Biogenic Silver Nanoparticles Research Articles

Harnessing Desert Flora: Biogenic Silver Nanoparticles from Desert Plants Combat Bacterial Infections and Biofilm Formation

Harnessing Desert Flora: Biogenic Silver Nanoparticles from Desert Plants Combat Bacterial Infections and Biofilm Formation

Green synthesis of silver nanoparticle prepared with Ocimum species and assessment of anticancer potential

Silver nanoparticles (AgNPs) have gained much attention due to their unique physical, and chemical properties. Integration of phytochemicals in nanoformulation might have higher applicability in healthcare. Current work demonstrates the synthesis of green AgNPs with O. gratissimum (gr-AgNPs) O. tenuiflorum (te-AgNPs) and O. americanum (am-AgNPs) followed by an evaluation of their antimicrobial and anticancer properties. SEM analysis revealed spherical-shaped particles with average particle sizes of 69.0 ± 5 nm for te-AgNPs, 46.9 ± 9 nm for gr-AgNPs, and 58.5 ± 18.7 nm for am-AgNPs with a polydispersity index below 0.4. The synthesized am-AgNPs effectively inhibited Klebsiella pneumonia, Escherichia coli, Staphylococcus aureus, Aspergillus niger, and Candida albicans with 23 ± 1.58 mm, 20 ± 1.68 mm, 22 ± 1.80 mm, 26 ± 1.85 mm, and 22 ± 1.40 nm of zone of inhibition respectively. Synthesized AgNPs also induced apoptotic cell death in MCF-7 in concentration-dependent manner. IC50 values for am-AgNPs, te-AgNPs, and gr-AgNPs were 14.78 ± 0.89 µg, 18.04 ± 0.63 and 15.41 ± 0.37 µg respectively which suggested that am-AgNPs were the most effective against cancer. At higher dose size (20 µg) AgNPs were equally effective to commercial standard Doxorubicin (DOX). In comparison to te-AgNPs and gr-AgNPs, am-AgNPs have higher in vitro anticancer and antimicrobial effects. The work reported Ocimum americanum for its anticancer properties with chemical profile (GCMS) and compared it with earlier reported species. The activity against microbial pathogens and selected cancer cells clearly depicted that these species have distinct variations in activity. The results have also emphasized on higher potential of biogenic silver nanoparticles in healthcare but before formulation of commercial products, detailed analysis is required with human and animal models.

Antifungal Activities of Biogenic Silver Nanoparticles Mediated by Marine Algae: In Vitro and In Vivo Insights of Coating Tomato Fruit to Protect against Penicillium italicum Blue Mold.

In an attempt to reduce such decay induced by pathogenic causes, several studies investigated the effectiveness of nanoparticles (NPs) that play a vital role in saving food products, especially fruits. Current research delves into biogenic silver nanoparticles (using marine alga Turbinaria turbinata (Tt/Ag-NPs) and their characterization using FT-IR, TEM, EDS, and zeta potential. Some pathogenic fungi, which cause fruit spoilage, were isolated. We studied the impact of using Tt/Ag-NPs to protect against isolated fungi in vitro, and the influence of Tt/Ag-NPs as a coating of tomato fruit to protect against blue mold caused by Penicillium italicum (OR770486) over 17 days of storage time. Five treatments were examined: T1, healthy fruits were used as the positive control; T2, healthy fruits sprayed with Tt/Ag-NPs; T3, fruits infected with P. italicum followed by coating with Tt/Ag-NPs (pre-coating); T4, fruits coated with Tt/Ag-NPs followed by infection by P. italicum (post-coating); and T5, the negative control, fruits infected by P. italicum. The results displayed that Tt/Ag-NPs are crystalline, spherical in shape, with size ranges between 14.5 and 39.85 nm, and negative charges. Different concentrations of Tt/Ag-NPs possessed antifungal activities against Botrytis cinerea, Rhodotorula mucilaginosa, Penicillium expansum, Alternaria alternate, and Stemphylium vesicarium. After two days of tomatoes being infected with P. italicum, 55% of the fruits were spoilage. The tomato fruit coated with Tt/Ag-NPs delayed weight loss, increased titratable acidity (TA%), antioxidant%, and polyphenol contents, and decreased pH and total soluble solids (TSSs). There were no significant results between pre-coating and post-coating except in phenol contents increased in pre-coating. A particular focus is placed on the novel and promising approach of utilizing nanoparticles to combat foodborne pathogens and preserve commodities, with a spotlight on the application of nanoparticles in safeguarding tomatoes from decay.

Biogenic silver nanoparticle synthesis using orange peel extract and its multifaceted biomedical application.

The aim of this study was to employ an agro-industrial byproduct, specifically Citrus sinensis peels, as a reservoir of polyphenols. The natural chemicals present in C. sinensis peels serve as reducing agents in an environmentally benign method for synthesizing silver nanoparticles (AgNPs). This methodology not only provides a more environmentally friendly method for synthesizing nanoparticles but also enhances the value of agricultural waste, emphasizing the sustainable utilization of resources. In our study, AgNPs were successfully synthesized using peel aqueous exact of C. sinensis and then their various biological activity has been investigated. The synthesized AgNPs were characterized by UV-vis spectroscopy, dynamic light scattering (DLS), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), and transmission electron microscopy (TEM) analysis. Furthermore, their effectiveness in inhibiting growth and biofilm formation of Escherichia coli, Staphylococcus aureus, and Candida albicans has been investigated. The minimum inhibitory concentrations (MIC) for E. coli and S. aureus were both 32μg/mL, and for C. albicans, it was 128µg/mL. At 250µg/mL of AgNPs, 94% and 92% biofilm inhibition were observed against E. coli and S. aureus, respectively. Furthermore, AgNPs demonstrated significant toxic effects against human prostate cancer cell line DU145 as investigated by anti-apoptotic, 4',6-diamidino-2-phenylindole (DAPI), reactive oxygen species (ROS), and acridine orange/ethidium bromide (AO/EtBr) assays. We also conducted uptake analysis on these pathogens and cancer cell lines to preliminarily investigate the mechanisms underlying their toxic effects. These findings confirm that AgNPs can serve as a cost-effective, non-toxic, and environmentally friendly resource for green synthesis of medicinal AgNPs. Moreover, this approach offers an alternative recycling strategy that contributes to the sustainable use of biological by-products.

Synthesis, Characterization, Acute Dermal Toxicity, Anti-inflammatory, and Wound Healing Potential of Biogenic Silver Nanoparticles in Balb C Mice.

The current study aimed to develop an economic plant-based therapeutic agent to improve the treatment strategies for diseases at the nano-scale. In the current research, silver nanoparticles were synthesized using Trillium govanianum aqueous extract. Characterizations were done using UV-Visible spectrophotometer, X-ray diffraction, scanning electron microscopy, and Fourier transform infrared spectroscopy. In vivo biological activities such as acute dermal toxicity, wound healing, and anti-inflammatory were done on Balb C mice. Absorbance at 295 nm corresponds to the out-of-plane quadrupole Plasmon-resonance while at 350 nm corresponds to in-plane dipole resonance. SEM images showed the morphology of TGAgNPs is not exactly spherical while XRD analysis shows that highly crystalline TGAgNPs with an average size of 27.94 nm. The FTIR spectrum represents sharp peaks of aldehyde, amide I, aromatic rings, and polysaccharides. The microscopic assessment did not find any epidermal and dermal layer abnormalities in Blab C mice when exposed to TGAgNPs during acute dermal toxicity. Results revealed that 1000 mg/kg is not a lethal dose. In the wound healing activity, no mortality and no abnormal signs were observed when petroleum jelly, Nitrofuranose, TGaqu, and TGAgNPs-based ointments were applied. Enhanced epithelization was recorded in TGaqu and TGAgNPs treated mice (p≤0.001). The wound contraction percentage was higher in nitrofuranose-treated mice (74%) followed by TGAgNPs (71%), and TGaqu (69%) compared to vehicle-treated and open-wounded mice. The paw edema model proved the potential use of TGAgNPs and TGaqu as anti-inflammatory agents. Hence, the results proved that both TGaqu and TGAgNPs are not toxic and possessed strong anti-inflammatory and wound-healing effects due to the presence of phytochemical constituents and could be used in various drug production as a therapeutic agent.

Chemical fingerprinting, antimicrobial, antioxidant, anti‐inflammatory, and anticancer potential of greenly synthesized silver nanoparticles from pistachio (Pistacia vera) nuts and senna (Cassia angustifolia Vahl.) leaves

AbstractThere is a growing interest in standardizing the biocompatible, cost‐effective, and eco‐friendly manufacturing techniques for metallic nanostructures due to their widespread applications in the industrial and medical sectors. In recent decades, green synthesis has been proven as the most suitable technique for synthesizing metal nanoparticles. The present research study investigates the use of Cassia angustifolia (senna) leaves and Pistacia vera (Pistachio) nuts to prepare crude aqueous extracts, ethanolic extracts, and biogenic silver nanoparticles (AgNPs). The prepared aqueous extracts were used as reducing, stabilizing, and capping agents for the production of silver nanoparticles. These AgNPs were characterized by scanning electron microscopy (SEM), Fourier‐transform infrared spectroscopy (FTIR), and ultraviolet–visible (UV–Vis) spectroscopy. The outcomes validated the formation of stable AgNPs with bioactive functional components. In vitro antibacterial, anticancer, anti‐inflammatory, and antioxidant potentials were assessed by Kirby–Bauer disk diffusion test, MIC test, MBC test, MTT assay, BSA denaturation inhibition assay, and DPPH antioxidant assay, respectively. Results confirmed that the tested plant extract possesses a variety of bioactive compounds with various biological activities and is therapeutically effective. These findings verified that C. angustifolia and P. vera are promising bioresources for the synthesis of therapeutic extracts and nanostructures with commendable therapeutic potency.

Plackett–Burman screening of physico-chemical variables affecting Citrus peel-mediated synthesis of silver nanoparticles and their antimicrobial activity

With the growing resistance of pathogenic microbes to traditional drugs, biogenic silver nanoparticles (SNPs) have recently drawn attention as potent antimicrobial agents. In the present study, SNPs synthesized with the aid of orange (Citrus sinensis) peel were engineered by screening variables affecting their properties via Plackett–Burman design. Among the variables screened (temperature, pH, shaking speed, incubation time, peel extract concentration, AgNO3 concentration and extract/AgNO3 volume ratio), pH was the only variable with significant effect on SNPs synthesis. Therefore, SNPs properties could be enhanced to possess highly regular shape with zeta size of 11.44 nm and zeta potential of − 23.7 mV. SNPs purified, capped and stabilized by cloud point extraction technique were then checked for their antimicrobial activity against Bacillus cereus, Listeria innocua, Listeria monocytogenes, Staphylococcus aureus, Enterobacter cloacae, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Salmonella typhimurium and Candida albicans. The maximum antimicrobial activity of SNPs was recorded against E. coli, L. monocytogenes and C. albicans with clear zone diameter of 33.2, 31.8 and 31.7 mm, respectively. Based on minimum inhibition concentration and minimum bactericidal concentration of SNPs (300 mg/l) as well as their effect on respiratory chain dehydrogenases, cellular sugar leakage, protein leakage and lipid peroxidation of microbial cells, E. coli was the most affected. Scanning electron microscopy, protein banding and DNA fragmentation proved obvious ultrastructural and molecular alterations of E. coli treated with SNPs. Thus, biogenic SNPs with enhanced properties can be synthesized with the aid of Citrus peel; and such engineered nanoparticles can be used as potent antimicrobial drug against E. coli.

Synthesis, Characterization and Application of Biogenic Silver Nanoparticles as Antibacterial and Antifungal Agents

In order to provide a straightforward, affordable, and environmentally friendly process for the synthesis of metallic nanoparticles, scientists are turning to natural ways like employing plant extract in response to rising antimicrobial resistance and the desire for novel biocidal agents. In this study, we evaluated the efficacy of phyto-fabricated silver nanoparticles and antimicrobial agents against selected indoor bacterial and fungal strains isolated from the lecture and office rooms of Chukwuemeka Odimegwu Ojukwu University, Uli Nigeria. The indoor microorganisms were isolated, identified, and quantified using standard methods. To prepare and generate the aqueous extract employed in the biological synthesis of the silver nanoparticle, fresh soursop seeds were room dried, crushed, heated to boiling, and double filtered. The phyto-fabricated nanoparticles were centrifuged, dried and used for physicochemical characterization and antimicrobial assay. The synthesized silver nanoparticles were characterized using UV-Vis spectrophotometry, Fourier transformed Infra-Red Spectroscopy and scanning electron microscopy analyses. The antimicrobial assay was carried out using agar well diffusion method. The results revealed that Aeromonas, Pseudomonas, Staphylococcus, Vibrio, Rhizopus, Aspergillus, Penicillium and Microsporum were identified as the predominant potential indoor bacterial and fungal pathogenic strains. The characterized biogenic nanoparticles revealed the optical, spectral and morphological features unique to silver nanoparticles. Also, the antibacterial screening revealed that the highest zone of inhibition was observed against Vibrio sp. (27.50 ± 7.5 mm) at a concentration of 30 μg/mL while standard antifungal drug (ketoconazole) had the highest zone of inhibition of 21.0 ± 1.0 mm at 3.25 μg/mL against Microsporum gypseum while standard antifungal drug (ketoconazole) and Ag-NPs had the lowest zone of inhibition of 11.0 ± 1.0 mm at 15.0 μg/mL and 7.5 μg/mL against Rhizopus sp. and Aspergillus flavus, respectively. The negative control (DMSO) had no zone of inhibition on any of the potential indoor bacterial and fungal pathogenic strains. Statistically, there was significant (P < 0.05) inhibition of bacterial and fungal pathogenic strains among the means of treatment doses of A. muricata AgNPs, ciprofloxacin and ketoconazole standard antibiotics. The excellent antimicrobial inhibition of the tested indoor bacterial and fungal strains by the A. muricata fabricated silver nanoparticles even at MIC of 3.25 μg/mL could be exploited as biostatic and biocidal agents where there is contamination or public health risk of pathogenic indoor bacteria and fungi.

Nanoremediation and Antioxidant Potential of Biogenic Silver Nanoparticles Synthesized Using Leucena's Leaves, Stem, and Fruits.

Synthetic dyes are persistent organic environmental pollutants that can cause extensive damage to living beings and to the ecosystem as a whole. Cost-effective, sustainable, and efficient strategies to deal with this type of pollution are necessary as it commonly resists conventional water treatment methods. Silver nanoparticles (AgNPs) synthesized using the aqueous extract from the leaves, stem, and fruits of Leucaena leucocephala (Leucena) were produced and characterized through UV-vis, TEM, EDS, SDL, XPS, XRD, and zeta potential, and they proved to be able to promote adsorption to remediate methylene blue and tartrazine pollution in water. The nanoremediation was performed and did not require direct exposure to sunlight or any special lamp or a specific reduction agent. The AgNPs produced using the extract from the leaves exhibited the best performance in nanoremediation and also presented antioxidant activity that surpassed the one from butylated hydroxytoluene (BHT). Consequently, it is an interesting nanotool to use in dye nanoremediation and/or as an antioxidant nanostructure.

Biogenic silver nanoparticles of Moringa oleifera leaf extract: Characterization and photocatalytic application

Abstract The current study proposed a novel simple and environmentally friendly approach for producing silver nanoparticles (AgNPs) using an extract of Moringa oleifera leaves (MOL) and optimizing the different experimental factors required for the formation and stability of AgNPs. The formation of nanoparticles was confirmed by a color change from yellow to reddish-brown with a surface plasmon resonance band at 412 nm. The morphology, size, and elemental composition of AgNPs were investigated by zeta potential dynamic light scattering, field emission scanning electron microscopy, energy dispersive X-ray, X-ray diffraction, and transmission electron microscopy analysis, which showed crystalline and spherical AgNPs. The identification of functional groups was supported by Fourier-transform infrared spectroscopy. The photocatalytic activities of AgNPs were assessed in the degradation of organic Malachite green (MG) dye in the aqueous solution. Two kinetic adsorption models, the pseudo-first-order model and the pseudo-second-order model, and three isotherm models, the Langmuir, Freundlich, and Temkin, were used to mathematically characterize the MG degradation process. The pseudo-second-order kinetics and the Freundlich isotherm model were found to be in good agreement with the experimental data. As a result of their synergistic interaction with the MOL extract solution, the photocatalytic activity of AgNPs increases and they can successfully adapt to the photodegradation of organic dyes in industrial effluents.

Ozone-induced oxidative stress alleviation by biogenic silver nanoparticles and ethylenediurea in mung bean (Vigna radiata L.) under high ambient ozone.

Ground-level ozone (O3) is the most phytotoxic secondary air pollutant in the atmosphere, severely affecting crop yields worldwide. The role of nanoparticles (NP) in the alleviation of ozone-induced yield losses in crops is not known. Therefore, in the present study, we investigated the effects of biogenicB-AgNPs on the mitigation of ozone-induced phytotoxicity in mung bean and compared its results with ethylenediurea (EDU) for the first time. Two mung bean cultivars (Vigna radiata L., Cv. SML-668 and PDM-139) were foliar sprayed with weekly applications of B-AgNPs (0 = control, 10 and 25ppm) and EDU (0 = control, 200 and 300ppm) until maturation phase. Morphological, physiological, enzymatic, and non-enzymatic antioxidant data were collected 30 and 60days after germination (DAG). The mean O3 and AOT40 values (8hday-1) during the cultivation period were approximately 52ppb and 4.4ppm.h, respectively. More biomass was accumulated at the vegetative phase due to the impact of B-AgNPs and EDU, and more photosynthates were transported to the reproductive phase, increasing yield. We observed that the 10ppm B-AgNPs treatment had a more noticeable impact on yield parameters and lower Ag accumulation in seeds for both cultivars. Specifically, SML-668 cultivar treated with 10ppm B-AgNPs (SN1) showed greater increases in seed weight plant-1 (124.97%), hundred seed weight (33.45%), and harvest index (37.53%) in comparison to control. Our findings suggest that B-AgNPs can enhance growth, biomass, yield, and seed quality, and can improve mung bean ozone tolerance. Therefore, B-AgNPs may be a promising protectant for mung bean.

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.

Laboratory-synthesized biogenic silver nanoparticles (AgNPs) with potential therapeutic applications

Laboratory-synthesized biogenic silver nanoparticles (AgNPs) with potential therapeutic applications

The synergic and addictive activity of biogenic silver nanoparticle associated with meropenem against carbapenem-resistant Acinetobacter baumannii.

Antibiotic management of infections caused by Acinetobacter baumannii often fails due to antibiotic resistance (especially to carbapenems) and biofilm-forming strains. Thus, the objective here was to evaluate in vitro the antibacterial and antibiofilm activity of biogenic silver nanoparticle (Bio-AgNP) combined with meropenem, against multidrug-resistant isolates of A. baumannii. In this study, A. baumannii ATCC® 19606™ and four carbapenem-resistant A. baumannii (Ab) strains were used. The antibacterial activity of Bio-AgNP and meropenem was evaluated through broth microdilution. The effect of the Bio-AgNP association with meropenem was determined by the checkboard method. Also, the time-kill assay and the integrity of the bacterial cell membrane were evaluated. Furthermore, the antibiofilm activity of Bio-AgNP and meropenem alone and in combination was determined. Bio-AgNP has antibacterial activity with minimum inhibitory concentration (MIC) and minimum bactericidal concentration ranging from 0.46 to 1.87 μg ml-1. The combination of Bio-AgNP and meropenem showed a synergistic and additive effect against Ab strains, and Bio-AgNP was able to reduce the MIC of meropenem from 4- to 8-fold. Considering the time-kill of the cell, meropenem and Bio-AgNP when used in combination reduced bacterial load to undetectable levels within 10 min to 24 h after treatment. Protein leakage was observed in all treatments evaluated. When combined, meropenem/Bio-AgNP presents biofilm inhibition for Ab2 isolate and ATCC® 19606™, with 21% and 19%, and disrupts the biofilm from 22% to 50%, respectively. The increase in nonviable cells in the biofilm can be observed after treatment with Bio-AgNP and meropenem in carbapenem-resistant A. baumannii strains. The combination of Bio-AgNP with meropenem can be a therapeutic option in the treatment of infections caused by carbapenem-resistant A. baumannii.

Activity of biogenic silver nanoparticles in planktonic and biofilm-associated Corynebacterium pseudotuberculosis.

Corynebacterium pseudotuberculosis is a gram-positive bacterium and is the etiologic agent of caseous lymphadenitis (CL) in small ruminants. This disease is characterized by the development of encapsulated granulomas in visceral and superficial lymph nodes, and its clinical treatment is refractory to antibiotic therapy. An important virulence factor of the Corynebacterium genus is the ability to produce biofilm; however, little is known about the characteristics of the biofilm produced by C. pseudotuberculosis and its resistance to antimicrobials. Silver nanoparticles (AgNPs) are considered as promising antimicrobial agents, and are known to have several advantages, such as a broad-spectrum activity, low resistance induction potential, and antibiofilm activity. Therefore, we evaluate herein the activity of AgNPs in C. pseudotuberculosis, through the determination of minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), antibiofilm activity, and visualization of AgNP-treated and AgNP-untreated biofilm through scanning electron microscopy. The AgNPs were able to completely inhibit bacterial growth and inactivate C. pseudotuberculosis at concentrations ranging from 0.08 to 0.312 mg/mL. The AgNPs reduced the formation of biofilm in reference strains and clinical isolates of C. pseudotuberculosis, with interference values greater than 80% at a concentration of 4 mg/mL, controlling the change between the planktonic and biofilm-associated forms, and preventing fixation and colonization. Scanning electron microscopy images showed a significant disruptive activity of AgNP on the consolidated biofilms. The results of this study demonstrate the potential of AgNPs as an effective therapeutic agent against CL.

Antimicrobial and optical properties of a new biogenic silica-coated silver nanoparticles incorporated into experimental resin.

Evaluate the effects of incorporating silica-coated silver nanoparticles (Ag@SiO2 NPs) into odontological clinic resin materials. Silver nanoparticles coated with silicon dioxide were added to the experimental resin matrix at 1, 3, and 5wt%. Degree of conversion (DC), optical properties (total transmittance and color change), and microstructural analysis were evaluated. Materials were tested for silver ion release, cytotoxicity in dental pulp fibroblasts, Streptococcus mutans biofilm growth by Colony-Forming Unit (CFU) and confocal laser scanning microscopy (CLSM). Groups had a similar DC, despite significant differences observed in transmittance and color change analysis for all groups with NPs. Silver ion release values were below the detection limit after 72h for all groups, and NPs incorporation did not show a statistical difference from the control on pulp fibroblasts assay. After 72h, the CFU count was significantly reduced by 74% from 3wt% of Ag@SiO2NPs. CLSM evaluation on S. mutans colonies showed a dose-dependent decrease in the emitted fluorescence. The application of Ag@SiO2 NPs in a resinous matrix, demonstrates a significant reduction of S. mutans CFU in oral biofilm, at concentrations from 3wt%, without an increase in cytotoxicity. The reduced transmittance values did not affect the DC, although a significant color change was perceived in all concentrations. Key words:Nanoparticles, Silver Compounds, Composite Dental Resin, Anti-Bacterial Agent, Optical Imaging.

Synthesis of biogenic silver and gold nanoparticles from Anemopsis californica extract with antibacterial and cytotoxic activities

Silver (Ag) and gold (Au) nanoparticles, have gained attention for their unique properties and diverse applications, including medicine and antimicrobial agents. To meet the demand for eco-friendly synthesis methods, we explored plant-mediated nanoparticle synthesis using Anemopsis californica extracts. The Anemopsis californica leaves were used to extract bioactive compounds with water, methanol, and isopropanol. These extracts served as reducing and stabilizing agents for Ag and Au nanoparticle synthesis. The process involved mixing the extract, a metallic precursor solution, and deionized water in specific volume ratios, resulting in nanoparticles denoted as W-(Ag or Au), M-(Ag or Au), and I-(Ag or Au) for water, methanol, and isopropanol, respectively. The synthesized nanoparticles ranged from 5 to 30 nm in size and displayed various shapes. UV-Vis spectroscopy confirmed their presence with surface plasmon resonance bands. Antibacterial tests on Staphylococcus aureus and Escherichia coli showed significant antibacterial effects of Ag nanoparticles, especially those synthesized in methanol. In contrast, Au nanoparticles had limited antibacterial impact, regardless of the solvent. Cytotoxicity evaluations with macrophage cells indicated that Ag nanoparticles were more cytotoxic than Au nanoparticles, with the synthesis solvent influencing cytotoxicity. The observed antibacterial effects of Ag nanoparticles align with their reputation as potent antimicrobial agents, particularly against Gram-positive strains. The limited antibacterial impact of Au nanoparticles suggests differences in their antibacterial mechanisms. Varying cytotoxicity between Ag and Au nanoparticles underscores the significance of the chosen synthesis method in shaping nanoparticle properties.

Mode of Action of Biogenic Silver, Zinc, Copper, Titanium and Cobalt Nanoparticles Against Antibiotics Resistant Pathogens

Mode of Action of Biogenic Silver, Zinc, Copper, Titanium and Cobalt Nanoparticles Against Antibiotics Resistant Pathogens

Modulation of Staphylococcus aureus Biofilm Formation through Subinhibitory Concentrations of Biogenic Silver Nanoparticles and Simvastatin

Staphylococcus aureus is a causative agent of nosocomial infections and its antibiotic-resistant strains give cause for concern. Solutions are being explored to improve treatment for these infections, including repositioning drugs such as statins and using nanoparticles with antimicrobial properties. This study evaluated the antimicrobial effects of simvastatin (SIM) and biologically synthesized silver nanoparticles (bio-AgNPs) in isolate form and in combination using assays of minimum inhibitory concentration (MIC), an in vitro biofilm model, and the association of antimicrobials against clinical strains of S. aureus. Bio-AgNPs showed a 53.8 ± 1.23 nm mean diameter and standard deviation, a 0.23 polydispersity index, and a −25.66 ± 2.19 mV mean potential and standard deviation. Transmission electron microscopy confirmed the formation of nanoparticles, and the presence of Ag0 and AgCl. S. aureus strains were sensitive to bio-AgNPs and SIM, showing 31.88–187.5 and 74.66–149.32 μM concentrations, respectively. The association assay showed 2.0 fractional inhibitory concentration indices (i.e., indifferent for clinical strains) and 0.32 values for the standard ATCC 29213 strain (synergy). Biofilm inhibition assays with isolated SIM and bio-AgNPs showed decreased biofilm formation 4× to ⅛ MICs concentrations, showing no synergism in association. These findings evince that simvastatin and bio-AgNPs at subinhibitory concentrations can serve as antimicrobial agents against S. aureus biofilm.

Разработка нового нанобиотехнологического метода и его применение для дифференциальной диагностики опухолей придаточного аппарата глаза

Aim: to develop a new nanobiotechnology method for the differential diagnosis of ocular adnexal tumors. Patients and Methods: 192 eyelid or conjunctival tumor samples from 192 patients were examined. Controls were healthy tissue samples from the same eye. To register and obtain significant differences in the generation of biogenic silver nanoparticles in situ, the key parameters of the reaction of the reduction of silver cations were selected and optimized. To generate de novo biogenic silver nanoparticles, tissue samples were placed in a sterile solution of a cation source in aseptic conditions. Nanoparticles were generated in situ using a sterile solution of Tollens' reagent (Ag(HN3)2NO3). Results: the optimal parameters of a new nanobiotechnology method were established to conduct the reduction reaction to generate biogenic silver nanoparticles. The required concentration of Tollens' reagent (source of cations) was 63 μg/ml. The wavelength used to observe the de novo generation of biogenic silver nanoparticles (λ) was 410 nm. Obtaining the most significant changes in the optical density of the reaction mixture with biogenic nanoparticles required 10 to 20 min, although the first changes were documented starting from the 5th minute of the reduction reaction. Benign and malignant tumors are characterized by different metabolic activities, i.e., benign eyelid and conjunctival tumors reduce cations more slowly than malignant tumors. The parameters of reducibility of benign ocular adnexal tumors did not significantly differ depending on tumor location and type. Among the malignant conjunctival tumors, melanoma is characterized by the highest reducibility p<0.05). Among the malignant eyelid tumors, no significant differences were found for different tumor types. Conclusions: this novel nanobiotechnology method provides a differential diagnosis of benign and malignant ocular adnexal tumors. The practical relevance of this method lies in differentiating benign and malignant tumors to schedule management strategies and surgical interventions. KEYWORDS: tumor, eyelids, conjunctiva, silver nanoparticles, biogenic synthesis, express diagnostics, ocular oncology. FOR CITATION: Saakyan S.V., Skladnev D.A., Alekseeva A.P., Beznos O.V., Sorokin V.V. Development of a new nanobiotechnology method for the differential diagnosis of ocular adnexal tumors. Russian Journal of Clinical Ophthalmology. 2024;24(1):25–29 (in Russ.). DOI: 10.32364/2311-7729-2024-24-1-5.