BIOSYNTHESIS OF SILVER NANOPARTICLES FROM SENNA AURICULATA AND SYMPLOCOS RACEMOSA FORMULATION AND ITS ANTIMICROBIAL MECHANISM OF ACTION AGAINST WOUND PATHOGENS

Abstract

Aim: To synthesize silver nanoparticles (AgNPs) using Senna auriculata and Symplocos racemosa extracts and evaluate their antimicrobial and antibiofilm activities against wound-associated bacterial pathogens.

Introduction: In this study, S. auriculata and S. racemosa were selected as plant sources for the eco-friendly, green synthesis of AgNPs, leveraging their known ethnopharmacological properties. Wound infections are often caused by antibiotic-resistant pathogens such as Pseudomonas sp., Actinobacter sp., Enterococcus faecalis, Escherichia coli, and Staphylococcus aureus, leading to delayed healing and increased morbidity. Silver nanoparticles have emerged as effective antimicrobial agents due to their broad-spectrum activity and ability to disrupt biofilms. Green synthesis using medicinal plants offers an eco-friendly, cost-effective route to nanoparticle production, combining phytochemicals with nanotechnology for enhanced therapeutic outcomes.

Methods: The visual confirmation by a color change and spectroscopically validated via UV-Vis absorption at 450 nm. Using an agar well diffusion assay, the AgNPs at different concentrations were tested against wound pathogens, and the inhibition zones were measured to determine antibacterial efficacy. For the Time-Kill Kinetics Assay, the bactericidal effect of AgNPs was analyzed over 5 hours using optical density and CFU counts to assess the time- and dose-dependent killing pattern at varying concentrations. For the Antibiofilm Assay, Mature biofilms of each pathogen were treated with AgNPs (25–100 µg/mL), and biofilm mass was quantified using ELISA at 590 nm after PBS washing and scraping.

Results: AgNPs showed excellent antimicrobial activity, with the largest zone of inhibition (13 mm × 10 mm) against Actinobacter sp. at 100 µg/mL, followed by Pseudomonas sp. and S. aureus. The time-kill assay revealed that 100 µg/mL of AgNP nanofilm significantly reduced viable bacterial counts within 3–4 hours, particularly in E. coli and S. aureus. Antibiofilm activity was also dose-dependent, with Actinobacter sp. biofilms exhibiting the highest sensitivity, followed by S. aureus and Pseudomonas sp.

Conclusion: The green-synthesized AgNPs from S. auriculata and S. racemosa demonstrated potent antimicrobial and antibiofilm effects against key wound pathogens. Their incorporation into polymeric nanofilms enhances sustained antimicrobial action, supporting their potential use in advanced wound dressings. These findings offer a promising, eco-friendly alternative for infection control and wound management in the context of rising antibiotic resistance.