Ultrasonic-driven synthesis of Cu-chlorophyllin-stabilized silver nanoparticles for high-efficiency antimicrobial surgical suture coatings

Abstract

A novel Cu-chlorophyllin-stabilized silver nanoparticle (Ag⁰_NPs-Chl_Cu) with potent antimicrobial properties was synthesized for the first time using an ultrasonically driven chemical reduction approach. In this approach, Cu-chlorophyllin (Chl_Cu) acts as a stabilizing ligand, while sodium borohydride functions as the chemical reductant. The formation mechanism of Ag⁰-NPs_CHL was elucidated, revealing that ultrasonic irradiation facilitates the in situ reduction of Ag (I) and its subsequent incorporation into the Chl_Cu complex. Four pyrrole rings coordinate with Ag⁰_NPs through four nitrogen atoms, which serve as adsorption sites for the anchorage of Ag⁰-NPs_CHL. Characterization by XPS revealed the presence of Ag-N bonding involving pyrrole units on the FCC structure of Ag⁰_NPs. Ag⁰_NPs-Chl_Cu demonstrated a zeta potential of (-) 35.57±3.54 mV with a spherical shape and an average size of 6.72±1.72 nm, resulting in a stable colloidal dispersion with a monodispersed index. The synthesized Ag⁰-NPs_CHL nanocomposites were subsequently deposited onto polyamide surgical sutures via an electrostatic Layer-by-Layer (LbL) self-assembly technique. The coated sutures exhibited >99.9 % antibacterial efficiency against E. coli (ATCC25922), S. aureus (ATCC25923), and A. baumanii (ATCC19606). While nanoparticle accumulation was observed in human primary epidermal keratinocyte (HEKa) cells, no cytotoxic effects were detected in the epidermis. This study highlights the effectiveness of Chl_Cu as a dual stabilizing and coordinating agent for Ag⁰_NPs, offering a promising approach for developing antimicrobial surgical materials.