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

A novel Cu-chlorophyllin-stabilized silver nanoparticle (Ag⁰NPs-ChlCu) with potent antimicrobial properties was synthesized for the first time using an ultrasonically driven chemical reduction approach. In this approach, Cu-chlorophyllin (ChlCu) acts as a stabilizing ligand, while sodium borohydride functions as the chemical reductant. The formation mechanism of Ag⁰-NPsCHL was elucidated, revealing that ultrasonic irradiation facilitates the in situ reduction of Ag (I) and its subsequent incorporation into the ChlCu complex. Four pyrrole rings coordinate with Ag⁰NPs through four nitrogen atoms, which serve as adsorption sites for the anchorage of Ag⁰-NPsCHL. Characterization by XPS revealed the presence of Ag-N bonding involving pyrrole units on the FCC structure of Ag⁰NPs. Ag⁰NPs-ChlCu 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-NPsCHL 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 ChlCu as a dual stabilizing and coordinating agent for Ag⁰NPs, offering a promising approach for developing antimicrobial surgical materials.