Biosynthesis of Silver Nanoparticles Using Thymus daenensis Celak Against Wound Causing Microbes

Abstract

Wounds provide an appropriate environment for pathogenic microorganisms to grow, causing tissue damage and inflammation. Remarkable progress has recently been made in nanoparticle formulation for various biological applications over the process of wound recovery. The present study is the first to examine the biosynthesis of silver nanoparticles using Thymus daenensis Celak and investigate its antimicrobial effects on strains causing wound such as Staphylococcus epidermidis, Staphylococcus aureus, Klebsiella pneumonia, Acinetobacter baumannii, Serratia marcescens, Pseudomonas aeruginosa, and Aspergillus niger. T. daenensis species habitat was first identified in the Daran region, Isfahan, Iran (46° 49′ 2ʺ longitude and 36° 54′ 170ʺ latitude). Flowering branches (leaves, stems, and flowers) of the studied species were then randomly collected from various bases (100 bases per region) in May 2022. Medicinal silver nanoparticles synthesis was confirmed based on UV–Visible, SEM, FTIR, and XRD results. Synthesized silver nanoparticles and the extract's antimicrobial activity were examined through diffusion in agar and determining minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC). UV–Visible results indicated the maximum absorption peak to have been at the 415 nm wavelength. FTIR analysis suggested that synthesized silver nanoparticles’ agent groups included aromatic alcohol, primary alcohol, carbonyl, amine, amide, alkyl halide, and carboxylic groups, which was consistent with the extract’s spectral pattern. Based on the results XRD, the Debye–Scherrer equation revealed the mean size of silver nanoparticles to be 4.09 nm. Moreover, FESEM analysis demonstrated that silver nanoparticles were rather cube-shaped and uniform with aggregates in 10–50 nm dimensions. Results of ANOVA suggested a significant difference between the growth inhibition halo diameter in T. daenensis extract, synthetic silver nanoparticles, and positive control antibiotics against the microbial strains (P ≤ 0.01). The largest growth-inhibition halo diameter was observed in synthesized silver nanoparticles against P. aeruginosa Gram-negative bacteria at 22.67 mm, indicating a twice as strong performance compared to the rifampin antibiotic. Moreover, synthesized silver nanoparticles demonstrated good inhibitory activity against baumannii (12.00 mm) and Gram-positive bacteria S. epidermidis (22.00 mm) and S. aureus (21.67 mm). On the other hand, the findings indicated that the MIC value of synthesized silver nanoparticles against Gram-negative bacteria P. aeruginosa and S. marcescens was 250 μg/mL, which was 6 times stronger than T. daenensis extract. Hence, silver nanoparticles synthesized from T. daenensis extract could offer possible promising potential as a natural and biocompatible alternative to combat these wound-causing microbial strains. However, further research should be done in the future to gain a complete insight into the toxicity and determine the optimal concentration for clinical applications.