Conquering Candida albicans using sustainably synthesized silver nanoparticles from Saraca asoca leaf extract

In response to growing environmental concerns related to water scarcity and industrial pollution, particularly from the textile sector, this study explores a green and sustainable method for synthesizing silver nanoparticles (Ag NPs) using Eucalyptus globulus leaf extract. The biosynthesized Ag NPs were applied for the degradation of Congo Red, a widely used but toxic azo dye. This approach not only offers an eco-friendly alternative to conventional wastewater treatment methods but also demonstrates the potential of plant-based NP synthesis in environmental remediation. The synthesized Ag NPs were thoroughly characterized to confirm their structure, composition, and morphology. UV-Vis spectroscopy indicated the presence of surface plasmon resonance band (405 nm), while STEM analyses revealed spherical NPs ranging around ⁓6 nm in size. EDX confirmed the silver content and XRD demonstrated the crystalline and metallic nature of the Ag NPs. FTIR analysis identified functional groups responsible for the bio reduction, capping, and stabilization, indicating successful green synthesis using Eucalyptus globulus extract. The biosynthesized Ag NPs demonstrated excellent photocatalytic activity, achieving up to 98.9% degradation of Congo Red (CR) dye within 8 min under visible light and 97.8% degradation within 55 under sun light irradiation. Optimization of parameters such as initial dye concentration, catalyst (Ag NP) dose, and light exposure time confirmed the efficiency of the process, which followed a pseudo-first-order kinetic model. These findings demonstrate that green-synthesized Ag NPs are highly effective for dye removal and hold significant potential for environmental and pharmaceutical applications.

Silver nanoparticles (Ag NPs) were green synthesized using native inulin as the reducing and capping agent with varied incubation temperatures, incubation times and Ag+ concentrations. The biosynthesized Ag NPs were characterized using UV-visible spectroscopy, Field Emission Transmission Electron Microscopy (FE-TEM) and X-ray powder diffraction. The UV visible spectra of the Ag NPs revealed a characteristic surface plasmon resonance peak at 420 nm. FE-TEM showed that the biosynthesized Ag NPs were spherically shaped and monodispersed nanoparticles. The sizes were 18.5 ± 0.9 nm and 20.0 ± 1.2 nm for the Ag NPs synthesized at 80 °C and 100 °C for 2 h using 0.1% inulin and 2 mM Ag+. Their PDIs were 0.180 ± 0.05 and 0.282 ± 0.13, respectively. Improving the incubation temperature, incubation time and silver nitrate concentration promoted Ag NP synthesis. The prepared Ag NPs were effective in the catalytic reduction of 4-NP and in inhibiting the growth of bacteria. The inhibition zone could reach 10.21 ± 2.12 mm and 9.92 ± 0.50 mm for Escherichia coli and Staphylococcus aureus. The kinetic rate constant (kapp) could reach 0.0113 s−1, and the maximum inhibitory zones were 10.21 ± 2.12 mm and 9.92 ± 0.50 mm, respectively, for the two microorganisms. This biosynthesis illustrates that native inulin could be a potential candidate in the green fabrication of Ag NPs, and this is promising in catalytic and bacteriostatic fields.

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

The topic of this investigation was to evaluate the microbial contamination of household sponges, biosynthesize of silver nanoparticles (Ag NPs) by Gliocladium deliquescens cell-free supernatant, and estimate the efficiency of Ag NPs as an acceptable disinfectant. The 23 factorial design was applied for the optimization of Ag NPs synthesis. Silver nitrate (AgNO3) concentration was the main positive impact on Ag NP biosynthesis. Various gamma irradiation doses were used in Ag NP production where the highest yield production was at 25.0 kGy. Ag NPs were characterized by UV-Vis. spectroscopy, The Fourier-transform infrared spectroscopy analysis (FTIR), dynamic light scattering (DLS), X-ray diffraction (XRD), and transmission electron microscope (TEM). Ag NPs were monodispersed spherical-shaped with 9.68 nm mean size. Two hundred sponge samples that were collected from different Egyptian household furniture and kitchens were highly contaminated by various contaminants including Salmonella spp., Staphylococcus spp., coliform bacteria, Gram-negative bacteria, yeasts, and molds. Ag NPs showed functional antimicrobial activity against all the microbial contaminants; Salmonella spp. was completely inhibited by Ag NP (50.0 μg/mL) treatment. The Ag NPs have the maximum inhibition zone against Salmonella spp. (14 mm) compared with the Staphylococcus spp. (12.3 mm). The minimum inhibitory concentration (MIC) of Ag NPs against Salmonella spp. and Staphylococcus spp. were 6.25 μg/ mL and 12.5 μg/ mL, respectively. The antibiofilm activity of Ag NPs was the highest at the concentration of 50.0 μg/mL recording 63.3 % for Salmonella spp. and 54.5 % for Staphylococcus spp. Ag NPs may find potent disinfectant applications for household purposes.

The high antibiotic resistance of Pseudomonas aeruginosa (PA) makes it critical to develop alternative antimicrobial agents that are effective and affordable. One of the many applications of silver nanoparticles (Ag NPs) is their use as an antimicrobial agent against bacteria resistant to common antibiotics. The key purpose of this research was to assess the antibacterial and antibiofilm effectiveness of biosynthesized Ag NPs against six biofilm-forming clinically isolated strains of PA and one reference strain (ATCC 27853). Ag NPs were biosynthesized using a seed extract of Peganum harmala as a reducing agent. Ag NPs were characterized by Ultraviolet–visible (UV–Vis) spectroscopy and scanning transmission electron microscopy (STEM). The effect of Ag NPs on biofilm formation and eradication was examined through micro-titer plate assays, and the minimal inhibitory (MIC) and minimum bactericidal (MBC) concentrations determined. In addition, real-time polymerase chain reactions (RT-PCR) were performed to examine the effects of Ag NPs on the expression of seven PA biofilm-encoding genes (LasR, LasI, LssB, rhIR, rhII, pqsA and pqsR). The biosynthesized Ag NPs were spherically-shaped with a mean diameter of 11 nm. The MIC for each PA strain was 15.6 µg/ml, while the MBC was 31.25 µg/ml. All PA strains exposed to Ag NPs at sub-inhibitory concentrations (0.22–7.5 µg/ml) showed significant inhibitory effects on growth and biofilm formation. Biomass and biofilm metabolism were reduced dependent on Ag NP concentration. The expression of the quorum-sensing genes of all strains were significantly reduced at an Ag NP concentration of 7.5 µg/ml. The results demonstrate the extensive in-vitro antibacterial and antibiofilm performance of Ag NPs and their potential in the treatment of PA infection. It is recommended that future studies examine the possible synergy between Ag NPs and antibiotics.

Nanotechnology is being investigated for its potential to improve nanomedicine for human health. The purpose of this study was to isolate carbapenemase-producing Gram-negative bacilli (CPGB), investigate the presence of carbapenemase resistance genes, determine their antibiogram and ability to biosynthesise silver nanoparticles (Ag NPs), and estimate the antibacterial activity of Acinetobacter baumannii-biosynthesised Ag NPs on CPGB alone and in combination with antibiotics. A total of 51 CPGBs were isolated from various specimens in the study. The automated Vitek-2 system was used to identify and test these strains' antimicrobial susceptibilities. The carbapenemase resistance genes were identified using a polymerase chain reaction (PCR). Under the CPGB, A. baumannii could biosynthesise Ag NPs. X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), and field emission scanning electron were used to characterise Ag NPs. The antibacterial activity of Ag NP alone and in combination with antibiotics against CPGB was determined using the broth microdilution method, and their synergistic effect was determined using the checkerboard assay. blaNDM and blaOXA-48 were the most commonly reported, and 90% of the isolates produced multiple carbapenemase genes. Tigecycline proved to be the most effective anti-CPGB antibiotic. Isolates with more resistance genes were more resistant to antibiotics, and isolates with three genes (42%) had the most extensively drug-resistant patterns (38%). A significant relationship was discovered between genetic and antibiotic resistance patterns. Only A. baumannii produced Ag NPs out of all the isolates tested. Ag NPs with a size of 10 nm were confirmed by UV–visible spectroscopy, FT-IR, XRD, and TEM analysis. The Ag NPs were effective against CPGB, with minimum inhibitory concentrations ranging from 64 to 8 μg/ml on average. Surprisingly, the combination of Ag NPs and antibiotics demonstrated synergistic and partial synergistic activity (fractional inhibitory concentration between 0.13 and 0.56) against CPGB, as well as a significant reduction in antibiotic concentrations, particularly in the case of A. baumanii versus ceftriaxone (1024 to 4 μg/ml). The notable synergistic activity of Ag NPs with antibiotics represents a valuable nanomedicine that may find clinical application in the future as a combined remedy.

Clerodendrum chinense-mediated biofabrication of silver nanoparticles: Mosquitocidal potential and acute toxicity against non-target aquatic organisms

The production of silver nanoparticles (Ag NPs) utilizing biological means with renewable resources is thought to be risk-free, environmentally benign, and safe. In this work, the capacity of Bauhinia variegata to produce Ag NPs was measured. Numerous methods, including UV–Vis spectroscopy, TEM, FTIR spectroscopy, and XRD, were employed for the analysis of the produced Ag NPs. Ag NP antimicrobial capacity has been examined through microtitreplate as well as agar well diffusion techniques. Ag NPs’ ability to scavenge free radicals at varying concentrations was assessed using the DPPH technique. The MICs were 1,000 µg·mL−1 against pathogenic microbes including Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans, while 500 and 250 µg·mL−1 were versus Bacillus subtilis and Escherichia coli, respectively. Silver showed an intriguing antioxidant capacity, achieving IC50 of 46.23 μg·mL−1. Additionally, Ag NPs demonstrated possible anticancer action when applied to the carcinoma cell lines Caco-2, with IC50 of 396.2 μg·mL−1 and cytotoxicity toward normal Vero cell lines with IC50 of 609.45 μg·mL−1. Furthermore, Ag NPs demonstrated a range of antibiofilm activities toward S. aureus (MRSA). In conclusion, Ag NPs biosynthesized via B. variegata show promise for a variety of safe biological applications.

Palm pollen (PP) has been widely used in nutrition, pharmaceutical and cosmetic industries. In the present study, we explored the potential of PP in the synthesis of a silver nanoparticle (Ag NP). PP was used as both reducing and stabilizing agent. The Ag/PP nanocomposite was examined by field emission electron microscopy, X-ray diffraction, Fourier transform infrared (FT-IR) spectroscopy, ultraviolet spectroscopy and zeta potential measurement. The biosynthesized NPs showed surface plasmon resonance centered at 425 nm with an average particle size measured to be 23 nm and a zeta potential of −30.9 mV. Prominent FT-IR signals were obtained and ascribed to phenolic and carbohydrate compounds involved in the formation of the Ag NPs, and proteins which participated in stabilization of the Ag NPs. The biologically synthesized Ag NPs were found to be extremely effective against E. coli (13.8 ± 0.25 mm) with a minimum inhibitory concentration of 20 µg/mL. Thus, such biosynthesized Ag NPs can be used in medicinal applications.

Due to the increasing adverse environmental effects of synthetic polymers, the need for environmentally friendly alternative biomaterials is increasing daily. In this context, the synthesis of novel Poly(vinyl alcohol) (PVA) -based composite materials was aimed. In this study, methacrylate-based poly(2-oxo-2-[4-(trifluoromethyl)anilino]ethyl-2-methylprop-2-enoate) (PTFMAM) polymer synthesized for the first time was blended with PVA by hydrothermal method. Biosynthesized silver nanoparticles (Ag NPs) were added to the PTFMAM-PVA blend using the hydrothermal method. Nanocomposites were characterized by XRD, SEM, TEM, and FTIR. The thermal stability of nanocomposites was determined by thermogravimetric analysis (TGA), and glass transition temperatures (Tg) were determined by differential scanning calorimetry (DSC) techniques. According to TGA data, the thermal stability of PVA was improved by blending with PTFMAM and loading with Ag NPs. While the Tg of PVA and PTFMAM-PVA were 78 °C and 103 °C, this value increased to 116 °C with 7% Ag NP loading. The dielectric properties of the nanocomposites also increased with the loading of Ag NPs. Ag NPs loading also decreased the solubility of PVA in water. Combining PVA with PTFMAM and Ag NP increased the oxidant/antioxidant activity. At the same time, increases in the antimicrobial activities of the nanocomposites were observed. The inhibition zones of the nanocomposites against E. coli, S. aureus, and C. albicans strains were between 8.56 and 15.08 mm. The results showed that PVA equipped with synthetic PTFMAM and biosynthesized Ag NPs caused improvements in thermal, dielectric, and biological properties. The produced PTFMAM-PVA/Ag nanocomposites showed that they could be alternative materials in areas where PVA is frequently used with their improved properties.

Surface-enhanced Raman spectroscopy (SERS) has been demonstrated as an ultrasensitive tool for various molecules. However, for the negatively charged molecules, the widely used SERS substrate [negatively charged Ag and Au nanoparticles (Ag or Au NPs (-)] showed either low sensitivity or poor stability. The best solution is to synthesize positively charged silver or gold nanoparticles [Ag or Au NPs (+)] with high stability and excellent SERS performance, which are currently unavailable. To this end, we revitalized the strategy of "charge reversal and seed growth". By selection of ascorbic acid as the reductant and surfactant, the surface charge of Ag or Au NP (-) seeds is adjusted to a balanced state, where the surface charge is negative enough to satisfy the stabilization of the NPs (-) but does not hinder the subsequent charge reversal. By optimization of the chain length and electric charge of polyamine molecules, the highly stable and size-controllable uniform Ag NPs (+) and Au NPs (+) were seed-growth synthesized with high reproducibility. More importantly, the SERS performance of both Ag NPs (+) and Au NPs (+) achieved the trace detection of negatively charged molecules at the level of 1 μg/L, demonstrating an improved SERS sensitivity of up to 3 orders of magnitude compared to the previously reported sensitivity. Promisingly, the introduction of polyamine-capped Ag NPs (+) and Au NPs (+) as SERS substrates with high stability (1 year shelf life) will significantly broaden the application of SERS.

Microwave mediated synthesis of catalytic fluorescent carbon dots (Cdots) has been reported using biodegradable starch as precursor. The as-synthesized Cdots were then characterized using various techniques such as fluorescence spectroscopy, fourier-transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM) and x-ray photoelectron spectroscopy (XPS) analysis. Interestingly, Cdots showed high catalytic activity in the photo-reduction of Ag+ to silver nanoparticles (Ag NPs). During the photo-reduction process, no additional surface passivating agents was needed to stabilize the Ag NPs. Further, TEM results indicated the formation of Cdot–Ag NP nanocomposite i.e. Ag NPs surrounded with Cdots, and the emission intensity of Cdots was significantly decreased whereas the lifetime of Cdots remained almost unaltered in the presence of Ag NPs following static quenching. Finally, combination therapy of Cdots and Ag NPs using Cdot–Ag NP nanocomposite was performed which indicated synergistic bactericidal activity against antibiotic resistant recombinant E. coli bacteria. The treatment elevated the reactive oxygen species (ROS) level as compared to its individual components. Additionally, the flow cytometer study demonstrated that combination therapy causing bacterial cell wall perforation that was possibly leading to synergistic bactericidal activity against both Gram positive and Gram negative bacteria. The presence of Cdots on the surface of the Ag NPs due to their ground state complexation, possibly facilitated electrons towards Ag NPs which enhanced the ROS production in comparison to only Ag NPs.

Valorization of pistachio (Pistacia vera L.) peel extract as an agricultural waste for green fabrication of bio-silver nanoparticles on cellulosic fabrics

To synthesize and characterize silver nanoparticles (Ag NPs) with different surface charges in order to evaluate their cytotoxicity and antibacterial activity in the absence and presence of dentine compared with NaOCl and CHX. Ag NPs with positive, negative and neutral surface charges were synthesized and characterized. The first phase of the experiment determined the minimum inhibitory concentrations (MICs) of NPs against planktonic E.faecalis and compared them with that of NaOCl and CHX. The second phase tested the elimination of E.faecalis at different contact times (5, 20 and 60min and 4 and 24h), and the role of dentine in their inactivation was assessed. In the third phase, the most effective Ag NP solution was selected for cytocompatibility assessment. An MTT-based cytotoxicity assay was used to evaluate the cytotoxicity of the selected NP solution in different concentrations on L929 fibroblasts compared to that of 2.5% NaOCl and 0.2% CHX. Student's t-test and repeated measures manova approach were used for statistical analyses. The characterization revealed synthesis of colloidal NPs in the size range of 5-10nm in diameter. The results indicated that Ag NP with a positive surface charge had the smallest MIC against planktonic E.faecalis, and it was active in very lower concentrations compared to NaOCl, CHX and the other tested AgNPs. Positive-charged Ag NPs at 5.7×10(-10) molL(-1) completely prevented the growth of E.faecalis after 5min of contact time, a finding comparable to 0.025% NaOCl. Dentine powder had variable inhibitory effects on all tested materials after 1 h incubation period, but after 24h, NaOCl and the positive-charged Ag NPs were not inhibited by dentine at any concentration used. CHX was the most and the positively charged Ag NP solution was the least toxic solutions to L929 fibroblasts (P<0.001). Ag NP surface charge was important in bactericidal efficacy against E.faecalis. The positively charged imidazolium-based ionic liquid-protected Ag NPs showed promising antibacterial results against E.faecalis and exhibited a high level of cytocompatibility to L929 cells.

Silver nanoparticles (Ag NPs) have been used widely for antibacterial applications; however, the effects of their sizes on antibacterial activities and toxicities to human cells, particularly for the laser‐generated Ag NPs, are not fully understood. In this study, sucrose gradient centrifugation was used to separate laser‐generated Ag NPs into different fractions by size. Transmission electron microscopy was used to analyze the size distribution of the Ag NPs, and well diffusion method was used to evaluate the antibacterial activity of the Ag NP fractions against the Escherichia coli. Results showed that the antibacterial effects of laser‐generated Ag NPs inversely correlated to the particle size. Among Ag NP fractions with average sizes ranging 19–47 nm, the 19‐nm Ag NPs presented the highest bactericidal effect. The smaller sized laser Ag NPs also significantly induced the generation of reactive oxygen species when applied to E. coli, compared with that of the larger sized laser Ag NPs. Cytotoxicity analysis revealed that the different sized laser‐generated Ag NPs were not significantly toxic to the human fibroblasts and lung epithelial cells in a 72‐h in vitro cell culture period. Understanding the size‐dependent functional properties of the laser‐generated Ag NPs helps informing the designs for future applications of the laser‐generated Ag NPs.