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The emergence of antibiotic-resistant bacteria necessitates the development of novel, sustainable, and biocompatible antibacterial agents. This study addresses cytotoxicity and environmental concerns associated with traditional silver nanoparticles (AgNPs) by exploring lignin, a readily available and renewable biopolymer, as a platform for AgNPs. We present a novel one-pot synthesis method for lignin-based AgNPs (AgNPs@AL) nanocomposites, achieving rapid synthesis within 5 min. This method utilizes various organic solvents, demonstrating remarkable adaptability to a wide range of lignin-dissolving systems. Characterization reveals uniform AgNP size distribution and morphology influenced by the chosen solvent. This adaptability suggests the potential for incorporating lignin-loaded antibacterial drugs alongside AgNPs, enabling combined therapy in a single nanocomposite. Antibacterial assays demonstrate exceptional efficacy against both Gram-negative and Gram-positive bacteria, with gamma-valerolactone (GVL)-assisted synthesized AgNPs exhibiting the most potent effect. Mechanistic studies suggest a combination of factors contributes to the antibacterial activity, including direct membrane damage caused by AgNPs and sustained silver ion release, ultimately leading to bacterial cell death. This work presents a straightforward, adaptable, and rapid approach for synthesizing biocompatible AgNPs@AL nanocomposites with outstanding antibacterial activity. These findings offer a promising and sustainable alternative to traditional antibiotics, contributing to the fight against antibiotic resistance while minimizing environmental impact. [ABSTRACT FROM AUTHOR]

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In this study, biosynthesis of silver nanoparticles (AgNPs) by using Eurotium cristatum, isolated from Fuzhuan brick-tea and its antibacterial activity has been demonstrated. AgNPs were characterized at 425 nm as maximum absorbance peak by ultraviolet-visible spectrophotometry. The images of transmission electron microscopy revealed that AgNPs are spherical shape with at 15–20 nm in size. The X-ray diffraction pattern corresponding to planes (111), (200), (220), (311), and (222) demonstrated the crystalline nature of AgNPs. Fourier transform infrared spectrum showed that functional groups involved in reduction of silver ions to metal nanoparticles. For antibacterial application, AgNPs showed antibacterial activity against Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus, Candida albicans, and Bacillus subtilis. It also acted synergistically with various antibiotics to inhibit growth of pathogenic strains, which produced an effect greater than the sum of their individual effects. For neomycin with no resistance to C. albicans, it combined with AgNPs, which had significant synergistic effect against C. albicans, with maximum inhibitory zone at 20.9 mm, which was 2.5-fold greater than that of AgNPs alone (8.2 mm). Other antibiotics combined with AgNPs also existed similar synergistic effect. Therefore, AgNPs-synthesized by E. cristatum could enhance antibacterial activity in combination with antibiotics against pathogenic strains through synergistic effects. It might provide a new strategy for treatment of resistant bacteria. [ABSTRACT FROM AUTHOR]

BACKGROUND: The low cost of aminoglycoside (AMG) antibiotics facilitates their excessive use in animal husbandry and the agriculture sector. This scenario has led to the occurrence of residues in the food chain. After several years of AMG use in antibacterial therapy, resistance to streptomycin has begun to appear. Most of the detection methods developed for AMG antibiotics lacks specificity. A broad target specific nanoprobe would be ideal for detecting the entire class of AMGs. A rapid and sensitive method for the detection of AMGs is urgently needed. RESULTS: Gallic acid‐coated silver nanoparticles (AgNPs) were demonstrated as a nanoprobe for the colorimetric detection of AMGs (yellow to orange / red). A linear dynamic range of 50–650 pmol L−1 was achieved readily by ratiometric spectrophotometry (A560/A400) with a limit of detection (LOD) as low as 36 pmol L−1. The amine‐groups of the AMGs function as molecular linkers, so that electrostatic coupling interactions between neighboring particles drive the formation of AgNP aggregates. The assay can also be applied for the determination of streptomycin residues in serum and milk samples. CONCLUSION: This study revealed the potential of an AgNP probe for the rapid and cost‐effective detection of low‐molecular‐weight target analytes, such as the AMGs. A ligand‐induced aggregation of AgNPs coated with gallic acid was reported to be a rapid and sensitive assay for AMGs. Analysis of streptomycin was demonstrated with excellent picomolar‐level sensitivity. Thus, the validated method can find practical applications in the ultrasensitive detection of AMGs in complex and diagnostic settings. © 2019 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

The ability of microorganisms to generate resistance outcompetes with the generation of new and efficient antibiotics; therefore, it is critical to develop novel antibiotic agents and treatments to control bacterial infections. An alternative to this worldwide problem is the use of nanomaterials with antimicrobial properties. Silver nanoparticles (AgNPs) have been extensively studied due to their antimicrobial effect in different organisms. In this work, the synergistic antimicrobial effect of AgNPs and conventional antibiotics was assessed in Gram-positive and Gram-negative bacteria. AgNPs minimal inhibitory concentration was 10–12 μg mL-1 in all bacterial strains tested, regardless of their different susceptibility against antibiotics. Interestingly, a synergistic antimicrobial effect was observed when combining AgNPs and kanamycin according to the fractional inhibitory concentration index, FICI: <0.5), an additive effect by combining AgNPs and chloramphenicol (FICI: 0.5 to 1), whereas no effect was found with AgNPs and β-lactam antibiotics combinations. Flow cytometry and TEM analysis showed that sublethal concentrations of AgNPs (6–7 μg mL-1) altered the bacterial membrane potential and caused ultrastructural damage, increasing the cell membrane permeability. No chemical interactions between AgNPs and antibiotics were detected. We propose an experimental supported mechanism of action by which combinatorial effect of antimicrobials drives synergy depending on their specific target, facilitated by membrane alterations generated by AgNPs. Our results provide a deeper understanding about the synergistic mechanism of AgNPs and antibiotics, aiming to combat antimicrobial infections efficiently, especially those by multi-drug resistant microorganisms, in order to mitigate the current crisis due to antibiotic resistance. [ABSTRACT FROM AUTHOR]

Developing of new antibiotics with synergistic properties is of great importance. Herein, the synthesis of cephalexin nanoparticles (CPNPs) is reported through ball milling method for the first time. Cephalexin powders had an initial size in the range of 10–100 μm. The average particle size, however, was reduced to about 100 nm after milling for 7 h, confirmed by SEM. Silver nanoparticles (AgNPs) with small particle size (<10 nm) were synthesized through chemical reduction of silver ions in citrate solution. The cytotoxicity of the prepared CPNPs and AgNPs at different concentrations were evaluated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) reduction assay. The antibacterial properties of CPNPs, AgNPs and their combination were investigated against Staphylococcus aureus . The results confirmed that AgNPs show synergistic properties in the presence of CPNPs and effectively increased their antibacterial properties. [ABSTRACT FROM AUTHOR]

Cipro-AgNPs showed the best antibacterial activity as compared to AgNPs alone and ciprofloxacin alone. B Methods and materials: b In this study, AgNPs were synthesized using the callus extract of Fagonia indica as a reducing agent with the addition of Very small doses ciprofloxacin antibiotic. The activity of Cipro-AgNPs and ciprofloxacin and AgNPs alone as control against resistant bacteria such as E. coli, C. amalonaticus, S. sonnei, and S. typhi was studied. [Extracted from the article]