Concentrations Of AgNPs Research Articles

Molecular insights into quercetin-enhanced crystalline silver nanoparticles: Implications for breast cancer cell cytotoxicity and antibacterial action in Kyllinga nemoralis

Amidst the ongoing global health crisis posed by cancer and antibiotic-resistant infections, innovative solutions are in high demand. The utilization of Kyllinga nemoralis leaf (KNL) extracts for synthesizing silver nanoparticles (AgNPs) represents a novel approach, with the potential to deliver profound advancements in healthcare, benefitting society on a broad scale. Successful synthesis of AgNPs by KNL extracts for treating breast cancer cells, specifically MDA-MB-231 cells, is recorded in this report. The adsorption mechanism of quercetin (Q) on Ag and its optimized structural characteristics were computed at the DFT level. According to FTIR analysis, quercetin, one of the flavonoids found in KNL extract, acts as a reducing and stabilizing agent for the conversion of Ag+ ions to Ag0, and carboxylates serve as ligands that cap the AgNPs. The small-sized (7 nm), spherical particles, which are uniform in size and monodispersed, exhibit regulation over the size of the AgNPs due to being shielded by enough flavonoids and gallic acid absorbed into the extract. The observed negative zeta potential of −20 mV indicates the moderate stability of the AgNPs colloid. It is noted that AgNPs prepared at higher concentrations of KNL extract showed lower minimum inhibitory concentration (MIC) values (80 µg/mL) and larger inhibition zones (22 mm) against Pseudomonas aeruginosa. The cell viability rate of MDA-MB-231 cell lines decreases with increasing concentration of AgNPs. The antibacterial and anticancer activity of AgNPs is observed in a size-dependent manner. This research raises the possibility of using plant-based, small-sized AgNPs therapeutically for breast cancer and as antibacterial agents.

In Situ Fabrication of Silver Nanoparticle-Decorated Polymeric Vesicles for Antibacterial Applications.

Silver/polymeric vesicle composite nanoparticles with good antibacterial properties were fabricated in this study. Silver nanoparticles (AgNPs) were prepared in situ on cross-linked vesicle membranes through the reduction of silver nitrate (AgNO3) using polyvinylpyrrolidone (PVP) via coordination bonding between the Ag+ ions and the nitrogen atoms on the vesicles. X-ray diffraction (XRD), ultraviolet-visible spectroscopy (UV-vis), and transmission electron microscopy (TEM) analyses confirmed the formation of AgNPs on the vesicles. The antibacterial test demonstrated good antibacterial activity against both Gram-negative bacteria (Escherichia coli) and Gram-positive bacteria (Staphylococcus aureus) for the produced AgNP-decorated vesicles. The minimum inhibitory concentration (MIC) values of the AgNP-decorated vesicles for E. coli and S. aureus were 8.4 and 9.6 μg/mL, respectively. Cell viability analysis on the A549 cells indicated that the toxicity was low when the AgNP concentrations did not exceed the MIC values, and the wound healing test confirmed the good antibacterial properties of the AgNP-decorated vesicles.

Suppression of Root Rot Fungal Diseases in Common Beans (Phaseolus vulgaris L.) through the Application of Biologically Synthesized Silver Nanoparticles.

The biosynthesis of silver nanoparticles (AgNPs) using plant extracts has become a safe replacement for conventional chemical synthesis methods to fight plant pathogens. In this study, the antifungal activity of biosynthesized AgNPs was evaluated both in vitro and under greenhouse conditions against root rot fungi of common beans (Phaseolus vulgaris L.), including Macrophomina phaseolina, Pythium graminicola, Rhizoctonia solani, and Sclerotium rolfsii. Among the eleven biosynthesized AgNPs, those synthesized using Alhagi graecorum plant extract displayed the highest efficacy in suppressing those fungi. The findings showed that using AgNPs made with A. graecorum at a concentration of 100 μg/mL greatly slowed down the growth of mycelium for R. solani, P. graminicola, S. rolfsii, and M. phaseolina by 92.60%, 94.44%, 75.93%, and 79.63%, respectively. Additionally, the minimum inhibitory concentration (75 μg/mL) of AgNPs synthesized by A. graecorum was very effective against all of these fungi, lowering the pre-emergence damping-off, post-emergence damping-off, and disease percent and severity in vitro and greenhouse conditions. Additionally, the treatment with AgNPs led to increased root length, shoot length, fresh weight, dry weight, and vigor index of bean seedlings compared to the control group. The synthesis of nanoparticles using A. graecorum was confirmed using various physicochemical techniques, including UV spectroscopy, Fourier-transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS) analysis. Collectively, the findings of this study highlight the potential of AgNPs as an effective and environmentally sustainable approach for controlling root rot fungi in beans.

Evaluating the antifungal effectiveness, leaching characteristics, flexural strength, and impact strength of polymethyl methacrylate added with small-scale silver nanoparticles - An in vitro study.

(1) To assess the release of stable silver nanoparticles (AgNPs) of small scale dimension added to heat polymerized polymethyl methacrylate (PMMA) in 6 months. (2) Assessing the influence of incorporating minimal concentrations of stable AgNPs with nanoscale dimensions into heat polymerized PMMA over a 6 month period on its antifungal efficacy (AF), flexural strength (FS), and impact strength (IS). Incorporating nanoparticles with a very small scale may have minimal impact on mechanical properties due to their diminutive size. However, the influence of these small scaled nanoparticles on antimicrobial efficacy and potential escalation in toxicity to host cells through leaching remains unexplored. AgNPs were prepared using an Ultrasonic Probe sonicator and the addition of ammonia to obtain stabilized AgNPs (< 0.01 nm) of small scale dimension. The characterization of these AgNPs involved ultraviolet visible spectroscopy, X ray diffraction, Zetasizer, and transmission electron microscopy with energy dispersive spectroscopy (TEM). The prepared AgNPs were then added in various percentages by weight (0%-0.5%) to fabricate 252 modified PMMA samples of sizes 10 mm × 3 mm (AF, n = 108), 65 mm × 10 mm × 3 mm (FS, n = 72), and 65 mm × 10 mm × 2.5 mm (IS, n = 72) as per ADA specification no. 12. These samples underwent testing for leaching out of AgNPs and efficacy against Candida albicans for 6 months. The effect on FS and IS was evaluated using the three point bending test and Charpy's Impact Tester, respectively. Intergroup comparison of CFU between various concentrations of AgNP was done using the Kruskal-Wallis ANOVA test succeeded by Mann-Whitney test for pair wise comparisons. Difference in CFU of various concentrations over 6 months was seen using one way ANOVA test. Intergroup comparison of FS and IS was performed using a one way ANOVA test, followed by a post hoc Tukey's test for pair wise comparisons. Repeated tests showed no leaching out of AgNPs from the denture base resin into the storage medium. All concentrations of AgNPs incorporated in resin showed inhibition of Candida growth. Intergroup comparison of FS and IS revealed highly statistically significant differences (F = 15.076, P < 0.01 and F = 28.266, P < 0.01) between the groups showing a reduction in strength. The AgNPs of small scale dimension incorporated into the denture base resin imparted a strong antifungal effectiveness against C. albicans, which did not decline during the study period and did not cause any release of nanoparticles. 0.5% showed the best antifungal efficacy. This may prove to be a viable and highly effective treatment for the prevention of Candida associated denture stomatitis. However, the inclusion of these particles resulted in a decrease in both FS and IS, and this reduction was directly proportional to the percentage of added AgNPs, with 0.5% demonstrating the least IS and FS.

Trachyspermum copticum aqueous seed extract-derived silver nanoparticles: Exploration of their structural characterization and comparative antibacterial performance against gram-positive and gram-negative bacteria

Abstract In this study, the aqueous seed extract of Trachyspermum copticum was employed to fabricate silver nanoparticles (AgNPs) for their antibacterial performance. The structural characteristics of the phytofabricated AgNPs were investigated using ultraviolet–visible, energy dispersive X-ray, dynamic light scattering, zeta potential, field emission scanning electron microscope, and Fourier transform infrared spectroscopy. Further, the antibacterial effects of AgNPs were evaluated against two standard gram-positive strains of Staphylococcus aureus and Streptococcus pyogenes and two standard gram-negative strains of Escherichia coli and Klebsiella pneumoniae. The findings showed the phytofabrication of spherical-shaped AgNPs with a Z-average diameter of 119.7 nm and the polydispersity index of 0.56. The minimum inhibitory concentration of AgNPs against S. aureus, S. pyogenes, E. coli, and K. pneumoniae strains was 0.25, 1, 0.5, and 0.5 μg·mL−1, respectively. In addition, the minimum bactericidal concentration of these nanoparticles (NPs) against the mentioned strains was 8, 16, 4, and 4 μg·mL−1, respectively. Furthermore, the AgNPs enhanced the generation of reactive oxygen species significantly in all studied bacteria compared to the control (P &lt; 0.05) suggesting an oxidative-associated antibacterial mechanism of AgNPs. Moreover, a dose-dependent cell death was found in all bacterial samples based on flow cytometry analysis. Overall, this study showed a biological approach for the biosynthesis of AgNPs with significant antibacterial effects.

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.

Combination of multiple routes to enhance DSSC performance: Flower-like structure of SnO2 as photoanode and modification with Ag nanoparticle

SnO2 is an attractive photoanode material for dye-sensitized solar cells (DSSCs), but it has many drawbacks and needs to be modified. In this study, flower-like SnO2 particles are firstly prepared by a simple one-step hydrothermal synthesis method respectively, and the effect of hydrothermal reaction time on the growth of the particles is explored. The morphological and structural characterisation reveals that the flower-like particles have a larger specific surface area can provide more adsorption sites for dye molecules and are more suitable for photoanode materials. Then the optimal flower-like SnO2 particles are selected to prepare the photoanode, which is also modified with different concentrations of Ag nanoparticles to successfully introduce the localized surface plasmon resonance (LSPR) effect, and the optimal modification concentration is explored. Conformal characterisation, dye adsorption and light absorption tests revealed that the modification of Ag nanoparticles not only optimises the photoanode conformal structure and improves the dye adsorption, but also works in conjunction with the LSPR effect to improve the light absorption and utilisation, thus increasing the cell efficiency. Many cell performances of DSSC are also greatly improved due to the above work, and the optimal cell performance of DSSC is achieved when the Ag nanoparticles doping concentration is 0.03 M. Compared with the pure flower-like SnO2-based photoanode DSSC, the short-circuit current density of the best Ag nanoparticle-modified DSSC is enhanced by 28.56% to 15.80 mA/cm2, and its efficiency is improved by 20.82%–5.92%.

Investigation of Antimicrobial Activity and Cytotoxicity of Silver Nanoparticle Synthesized using Dopamine as a Reducing and Capping Agent

AbstractWe present a study focused on the controlled fabrication of silver nanoparticles (AgNPs) through colloidal synthesis, employing dopamine as a reducing and capping agent. By manipulating the concentration of silver nitrate, the production of spherical AgNPs with distinct particle diameters (16, 24, 48, and 74 nm) was achieved. The investigation extended to the evaluation of AgNPs′ impact on human embryonic kidney cells, revealing a concentration‐dependent response. At lower AgNPs concentrations, cell viability remained nearly 100 %, progressively declining with rising AgNPs concentrations. Importantly, the cytotoxic thresholds observed were notably elevated, underscoring the relatively mild to moderate toxicity profile of the nanoparticles. Furthermore, the antimicrobial efficacy of these synthesized AgNPs was probed against E. coli and S. aureus bacterial strains. Notably, the AgNPs exhibited robust antimicrobial activity, with superior performance exhibited by smaller‐sized particles compared to larger ones. Impressively, the minimum inhibitory concentration reached as low as 3.5 μg/mL, indicating their potent antimicrobial potential. The achieved distinct particle diameters, concentration‐dependent cytotoxic responses, and potent antimicrobial efficacy against bacterial strains underscore the multifaceted potential of these nanoparticles. These findings contribute valuable insights for their application in diverse fields, from biomedicine to antimicrobial solutions.

Unravelling the Antimicrobial, Antibiofilm, Suppressing Fibronectin Binding Protein A (fnba) and cna Virulence Genes, Anti-Inflammatory and Antioxidant Potential of Biosynthesized Solanum lycopersicum Silver Nanoparticles.

Background and Objectives: Urinary tract infections [UTIs] are considered the third most known risk of infection in human health around the world. There is increasing appreciation for the pathogenicity of Gram-positive and Gram-negative strains in UTIs, aside from fungal infection, as they have numerous virulence factors. Materials and Methods: In this study, fifty urine samples were collected from patients suffering from UTI. Among the isolates of UTI microbes, six isolates were described as MDR isolates after an antibiotic susceptibility test carried out using ten different antibiotics. An alternative treatment for microbial elimination involved the use of biosynthesized silver nanoparticles (AgNPs) derived from Solanum lycopersicum [S. cumin]. Results: The sizes and shapes of AgNPs were characterized through TEM imaging, which showed spherical particles in a size range of 35-80 nm, of which the average size was 53 nm. Additionally, the silver nanoparticles (AgNPs) demonstrated inhibitory activity against Staphylococcus aureus (OR648079), exhibiting a 31 mm zone of inhibition at a minimum inhibitory concentration (MIC) of 4 mg/mL and a minimum bactericidal concentration (MBC) of 8 mg/mL. This was followed by Aspergillus niger (OR648075), which showed a 30 mm inhibition zone at an MIC of 16 mg/mL and a minimum fungicidal concentration (MFC) of 32 mg/mL. Then, Enterococcus faecalis (OR648078), Klebsiella pneumoniae (OR648081), and Acinetobacter baumannii (OR648080) each displayed a 29 mm zone of inhibition at an MIC of 8 mg/mL and an MBC of 16 mg/mL. The least inhibition was observed against Candida auris (OR648076), with a 25 mm inhibition zone at an MIC of 16 mg/mL and an MFC of 32 mg/mL. Furthermore, AgNPs at different concentrations removed DPPH and H2O2 at an IC50 value of 13.54 μg/mL. Also, AgNPs at 3 mg/mL showed remarkable DNA fragmentation in all bacterial strains except Enterococcus faecalis. The phytochemical analysis showed the presence of different active organic components in the plant extract, which concluded that rutin was 88.3 mg/g, garlic acid was 70.4 mg/g, and tannic acid was 23.7 mg/g. Finally, AgNPs concentrations in the range of 3-6 mg/mL showed decreased expression of two of the fundamental genes necessary for biofilm formation within Staphylococcus aureus, fnbA (6 folds), and Cna (12.5 folds) when compared with the RecA gene, which decreased by one-fold when compared with the control sample. These two genes were submitted with NCBI accession numbers [OR682119] and [OR682118], respectively. Conclusions: The findings from this study indicate that biosynthesized AgNPs from Solanum lycopersicum exhibit promising antimicrobial and antioxidant properties against UTI pathogens, including strains resistant to multiple antibiotics. This suggests their potential as an effective alternative treatment for UTIs. Further research is warranted to fully understand the mechanisms of action and to explore the therapeutic applications of these nanoparticles in combating UTIs.

Superhydrophobic, antibacterial, and EMI shielding properties of Ag/PDMS-coated cotton fabrics

In this study, three functionalities of superhydrophobicity, antibacterial activity and electromagnetic interference (EMI) shielding of cotton fabrics coated with Ag/PDMS were studied, and the role of coating composition was discussed. Special attention was paid to understanding the relationships between the surface roughness of coated fibres with the developed superhydrophobicity and antibacterial activity. The superhydrophobicity of fabrics was analysed based on water contact angle (WCA) and contact angle hysteresis (CAH) values while the antibacterial activity was tested against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) bacteria. It was found that the surface roughness on fibres, which changed by altering the concentrations of Ag NPs (0.2–4 g/L) and PDMS (20 and 40 g/L), affected the obtained superhydrophobicity. The most superhydrophobic fabric (WCA 171°) was coated with a formulation containing Ag NPs (2 g/L), and PDMS (20 g/L), and had the highest surface roughness. Increasing the ingredients’ concentrations, however, deteriorated the optimum roughness as measured using a 3D Surface Laser Scanning Microscopy method. The coated fabrics showed efficacy against both types of bacteria, and it was confirmed that the Ag NPs content was the key factor in determining the antibacterial performance. Moreover, testing the EMI shielding performance of fabrics demonstrated that increasing the concentrations of Ag NPs and PDMS both enhanced the reflection coefficient (R) of fabrics against incident X-band electromagnetic (EM) wave by around >500%, which was due to the deposition of a higher amount of Ag NPs on fabrics. The superhydrophobicity of fabrics was durable after 1000 abrasion cycles, and the fabrics retained their antibacterial activity even after numerous washings.Graphical

Restoration of Antibacterial Activity of Inactive Antibiotics via Combined Treatment with AgNPs.

Antimicrobial resistance poses a huge threat to human health around the world and calls for novel treatments. Combined formulations of NPs and antibiotics have emerged as a viable nanoplatform for combating bacterial resistance. The present research work was performed to investigate the effect of combined formulations of AgNPs with streptomycin, cefaclor, ciprofloxacin, and trimethoprim against multidrug-resistant (MDR) isolates of Staphylococcus aureus and Klebsiella pneumoniae. AgNPs have been synthesized by using the Nigella sativa seed extract, and their characteristics were analyzed. AgNPs depicted concentration-dependent antibacterial effects, as the highest concentration of AgNPs showed the strongest antibacterial activity. Interestingly, AgNPs in conjugation with antibiotics showed an enhanced antibacterial potential against both S. aureus and K. pneumoniae, which suggested synergism between the AgNPs and antibiotics. Against S. aureus, streptomycin and trimethoprim in conjugation with AgNPs presented a synergistic effect, while cefaclor and ciprofloxacin in combination with AgNPs showed an additive effect. However, all of the tested antibiotics depicted a synergistic effect against K. pneumoniae. The lowest value of MIC (0.78 μg/mL) was shown by AgNPs-Stp against S. aureus, whereas AgNPs-Tmp showed the lowest value of MIC (1.56 μg/mL) against K. pneumoniae. The most important point of the present study is that both organisms (S. aureus and K. pneumoniae) showed resistance to antibiotics but turned out to be highly susceptible when the same antibiotic was used in combination with AgNPs. These findings highlight the potential of nanoconjugates (the AgNPs-antibiotic complex) to mitigate the present-day crisis of antibiotic resistance and to combat antimicrobial infections efficiently.

Synergistic augmentation of dielectric and photocatalytic properties of ZnO via Ag nanoparticle integration

This study investigates the effect of Ag incorporation on dielectric and photocatalytic properties of the ZnO matrix. The synthesized samples were characterized using X-ray diffraction (XRD), diffused reflectance spectroscopy (DRS), scanning electron microscopy (SEM), elemental dispersive X-ray spectroscopy (EDX), impedance spectroscopy, and UV–visible infrared spectroscopy. XRD confirmed the successful synthesis of Ag/ZnO nanocomposites without any secondary phase. SEM micrographs showed discs and rods-like morphology of ZnO and Ag NPs, respectively. Furthermore, an increased agglomeration was also observed in the nanocomposite as the concentration of Ag NPs was increased in Ag/ZnO Nanocomposite. The dielectric study revealed that the incorporation of Ag nanoparticles (Nps) increased the dielectric constant of ZnO by 100 times (102 Hz), with minimal tangent loss in Ag/ZnO (20 %). Complex plane plots disclosed the presence of two relaxation processes with different relaxation times in the synthesized samples. The metallic nature of Ag NPs contributed to the reduction of the charge transfer resistance of the nanocomposite. Furthermore, the enhanced dielectric behavior was ascribed to the formation of micro/nano capacitors due to the interaction of conductive Ag NPs with relatively less conducting ZnO grains. The photocatalytic performance of the synthesized nanocomposites was also evaluated for the degradation of methylene blue. The presence of Ag NPs increased the photocatalytic activity due to its enhanced conductivity and sluggish electron-hole recombination. Ag/ZnO (20 %) nanocomposite showed the best photocatalytic activity with a reaction rate of 0.239 min−1. The exceptional dielectric properties demonstrate the potential of Ag/ZnO nanocomposites for low-frequency applications. Furthermore, the enhanced photocatalytic activity of ZnO upon Ag inclusion discloses the potential of the synthesized nanocomposite for water remediation applications.

Unveiling the silver lining: examining the effects of biogenic silver nanoparticles on the growth dynamics of in vitro olive shoots

The current study aimed to evaluate the effects of biogenic silver nanoparticles (AgNPs) on growth behavior and leaf anatomy of in vitro growing shoots of ‘Picual’ and ‘Dolce’ olive cultivars. Biosynthesis of AgNPs was carried out using the cell-free filtrate of Fusarium oxysporum. The dimension and shape of the synthesized AgNPs have been analyzed using spectroscopy and topography analysis tools, confirming that the biosynthesis of AgNPs is a crystalline nanostructure with an average particle size of 37 nm. The shoots of the selected olive cultivars were cultured on Rugini olive medium-supplemented AgNPs at 0, 10, 20, and 30mg L− 1. The effect of genotypes on shoot multiplication was significant, ‘Picual’ recorded higher values of shoot growth parameters compared with ‘Dolce’ cultivar. Adding AgNPs to the culture medium significantly affected the growth of in vitro olive shoots. AgNPs at 20 and 30mg L− 1 produced higher values of the number of shoots, shoot length, and leaf number of Picual cv. compared with the control treatments, but the higher AgNPs concentration harmed the growth parameters of Dolce cv. and recorded lower growth values compared with the lower concentration (10mg L− 1). AgNPs had a significant effect on leaf morphology and their anatomical structure. The current results showed that the stimulatory effect of AgNPs on shoot growth of in vitro olive shoots is highly dependent on plant genotype and nanoparticle concentration.

Endophytic Aspergillus hiratsukae mediated biosynthesis of silver nanoparticles and their antimicrobial and photocatalytic activities.

In the current study, endophytic Aspergillus hiratsukae was used for the biosynthesis of silver nanoparticles (Ag-NPs) for the first time. The characterizations were performed using X ray diffraction (XRD), Transmission electron microscopy (TEM), Scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), Dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FT-IR), and UV-Vis spectroscopy. The obtained results demonstrated the successful formation of crystalline, spherical Ag-NPs with particle diameters ranging from 16 to 31 nm. The FT-IR studied and displayed the various functional groups involved, which played a role in capping and reducing agents for Ag-NPs production. The SEM-EDX revealed that the main constituent of the AS-formed sample was primarily Ag, with a weight percentage of 64.2%. The mycosynthesized Ag-NPs were assessed for antimicrobial as well as photocatalytic activities. The antimicrobial results indicated that the synthesized Ag-NPs possess notable antibacterial efficacy against Staphylococcus aureus, Bacillus subtilis, and Escherichia coli, with minimum inhibitory concentrations (MICs) of Ag-NPs ranging from 62.5 to 250 μg/mL. Moreover, the biosynthesized Ag-NPs demonstrated weak antifungal activity against Aspergillus brasiliensis and Candida albicans, with MICs of 500 and 1,000 μg/mL, respectively. In addition, the mycosynthesized Ag-NPs exhibited photocatalytic activity toward acid black 2 (nigrosine) dye under both light and dark stimulation. Notably, After 300 min exposure to light, the nigrosine dye was degraded by 93%. In contrast, 51% degradation was observed after 300 min in darkness. In conclusion, Ag-NPs were successfully biosynthesized using endophytic A. hiratsukae and also exhibited antimicrobial and photocatalytic activities that can be used in environmental applications.

Improving the optical, thermal, mechanical, electrical properties and antibacterial activity of PVA-chitosan by biosynthesized Ag nanoparticles: Eco-friendly nanocomposites for food packaging applications

In this study, nanocomposite films were produced by blending polyvinyl alcohol (PVA) and chitosan (Cs) polymers with 70 % PVA and 30 % Cs, incorporating silver nanoparticles (Ag NPs) via a solution-casting method. The research aims to investigate the impact of the biosynthesized Ag NPs by Chenopodium murale leaf extract on optical, morphological, mechanical, thermal, electrical, and antibacterial properties. XRD analysis showed a decrease in crystallinity degree with Ag NPs addition. TEM revealed Ag NPs in cubic and spherical shapes with an average size of 23.4 nm. SEM and AFM indicated surface morphology changes. FT-IR spectra showed interaction between Ag ions and the blend. The energy gap decreased with increasing Ag NPs concentration. TGA exhibited enhanced thermal stability. Mechanical properties improved significantly. AC electrical conductivity and dielectric parameters were studied. Antibacterial activity against Gram-positive and Gram-negative bacteria was observed. Overall, PVA/Cs-Ag NPs films show promise for food packaging and optoelectronic applications.

Aerva lanata flower extract mediated green synthesis of silver nanoparticles: Their characterization, in vitro antioxidants and antimicrobial investigations

AbstractThe production of nanoparticles (NPs) using biological methods may lead to the enhancement of clean, non‐hazardous, and environmentally acceptable procedures. With this context, in the present study silver nanoparticles (AgNPs) were synthesized using the flower extract of Aerva lanata (A. lanata). The following techniques, including UV–visible spectroscopy, XRD, Scanning Electron Microscopy (SEM), and Fourier Transform Infrared Spectroscopy (FTIR), are used to study the crystalline nature, size, shape, and elemental composition of the biosynthesized AgNPs, and antimicrobial applications of the NPs also studied. In UV–visible spectroscopy results a strong absorbance peak at 425 nm confirmed the AgNPs. The SEM results confirmed the spherical shape of the NPs and their average size of 45.05 nm. X‐ray diffractometry XRD spectra confirmed the crystalline nature of the AgNPs. Against the DPPH (2,2‐diphenyl‐1‐picrylhydrazyl), nitric oxide and superoxide radicals, Alf‐AgNPs and ascorbic acid had significant scavenging effects at higher concentration of 250 μg/mL, exhibited 65.76 ± 0.41% and 86.42 ± 0.69%, 78.39 ± 0.49% and 72.72 ± 0.14% and 70.79 ± 0.87% and 72.79 ± 0.33% inhibition, respectively. As produced AgNPs had strong antibacterial and moderate antifungal activities against pathogenic test bacterial strains viz. Staphylococcus aureus (S. aureus), Bacillus subtilis (B. subtilis), Escherichia coli (E. coli), and Klebsiella pneumonia (K. pneumonia) with the maximum zone of inhibition 15 ± 1.07 mm, 12 ± 0.96 mm, 14 ± 1.05 mm, and 15 ± 2.54 mm, respectively at maximum (75 μg/mL) concentration of AgNPs, and the zone of inhibition of fungal strains Aspergillus fumigatus (A. fumigatus) (9 ± 0.67 mm) and Candida albicans (C. albicans) (7 ± 0.75 mm) at 75 μg/mL. It was eventually concluded that the biosynthesized Alf‐AgNPs showed promising antioxidant and antimicrobial agents with very low concentrations.

Attenuation of photosynthesis in nanosilver-treated Arabidopsis thaliana is inherently linked to the particulate nature of silver

Silver nanoparticles (AgNPs) are known to affect the physiology and morphology of plants in various ways, but the exact mechanism by which they interact with plant cells remains to be elucidated. An unresolved question of silver nanotoxicology is whether the interaction is triggered by the physical features of the particles, or by silver ions leached from their surface. In this study, we germinated and grew Arabidopsis thaliana seedlings in synthetic medium supplemented with sub-morbid concentrations (4 μg/mL) of AgNPs and silver nitrate (AgNO3). This treatment led to in planta accumulation of 106 μg/g and 97 μg/g of silver in the AgNO3- and AgNP-exposed seedlings, respectively. Despite the statistically indistinguishable silver accumulation, RNA sequencing data demonstrated distinct changes in the transcriptome of the AgNP-exposed, but not in the AgNO3-exposed plants. AgNP exposure induced changes in the expression of genes involved in immune response, cell wall organization, photosynthesis and cellular defense against reactive oxygen species. AgNO3 exposure, on the other hand, caused the differential expression of only two genes, neither of which belonged to any AgNP-enriched gene ontology categories. Moreover, AgNP exposure led to a 39% reduction (p < 0.001) in total chlorophyll concentration relative to untreated plants which was associated with a 56.9% and 56.2% drop (p < 0.05) in carbon assimilation rate at ambient and saturating light, respectively. Stomatal conductance was not significantly affected by AgNP exposure, and limitations to carbon assimilation, as determined through analysis of light and carbon dioxide (A/Ci) curves, were attributed to rates of electron transport, maximum carboxylation rates and triose phosphate use. AgNO3-exposure, on the other hand, did not lead to significant reduction either in chlorophyll concentration or in carbon assimilation rate. Given these data, we propose that the impact of AgNPs cannot be simply attributed to the presence of the metal in plants, but is innate to the particulate nature of nanosilver.

Metal nanoparticles to improve the heat resilience in wheat (Triticum aestivum L.)

This study evaluated the efficacy of phytogenic silver and zinc nanoparticles in improving heat resilience in various wheat varieties. The silver and zinc nanoparticles were synthesized using plant leaf extract and characterized using various techniques. Four wheat varieties (DBW187, Black Wheat, DBW 50, and PBW 621) were subjected to field trials. The random block design was used, and nanoparticles in different concentrations were applied at various growth stages and morphologically, and yield parameters were recorded. UV–vis spectroscopy spectral analysis showed peaks for Ag nanoparticles at 420 nm wavelength and Zn nanoparticles at 240 and 350 nm wavelength, depicting the preliminary confirmation of nanoparticle synthesis. Electron microscopic analysis (TEM and SEM) provided morphological insights and confirmed synthesis of fine-sized particle mostly in a range between 10 and 60 nm. Energy dispersive x-ray analysis confirmed the elemental composition of the synthesized nanoparticles, with Ag and Zn elements detected in their respective samples. It also confirmed the oxide nature of synthesized ZnNPs. Dynamic light scattering analysis provided size distribution profiles, indicating average sizes of approximately 61.8 nm for Ag nanoparticles and 46.5 nm for Zn nanoparticles. The concentrations of Ag and Zn nanoparticles in the samples were found to be 196.3 ppm and 115.14 ppm, respectively, through atomic absorption spectroscopic analysis. Fourier transform infrared spectroscopy analysis revealed characteristic functional groups present in the nanoparticles. The results of field experiments established that Ag nanoparticles at 75 ppm concentration exhibited the most significant enhancements in plant growth. Conversely, Zn nanoparticles at a 100 ppm concentration demonstrated the most substantial improvements in the growth and yield of heat-stressed wheat varieties. The study concludes that optimized concentrations of silver and zinc nanoparticles can effectively improve heat stress resilience in wheat. These findings are promising to enhance abiotic stress resilience in crops.

Enhancing antibacterial efficacy and accelerating infectious wound healing in rats using biogenic metal nanoparticles from marine Bacillus subtilis

IntroductionMicroorganisms originating from the marine environment, such as bacteria, fungi, and algae, are deliberately employed in the production of nanoparticles on account of the wide array of bioactive compounds they produce.MethodsCell-free aqueous extracts of marine Bacillus subtilis (CBPPR1) were used to synthesise AuNPs (CBPPR1AuNPs) and AgNPs (CBPPR1AgNPs). Zetasizer Nano ZS (Malvern Instruments) zeta size and zeta potential, field emission and transmission scanning electron microscopy (FE-SEM and HR-TEM), UV-visible (UV-Vis), X-ray diffraction (XRD), Fourier transform infrared (FT-IR), and EDAX were used to characterize biogenically synthesized nanoparticles (NPs). Their antibacterial activities against Escherichia coli, Klebsiella pneumoniae, and Staphylococcus aureus were investigated. The anticancer efficacy of CBPPR1Au and AgNPs was investigated in human colorectal adenocarcinoma cell lines (HT-29, HT-116). CBPPR1AgNPs formulation was studied in vitro and in-vivo rat models. The assessment focused on its efficacy in wound healing and antibacterial capabilities, comparing them against a commercial product. To determine the effectiveness of CBPPR1AgNPs in wound healing, a cutaneous wound model was employed, which included infection with S. aureus.Results and discusionCBPPR1Au and AgNPs significantly inhibited the growth of S aureus at MIC of 125 µg (CBPPR1AuNPs) and 62.5 µg (CBPPR1AgNPs) respectively. FE-SEM and HR-TEM observations confirmed that NPs caused bacterial cell leakage, damage, and shrinkage. Cancer cell viability was reduced upon treatment with increasing concentrations of CBPPR1Au and AgNPs, and apoptosis was increased in cells treated with CBPPR1Au and AgNPs relative to untreated cells (p &amp;lt; 0.001). CBPPR1Au and AgNPs showed significant cytotoxic activity against HT-29 (15.5 M) and HT-116 (62.5 M) cells. In-vivo experiments on rats showed minimal pus formation in groups CBPPR1AgNPs (62.5 µg/ml) G2, CBPPR1AgNPs (125 µg/ml) G3, and silver sulfadiazine G4, indicating the effective control of infections. CBPPR1AgNPs-treated wounds showed complete closure, whereas untreated G1 wounds remained unhealed. Histopathological analysis showed no adverse effects of CBPPR1AgNPs on kidneys and livers of rats. These findings suggest that CBPPR1AgNPs play a pivotal role in wound healing because of their potent antibacterial properties.

Anti-Bacterial Activity of Green Synthesised Silver and Zinc Oxide Nanoparticles against Propionibacterium acnes.

Propionibacterium acnes plays a critical role in the development of acne vulgaris. There has been a rise in the number of patients carrying P. acnes strains that are resistant to antibiotics. Thus, alternative anti-microbial agents are required. Zinc oxide (ZnO-NPs) and silver (Ag-NPs) nanoparticles can be used against several antibiotic-resistant bacteria. The impact of Ag-NPs and ZnO-NPs against two clinical strains of P. acnes, P1 and P2, and a reference strain, NCTC747, were investigated in this research. A chemical approach for the green synthesis of Ag-NPs and ZnO-NPs from Peganum harmala was employed. The microtiter plate method was used to examine the effects of NPs on bacterial growth, biofilm development, and biofilm eradication. A broth microdilution process was performed in order to determine minimal inhibitory (MIC) concentrations. Ag-NPs and ZnO-NPs had a spherical shape and average dimensions of 10 and 50 nm, respectively. MIC values for all P. acnes strains for Ag-NPs and ZnO-NPs were 125 µg/mL and 250 µg/mL, respectively. Ag-NP and ZnO-NP concentrations of 3.9- 62.5 µg/mL and 15-62.5 µg/mL significantly inhibited the growth and biofilm formation of all P. acnes strains, respectively. ZnO-NP concentrations of 15-62.5 μg/mL significantly inhibited the growth of NCTC747 and P2 strains. The growth of P1 was impacted by concentrations of 31.25 μg/mL and 62.5 μg/mL. Biofilm formation in the NCTC747 strain was diminished by a ZnO-NP concentration of 15 μg/mL. The clinical strains of P. acnes were only affected by ZnO-NP titres of more than 31.25 μg/mL. Established P. acne biofilm biomass was significantly reduced in all strains at a Ag-NP and ZnO-NP concentration of 62.5 µg/mL. The findings demonstrated that Ag-NPs and ZnO-NPs exert an anti-bacterial effect against P. acnes. Further research is required to determine their potential utility as a treatment option for acne.