Trans-Cinnamaldehyde-Driven Silver Nanoparticles: Dual Role in Targeting Biofilm Disruption and Control of Biofilm‑Forming Pathogens via Impairing Ferrous Ion Uptake.

Purpose: Biofilm-related infections, especially those associated with medical devices like catheters, pose significant clinical challenges due to their resistance to conventional treatments. This study investigates a green chemistry-based approach to synthesize silver nanoparticles (AgNPs) stabilized with trans-cinnamaldehyde (t-CA) and evaluates their potential for combating microbial biofilms and based on novel mechanism of action.

Methods: Silver nanoparticles (t-CA-AgNPs) were synthesized using t-CA as both a reducing and stabilizing agent. The NPs were then thoroughly characterized using UV-Vis spectroscopy, X-ray diffraction (XRD), electron microscopy (TEM, SEM, STEM), and dynamic light scattering (DLS). We evaluated its antimicrobial potential against the most prevalence biofilm-forming pathogens including Pseudomonas aeruginosa, Escherichia coli and Candida albicans using minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) assays. Moreover, we investigated the mechanism of action of t-CA-AgNPs underlying biofilm inhibition. Biofilm formation and structure were verified by SEM imagining.

Results: DLS analysis confirmed that t-CA-AgNPs had an average particle diameter of 2.5 nm, coupled with a notably negative zeta potential (-45 mV), indicative of good colloidal stability. t-CA-AgNPs displayed potent antimicrobial properties, with MIC values ranging from 26 to 412 µg/mL and MBC values from 103 to 825 µg/mL. Biofilm formation inhibitory properties reached 88.74% of inhibition for P. aeruginosa and 70.60% for E. coli. Moreover, we found potent metal ion-chelating capabilities, importantly, in binding and reducing ferrous ions, the crucial factor of biofilm formation. Furthermore, t-CA-AgNPs substantially impaired biofilm development on catheter surfaces, underscoring their robust antibiofilm potential.

Conclusion: Presented here t-CA-AgNPs exhibit significant antimicrobial and antibiofilm activity. By effectively targeting critical elements in biofilm formation, such as ferrous ions, coupled with antimicrobial potential of both active compounds, these green-synthesized NPs have potential applications in significantly improving the safety and effectiveness of medical devices. However, further studies are needed to ensure their efficacy in clinical use.