Concentrations Of AgNPs Research Articles

Green synthesis of silver nanoparticle by Hyoscyamus muticus L. extract and study of its effect on tomato infected with Meloidogyne javanica

In this study, the aqueous leaf extract of Hyoscyamus muticus L Plant leaf was prepared using three methods: maceration (MAC), microwave-assisted extraction (MAE), and ultrasonic-assisted extraction (UAE). Then, the extracts were used to synthesize silver nanoparticles (Ag NPs) in an environmentally friendly approach. The characterization of the synthesized Ag NPs was carried out by various techniques. The XRD results confirmed the successful synthesis of nano-sized Ag crystals with spherical structure. The SEM images showed the formation of Ag NPs, which were smaller than 75 nm. The UV-Vis studies showed an obvious absorption peak for Ag NPs between 400-500 nm, with a clear peak around 450 nm for all samples. The elemental analysis using the EDS technique confirmed the presence of silver in the synthesized Ag NPs. Furthermore, the effect of different concentrations of Ag NPs was investigated on hatching and second-stage juvenile (J2s) mortality of Meloidogyne javanica, under controlled conditions. The results showed that increasing concentrations of Ag NPs led to higher percentages of inhibition of egg hatching and J2s mortality. Additionally, the Ag NPs synthesized by ultrasonic-assisted extraction with lower lethal concentration were found to be more toxic to M. javanica than the extract prepared by soaking. According to the results, Ag NPs showed a stronger inhibitory effect on M. javanica egg hatching and J2s mortality compared to the total extracts and chemically synthesized Ag NPs. Also, the lowest LC50 was observed for the Ag NPs synthesized using the plant extract as: UAE > MAE (180 w) > MAE (90 w) > MAC methods. The highest inhibition of egg hatch occurred at 0.5 % v/v of Ag NPs after 72 hours and remained consistent after 120 hours.

Comparison of silver nanoparticles and AgNO<sub>3</sub> toxic effects on <i>Caenorhabditis elegans</i> with a genetic disorder of copper metabolism

BACKGROUND: Silver nanoparticles are widely used in various types of industry, but their safety for humans has not been strictly proven. The experimental data currently available on the comparison of the toxic effect of silver nanoparticles and AgNO3 are contradictory and the question of the priority use of silver nanoparticles remains open, especially for organisms with impaired copper metabolism. AIM: The main aim of this study is to compare the effects of silver nanoparticles and AgNO3 on the nematode with normal and impaired copper metabolism and draw conclusions about their toxicity. MATERIALS AND METHODS: In this work, we determined the sublethal concentration (LC50) of AgNPs and AgNO3 for H828Q nematode strain. Using the results obtained, we performed the development assay, thrashing assay and lifespan analysis of the animals. RESULTS: It has been shown that LC50 of silver nanoparticles is lower than the one for AgNO3. Caenorhabditis elegans with impaired copper metabolism treated with silver nanoparticles have a statistically significant reduction in development, level of mobility and lifespan, comparing to animals treated with AgNO3. CONCLUSIONS: The results obtained allow us to conclude that the toxic effect of silver nanoparticles on C. elegans with a genetic defect in copper metabolism is higher comparing to ionic silver.

Eco-friendly synthesis of silver nanoparticles using Phyllanthus niruri leaf extract: Assessment of antimicrobial activity, effectiveness on tropical neglected mosquito vector control, and biocompatibility using a fibroblast cell line model

Abstract Mosquitoes are rapidly advancing as vectors of several severe diseases. The increasing resistance of mosquitoes and the environmental harm caused by insecticides pose significant challenges for eradicating mosquito vectors. In this study, 18 plant extracts were tested for larvicidal properties against Aedes aegypti, Culex quinquefasciatus, and Anopheles stephensi larvae. Phyllanthus niruri (Pn) showed enhanced larvicidal activity in both laboratory and field trials. The biosynthesis of silver nanoparticles (AgNPs) using Pn leaf methanol extract (Pn-LME) was confirmed by UV-visible spectroscopy, X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and Fourier-transform infrared spectroscopy. Among various concentrations, 3 mM AgNPs exhibited significant LC90 values of 0.83, 1.46, and 9.11 ppm compared to 9.25, 93.48, and 14.60 ppm of Pn-LME against A. stephensi, C. quinquefasciatus, and A. aegypti, respectively. This indicates the high mortality of mosquito vectors at low AgNP concentrations. Additionally, Pn-AgNPs showed enhanced antibacterial activity and no cytotoxicity in normal fibroblast cells (L929). Field trials demonstrated a 98.70% decrease in mosquito larval density at A. stephensi breeding sites, a 96.55% reduction at C. quinquefasciatus sites, and a 97.85% reduction at Ae. aegypti sites. This study presents an eco-friendly and cost-effective AgNP bio-pesticide synthesized from Pn leaves for controlling and preventing the transmission of filarial, dengue, and malaria vectors.

Antimicrobial, anticancer and photocatalytic dye degradation activities of silver nanoparticles phytosynthesized from Secamone emetica aqueous leaf extract

Secamone emetica (Family: Apocynaceae) is traditionally used for several ailments among indigenous people due to the bioactive components present in it. Nanomedicine has undergone impressive modifications and the development of new drugs with significant healthcare outcomes. The purpose of the present study was to green synthesize and characterize silver nanoparticles (Ag-NPs) using aqueous leaf extract of S. emetica, and to study their in vitro antimicrobial, anticancer and photocatalytic dye degradation activities. Various spectroscopic and microscopic analytical tools were used to characterize the Ag-NPs. Selective G+ve, G−ve bacteria and fungal species were used to test the Ag-NPs antibacterial and antifungal activity. Anticancer efficacy of the Ag-NPs was appraised by MTT test using MDA-MB 231 human breast cancer cells. Degradation of Rhodamine B dye by the Ag-NPs under visible light was assessed. The characterization studies confirmed the formation of Ag-NPs which were crystalline cubical symmetry with an average size of 26.69 nm. Dose dependent antimicrobial activity displayed a maximum zone of inhibition of 22.39 mm against E. coli followed by 21.28 mm against S. aureus at 100 µL/mL concentration of Ag-NPs. The IC50 value of synthesized Ag-NPs on MDA-MB 231 cell lines was 0.5 μg/mL. The Ag-NPs catalyst degraded 96 % of Rhodamine B dye in 150 min under visible light. Phytosynthesized Ag-NPs showed strong antimicrobial and anticancer properties and also revealed excellent dye degradation capacity. It is possible to further utilize the biosynthesized Ag-NPs as a possible source of antimicrobial, anticancer, and dye-degradation activities.

Insecticidal activity of silver nanoparticles synthesised from aqueous leaf extract of Eucalyptus tereticornis on horn flies

An insecticidal efficacy of silver nanoparticles (AgNps) synthesised from aqueous leaf extract of Eucalyptus tereticornis, was carried out against adults, larval and pupal stages of Haematobia flies. In in vitro adulticidal and larvicidal assays the mortality ranged between 30.0 to 67.0 and 5.0 to 75.0 per cent in treated groups after 24 hours at different concentrations, respectively. The inhibition of pupation ranged between 5.0 to 30.0 per cent after 24 hours by dipping method. The lethal concentration values were calculated for all the assays. The probit analysis revealed the significant (p<0.05) effect at different concentrations of AgNPs synthesised from aqueous leaf extract of E. tereticornis on adults, larvae and pupal mortality Keywords: Haematobia flies, silver nanoparticles, in vitro assays

Silver nanoparticles exhibit in vitro anthelmintic and antimicrobial activities against Dactylogyrus minutus (Kulwieć, 1927), and Aeromonas hydrophila in Cyprinus carpio Koi

The study aimed to evaluate the in vitro anthelminthic and antimicrobial activity of silver nanoparticles (AgNPs) against Dactylogyrus minutus and Aeromonas hydrophila, pathogens of Cyprinus carpio Koi. Gill arches of the fish were removed and placed into six-well plates containing 10 mL of tank water with varying concentrations of AgNPs: 100, 400, 500, 600, and 800 mg/L, along with control groups using tank water and distilled water. Each group was tested in triplicate. Parasites were observed every 10 min for 300 min (5 h) using a stereomicroscope, and mortality rates were recorded. Anthelminthic efficacy was calculated at the end of the tests. For the in vitro antimicrobial test, the Minimum Inhibitory Concentration (MIC) of AgNPs was determined by adding 100 μL of Poor Broth (PB) culture medium to all 96 wells of a microplate. The first well was filled with 100 μL of AgNPs, followed by serial dilutions (1:2 ratio). Subsequently, 50 μL of A. hydrophila (1 × 107 CFU/mL) was added to all wells and incubated for 24 h at 28 °C. Results showed that 800 mg/L of AgNPs achieved 87% anthelminthic efficacy within 300 min, while 100 mg/L achieved 47% efficacy. The MIC showed bacterial growth inhibition at 125 mg/mL. Despite the 87% efficacy against parasites within 300 min, AgNPs did not reach 100% efficacy quickly, limiting their potential use in ornamental fish farming. Further studies are needed to assess the toxicity of AgNPs in fish.

Synergy of photoluminescence emission and antibacterial activity of Ag-Cu2O nanocomposite

Conglomerate nanocomposites comprising metal and metal oxide hold significant potential for exhibiting properties that surpass the combined characteristics of their individual components, owing to the interactions occurring at the interfaces between the metal and metal oxide elements. In this study, we present the synthesis of Cu2O nanoparticles (NPs) (with diameters ranging from 40 to 53 nm) and Ag-Cu2O nanocomposites using an aqueous solution method at room temperature, employing varying concentrations of Ag NPs. Through optical absorption studies, we determined the optical band gap of Cu2O NPs in 0.5Ag-Cu2O, 1Ag-Cu2O, and 1.5Ag-Cu2O nanocomposites samples to be 2.13 eV, 2.25 eV, 2.34 eV, and 2.41 eV, respectively. The x-ray diffraction data are analysed using the Williamson–Hall technique and revealed noteworthy variations in microstructural characteristics such as strain and stress within the Cu2O nanocrystallites fabricated under different Ag concentrations. The nanocomposites amplified the intensities of violet-blue, blue, and green photoluminescence (PL) emissions, attributable to the interfaces between Ag and Cu2O, lattice mismatches, and the induced microstructural parameters lattice strain, and stress of Cu2O nanocrystallites. The enhanced PL intensities can be attributed to the influence of the local electric field on the Ag core composites. The Ag-Cu2O nanostructure exhibits potential applications in water purification technologies, while the PL emission properties and low band gap (∼2.13 eV) hold promising applications in optoelectronic devices. The antibacterial activities of Cu2O and Ag-Cu2O nanomaterials against Enterococcus faecalis and Escherichia fergusonii are examined using MH agar well plate diffusion methods. Here, Ag NPs enhance bactericidal effectiveness through enhanced interaction with bacteria and the release of Ag+ ions, while the Cu2O shell discontinuity on Ag NPs contributes to their unique antibacterial properties.

Enhancing antifungal and antibacterial properties of denture resins with nystatin-coated silver nanoparticles

Long-term oral health issues caused by fungi and bacteria are a primary concern for individuals who wear dentures. Denture stomatitis, primarily caused by Candida albicans (C. albicans), is a prevalent condition among denture users. Metal nanoparticles exhibit improved antimicrobial effectiveness and fewer adverse effects. This study aimed to evaluate the antifungal and antibacterial effects of nystatin-coated silver nanoparticles (Nys-coated AgNPs) embedded in acrylic resin as a more biocompatible material for denture resins. AgNPs and Nys-coated AgNPs were synthesized and characterized using UV-Vis, SEM, EDX, and DLS. Specimens of polymethyl methacrylate (PMMA) with three different concentrations of Nys, AgNPs, and Nys-coated AgNPs (0.1%, 1%, 10% w/w) were prepared. The water absorption properties of the disks and drug release were investigated for 14 days and 120 h, respectively. The hydrophilic and hydrophobic properties of the samples and their contact angles were evaluated using the sessile drop technique. The antifungal and antimicrobial activity of the prepared discs was studied against C. albicans and Streptococcus mutans, respectively. Adding Nys-coated AgNPs decreased the contact angle of discs from 67° to 49°. Furthermore, the water absorption rates of the different discs were not significantly different from those of the control groups. Results showed that Nys-coated AgNPs (10% w/w) in PMMA effectively inhibited C. albicans growth better than Nys composites (10% w/w). Additionally, Nys-coated AgNPs composites, as well as AgNPs-containing composites, showed considerable antibacterial activity against S. mutans. Nys-coated AgNPs (10% w/w) had no toxic effect on NIH3T3 cells. In conclusion, Nys-coated AgNPs could be considered a good candidate for incorporation into denture resins to address chronic oral diseases.

Silver nanoparticles exhibit ecotoxicological effects via oxidative stress, inflammation, and reproductive toxicity in Asian clam (Corbicula fluminea)

Silver nanoparticles (AgNPs) are pervasive environmental pollutants capable of inducing toxicological impacts on benthic organisms. In this study, the effects of AgNPs on the antioxidant enzyme activities, tissue damage, inflammatory responses, and reproductive toxicity of Corbicula fluminea were investigated. C. fluminea was exposed to four concentrations of AgNPs (0, 5 mg/L, 10 mg/L, and 125 mg/L) for 48 h. The results showed that the higher concentrations of AgNPs caused severe tissue damage in multiple organs of C. fluminea, induced oxidative stress and an imbalance of the antioxidant enzyme activities (such as SOD, CAT, MDA), and increased the inflammatory immune response involving NFκB, TLR2/4, HSP70/90, IL1β, and TNFα. Notably, further transmission electron microscopy and cytological analyses revealed that AgNPs exposure induced apoptosis in the gonad tissues, resulting in significant loss and damage in the oocytes and spermatids. The present study demonstrates the ecotoxicological impacts of AgNPs on freshwater bivalves, particularly highlighting their reproductive toxicity on germ cells, signifying the potential toxic effects of heavy metal pollution on aquatic ecosystems.

Effect of silver nanoparticles on donkey sperm parameters and ultrastructure.

The aim of this study was to determine the effect of silver nanoparticles (AgNPs) on donkey sperm parameters and ultrastructure. AgNPs were synthesized, purified and resuspended in the extender. Nine frozen-thawed donkey sperm samples were exposed to different concentrations of AgNPs (0, 1.25, 2.5, 5, 12.5, 25 and 50 μg/mL). Sperm parameters: total (TMOT, %) and progressive (PMOT, %) sperm motility, plasma (LIVE, %) and acrosomal membrane integrity (AIS, %), and sperm morphology (MORF, %) were evaluated immediately after AgNPs exposure (T0) and after 2 h of incubation (T2). The interaction beween AgNPs and spermatozoa was visualized by transmission electron microscopy (TEM). At T0, sperm motility and AIS were reduced (p < .05) when using concentrations ≥50 and ≥25 μg/mL, respectively. At T2, sperm motility and LIVE were significantly decreased (p < .05) in concentrations ≥25 and ≥50 μg/mL, respectively. TEM analysis revealed nanoparticle adhesion to the acrosomal region of the plasma membrane. In conclusion, AgNPs at concentrations ≥25 μg/mL impair motility, acrosome and plasma membrane integrity of donkey sperm, which may be mediated by adhesion to the acrosomal region of the sperm surface membrane.

Impact of Silver Nanoparticles (Ag-NPs) as a Dietary Supplement on Growth Performance, Carcass Traits, Blood Metabolites, Digestive Enzymes, and Cecal Microbiota of Growing Rabbits

Abstract The present study investigated the impact of silver nanoparticles (Ag-NPs) on growth performance, carcass traits, liver and kidney functions, immunity and antioxidant indicators, digestive enzymes, and cecum bacteriology of growing rabbits. One hundred 5-week-old New Zealand White (NZW) male rabbits were randomly divided into 5 equal groups and fed for 8 weeks on the basal diet only or on the basal diet supplemented with different levels of Ag-NPs (0.25, 0.50, 0.75, or 1.00 mg/kg diet). Animals in each group were randomly distributed in 10 cages (replicates), with two rabbits each. Different dietary concentrations of Ag-NPs significantly increased live body weight (LBW) and feed conversion ratio (FCR). Also, body weight gain (BWG) increased dramatically during all experimental periods except 11–13 weeks of age. Levels of 0.25 and 1 mg of Ag-NPs/kg diet showed the highest increase in LBW, BWG, and FCR. All studied carcass traits, except liver %, were not affected by Ag-NPs levels. Rabbits fed diet supplemented with 1 mg Ag-NPs had the highest liver %. Serum total protein, albumin, and globulin levels were increased (P&lt;0.05) in groups treated with 0.25 and 0.75 mg Ag-NPs. In contrast, serum values of aspartate transaminase (AST) and alanine transaminase (ALT), urea and creatinine were significantly reduced with the supplementation of Ag-NPs up to 0.75 mg/kg diet. The immunoglobulins M, G, and A (IgM, IgG, and IgA), complement 3 (C3) and lysozyme activity were improved with the inclusion of nano-silver in the rabbit feeds, particularly at the level of 0.25 mg Ag-NPs/kg feed. The inclusion of Ag-NPs in rabbit diets at different concentrations increased the total antioxidant capacity and the activities of superoxide dismutase, catalase, and glutathione peroxidase. Growing rabbits fed on diets supplemented with Ag-NPs had higher levels of digestive enzymes than the control group. The addition of Ag-NPs reduced the load of E. coli, Salmonella spp. and coliform in the rabbit cecum. Overall, the inclusion of 0.25–1 mg Ag-NPs/kg to NZW rabbit diets has shown beneficial effects on health and performance.

Preparation of modified silica gel supported silver nanoparticles and its evaluation using zone of inhibition for water disinfection

In this work, preparation of modified silica gel supported silver nanoparticles and its evaluation using zone of inhibition for water disinfection were investigated. The silica contents of the teff straw [TS] and teff straw ash [TSA] are 5.92 and 92.21 %, respectively. The calcinated TS ash at 700 °C was mixed with NaOH solution. The solution is then neutralized with HCl solution and then gel formation using the sol gel method. The silica gel yield was recorded and characterized. The SG with major silica functional group, amorphous structure, high porosity from the morphology, high surface area of 807.163 m2/g, pore volume of 0.34 cm3/g, pore diameter of 1.70 nm and silica gel purity of 99.39 % were achieved at a calcination temperature of 700 °C. It is then; further modified using trimethylchlorosilane (TMCS)/ethanol/hexane at different volumetric ratio and the resulting product is modified silica gel (MSG). MSG has excellent hydrophobic properties that have been required during water treatment. In this method, MSG with a major silica functional group, well ordered structure due to the TMCS modifier, maximum surface area of 510.40 m2/g was achieved at volumetric ratio of 0.25:0.25:1 of TMCS/ethanol/hexane, respectively. Then, MSG supported AgNPs (MSG-AgNPs) was prepared by mixing different concentrations of AgNPs-MSG and characterized. The MSG-AgNPs have shown AgNPs on the surface of MSG from the EDX result, different absorbance, pore from the morphology, with a maximum surface area of 475.0 m2/g was obtained at 1.5 mM of AgNPs concentrations. The performance of MSG-AgNPs was evaluated using zone of inhibition measurement and batch disinfection studies against E. coli and S. aureus. At 1.5 x 108 CFU/mL initial bacterial concentrations, the maximum inhibition zone diameter was 12.80 and 14.30 mm for E. coli and S. aureus, respectively.

Development of Poly(lactic acid)-Based Biocomposites with Silver Nanoparticles and Investigation of Their Characteristics

Nowadays, the demand for food packaging that maintains the safety and quality of products has become one of the leading challenges. It can be solved by developing functional materials based on biodegradable polymers, such as poly(lactic acid) (PLA). In order to develop PLA-based functional materials with antibacterial activity, silver nanoparticles (AgNPs) were introduced. In the present study, AgNPs stabilized by a copolymer of ethylene and maleic acid were used. Under the joint action of shear deformations and high temperature, the biocomposites of PLA with poly(ethylene glycol) and AgNPs were produced. Their mechanical and thermal characteristics, water absorption, and structure were investigated using modern methods (DSC, FTIR, Raman spectroscopy, SEM). The effect of AgNP concentration on the characteristics of PLA-based biocomposites was detected. Based on the results of antibacterial activity tests (against Gram-positive and Gram-negative bacteria, along with yeast) it is assumed that these systems have potential as materials for extending the storage of food products. At the same time, PLA–PEG biocomposites with AgNPs possess biodegradability.

Optical properties of SiO2 opal crystals decorated with silver nanoparticles

SiO2 opal crystals decorated with silver nanoparticles (AgNPs) have been successfully fabricated. SEM analysis revealed that the SiO2 opals have an ordered region of 25–30 μm2, and AgNPs are located into the gaps between the SiO2 nanospheres. The effect of the plasmons of AgNPs on the photoluminescence of SiO2 opal crystals were investigated. Under excitation of a 325 nm laser, we observed the quenching of the intrinsic defect emission in SiO2 as the concentration of AgNPs increased. The cause of the observed photoluminescence behavior is attributed to the interaction between surface plasmon induced by AgNPs and photoluminescence centers in SiO2 opal crystals. Then, we utilized SiO2 opals crystals decorated with AgNPs as a SERS substrate. The final enhancement factor of the Raman shift was 1.64 × 107, enabling the trace detection limit for a case of malachite green to be as low as 0.05 ppm, with a relative standard deviation of less than 1.75 %. This outcome suggests the potential for direct application of the prepared substrates in ultra-fast chemical analysis.

Antibacterial Efficacy of AgNPs synthesized from Aloe vera extract and Staphylococcus aureus Culture Supernatant

Biological synthesis of silver nanoparticles (AgNPs) is an emerging method that avoids the need for costly equipment and hazardous chemicals. Therefore, in this study, Aloe vera (AV) extract and culture supernatant of Staphylococcus aureus (CS-S. aureus) were used to reduce and stabilise silver nanoparticles. The NPs were characterized using UV–vis spectrophotometry at 445 nm for AV-AgNP and 444.5 nm for CS-S.aureus AgNP, and the presence of silver was confirmed by energy dispersive X-ray (EDX). Furthermore, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed that the AV-CS of S. aureus-AgNPs had irregular and spherical shapes, with average sizes of 18.5 nm for AvAgNPs and 7.03 nm for CS-S. aureus-AgNPs. Additionally, the minimum inhibitory concentration (MIC) of both AgNPs showed a similar reaction. K. pneumoniae, P. aeruginosa, and S. epidermidis were more sensitive to the AgNPs compared to methicillin-resistant Staphylococcus aureus (MRSA). In conclusion, our study used a green method to synthesise silver nanoparticles using AV extract and CS of S. aureus. The NPs showed a remarkable antibacterial effect, especially CS-S. aureus-AgNP, which could have application as a treatment against both Gram-positive and Gram-negative bacteria.

Green-synthesized silver nanoparticles from Zataria multiflora as a promising strategy to target quorum sensing and biofilms in Pseudomonasaeruginosa

The global challenge to human health is significantly heightened by the resistance of harmful bacteria to antimicrobial treatments. Given the limited advancement in developing new antimicrobial medications, exploring innovative strategies is imperative to tackle the challenge of resistance to multiple drugs. Furthermore, there is a growing emphasis on the environmentally friendly synthesis of nanoparticles with potent medicinal attributes, specifically those targeting virulence, to combat the rise of multidrug resistance. Focusing on the inhibition of virulence factors and biofilms influenced by quorum sensing has become a promising and novel strategy in the development of anti-infective drugs. An aqueous extract of Zataria multiflora leaves was used to create green-synthesized silver nanoparticles, or AgNPs. X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and UV–visible absorption spectroscopy were used to characterize the AgNPs. The impact of AgNPs on the virulence factors and biofilms of Pseudomonas aeruginosa PAO1, mediated by quorum sensing, was assessed at concentrations below the minimum inhibitory concentration (sub-MIC). Sub-MIC concentrations of Green-synthesized AgNPs inhibited various P. aeruginosa virulence factors, including bacterial motility (89 % inhibition), pyocyanin production (81.48 % inhibition), pyoverdin production (55.80 % inhibition), elastase activity (87.43 % inhibition), exoprotease activity (75.60 % inhibition), and rhamnolipid production (71.28 % inhibition). Additionally, these AgNPs demonstrated 80 % inhibition of P. aeruginosa biofilms. The in vitro efficacy of green-synthesized AgNPs against P. aeruginosa can be utilized for the creation of alternative therapeutic agents for managing bacterial infections, particularly for topical application in cases such as wound infections. Additionally, they can be used for surface coating to inhibit the attachment of bacteria to medical devices.

Ecofriendly Filtration of Silver Nanoparticles for Ultrasensitive Surface-Enhanced (Resonance) Raman Spectroscopy-Based Detection.

In this study, a widely used colloid of Creighton AgNPs (ORI, 1-100 nm, mostly ≤ 40 nm, ∼10 μg mL-1) was rapidly manipulated via tangential flow filtration (TFF) for highly reproducible surface-enhanced (resonance) Raman spectroscopy (SE(R)RS) experiments down to the single-molecule (SM) level. The quasi-spherical AgNPs were size-selected, purified, and concentrated in two TFF fractions of a cutoff diameter of ∼40 nm: AgNP ≤ 40 (∼900 μg mL-1) and AgNP ≥ 40 (∼100 μg mL-1). The SE(R)S-based sensing capabilities of the two TFF fractions were then tested under pre-resonance (632.8 nm) and resonance (532.1 nm) excitation conditions for rhodamine 6G (R6G, 10-6-10-15 M). Both TFF isolates, AgNP ≤ 40 and AgNP ≥ 40, were more effective in adsorbing the R6G analyte (≥91%) than the original colloid (≥78%) at submonolayer coverages. Furthermore, the surface enhancement factors (SEF) of the two TFF fractions were markedly superior to those of ORI under all excitation conditions. SERS at 632.8 nm: only AgNP ≥ 40 enabled the detection of R6G at 10-9 M and produced the largest SEF (2.1 × 106). SE(R)RS and SM-SERRS at 532.1 nm: AgNP ≥ 40 gave rise to the largest SEF values (2.5 × 1010) corresponding to the SM regime down to 10-15 M of R6G. Nevertheless, AgNP ≤ 40 compensated for the size-dependence of the electromagnetic enhancements by an increase in the silver concentration, which led to SEF values comparable to those of AgNP ≥ 40 through additional resonance enhancements. TFF resulted into a ∼100-fold increase (AgNP ≤ 40) in the number of negatively charged AgNPs that were available to electrostatically bridge R6G cations and form SERRS "hot-spots" (AgNP-R6G-AgNP) within the focal volume. Evidently, the interplay between AgNP size, AgNP concentration, and excitation wavelength governs the SE(R)RS enhancements. This study demonstrated that TFF can facilitate the ecofriendly isolation of spherical AgNPs of controlled morphological and plasmonic properties for further enhancing their sensing capabilities as SE(R)RS substrates.

Aspergillus fumigatus-induced biogenic silver nanoparticles' efficacy as antimicrobial and antibiofilm agents with potential anticancer activity: An in vitro investigation

A worldwide hazard to human health is posed by the growth of pathogenic bacteria that have contaminated fresh, processed, cereal, and seed products in storage facilities. As the number of multidrug-resistant (MDR) pathogenic microorganisms rises, we must find safe, and effective antimicrobials. The use of green synthesis of nanoparticles to combat microbial pathogens has gained a rising interest. The current study showed that Aspergillus fumigatus was applied as a promising biomass for the green synthesis of biogenic silver nanoparticles (Ag NPs). The UV–visible spectra of biosynthesized Ag NPs appeared characteristic surface plasmon absorption at 475 nm, round-shaped with sizes ranging from 17.11 to 75.54 nm and an average size of 50.37 ± 2.3 nm. In vitro tests were conducted to evaluate the antibacterial, antioxidant, and anticancer effects of various treatment procedures for Ag NP applications. The synthesized Ag NPs was revealed antimicrobial activity against Aspergillus flauvas, A. niger, Bacillus cereus, Candida albicans, Esherichia coli, Pseudomonas aerugonosa, and Staphylococcus aureus under optimum conditions. The tested bacteria were sensitive to low Ag NPs concentrations (5, 10, 11, 8, 7, 10, and 7 mg/mL) which was observed for the mentioned-before tested microorganisms, respectively. The tested bacterial pathogens experienced their biofilm formation effectively suppressed by Ag NPs at sub-inhibitory doses. Antibacterial reaction mechanism of Ag NPs were tested using scanning electron microscopy (SEM) to verify their antibacterial efficacy towards S. aureus and P. aeruginosa. These findings clearly show how harmful Ag NPs are to pathogenic bacteria. The synthesized Ag NPs showed antitumor activity with IC50 at 5 μg/mL against human HepG-2 and MCF-7 cellular carcinoma cells, while 50 mg/mL was required to induce 70 % of normal Vero cell mortality. These findings imply that green synthetic Ag NPs can be used on cancer cell lines in vitro for anticancer effect beside their potential as a lethal factor against some tested pathogenic microbes.

Effect of silver nanoparticles foliar application on the nutritional properties of potato tubers

The aim of presented study was to test nutritional properties of potato tubers and silver ions accumulation pattern after foliar application of silver nanoparticles (AgNPs) during potato vegetation. Potato plants were sprayed with different concentration of Ag nanoparticles (0.1, 1.0 and 10 mg·dm−3) synthesized with incorporation with sodium dodecyl sulphate (SDS) and sodium citrate as stabilizing agent. The lowest amounts of silver ions were transported to the tubers after spraying with AgNPs synthesized with SDS, rather than with citrate. Nevertheless silver ions accumulation in tubers was negligible. SDS method of synthesis was more favourable in terms of nutritional properties of potato tubers. The highest tested concentration of AgNPs_SDS had a favourable effect on a variety of macro- and micronutrients, ascorbic acid and soluble sugars. In turn, lower concentrations of AgNPs_SDS increased the content of phenolic compounds and free radical scavenging efficiency of tubers. These correlations were also confirmed by Principal Component Analysis.

Exploring antibacterial effectiveness: A comparative analysis of green and chemical synthesis of silver nanoparticles against Staphylococcus aureus

BackgroundSilver nanoparticles (AgNPs) are renowned for their broad-spectrum antibacterial properties. Various synthesis methods, particularly green synthesis using biogenic agents, have garnered significant attention. However, the detailed impact of green-synthesized AgNPs on the antibacterial mechanism against Staphylococcus aureus remain unclear, limiting the full potential of green synthesis compared to chemical methods. MethodsAgNPs were synthesized via chemical (sodium citrate, NaBH4) and green synthesis (green tea leaves, cassia seed extract) methods. The synthesized AgNPs were evaluated for toxicity and antibacterial activity against Staphylococcus aureus. Significant findingsThis study revealed a strong correlation (R2>0.9) between minimal inhibitory concentration (MIC) and AgNP size for both synthesis methods, with a similar exponential trend. MIC values were 45, 40, 25, and 5 µg mL-1 for citrate-, NaBH4-, green tea extract-, and cassia seed extract-assisted synthesis, respectively. Green-synthesized AgNPs showed higher antibacterial activity than chemical AgNPs at comparable sizes. Chemical AgNPs exhibited low and fluctuating scavenging activity, while green methods were more consistent. Cytotoxicity was noted in chemical AgNPs and at high concentrations of green tea extract-assisted AgNPs. Bacterial membrane disruption and ROS accumulation were also observed, contributing to the enhanced antibacterial activity of green-synthesized AgNPs.