random coil of lichenan acted as a micro-reactor to disperse and stabilize AgNPs via the Ag-O bonding interaction. In the participation of NaBH4, L-AgNP nanocomposite could achieve greater catalytic efficiency for catalyzing reduction of 4-nitrophenol (∼120 s, 34.34 × 10−3 s−1) with the smaller size of AgNPs or the higher content of Ag. The nanocatalyst also exhibited outstanding catalytic efficiency for congo red, rhodamine B, methylene blue, and methyl orange. The L-AgNP could be easily recycled through ethanol precipitation and continuously reused for ten cycles with a tiny loss of conversion rate. Furthermore, L-AgNP also displayed favorable antibacterial activity, inhibiting the growth of Escherichia coli and Staphylococcus aureus with more than 98 % disinfection ratio. This work provides a green strategy to develop polysaccharide-based multifunctional homogeneous catalysts focusing on wastewater purification.

Probing the structural and spectroscopic characteristics of Ag2O-modified Li2O–CaO–B2O3 glasses doped with Nd2O3

Currently, there is growing interest in Ag2O doping in oxide glasses through optimal selection of excitation wavelengths to achieve efficient luminescence via either up or down-conversion processes. In this present work, we report the influence of Ag nanoparticles/aggregates on the structural and spectroscopic characteristics of melt-quenched Ag2O - co-doped (19.5-x)Li2O+70B2O3+10CaO+0.5Nd2O3+xAg2O glasses. Systematic studies were conducted using XRD, Raman spectroscopy, HR-TEM, MAS-NMR, UV–Visible–NIR, Photoluminescence, and decay kinetics techniques. The XRD analysis conclusively indicates the absence of crystalline peaks. However, HR-TEM analysis showed a reduction in the size of AgNPs from 14 nm to 11 nm with an increase of Ag2O concentration from 0.25 mol% to 0.5 mol%, respectively. The RAMAN and MAS-NMR (11B and 7Li) revealed the modification in the local structure induced by the Ag2O as revealed by the predominant borate structural units, and silver (Ag) acted as a modifier in the glass matrix. The absorption spectra of all samples exhibit a characteristic peak of Nd3+ ions. Interestingly, the LCBNd0.5Ag0.5 glass sample exhibits the SPR peak at 416 nm, indicating that the lower limit of Ag2O in LCBNd0.5 is <0.5 mol%. Luminescence studies at different excitation wavelengths (350, 525, and 584 nm) reveal the predominant emission at 877 nm and 1058 nm, whose emission intensity increased with Ag2O concentration. Samples with Ag2O-doped LCBNd glasses exhibit identical lifetime values, indicating the absence of luminescence-quenching and the presence of Ag aggregates leading to the SPR effect. Based on our findings, the LCBNd0.5Ag0.5 sample demonstrated superior performance to other samples, with the highest emission under an excitation of 350 nm.

Insight into the role of metal support interface through the synergistic effect between Ag and α-Bi2Mo3O12 support for the selective oxidation of propylene to acrolein

Pre-synthesized morphologically tailored size and shape selective silver nanoparticles (AgNPs) decorated on bismuth molybdate support (AgNPs/α–Bi2Mo3O12) using simple wet impregnation method was employed. The prepared AgNPs/α-Bi2Mo3O12 nanocatalysts were tested in the selective partial oxidation of propylene to acrolein reaction. The introduction of well-defined size and shape of AgNPs on α–Bi2Mo3O12 is greatly promoted the strong metal support interactions (SMSI), creation of oxygen vacancies (Ov) and high propylene adsorption binding energy (calculated by DFT). The strong metal support interactions between Ag and α-Bi2Mo3O12 is clearly elucidated by the high quality HRTEM and STEM–HAADF microscopic images. In addition, surface atomic molar ratio measured by XPS analysis determined the key redox properties of AgNPs/α–Bi2Mo3O12 system and their influence on the overall catalytic efficiency in the oxidation of propylene via reduction of Mo6+ to Mo5+ initiated at low temperatures in Ag/α–Bi2Mo3O12 system. The Mo reduction is further confirmed by the activated oxygen removal from the MoO42– moieties after Ag incorporation on α–Bi2Mo3O12. Thus, confirmed the oxidation reaction pathway follows a Mars–van–Krevelen process. Further, DFT calculations supported the propylene adsorption is more favorable over Ag/α–Bi2Mo3O12 than bare α–Bi2Mo3O12 support. The propylene oxidation performance over Ag/α–Bi2Mo3O12 system was 5.5 times higher than bare α–Bi2Mo3O12 support, probably due to an enabled strong metal support interaction and increased oxygen vacancies.

Mikania micrantha silver nanoparticles exhibit anticancer activities against human lung adenocarcinoma via caspase-mediated apoptotic cell death

Green-mediated synthesis of nanoparticles has earned a promising role in the area of nanotechnology due to their biomedical applications. This study describes the synthesis of silver nanoparticles (AgNPs) using Mikania micrantha leaf extract and its functional activities against cancer. The synthesis of AgNPs was confirmed using Ultraviolet-Visible (UV-Vis) spectrum that exhibited an absorption band at 459 nm. The bioactive compounds of M. micrantha leaf extract that functioned as reducing and capping agents were confirmed by a shift in the absorption bands in Fourier Transform Infra-red Spectroscopy (FT-IR). Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) studies validated the spherical shape and size of AgNPs, respectively. Energy Dispersive Spectroscopy (EDS) analysis revealed the presence of elemental silver. The crystalline nature of AgNPs was confirmed by the X-ray Diffraction Analysis (XRD). AgNPs effectively induced cytotoxicity and prevented A549 cell colony formation in a dose-dependent manner. Treatment of A549 cells with AgNPs also increased DNA damage, which was coupled with elevated lipid peroxidation and decreased antioxidant enzymes such as glutathione (GSH), glutathione-s-transferase (GST), and superoxide dismutase (SOD). Following AgNPs treatment, the mRNA expression levels of the pro-apoptotic genes as well as the activities of caspases were significantly elevated in A549 cells while the expression levels of anti-apoptotic genes were downregulated. Our study demonstrates the potential of the synthesised AgNPs for cancer therapy possibly targeting the apoptotic pathway.

Chemically reduced silver nanoparticles: preparation and applications

By virtue of their unique physiochemical properties, silver nanoparticles (AgNPs) have attracted enormous research interest for versatile applications. It is critical to study the effect of the microstructure – for example, the shape and the size of AgNPs – on their performance. Herein, AgNPs with varying shapes and sizes were synthesized by varying the manner that the reducing agent sodium borohydride (NaBH4) was added (i.e. multistep and one-step reduction methods) and then were studied for photocatalysis of dyes and electrocatalytic oxidation of glucose. The results showed that triangular AgNPs, spherical AgNPs or a mixture of triangular- and spherical-shaped AgNPs was obtained from the multistep reduction method, whereas only spherical-shaped AgNPs were yielded from the one-step reduction method. The sizes could be manipulated by changing the concentrations of the reagents or the reaction temperature. The triangular-shaped and smaller-sized AgNPs were more effective for photocatalysis of dyes, and the degradation percentage of methylene blue was enhanced to 95% for the silver (Ag)–titanium dioxide (TiO2) complex from 50% for pure titanium dioxide. Moreover, the spherical-shaped AgNPs with a smaller size could effectively detect glucose at a very low concentration of 5–10 mM with an excellent glucose tolerance.

Ultrasound-assisted facile and green preparation of Ag nanoparticle conductive ink for printing electronics

The development of low-cost, high-efficiency, and environment-friendly methods for the preparation of Ag nanoparticle (NP) conductive inks is key to promoting the application of such inks for printing flexible electronic components. This article presents an effective method for preparing a AgNP ink by reducing silver compounds in a polyol solution with ultrasonication. When the silver solution was ultrasonicated at 640 W, 21-nm AgNPs were readily produced within 5 min, and the particles grew considerably to 53 nm as the reaction was continued for 15 min. Thereafter, the NP size increased marginally with further increase in reaction time. When the reaction was conducted for a fixed duration of 15 min and the ultrasonic power was increased from 480 to 760 W, the AgNP size decreased from 63 to 48 nm. During ultrasonication, the bubble eruption in the solution generates large temperature and pressure gradients, inducing the rapid reduction of the Ag(I) to Ag(0). Printing experiments revealed that the synthesized AgNP ink has good inkjet printability. During the sintering of the printed film, the bridge connections between large particles increased and the interparticle voids decreased gradually, resulting in a decrease in film resistivity. A relatively low resistivity of 40×10−5 Ωcm was obtained when the flexible AgNP pattern was heated at 250 °C for 80 min. The facile synthesis process and the favorable conductive properties of the obtained ink render this preparation method promising for the low-cost production of flexible electronics.

Structures, physical properties and antibacterial activity of silver nanoparticles of Lactiplantibacillus plantarum exopolysaccharide

Lactic acid bacteria (LAB) exopolysaccharide (EPS) has good water absorption, high viscosity, good stability, so it was widely used in probiotics fields. In this study, EPS-producing LAB strain Lactiplantibacillus plantarum HDL-03 was isolated and identified. Moreover, the HDL-03 EPS was used as a stabilizer and mixed with AgNO3 to synthesize a novel nanoparticle AgNPs whose structure and properties were explored. The monosaccharide composition and molecular weight indicated that HDL-03 EPS was a heteropolysaccharide composed of mannose and glucose. Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR) spectroscopy analysis and methylation results jointly proved it was a heteropolysaccharide containing 1,3-Manp and 1,6-Glcp. The X-Ray diffraction (XRD) results showed that this EPS has an amorphous structure, while the synthesized AgNPs have crystalline properties. The scanning electron microscopy (SEM) and transmission electron microscopy (TEM) results indicated EPS had a smooth and dense sheet structure, while the surface of AgNPs became rougher and large holes appeared after synthesis. Zeta particle size analysis suggested that the particle size of AgNPs increased by 36.63 nm compared to HDL-03 EPS. FT-IR analysis exhibited that the position of the characteristic peaks of AgNPs changed. The OH moving from a wavelength of 3388.49 cm−1 to a wavelength of 3316.79 cm−1 and telescopic vibration peak changed from 1356.07 cm−1 to 1344.22 cm−1. A plate inhibition test revealed the effect of different concentrations of EPS and AgNO3 synthesized AgNPs on the diameter of inhibition circle produced by the indicator bacteria Escherichia coli and Staphylococcus aureus. Furthermore, AgNPs were applied to the indicator bacteria, which the minimum inhibitory concentration (MIC), time-inhibitory curve, and changes in extracellular conductivity, nucleic acids, proteins, ATP, and lactate dehydrogenase (LDH) levels were determined. The AgNPs inhibited the growth of E. coli and S. aureus and exhibited outstanding antimicrobial properties. With the increase of treatment time, the degree of cell membrane damage increased, the permeability enhanced, and the intracellular substances leaked. These results indicate that HDL-03 EPS has good potential for applications in the production of food packaging, antimicrobials, catheters, textiles and coatings.

Rocephin-graphene oxide-silver nanocomposites: A versatile platform for biomedical applications.

For many years, the synthesis of graphene oxide (GO) had involved exfoliating graphite flakes, and the methods applied were expensive and time-consuming. Thus, an attempt had been made to create an inventive, less expensive method for the synthesis of GO using unrefined, raw carbon-containing material. Modified Hummer's method was used to prepare GO from banana peel. In addition, the metallic silver nanocomposite was also synthesized along with laoding of drug Rocephin where they interact with each other through electrostatic hydrogen bond interaction. The degree of crystallinity and the crystallite size were through x-ray diffraction (XRD) analysis and the crystallite size of AgNPs was found to be 40.40 nm. The scanning electron microscopy (SEM) analysis shows that the morphology of the GO gradually changes with the addition of AgNPs and Rocephin. A blue shift was seen in the absorbance maxima of the raw carbon upon the conjugation of Rocephin in UV analysis. The Fourier-transform infrared spectroscopy, and energy dispersive X-ray (EDX) spectroscopy were used to determine the chemical composition of the samples. Furthermore, a broad biological screening of the synthesized samples had been carried out following the total reducing power (TRP), total antioxidant capacity (TAC), antibacterial, antifungal, MTT (Cytotoxicity of biologically synthesized silver nanoparticles in MDA-MB-231 human breast cancer cells) cell viability, brine shrimp lethality, and hemolytic protocols. Significant results were obtained, and the Rocephin-GO-AgNPs had depicted promising activity as compared with their counterparts. RESEARCH HIGHLIGHTS: The GO was prepared from the raw carbon extracted from banana peels and was used as a substrate for the synthesis Graphene oxide silver nanoparticles (GO-AgNPs) and Rocephin-loaded graphene oxide silver nanoparticles (Rocephin-GO-AgNPs) The structural and compositional analysis of the nanomaterial was carried out, and they were screened for several biomedical applications. The Rocephin-GO-AgNPs exhibit the highest activity as compared with their counterparts.

Microfluidic production of silver nanoparticles demonstrates ability for on demand synthesis of a wide size distribution of particles

Silver nanoparticles (AgNP) can help prevent infection of virus and bacteria. The size and morphology of AgNP can be crucial to function, with smaller nanoparticles (< 20 nm) able to penetrate the cell wall. This is significant as oxidative stress and genotoxicity are associated with some sizes and coatings of AgNP, contraindicating the use of AgNP to reduce infection. We present evidence that a microfluidic chip can synthesize larger sizes and distributions of AgNP from the nano-to-micro size range. We show results from a microfluidic mixing chip that can produce a wide range of nano-to-micro size (~ 24–400 nm) AgNP. Synthesis is based on a modified Turkevich method, using a single-step AgNP synthesis on the microfluidic chip using two chemical components, trisodium citrate (NaCit) and AgNO3. To make AgNP more accessible, we describe the microfluidic chip and conditions capable of synthesis. We also describe how modification of flow rate and chemical reagent concentration change particle diameter during production. In our experiments, we found that AgNP production created a visible adsorption line in the microfluidic device, possibly owing to AgNP surface interaction at the polydimethylsiloxane (PDMS) interface. We characterize these particles with dynamic light scattering (DLS), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). Based on optical light microscopy, we hypothesize that AgNP formation primarily occurs at the interface between the two chemical reagent streams. We also conclude that AgNP size increases could be due to interaction with the PDMS surface, which is known to be porous. Future work will help to understand how surface interaction may influence the formation of larger particles.

Humic Polyelectrolytes Facilitate Rapid Microwave Synthesis of Silver Nanoparticles Suitable for Wound-Healing Applications.

This article describes the one-pot microwave synthesis of silver nanoparticles (AgNPs) assisted with natural polyelectrolytes-humic substances (HS). The humic polyelectrolytes served both as chemical reductants for silver ions and as end-capping agents for AgNPs. Three commercially available sodium humates extracted from lignites and leonardite and one sodium fulvate isolated from natural brown water seeped through peat deposits were used in this study. The dynamics of the growth rate of AgNPs was characterised by UV-VIS spectroscopy by measuring the intensity of surface plasmon resonance at 420 nm. Transmission electron microscopy was used to characterise the size and morphology of AgNPs. Dynamic light scattering was used to determine size distributions of the synthesised AgNPs in the solutions. It was established that both conventional and microwave syntheses assisted with the coal humates produced small-size AgNPs in the range from 4 to 14 nm, with the maximum share of particles with sizes of (6 ± 2) nm by TEM estimates. The peat fulvate yielded much larger NPs with sizes from 10 to 50 nm by TEM estimates. DLS measurements revealed multimodal distributions of AgNPs stabilised with HS, which included both single NPs with the sizes from 5 to 15 nm, as well as their dominating aggregates with sizes from 20 to 200 nm and a smaller portion of extra-large aggregates up to 1000 nm. The given aggregates were loosely bound by humic polyelectrolyte, which prevented the coalescence of AgNPs into larger particles, as can be seen in the TEM images. The significant acceleration in the reaction time-a factor of 60 to 70-was achieved with the use of MW irradiation: from 240 min down to 210-240 s. The coal humate stabilised AgNPs showed antimicrobial properties in relation to S. aureus. A conclusion was made regarding the substantial advantages of microwave synthesis in the context of time and scaling up for the large-scale production of AgNP-HS preparations with antimicrobial properties suitable for external wound-healing applications.

Application of Green Synthesized Silver Nanoparticles for Dye Wastewater Treatment

A facile one-pot synthesis of silver nanoparticles (AgNPs) was achieved using the ethanolic extract of Cavendish banana florets as source of reducing agents for the conversion of Ag+ to Ag. The appearance of surface plasmon resonance peak between 410–435 nm in the UV Vis spectra confirmed the formation of AgNPs. The effects of different reaction conditions on the size and concentration of AgNPs were evaluated. The optimum conditions identified were pH 7 at 80 °C. Transmission electron microscopy (TEM) revealed spherical AgNPs with a mean particle size of 13.55 nm. On the other hand, energy-dispersive X-ray (EDX) analysis confirmed the presence of silver (Ag) as the bulk element (87.25%). Other elements such as carbon (C) and oxygen (O) are attributed to the capping agents of AgNPs which agrees with the results in the Fourier-transform infrared spectroscopy (FTIR) analysis. The optimized AgNPs were used for dye degradation using methyl orange (MO) as the model dye under acidified conditions. The maximum MO dye degradation of 96.07% and 77.32% at pH 1.5 and 2 were achieved after 10 min and 1320 min, respectively. This highlights the potential use of green-synthesized AgNPs for dye wastewater treatment.