Formation Of Silver Nanoparticles Research Articles

Green Synthesis of Noble Metal Nanoparticles: Nonlinear Optics and Applications

This study presents a green method for synthesising gold nanoparticles (AuNPs) and silver nanoparticles (AgNPs) employing Gum Arabic extract as a reducing and stabilising agent. The synthesised nanoparticles are characterised using UV-Vis absorption spectroscopy and transmission electron microscopy (TEM). The visible colour change and the presence of surface plasmon resonance (SPR) peaks confirmed the formation of silver and gold nanoparticles. The size of the nanoparticles was determined from the UV-Vis spectra data, and the results were compared to sizes measured by TEM. The nonlinear refraction (n2) and nonlinear absorption (b) coefficient of AgNPs and AuNPs at 488 and 514 nm were investigated under continuous wave (CW) mode excitation using the Z-scan technique. By fitting the experimental data to the Z-scan theoretical equations, the nonlinear refraction index and the nonlinear absorption coefficient were found. The origin of the nonlinearities was discussed, and it was proposed to be of thermal effect for the nonlinear refractive index and Reverse Saturation Absorption (RSA) for nonlinear absorption. Optical limiting and switching were demonstrated by taking advantage of the samples' nonlinear optical characteristics.

Green Synthesis of Silver Nanoparticles Using Sclerorhachis Leptoclada Rech. F. Leaf Extract: Characterization and Investigation of Antibacterial Activities

Introduction: The environmentally friendly method of green nanoparticle production has garnered significant interest because of its cost-effectiveness and ease of implementation. In this study, in addition to the green synthesis of silver nanoparticles using the leaf extract of the Sclerorhachis leptoclada Rech. f. (SLL@AgNPs) and the morphological study of the SLL@AgNPs, the antibacterial properties of the SLL@AgNPs were compared with the extract of the S. leptoclada plant and silver nanoparticles alone. Methods: In this experimental investigation, the features of SLL@AgNPs synthesized via a green method were analyzed using various techniques, including spectrophotometry, X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), dynamic light scattering (DLS), and transmission electron microscopy (TEM). Ultimately, the antibacterial properties were assessed through the broth micro-dilution method. Results: DLS and zeta potential showed the formation of SLL@AgNPs with a hydrodynamic diameter of 130 nm and a surface charge of -38.82 mV, respectively. XRD and TEM analysis also confirmed the formation of pure silver nanoparticles with spherical and elliptical morphology with an average diameter of 20-30. The SLL@AgNPs exhibited antibacterial activity against Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Staphylococcus aureus, and Enterococcus faecalis, with minimum inhibitory concentrations (MIC) of 0.039, 0.078, 0.039, 0.078, and 0.31 mg/ml, respectively. These findings indicate that SLL@AgNPs significantly enhanced the antibacterial properties of the S. leptoclada plant. Conclusion: As evidenced by the obtained results, S. leptoclada plant extract significantly increased the antibacterial activity of silver nanoparticles. This research demonstrated the potential of environmentally friendly silver nanoparticles synthesized in the presence of S. leptoclada extract with significant antibacterial effects for various biomedical applications.

Extracellular Biosynthesis, Characterization and Antimicrobial Activity of Silver Nanoparticles Synthesized by Filamentous Fungi.

The green synthesis of metal nanoparticles has received substantial attention due to their applications in various domains. The aim of the study was to obtain silver nanoparticles (AgNPs) by green synthesis with filamentous fungi, such as Cladosporium cladosporoides, Penicillium chrysogenum, and Purpureocillium lilacinum. Fungal species were grown on nutrient media and aqueous mycelium extracts were used to reduce Ag+ to Ag (0). The silver nanoparticles were analyzed by various techniques, such as UV-Visible spectroscopy (UV-Vis), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), dynamic light scattering (DLS), and Zeta potential. The formation of silver nanoparticles was confirmed by UV-Vis spectroscopy and the color change of the mixture containing metal precursor and aqueous mycelium extract. FTIR displayed different functional groups as capping and reducing agents for the biosynthesis of AgNPs. SEM and TEM provided information on the particles' morphology. DLS diagrams indicated mean particle diameters in the 124-168 nm region. All biosynthesized AgNPs had negative zeta values, which is a sign of good stability. Silver nanoparticles were evaluated for antimicrobial activity, and the most active were those synthesized with metabolites from Cladosporium, leading to 93.75% inhibition of Staphylococcus aureus, 67.20% of Escherichia coli, and 69.56% of Candida albicans. With the highest microbial inhibition percentage and a very good Poly Dispersion Index (Pd I), Cladosporium cladosporoides was selected as an environmentally friendly source of silver nanoparticles that could be used as a potential antimicrobial agent.

SILVER NANOPARTICLES-AQUEOUS LEAF EXTRACT OF SIDAGURI (SIDA RHOMBIFOLIA) AS REDUCING AGENTS

The Sidaguri leaf, scientifically known as Sida rhombifolia, is a plant species rich in flavonoids that have the ability to act as reducing agent in formation of silver nanoparticles. This study presented the synthesis of silver nanoparticles (AgNp-Sid) using aqueous leaf extract of sidaguri. This study utilized a concentration ratio of 2:90 mL aqueous leaf extract of Sidaguri and AgNO3 1 mM. The size and morphology of AgNp-Sid was measured using UV-Visible Spectrophotometer, PSA, FT-IR, SEM-EDS, and XRD. The investigation revealed an ordinary particle size of 63.5 nm with polydispersity index (PI) of 0.284. The maximum wavelength varies between 405.4 nm and 407.8 nm with the increasing of time. AgNp-Sid exhibited a spherical morphology and had a crystalline structure that is face-centered cubic. The results suggested that the aqueous leaf extract of sidaguri had the ability to function as a reducing agent in the synthesis of silver nanoparticles, offering a safe, cost-effective, and environmentally friendly alternative.

Synergistic blend: Curcumin-loaded silver nanoparticles synthesized from Talaromyces atroroseus pigment for bio evaluation

Metallic silver, particularly in the form of silver nanoparticles (AgNPs), has gained renewed attention as a powerful antimicrobial solution. In the present investigation, AgNP was synthesized using pigments produced by Talaromyces atroroseus, and Curcumin was loaded onto these AgNP to evaluate their potent antimicrobial, anti-inflammatory, antioxidant and anticancer activities. The maximal biosynthesis of silver nanoparticles (AgNP) was achieved at an optimized precursor concentration of 6 mM silver nitrate (AgNO₃) and a reducing agent concentration of 0.5 g/L fungal pigment. The incorporation efficiency of curcumin onto AgNP was determined to be 11 %. Comprehensive characterization of both curcumin-loaded and unloaded AgNPs was performed using EDS, SEM, FTIR and XRD. Antibacterial assays revealed that both formulations exhibited antimicrobial properties, with the curcumin-loaded AgNPs displaying significantly enhanced inhibitory effects, particularly against Staphylococcus aureus, showing an inhibition zone of 16 ± 0.33 mm. Furthermore, curcumin-loaded AgNPs demonstrated moderate antioxidant activity, with a 36.32 % free radical scavenging rate and an IC50 of 71.9 µg mL−1. The nanoparticles also exhibited potent anti-inflammatory properties, achieving 84.05 % inhibition of inflammation and an IC50 of 96.69 µg mL−1. Notably, curcumin-loaded AgNPs demonstrated cytotoxicity in 100 µg mL−1 of the concentration tested on lung cancer cell line (A549) at 96 hrs. These results suggest that the extended incubation hours or increasing the concentrations of the AgNPs could be lethal concentrations that could completely inhibit the proliferation of lung cancer cells. However, further validation in in-vivo models for toxicity and clearance of AgNPs from the system has to be studied. The observed synergistic effects of biosynthesized curcumin-loaded AgNPs suggest a promising alternative to conventional antibiotic therapies.

Evaluation of silver nanoformulated plant extracts against larvae of the fall armyworm, Spodoptera frugiperda (J. E. Smith), under laboratory and field conditions

AbstractThe fall armyworm, Spodoptera frugiperda (J. E. Smith), is a destructive pest of Zea mays (maize) and other agricultural crops. The synthetic insecticides predominantly used against this pest lead to pest resistance, environmental contamination and health hazards. This study evaluated nanoformulated aqueous extracts of some promising local plant species against third instar larvae of S. frugiperda under laboratory and field conditions. The initial screening bioassay showed highest larval mortality with a 20% extract of Nicotiana tabacum L. (66.67%), followed by Azadirachta indica A. Juss. (53.33%), Withania somnifera L. (46.67%), Melia azedarach L. (40%) and Dodonaea viscosa Jacq. (33.33%). The two most effective plant extracts (A. indica and N. tabacum) were further nanoformulated with silver nitrate (AgNO3) and bioassayed against S. frugiperda larvae using different concentrations. The results showed that these nanoformulated extracts caused significant larval mortality, with LC50 (lethal concentration that kills 50% of the population) and LT50 (lethal time to kill 50% of the population) values of 37.36 and 28.21% at 72 h, and 52.19 and 33.25 h at 80% concentration, respectively. Field experiments on Zea mays L. (maize) plants showed maximum larval reduction by nanoformulated A. indica extract (48%), followed by N. tabacum extract (36%), whereas 80% and 20% larval reduction was noted for the positive (SuperLock®, emamectin benzoate and tebufenozide) and the negative (water) controls, respectively. Furthermore, characterization of both silver nanoparticles‐based plant extract formulations was performed using ultraviolet–visible (UV–vis) spectroscopy, Raman spectroscopy and scanning electron microscopy (SEM) techniques, which confirmed the formation of silver nanoparticles. It is concluded that nanoformulated plant extracts can be an effective alternative to synthetic pesticides in combatting S. frugiperda and other lepidopteran pests.

The green formulation of silver nanoparticles for the anticancer and lupus nephritis treatment applications and reducing the inflammatory cytokines in the rat periodontal model

In this study, a novel bio-inspired synthesis for the preparation of Ag NPs by Calendula persica flower extract has been researched. Also, the effects of the recent composite on lupus nephritis by following the TGF-β1 signaling pathway in mice and gingival amounts of IL1-β and TNF-α in the animal periodontal model were determined. To assess the crystal nature, morphology and size of the prepared nanoparticles, X-ray diffraction (XRD), transmission electron microscopy (TEM), ultraviolet–visible (UV–Vis) and field emission-scanning electron microscopy (FE-SEM) analyses were applied in this study. The prepared Ag NPs was employed for its effectiveness against colon cancer cell line (C26). The bio-synthesized Ag NPs had also cytotoxic property versus colon cancer based on MTT protocol. Collectively, the Ag NPs fabricated by biological way has potential applications in inflammatory treatment. In lupus nephritis section, indexes in animal tissues and serum were identified using specific kits, while pathological alterations in the mice kidney were examined through H&E staining. Additionally, qPCR was employed to determine the expression related to TGF-β 1 in kidney, thereby providing further insight into the silver nanoparticles mechanism. The findings indicated that silver nanoparticles reduced the mRNA expression levels of TGF-β 1 and NF-κB in the kidneys, while simultaneously increasing the Mn-SOD and IκB-α expression. Histological examination of H&E-stained sections revealed that silver nanoparticles mitigated the morphological abnormalities of the glomeruli and the inflammatory infiltration associated with nephritis. Silver nanoparticles demonstrated an inhibitory effect on the dsDNA positive rate in animal suffering from nephritis. Silver nanoparticles were found to reduce the increase in urinary protein and the pro-inflammatory cytokines concentrations in both the kidney and serum. In the periodontal model study, 0-3 ligatures were applied to induce the inflammatory periodontitis in right mandibular first molar neck in rats. The levels of inflammatory cytokines (IL1-β, CINC-1, IL-10 and TNF-α) were determined by common immunological test, ELISA. The findings revealed that Ag NPs administration could decease the IL1-β and TNF-α production in the rat periodontal model gum tissue. In addition, the outcome of this research indicated that IL1-β and TNF-α levels raised in the rat periodontal model gum tissue compared to control group. Ag NPs increased the levels of superoxide dismutase, catalase, and plasma bone alkaline phosphatase and reduced the IL1-β, TNF-α, inducible nitric oxide synthase and RANK genes mRNA expression. The results indicate that pre/post-treatment with Ag NPs because of its direct activity on pro-inflammatory cytokines inhibition improved the inflammatory symptoms in the periodontitis and lupus nephritis animals.

Effect of Environmental Factors on The Production of Silver Nanoparticles by Yeast Strains

In the presented work, the literature data on the influence of various environmental factors were analyzed on the formation of silver nanoparticles by yeast strains. It was determined that the optimal conditions for the synthesis of silver nanoparticles by the yeast strain Saccharomyces ellipsoideus BSU-XR1 were on the 21st day of incubation, on 4-6 days of incubation in different strains of Saccharomyces cerevisiae, and between 2-10 days in Candida strains. The optimal amount of wet biomass was between 8 and 10 g for Candida strains and 10 g for Saccharomyces strains. The temperature limit for Saccharomyces was observed at 25-35°C, and for Candida at 25-37°C. For strains, synthesis of silver nanoparticles was optimal in the pH range of 4-10, and pH range of 7 for Candida strains. Depending on the concentration of AgN03 salt, the optimal synthesis of silver nanoparticles occurred at concentrations of 0.5 and 1 mM for Saccharomyces, and 1 mM for Candida. The optimal incubation conditions for both sexes were under dark environment.

Ultrafast laser triggering nanocrystallization inside Nd-doped photo-thermo-refractive glass and its application in Q-switched laser.

Photo-thermo-refractive (PTR) glass doped with rare-earth ions has attracted considerable attention due to its excellent linear photosensitivity and laser performance. This study investigates the nonlinear photosensitive nanocrystallization induced by ultrafast laser irradiation in Nd-doped PTR glass. Phase contrast microscopy reveals that both Gaussian and Gaussian-Bessel beams can modulate the refractive index positively or negatively, depending on specific conditions. Notably, Gaussian-Bessel beams can significantly extend the thickness of the laser-modified layer. Optical spectra indicate the formation of silver nanoparticles, with concentration increasing as pulse energy increases. Furthermore, X-ray diffraction and transmission electron microscopy confirm the precipitation of nanocrystals with the composition of NaF following laser irradiation and thermal treatment, consistent with conventional PTR glass. The nonlinear optical characteristics of the treated sample are evaluated and successfully applied in a passive Q-switched laser, exhibiting both gain characteristics and saturable absorption. This study provides an effective strategy for multifunctional integrated on-chip devices that possess high damage thresholds and enhanced stability.

Electrospun poly(N-vinylpyrrolidone) membranes with Ag nanoparticles for wound dressings: Production and characterization

Wound dressings have long been used to promote the healing of skin injuries. In the work reported here, fibrous membranes were produced by electrospinning poly(N-vinylpyrrolidone) (PVP) solutions containing silver nitrate at varying mass ratios (1:200, 1:100 and 1:50 AgNO3:PVP). PVP solutions without AgNO3 were used as a control. The electrospun membranes were irradiated using 254 nm UV light to simultaneously photo-crosslink PVP and promote the formation of silver nanoparticles (AgNPs). The formation of AgNPs was confirmed by scanning electron microscopy and transmission electron microscopy, as well as by detecting the surface plasmon resonance peak at 420 nm in the UV–Vis spectrum during release studies. The swelling rate of fibrous membranes was lower for those containing AgNPs compared to PVP-only membranes. The Kirby-Bauer diffusion test performed against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Staphylococcus epidermidis and Candida albicans showed that all AgNPs-containing membranes exhibited an inhibitory effect on all microorganisms tested. The in vitro cytotoxicity assay showed that membranes with lower silver concentration were less cytotoxic. This study presents a simple route to producing a wound dressing with antimicrobial action that has a swelling behavior capable of absorbing exudates, provides controlled release of silver and has low cytotoxicity.

Solution plasma synthesis of nitrogen-doped carbon dots from glucosamines: Comparative fluorescence modulation for dopamine detection

The intriguing fluorescence characteristics of carbon dots (CDs) have led to many sensor applications, particularly for dopamine (DA), a molecule linked to various diseases. This study prepares CDs from glucose and glucosamine (nitrogen-free and nitrogen-containing precursors) using a simple solution plasma process (SPP). We explore how nitrogen elements and counterions in glucosamine (hydrochloride and sulfate) affect CD properties and their ability to modulate fluorescence for DA detection. Glucosamine offers three advantages over glucose: (i) single-step CD synthesis via SPP, (ii) enhanced fluorescence of CDs, and (iii) improved fluorescence response to DA. We investigate the DA detection capabilities of N,S-CDs (from glucosamine sulfate) and N,Cl-CDs (from glucosamine hydrochloride). Both can sense DA with distinct photoluminescence responses. N,S-CDs show selectivity and fluorescence brightening upon DA interaction, with a detection limit of 33.05 μM. N,Cl-CDs demonstrate higher sensitivity with a lower detection limit of 0.1212 μM through fluorescence quenching. Silver ions (Ag+) may also contribute to N,Cl-CDs quenching; however, the observed color change to gray due to silver nanoparticle (AgNP) formation helps pinpoint the quenching substance. The varied photoluminescence responses arise from different surface functional groups: N,S-CDs have amino-rich surfaces, while N,Cl-CDs have conjugated carbonyl-rich surfaces. This study illustrates the mechanisms of DA detection and AgNP formation, suggesting the potential of CDs in medical diagnostics as selective tools for disease diagnosis. Additionally, we compare the DA sensing methodology of our CDs with existing literature, highlighting the advantages of our sensor.

Non-enzymatic Determination of Glucose in Artificial Urine Using 3D-µPADs through Silver Nanoparticles Formation

Patients with diabetes often experience blood glucose fluctuations, making monitoring crucial. Traditional blood sampling methods pose risks of infection and pain. An alternative non-invasive approach using urine tests has been explored. Recent studies highlight microfluidic paper-based analytical devices (µPADs) as convenient, simple, and easily fabricated tools for non-invasive glucose measurement. This study aims to develop a concept of measuring glucose in artificial urine using 3D-µPADs in a non-enzymatic manner by utilizing glucose as a reducing agent for silver nanoparticle (AgNPs) formation. Embedding three-dimensional connectors in µPADs links the sample and detection zones to limit reagent mixing and improve glucose detection resolution. The optimal conditions were NaOH 10 M, starch 1%, and AgNO3 30 mM, with sample and detection zone volumes of 10 and 9 µL, respectively. The fifth reaction sequence involved AgNO3 in the detection zone and a solution of glucose, NaOH, and starch in the sample zone at 1:1:1 volume ratio. The reagent drying time was 15 min, with immobilization once and reaction time of 9 min. The method showed excellent linearity (R2 = 0.9905), precision (%RSD = 4.27%), accuracy (77.32–92.58%), and limit of detection (11.11 mg/dL).

Zinc oxide (ZnO) Enhanced with Silver (Ag) is Used to Improve the Photocatalytic Degradation of Phenol in Aqueous Solutions

Silver-modified zinc oxide (Ag/ZnO) photocatalysts were synthesized and characterized to evaluate their efficiency in degrading phenol under UV irradiation. X-ray fluorescence, surface area analysis, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and UV-visible reflectance spectroscopy confirmed successful deposition of metallic silver (Ag0) nanoparticles on the ZnO surface. The abundance of silver particles correlated directly with Ag concentration. Surface plasmon resonance bands indicated silver nanoparticle formation. Photocatalytic testing showed increased phenol degradation with Ag/ZnO versus pure ZnO, with 0.88 wt% Ag being optimal. Further experiments found 50 mg/L initial phenol and 0.15 g/L photocatalyst dosage optimized performance. Finally, almost complete elimination of phenol from drinking wastewater occurred after 180 minutes with the enhanced Ag/ZnO photocatalyst under UV irradiation.

Chitosan Coupled Silver Nanoparticles Electrocatalyst Synthesis and Characterization

This study sought to find a suitable technique for synthesizing and characterizing silver nanoparticles due to its applications in various fields such as nanotechnology and medical. The synthesized silver nanoparticles were characterized using SEM microscopy, FT-IR and UV-Vis spectroscopy. The maximum absorbance from the UV-Vis spectrophotometer showed the formation of silver nanoparticles with λ max of 418 nm. The FTIR analysis envisaged a strong symmetrical stretching at 1400 cm-1 to 1200 cm-1 with the major peaks recorded at 1390 cm-1 and 1380 cm-1, indicating the presence of nitro components in the sample. The signal at 1658 cm−1 corresponded to the amide (C=O) bonds stretching vibrations, at 1089 cm−1 C-O-C bonds and at 564 cm−1 plane with bends NH, plane-out and bends C−O. C-H stretching vibrational signal was noted at 2927 cm−1, and a broader band at 3426 cm−1 with an overlap between the O−H stretching vibration and N−H stretching vibration of the oligosaccharide applied in the capping. The concentration of chitosan on transmittance was done using 0.5%, 1.0%, 1.5% and 2.0% solutions with the results from FT-IR showing elaborate intensity at 2.0 % chitosan capping and the least at 0.5 %. Scanning microscope validated characterized silver nanoparticles morphology at 500nm. The results obtained from SEM depicted a size range of 100 nm with resolutions between 0.5 to 4 nm

PH‐responsive bionanocomposite pectin grafted with dimethylaminoethyl methacrylate and acrylic acid copolymer along with silver nanoparticles for breast cancer drug delivery

AbstractIn this study, we developed a pH‐responsive hydrogel membrane composed of pectin, dimethylaminoethyl methacrylate (DMAEMA), and acrylic acid (AA) through a free radical‐triggered graft copolymerization method. Freshly formed silver nanoparticles (AgNPs) produced from the reduction reaction were embedded in the produced hydrogel. Pectin‐grafted dimethylaminoethyl methacrylate and acrylic acid copolymer [poly (DMAEMA‐co‐AA)‐g‐pectin] and its bionanocomposite with AgNPs were confirmed by Fourier‐transform infrared spectroscopy (FT‐IR), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The swelling behavior of poly (DMAEMA‐co‐AA)‐g‐pectin in solutions with diverse pH values was assessed. For use as a controlled drug delivery agent, the hydrogel was loaded with 5‐fluorouracil (5‐FU). The incorporation of AgNPs had a great impact on the entrapment efficiency of 5‐FU. At pH 7.4, nearly 48% of the 5‐FU was released in vitro from the polymeric nanocomposite within 24 h. Moreover, poly (DMAEMA‐co‐AA)‐g‐pectin and poly (DMAEMA‐co‐AA)‐g‐pectin/AgNPs presented high cytocompatibility toward normal skin fibroblast cells (BJ1), and the drug delivery system strongly inhibited human Caucasian breast adenocarcinoma cells (MCF‐7). These results demonstrated that these poly (DMAEMA‐co‐AA)‐g‐pectin/AgNPs are an excellent candidate for use in anticancer drug delivery systems.Highlights Free radical polymerization of nanocomposites incorporated with nanoparticles. Nanoparticles improve the bionanocomposites' drug loading. The developed bionanocomposites exhibit control drug release. The novel bionanocomposites acts as an excellent anticancer drug carrier.

Exploring the effects of cellulose sources on silver reduction and the bacterial removal of nanocellulose-based hydrogel beads

With water access challenged, there is a need to develop efficient and sustainable alternatives for water purification. Here, cellulose nanofibrils (CNFs) isolated from three source materials (softwood, soybean hulls and oat straw) were compared for the generation of hydrogels beads, and compared as support and reducing agent for silver nanoparticles formation. The silver-functionalized hydrogel beads (Ag-CNFs) were characterized, and the surface energy and specific surface area were evaluated. Antimicrobial testing was conducted to assess the efficacy of the Ag-CNFs against E. coli. The results showed that the Ag-CNFs had a higher specific surface area and lower surface energy compared with unmodified CNFs. Softwood-based Ag-CNFs exhibited the highest silver content and specific surface area, while the soybean hull based showed the highest hydrophobic character. The silver-functionalized soybean hull beads (Ag-sbCNF) showed the highest efficacy in reducing the growth of bacteria. Overall, this study highlights the potential of silver-functionalized CNFs hydrogel beads as a promising environmentally friendly and sustainable material for water filtration and disinfection. The findings also suggest that lower surface energy of the Ag-CNFs play an important role in their antimicrobial effect on tested water by enabling shorter retention, providing useful insights into the design of future water filtration materials.

Biofilm inhibition of Staphylococcus aureus by silver nanoparticles derived from Hellenia speciosa rhizome extract

Staphylococcus aureus is the most common cause of serious health conditions because of the formation of biofilm, which lowers antibiotic efficacy and enhances infection transmission and tenacious behavior. This bacteria is a major threat to the worldwide healthcare system. Silver nanoparticles have strong antibacterial characteristics and emerged as a possible alternative. This work is most relevant since it investigates the parameters influencing the biogenic nanoparticle-assisted control of bacterial biofilms by Staphylococcus aureus.Nanoparticles were fabricated utilizing Hellenia speciosa rhizome extracts, which largely comprised physiologically active components such as spirost-5-en-3-yl acetate, thymol, stigmasterol, and diosgenin, enhanced with the creation of silver nanocomposites. GC-MS, XRD, DLS, SEM, EDX, FTIR and TEM were used to investigate the characteristics of nanoparticles. The microtiter plate experiment showed that nanoparticles destroyed biofilms by up to 92.41 % at doses that ranged from 0 to 25 μg/ml. Fluorescence microscopy and SEM demonstrated the nanoparticles' capacity to prevent bacterial surface adhesion. EDX research revealed that the organic extract efficiently formed silver nanoparticles with considerable oxygen incorporation, which was attributed to phytochemicals that stabilize AgNPs and prevent accumulation. FTIR spectroscopy indicated the existence of hydroxyl, carbonyl, and carboxylate groups, which are essential for nanoparticle stability. TEM revealed that the AgNPs were spheroidal, with diameters ranging from 40 to 60 nm and an average of 46 nm. These results demonstrate the efficacy of H. speciosa extract in creating stable, well-defined AgNPs suited for a variety of applications. This work underlines the potential of green-synthesized AgNPs in biomedical applications, notably in the treatment of S. aureus biofilm-associated illnesses. The thorough characterization gives important information on the stability and efficiency of these biogenic nanoparticles.

Synthesis and Characterization of Silver Nanoparticles Stabilized with Biosurfactant and Application as an Antimicrobial Agent.

Surfactants can be used as nanoparticle stabilizing agents. However, since synthetic surfactants are not economically viable and environmentally friendly, biosurfactants are emerging as a green alternative for the synthesis and stabilization of nanoparticles. Nanoparticles have been applied in several areas of industry, such as the production of biomedical and therapeutic components, packaging coating, solar energy generation and transmission and distribution of electrical energy, among others. The aim of this study was to synthesize, in a simple and green way, silver nanoparticles (AgNPs) using the biosurfactant produced by Candida lipolytica UCP 0899 as a stabilizer. AgNPs were examined and morphologically characterized using the techniques of ultraviolet-visible spectroscopy (UV-visible), scanning electron microscopy (SEM), zeta potential and energy dispersive X-ray spectroscopy (EDS). Newly formed silver nanoparticles showed a maximum UV-visible absorption peak at 400 nm, while a shift to 410 nm was observed in those stored for 120 days. SEM micrograph confirmed the formation of nanoparticles with an average size of 20 nm and with a predominant spherical structure, while a zeta potential of -60 mV suggested that the use of the biosurfactant promoted their stability. Stabilized nanoparticles were tested for their antimicrobial activity against bacterial isolates of Pseudomonas aeruginosa, Staphylococcus aureus, Escherichia coli and Enterobacter sp., as well as fungal isolates of Candida albicans and Aspergillus niger. At a concentration of 16.50 µg/mL, AgNPs inhibited the growth of all target microorganisms according to the following decreasing order: E. coli (95%), S. aureus, C. albicans (90%), A. niger (85%), Enterobacter sp. (75%) and P. aeruginosa (71%). These results suggest the potential use of the biosurfactant as a stabilizer of silver nanoparticles as an antimicrobial agent in different industrial sectors. Furthermore, the in vivo toxicity potential of biosurfactants was evaluated using the Tenebrio molitor model. The larvae were treated with concentrations in the range of 2.5, 5.0 and 10 g/L, and no mortality was observed within the 24 to 72 h period, demonstrating non-toxicity within the tested concentration range. These findings support the safety, efficacy and non-toxicity of biosurfactant-stabilized nanoparticles.

Characterization of Silver Nanoparticles Synthesized With Fungi Isolated From Cocoa and Orange Plantation Soils

Green synthesis of nanoparticles with various metals is being interested among researchers globally attention for due to their safety, environmental friendliness and non-toxicity in contrast to chemical synthesis. Here, fungi were isolated from rhizosphere of cocoa and orange obtained from Federal University of Technology, Akure using standard mycological techniques with the aim of synthesizing silver nanoparticles. The silver nanoparticles synthesized by these fungal isolates were characterized using Ultraviolet-Visible (UV-Vis) and Fourier Transmission Infra- Red (FTIR) spectroscopy. Seven fungi isolated from the soil samples viz. Nigrospora sphaerica, Penicillium discolor, P. digitatum, Neurospora crassa, Alternarium infectoria, Trichophyton verrucosum and Mucor mucedo. The colour transformation from yellow to brown indicated the formation of silver nanoparticles. All the isolates showed an intense peak in the wavelength range of 410-440 nm. The FTIR analysis of silver nanoparticles synthesized by N. sphaerica, P. discolor, P. digitatum, N. crassa, A. infectoria, T. verrucosum and M. mucedo revealed the existence of a band at different stretches of bonds at different peaks of 3314.36 cm-1, 3310.47 cm-1, 2412.22 cm-1, 3912.33 cm-1 3614.52 cm-1, 3852.11 cm-1 and 2112.11 cm-1, respectively. The silver nanoparticles synthesized could have the potential application in agricultural, pharmaceutical and food industries as well as petrochemical industries for the clean - up of crude oil contaminated soils. J. Bio-Sci. 32(2): 31-44, 2024

Eco-friendly synthesis and antibacterial potential of chitosan crosslinked-EDTA silver nanocomposite (CCESN)

This study presents a novel and eco-friendly approach for synthesizing silver nanocomposite at room temperature. The method utilizes chitosan derived from snail (Archachatina marginata) shell waste crosslinked with EDTA as a combined reducing and capping agent. The existence of silver nanoparticles in the composite was confirmed by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffractometry (XRD), energy dispersive X-ray (EDX), energy dispersive X-ray fluorescence (EDXRF) and thermogravimetric analysis (TGA). The TEM, SEM, XRD, and analyses revealed that the silver nanoparticle has a face-centered cubic structure with an average size of 45.30 nm respectively. EDX and EDXRF showed characteristic silver peaks confirming the formation of silver nanoparticles in the composite while TGA indicated that silver nanoparticles contributed to good thermal stability of the composite. The formation of silver nanoparticles was indicated by a brown color transformation and an ultraviolet visible (UV Vis) absorption peak at 435 nm. The synthesized nanocomposite demonstrated promising antibacterial activity against both Staphylococcus saprophyticus DSM 18669 and Escherichia coli O157 strains, with S. saprophyticus showing higher susceptibility. This highlights the potential of chitosan-EDTA silver nanocomposites as alternative antimicrobial agents.