Reduction Of Silver Nitrate Research Articles

Antimicrobial effect of silver nanoparticles as a potential healing treatment for wounds contaminated with Staphylococcus aureus in wistar rats

Currently, the main challenges associated with conventional treatments for complex wounds include antibiotic resistance, persistent infections, delayed healing, pain and discomfort, lesion recurrence, and limited patient adherence. Silver nanoparticles (AgNPs) have demonstrated potential for bacterial control in contaminated wounds while promoting tissue regeneration. The aim of this study was to evaluate the bactericidal activity of AgNPs in wounds contaminated and non-contaminated with S. aureus. An aqueous suspension of AgNPs at a concentration of 117 μg/mL was synthesized by reducing silver nitrate in a medium containing tannic acid and sodium citrate. The resulting nanoparticles were spherical, with an average diameter of 24.3 ± 0.18 nm, a polydispersity index (PDI) of 0.25 ± 0.013, and a ζ-potential of −60.0 ± 3.07 mV. The bactericidal effect of AgNPs was observed at concentrations of 58.5 μg/mL for Escherichia coli and 6.74 μg/mL for S. aureus and Pseudomonas aeruginosa. Fibroblast viability (L929 cells) was maintained at confluence with AgNPs concentrations ranging from 0.1 μg/mL to 7.3 μg/mL. On the 7th day post-wound induction, animals treated with AgNPs exhibited 90 % re-epithelialization along with effective microbiological control. Histological analysis revealed a significant increase in fibroblast production in the treated groups compared to controls (p < 0.01). These results indicate that AgNPs hold promise for topical applications in bacterial control and wound healing.

Green synthesis of Brassica carinata microgreen silver nanoparticles, characterization, safety assessment, and antimicrobial activities

Nanotechnology has been a central focus of scientific investigation over the past decades owing to its versatile applications. The synthesis of silver nanoparticles (AgNPs) through plant secondary metabolites is a cost-effective and eco-friendly approach. The present study employed Brassica carinata microgreen extracts (BCME) to promote the reduction of silver nitrate (AgNO3) salt into Brassica carinata microgreen silver nanoparticles (BCM-AgNPs). The physicochemical properties of the biosynthesized AgNPs were characterized through both spectroscopy and microscopy techniques. Furthermore, the antimicrobial property of the biosynthesized AgNPs was assessed against six selected pathogenic microorganisms, and finally, their safety was evaluated on a normal Vero cell line through an MTT cytotoxicity assay. The UV-visible spectrum revealed that BCM-AgNPs exhibited an absorption peak at 420 nm. The potential functional groups involved in the biosynthesis of AgNPs were identified by Fourier transform infrared (FTIR) analysis. Scanning electron microscopy (SEM) revealed a spherical nature of the biosynthesized AgNPs. Transmission electron microscopy (TEM) analysis revealed the crystallinity of the AgNPs, averaging 34.68 nm in size. X-ray diffraction (XRD) investigation further confirmed the crystalline structure of the AgNPs. The zeta potential exhibited a significant value of − 22.5 ± 1.16 mV. Regarding the antimicrobial potential, BCM-AgNPs exhibited promising antimicrobial activity against the tested pathogens, with a minimum inhibitory concentration (MIC) of 62.5 µg/mL observed in Pseudomonas aeruginosa. Further cytotoxicity assessment of BCM-AgNPs conducted on Vero cells demonstrated their safety. This study presents a novel approach to synthesizing AgNPs using a nutraceutical microgreen, offering a biocompatible and promising alternative for combating multi-drug resistance.

Beet Root Peel Extract as a Natural Cost‐Effective pH Indicator and Food Preservative in Edible Film: Shelf Life Improvement of Cold‐Stored Trout Fillet

ABSTRACTIn this study, chitosan (C)‐polyvinyl alcohol (P) edible film containing bio‐fabricated nanosilver particles (nAg) (as antimicrobial agent) and beetroot peel extract (BRPE) (as antioxidant agent and pH indicator) was used as spoilage indicator in cold‐stored rainbow trout fillets. DPPH (2,2‐diphenyl‐1‐picrylhydrazyl) radical scavenging activity (43.02%), reducing power (2.87), and total phenolic content (360.50 mg GAE/g) of ethanolic BRPE were higher than aqueous extract. Silver nanoparticles were biosynthesized using silver nitrate reduction by chitosan, confirmed by UV–Visible spectroscopy, optical and scanning electron microscope images, and X‐ray diffraction analysis. The highest tensile strength (4.20 MPa) and elongation at break (118%) belonged to the CP‐BRPE film, and the lowest water vapor permeability (2.45 10−5 g/s/m/P) was related to the CP‐nAg film. Also, the lowest total viable count (6.17 log CFU/g), psychrotrophic bacteria (6.27 log CFU/g), Enterobacteriaceae (4.9 log CFU/g), pH (5.66), total volatile basic‐nitrogen (TVB‐N) (22.1 mg/100 g of fish), and thiobarbituric acid reactive substances (TBARS) (0.705 mg MDA/kg of fish) values of the packaged trout fillets were significantly (p ≤ 0.05) observed in CP‐BRPE‐gnAg treatment among the other treatments at the end of the storage period, and CP‐gnAg, CP‐BRPE, and CP treatments were in the next ranks, respectively. Colorimetric analysis of the used films showed that the films containing BRPE depicted color spectra of red to yellow at the same time as the spoilage symptoms initiated in the packaged fillets. It is concluded that BRPE not only increased the preservative effects of chitosan‐polyvinyl alcohol film containing green silver nanoparticles but also can be considered as a natural cost‐effective spoilage indicator of the rainbow trout fillets during cold storage time.

In vivo assessment of topically applied silver nanoparticles on entire cornea: comprehensive FTIR study

Silver nanoparticles (AgNPs) have gained attention in medicine for their potent antibacterial, antiviral, and anti-inflammatory properties. The use of silver nanoparticles in ophthalmic solutions raises concerns regarding potential toxicity of nanoparticles to ocular tissues, such as the cornea, conjunctiva, and retina, which necessitates further toxicity assessments aiding in the development of safer ophthalmic solutions. This study investigates the impact of AgNPs on corneal tissue using ophthalmic investigations, Fourier transform infrared (FTIR) spectroscopy, and chemometric analyses. Three concentrations of AgNPs (0.48 µg/mL, 7.2 µg/mL, and 15.5 µg/mL) were topically applied twice daily for 10 days, synthesized biologically by reducing silver nitrate with almond kernels water extract. Corneas, obtained by cutting 2–3 mm below the ora serrata, were analyzed with FTIR spectroscopy and subjected to chemometric analyses. Results reveal AgNPs’ influence on constituents with OH and NH groups, affecting corneal lipids and reducing the lipid saturation index. AgNPs alter both bulk and interfacial water, leading to changes in corneal hydration thus modifying corneal physico-chemical properties. The influence extends to the water environment around proteins and lipids, releasing bound water from phospholipids and disrupting hydrogen bonding networks around proteins. In conclusion, the applied AgNPs concentrations can be linked to dry eye onset.

Green Synthesis of silver nanoparticles from clematis gouriana leaf extract: Physicochemical characterization and antibacterial activity determination for treatment of blood stream infections

BackgroundThe global incidence of bloodstream infections (BSIs) is rising, necessitating the development of effective therapeutic strategies to achieve complete eradication. This study focuses on the synthesis of silver nanoparticles (AgNPs) functionalized with Clematis gouriana extract (CG) (CG-AgNPs) as a potential alternative to conventional treatments for combating BSIs caused by bacterial pathogens. MethodsAgNPs were synthesized by reducing silver nitrate (AgNO₃) using CG extract. The formation of CG-AgNPs was confirmed through UV-Vis spectroscopy, while their characterization included the determination of mean particle size and zeta potential. Elemental composition was analyzed using energy-dispersive X-ray (EDX) spectroscopy. The in vitro antibacterial efficacy of CG-AgNPs was assessed through multiple assays, including a time-kill assay, a film bioadhesion assay, and measurement of reactive oxygen species (ROS) generation. ResultsSPR (surface plasmon resonance) has been employed to validate the development of AgNPs by observing a colour shift to dark brown. The mean particle size and zeta potential of the CG-AgNPs were found to be 38 ± 2nm (PDI 0.104 ± 0.03) and -31.2 ± 1.4mV, respectively. Additionally, E-XRD results show that the prepared AgNPs comply with the silver presence. The minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) of the CG-AgNPs against Staphylococcus aureus (S. aureus) were observed to be 6.25 ± 0.8µg/mL and 13.5 ± 2.4µg/mL, respectively.Similarly, the MIC and MBC of CG-AgNPs against Escherichia coli (E. coli) were found to be 13.5 ± 1.5μg/mL and 26 ± 2.8μg/mL, respectively. CG-AgNPs also prevented biofilm formation and bacterial adhesion in a dose-dependent manner; 100% inhibition was achieved in 48h at MBC. In addition, CG-AgNPs remarkably escalated the ROS level within cells, indicating their mechanism of antimicarobial activity. ConclusionsThe findings of this study demonstrate that CG-AgNPs synthesized via green synthesis exhibit significant antibacterial activity, highlighting their potential as an effective alternative for the treatment of BSIs. However, further in vivo studies are required to optimize a suitable dosage form and validate their therapeutic efficacy against bacterial infections in clinical settings.

Phyto-mediated biosynthesis of silver nanoparticles using Aloe barbadensis Miller leaves gel with improved antibacterial, anti-fungal, antioxidant, anti-inflammatory, anti-diabetic, and anti-cancer activities

An effective topical therapeutic agent requires a multifunctional attribute such as antibacterial, antioxidant, and anti-inflammatory efficacy. The green-synthesized metallic and metallic oxide nanoparticles have shown significant applicability in this regard. Hence a biosynthesis of silver nanoparticles (AgNPs) using Aloe barbadensis miller leaf gel was fabricated and evaluated for effect of imperative influences such as temperature, time, and concentration of reactant on AgNPs synthesis. Furthermore, the biomimetic qualities were assessed to ensure the safety and efficacy. The synthesis of stabilized and capped AgNPs presented a UV–vis–based plasmonic resonance at ∼ 400 nm. The reduction of silver nitrate was further confirmed by the shift in FTIR spectra for -OH around 2870 cm−1. SEM and TEM images revealed cubic shape of the AgNPs. Whereas X-ray diffraction pattern indicated crystalline structure (crystallite size of ∼ 31.14 nm) with an inter-planar spacing value of 2.77, 1.96, and 1.67 Å for (200), (220), and (311) planes, respectively. In addition, AgNPs indicated a steady dispersion, homogeneity, and strong anionic zeta potential (∼ 35.4 mV). The results of antibacterial and antifungal activity demonstrated the potential of phyto-synthesized AgNPs in mitigation of infection associated with tested bacterial strain Bacillus subtilis, Bacillus megaterium, Shigella flexneri, Trichoderma viride, Aspergillus niger, and Penicillium crysogenum. Moreover, the results of hydrogen peroxide-based scavenging, anti-inflammatory, and anti-diabetic study revealed that the biosynthesized AgNPs exhibit an improved biomimetic attribute. Additionally, the biocompatibility assay demonstrated > 80 % of CaCO-2 and L-929 cells viability at 1.67 μg/mL and 3.35 μg/mL, respectively. The anticancer activity of synthesized AgNPs against epithelium-like phenotype oral squamous carcinoma cells (CLS-354/WT) displayed IC50 of 11.58 μg/mL. The results indicate that biogenic produced AgNPs may find suitable use as a potential therapeutic agent due to multifunctional attribute.

Therapeutic potential of green-synthesized silver nanoparticles: Combating biofilms of multidrug-resistant Staphylococcus aureus RM-Ph8 and modulating the immune response in the liver tissue of rats.

The emergence of multidrug-resistant Staphylococcus aureus (MRSA) strains poses a significant threat to healthcare settings. Although various studies have explored alternative antibiotics, discovering novel therapeutic agents remains crucial. This study aimed to synthesize green silver nanoparticles (AgNPs) as bactericidal agents, identify a multidrug-resistant isolate of Staphylococcus aureus, and explore their biofilm formation ability. To estimate the role of phyto-AgNPs in the perfection of immune markers and healing hepatic lesions in vivo. The clinical isolate of MRSA was identified using 16S rRNA New green AgNPs derived from Artemisia annua extract were synthesized. The nanoparticles (NPs) were characterized, and their minimum inhibitory concentration was estimated for fighting MRSA biofilm. A study was conducted on rats to evaluate the effect of new NPs on their immune response to MRSA infection. The new clinical isolate of MRSA RM-Ph8 was identified by molecular phylogenetic analysis as S. aureus, and 16S rRNA sequence analysis confirmed that the new strain was similar to S. aureus with 98.12% identity with accession number OQ421819. The FTIR of the new phyto-AgNPs displayed different functional groups that work as reducing silver nitrate agents. Transmission electron microscopy and scanning electron microscopy images showed spherical particles with an average diameter of 6-28 nm smaller. The chemical method led to complete cell destruction of the multidrug strain within 24 h. Biofilm formation showed that the new MRSA clinical strain was strongly adherent (88%). Notably, the phyto-AgNPs exhibited significant bactericidal activity against the new MRSA strain, with an MIC of up to 50 mg/mL. Moreover, phyto-AgNPs significantly decreased reversed MRSA-induced liver and kidney function impairment, with improvement in both the histopathological lesions and immune histochemical expression of tumor necrosis factor-α and inducible nitric oxide synthase at p < 0.05 compared with the untreated group. Green AgNPs are a promising therapeutic approach against multidrug-resistant bacterial infections, surpassing the effectiveness of conventional antibiotics.

MICROWAVE-ASSISTED SYNTHESIS OF SILVER NANOPARTICLES USING OPUNTIA FICUS-INDICA CLADODE EXTRACT WITH ITS BIOLOGICAL AND CATALYTIC ACTIVITIES

In the current study, silver nanoparticles (AgNPs) were synthesized with silver nitrate and cladode extract of Opuntia ficus-indica being used as precursor and phyto-reducing agent, respectively. The reaction combination was irradiated with microwaves (using a domestic microwave oven) for the spontaneous and stable synthesis of AgNPs. AgNPs were also synthesized using chemical methods, to evaluate the difference in microbial activities of AgNPs prepared by two different methods. The AgNPs development was confirmed by UV-Vis spectroscopy. The involvement of phytochemicals of the extract in the reduction of silver nitrate was confirmed by FTIR- spectroscopy. For the determination of the crystal structure of silver nanoparticles, X-ray diffraction examination was performed. Distribution of size and zeta potential of AgNPs was studied by dynamic light scattering (DLS). The dimensions and form of AgNPs were determined using transmission electron microscopy (TEM). The present study confirms activity against Escherichia coli and Micrococcus luteus and catalytic activity against 4-nitrophenol. The green synthesized silver nanoparticles showed more antibacterial activity than those synthesized by the chemical reducing method.

Enhancing virus inhibition in track-etched membranes through surface modification with silver nanoparticles and curcumin

The present work reports on the use of silver nanoparticles (AgNPs) and curcumin immobilized on the surface of microfiltration track-etched membranes (mTMs) as antiviral filtration materials. AgNPs were synthesized through the direct reduction of silver nitrate by sodium borohydride in the presence of a stabilizing agent. The synthesized nanoparticles and curcumin were immobilized on polyethyleneimine (PEI)-modified mTMs through a static sorption process. TEM, SEM, UV–vis. spectroscopy and luminescence measurements revealed a uniform distribution of AgNPs and confirmed the presence of curcumin on the membrane surface. The resulting TM-PEI-AgNPs-PVP and TM-PEI-Curcumin hybrid membranes were employed for the filtration of HSV-1, VSV, IAV, and EMCV viruses. While both membrane types exhibited insignificant inhibition for the latter two, they achieved 95 and 99 % inhibition for HSV-1 and VSV, respectively. These findings suggest that hybrid membranes with immobilized AgNPs and curcumin can have potential as antiviral filtration materials.

Green Synthesis of Silver Nanoparticles Using Origanum onites Extract: Effect of Temperature and Time on Antioxidant and Antimicrobial Activity

Origanum species are known to be powerful antioxidants due to the secondary metabolites they contain. It is therefore hypothesized that nanoparticles synthesized by origanum species may have applications in medicine, cosmetics, and food production. This study aimed to investigate the antioxidant and antimicrobial activities of silver nanoparticles obtained at different times (60, 120, and 180 min) and temperatures (30, 60 and 90°C) using O. onites extract. The initial synthesis of Ag Nanoparticles (AgNps) was characterized by UV- spectrophotometry and the surface plasmon resonance band was observed at 430-450 nm under all conditions. The highest absorbance was observed at a wavelength of 425 nm for 180 min at 90°C. The FTIR spectrum showed a peak in the 3.000-3.500 cm-1 range compared to the control, confirming the reduction of silver nitrate. When the particle distribution of AgNPs prepared at three different reaction times was examined by SEM, it was observed that AgNPs with very similar particle sizes were formed. The average particle size was determined to be 171 nm, 169 nm, and 152 nm, respectively, for reaction times of 60, 120, and 180 minutes at 90°C, based on the results of the EDX analysis. The highest DPPH scavenging activity was observed in nanoparticles obtained at the third hour of the 60°C and 90°C reactions. AgNPs obtained at all 3 temperatures showed antimicrobial activity on S. aureus, E. coli, and C. albicans, however, the highest activity was found in AgNPs synthesized at 60°C and 90°C at the 3rd hour. Nanoparticles synthesized from natural materials should not display toxic properties. The AgNPs produced in this study did not exhibit toxicity towards healthy human fibroblasts. The results demonstrated that the AgNPs synthesized within the scope of this study have potential applications in biomedical fields. It was determined that the AgNPs with the highest activity were synthesized at temperatures of 60°C and 90°C at the 3rd hour.

Preparation and properties of silver-carrying nano-titanium dioxide antimicrobial agents and silicone composite

The characteristics of dopamine self-polymerization were used to cover the nano-titanium dioxide (TiO2) surface and produce nano-titanium dioxide-polydopamine (TiO2-PDA). The reducing nature of dopamine was then used to reduce silver nitrate to silver elemental particles on the modified nano-titanium dioxide: The resulting TiO2-PDA-Ag nanoparticles were used as antimicrobial agents. Finally, the antibacterial agent was mixed with silicone to obtain an antibacterial silicone composite material. The composition and structure of antibacterial agents were analyzed by scanning electron microscopy, transmission electron microscopy, X-ray photoelectron energy spectroscopy, and X-ray diffraction. Microscopy and the antibacterial properties of the silicone antibacterial composites were studied as well. The TiO2-PDA-Ag antimicrobial agent had good dispersion versus nano-TiO2. The three were strongly combined with obvious characteristic peaks. The antibacterial agents were evenly dispersed in silicone, and the silicone composite has excellent antibacterial properties. Bacillus subtilis (B. subtilis) adhesion was reduced from 246 × 104 cfu/cm2 to 2 × 104 cfu/cm2, and colibacillus (E. coli) reduced from 228 × 104 cfu/cm2 leading to bacteria-free adhesion.

Silver nanoparticle with potential antimicrobial and antibiofilm efficiency against multiple drug resistant, extensive drug resistant Pseudomonas aeruginosa clinical isolates

BackgroundThe study aims to investigate the effect of combining silver nanoparticles (AGNPs) with different antibiotics on multi-drug resistant (MDR) and extensively drug resistant (XDR) isolates of Pseudomonas aeruginosa (P. aeruginosa) and to investigate the mechanism of action of AGNPs.MethodsAGNPs were prepared by reduction of silver nitrate using trisodium citrate and were characterized by transmission electron microscope (TEM) in addition to an assessment of cytotoxicity. Clinical isolates of P. aeruginosa were collected, and antimicrobial susceptibility was conducted. Multiple Antibiotic Resistance (MAR) index was calculated, and bacteria were categorized as MDR or XDR. Minimum inhibitory concentration (MIC) of gentamicin, ciprofloxacin, ceftazidime, and AGNPs were determined. The mechanism of action of AGNPs was researched by evaluating their effect on biofilm formation, swarming motility, protease, gelatinase, and pyocyanin production. Real-time PCR was performed to investigate the effect on the expression of genes encoding various virulence factors.ResultsTEM revealed the spherical shape of AGNPs with an average particle size of 10.84 ± 4.64 nm. AGNPS were safe, as indicated by IC50 (42.5 µg /ml). The greatest incidence of resistance was shown against ciprofloxacin which accounted for 43% of the bacterial isolates. Heterogonous resistance patterns were shown in 63 isolates out of the tested 107. The MAR indices ranged from 0.077 to 0.84. Out of 63 P. aeruginosa isolates, 12 and 13 were MDR and XDR, respectively. The MIC values of AGNPs ranged from 2.65 to 21.25 µg /ml. Combination of AGNPs with antibiotics reduced their MIC by 5–9, 2–9, and 3-10Fold in the case of gentamicin, ceftazidime, and ciprofloxacin, respectively, with synergism being evident. AGNPs produced significant inhibition of biofilm formation and decreased swarming motility, protease, gelatinase and pyocyanin production. PCR confirmed the finding, as shown by decreased expression of genes encoding various virulence factors.ConclusionAGNPs augment gentamicin, ceftazidime, and ciprofloxacin against MDR and XDR Pseudomonas isolates. The efficacy of AGNPs can be attributed to their effect on the virulence factors of P. aeruginosa. The combination of AGNPs with antibiotics is a promising strategy to attack resistant isolates of P. aeruginosa.

Ag0, Re0, and Ag@Re heterogeneous persulfate activators for reactive radical based oxidation of water contaminant

Silver-rhenium bi-metallic nanoparticles (Ag-Re) were prepared by the combination of colloidal sols of silver and rhenium at room temperature. The silver and rhenium sols were synthesized by using the chemical reduction of silver nitrate and ammonium perrhenate with sodium borohydride in presence of cetyltrimethylammonium bromide (CTAB). The morphology (shape, size, elemental composition, oxidation states, and crystalline nature) and textural properties (pore size, pore volume, and surface area) of Ag0-Re0 were determined with EDX, SEM, TEM, XPS, XRD, and nitrogen adsorption-desorption isotherm. The Ag0-Re0 was used as heterogeneous persulfate (S2O82−) activator to generate reactive radical species (SO4−• and HO•) for the degradation of xylenol orange (XO) at 434 nm. The Ag-Re exhibits higher XO degradation efficiency than that of mono-metallic Ag0 and Re0 nanoparticles, respectively. The degradation efficiency strongly depends on the concentrations of S2O82−, XO, pH, temperature, and amount of Ag0-Re0. The role of SO4−• and HO• were established by using ethanol, and tertiary butanol as radical scavengers. The activation energy was found to be 85.2, 63.5, and 32.6 kJ/mol, respectively, to the degradation of XO by activated S2O82− with Re0, Ag0, and Ag0-Re0.

Design and synthesis of dexmedetomidine capped silver nanoparticles: Investigation of its catalytic application for reduction of nitrobenzenes and its effects on anesthetic, anti-inflammatory, antioxidant and analgesic applications

In the present work, the mono-dispersed produced dexmedetomidine capped silver nanoparticles were described. Dexmedetomidine-stabilized silver nanoparticles were prepared from the facile reduction of silver nitrate by NaBH4 as a reducing agent and dexmedetomidine as a stabilizing agent. The successful reduction of Ag+ ions into Ag0 NPs was confirmed by a visual formation of a deep brown color solution and the appearance of λmax nearing 450 nm in the UV–Vis study. The desired Ag NPs/Dexmedetomidine nanocomposite were characterized by various techniques such as UV/Vis, SEM-EDX, TEM and XRD. The abundant amino groups of dexmedetomidine provided the uniform dispersion and nano spherical shape of silver with sizes of 30–40 nm. The Ag NPs/Dexmedetomidine nanocomposite was applied in the catalytic reduction of diverse aromatic nitro functions using sodium borohydride as reducing agent. An excellent yield were achieved within very short reaction time. During the in vivo study, it was noted that the combination of Ag NPs/Dexmedetomidine showed local anesthetic properties in frog and guinea pig models. Additionally, oral administration of Ag NPs/Dexmedetomidine led to a notable decrease in paw edema in mice. The convulsive episodes triggered by acetic acid were markedly decreased in a dose-dependent manner in every group that was administered Ag NPs/Dexmedetomidine treatment. Additionally, the pain-relieving and anti-inflammatory properties of Ag NPs/Dexmedetomidine were assessed at different dosage levels. The data of this research provide evidence for the Ag NPs/Dexmedetomidine potential use as a pain-relieving and anesthetic substances in future investigations and medical trials involving human participants. In the antioxidant assessment, Ag NPs/Dexmedetomidine demonstrated IC50 values of 77 µg/mL against DPPH free radicals.

Microwave‐Assisted Tragacanth Gum–Based Grafted Silver Nanocomposite Hydrogel for Sustained Release Formulations of Diclofenac Sodium and Antibacterial Assay

ABSTRACTIn this work, novel tragacanth gum‐graft‐poly(2‐acrylamido‐2‐methylpropanesulfonic acid) (TG‐g‐PAMPS) hydrogel was synthesized via free radical copolymerization of TG, 2‐acrylamido‐2‐methylpropanesulfonic acid by using ammonium peroxodisulfate and N,N‐methylene‐bis‐acrylamide under microwave radiation, resulting in the cross‐linked graft copolymer network. Silver nanoparticles (SNs) were formed and stabilized by the reduction of silver nitrate using tri‐sodium citrate. The TG‐g‐PAMPS gel and its nanocomposite were characterized and confirmed using FTIR, TGA, XRD, SEM, EDS, and TEM techniques. It is observed that the presence of SNs significantly improves the swelling ability of the TG‐g‐PAMPS gel. Degradation studies of both hydrogels were studied using the soil burial method and determining the respective weight loss. The presence of SNs is found to impart significant antibacterial properties to the gel against Pseudomonas aeruginosa and Escherichia coli bacteria. Further, the TG‐g‐PAMPS gel and TG‐g‐PAMPS‐SN were evaluated as matrix materials for the release of the drug (diclofenac sodium) and the effect of SNs on the release was examined. The in‐vitro released data were analyzed using empirical equations to understand the mechanism of release. Among the various models, the released data were well fitted into the Korsmeyer–Peppas equation and the released kinetics followed non‐Fickian diffusion.

Synergistic remediation of hydrocarbons using a hybrid approach: Harnessing biosurfactant and silver nanoparticles

A biosurfactant is an amphiphilic molecule that has both hydrophobic and hydrophilic properties. Biosurfactants from microbial sources with oil degradation potential were isolated from hydrocarbon-contaminated sites. Oil displacement and emulsification tests in this study identified the biosurfactant produced. The biosurfactants produced by the isolated bacteria possess anti-microbial properties. The cell-free supernatants of Bacillus subtilis and Pseudomonas aeruginosa showed positive results for the oil displacement method. The drop collapse test supported the biosurfactant production by these isolates. The synthesis of silver nanoparticles from Acalypha indica plant leaf extract was carried out. The biosurfactants (BS) and silver nanoparticles (AgNP) was also carried out. Their application as individual and synergistic effects in the bioremediation of hydrocarbons (engine waste oil) was discussed. Gravimetric analysis was used to analyse the degradation of engine oil. Silver nanoparticles showed absorbance in the range of 200 and 400 nm. Seven discrete peaks were obtained in FT-IR, representing the main functional group of AgNPs. The reduction of silver nitrate (AgNO3) into silver nanoparticles (AgNP) occurred due to the presence of biomolecules. The SEM analysis showed that the size of the nanoparticle is between 69 and 87 nm and is crystalline. The average distribution of the diameter of the silver nanoparticles was 186.9 nm. Broader peaks of XRD reflect the influence of the experimental circumstances on the nucleation and development of the crystal nuclei and indicate smaller particle sizes. The biosurfactants showed less degradation than the synergistic method employed with biosurfactants and silver nanoparticles. Therefore, it is concluded that the silver nanoparticles influenced the biosurfactant and increased the rate of degradation of the engine waste oil.

Metallic nanostructures arrays by direct nanoimprinting of silver nanoparticles

The direct nanoimprinting of silver nanoparticles (Ag NPs) generated a plasmonic metallic nanostructure. The Ag NPs used in this study have been synthesized by a phase transfer method. The procedure comprised the utilisation of sodium borohydride to reduce silver nitrate in the presence of a stabilizing agent, which facilitated the transfer of the NPs from the aqueous phase to an organic phase, resulting in uniform and stable particles. The size and shape of the Ag NPs were characterized using electron microscopy, revealing spherical particles with an average diameter of 9 nm. The XRD examination revealed that the nanoparticles exhibit a high degree of crystallinity and possess a cubic geometric phase. The UV-visible absorption spectra demonstrate a significant level of homogeneity in the size. The silicon surface imprinted with Ag NPs exhibits hydrophobic behaviour towards water molecules. This approach allows for precise control of Ag NPs on the substrate, resulting in a robust and effective platform for future applications in sensor technology. Furthermore, the hydrophobic nature of the imprinted surface suggests potential applications in water-repellent coatings or self-cleaning materials.

How Plasmon Ag Nanoparticles can Enhance the Power Performance of a Thermoelectric Generator.

The development of wearable thermoelectric generators (wTEG) represents a promising strategy to replace batteries and supercapacitors required to supply electrical energy for portable electronic devices. However, the main drawback of wTEGs is that the thermal gradient between the skin and the ambient is minimal, reducing the power output produced by the generator. Therefore, it is necessary to improve the thermal management of wTEG in order to increase its efficiency. This work deals with the preparation of a thermoelectric generator that harnesses the plasmonic heating effect to enhance the thermal gradient of the final device. The thermoelectric layer is created through the in situ polymerization of terthiophene (3T) within a polyurethane matrix, utilizing silver (Ag) (I) and copper (II) perchlorate as oxidants. The plasmonic film, composed of Ag-NP (nanoparticles), is formed via photocatalytic reduction of silver nitrate in the presence of titanium oxide. These layers are then meticulously assembled to yield the hybrid plasmonic/thermoelectric generator.

Pseudomonas otitidis-mediated synthesis of silver nanoparticles: characterization, antimicrobial and antibiofilm potential.

This study explores the eco-friendly synthesis of silver nanoparticles (AgNPs) using soil bacteria, Pseudomonas otitidis. The bio-synthesized AgNPs were characterized using various techniques, including UV-visible spectroscopy, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and X-ray diffraction (XRD). UV-visible spectroscopy revealed a distinct broad absorption band in the range of 443 nm, indicating the reduction of silver nitrate to AgNPs. XRD analysis provided evidence of the crystalline nature of the particles, with sharp peaks confirming their crystallinity and an average size of 82.76 nm. FTIR spectroscopy identified extracellular protein compounds as capping agents. SEM examination revealed spherical agglomeration of the crystalline AgNPs. The antimicrobial assay by a disc diffusion method, minimum inhibitory concentration, and minimum bactericidal concentration testing revealed that the biosynthesized AgNPs showed moderate antibacterial activity against both pathogenic Gram-negative (Klebsiella pneumoniae, Pseudomonas aeruginosa, and Acinetobacter baumannii) and Gram-positive (Bacillus cereus, Staphylococcus aureus, and Streptococcus mutans) bacterial strains. Furthermore, the AgNPs significantly disrupted the biofilm of P. aeruginosa, as confirmed by crystal violet assay and fluorescent microscopy. Overall, this study underscores the potential of microbial-synthesized nanoparticles in biomedical applications, particularly in combating pathogenic bacteria, offering a promising avenue for future research and development.

Silver nanoparticle biosynthesis utilizing Ocimum kilimandscharicum leaf extract and assessment of its antibacterial activity against certain chosen bacteria.

The use of plants in the biological production of silver nanoparticles for antibacterial applications is a growing field of research. In the current work, we formulated Ocimum kilimandscharicum extracts using silver nanoparticles, and evaluated its potential antibacterial activity. Aqueous and methanol plant extracts were used to reduce silver nitrate at different time intervals (30 to 150 minutes) and pH (2 to 11). The UV-visible absorption spectrum recorded for methanol and aqueous extracts revealed a successful synthesis of AgNPs for methanol and aqueous extracts. The antimicrobial activity of the AgNPs was evaluated against Escherichia coli ATCC 25922, Salmonella choleraesuius ATCC 10708, and Staphylococcus aureus ATCC 25923 The best inhibition zone for the methanol and aqueous-mediated AgNPs, ranging from 12 ± 1 to 16 ± 1mm. Additionally, the methanol and aqueous extract silver nanoparticles had the same Minimum Inhibitory Concentration (6.25 ± 0.00 mg/ml), whereas the Minimum Bactericidal Concentrations were 12.5 ± 0.00 and 25 ± 0.00 mg/ml, respectively. The highest inhibition zone of 16 ± 1 mm was observed against Salmonella choleraesuius with 50 ± 0.00 mg/ml aqueous silver nanoparticles. The results show that the silver nanoparticles made with Ocimum kilimandscharicum have antibacterial action against those microorganisms.