Amino acids and related polymers-mediated versatile noble metal nanomaterials: Engineered design, antibacterial...

Amino acids, peptides, and proteins with reducing groups (-NH₂, -SH, indole ring) have been employed as reducing and stabilizing agents to synthesize versatile noble metal nanomaterials (NM NMs). Meanwhile, side chains of amino acids, flexible conformations of peptides and proteins, are selectively coordinated to specific crystal surfaces with different coordination strengths, regulating nucleation rates and growth direction of NM NMs, achieving sizes (1-100 nm) and morphologies (e.g., spherical, triangular, hexagonal) engineered. Notably, small-sized NM NMs with sustained electron transfer generate ROS to oxidatively damage bacteria. In contrast, large-sized/anisotropic NM NMs with excellent photothermal properties disrupt bacterial physiological homeostasis. Interestingly, cationic amino acids/antimicrobial peptides modified on the NM NMs further enhance their antimicrobial effects via charge and polarity effects. Besides, these NM NMs can also target and damage bacterial DNA and proteins. This paper provides insights into the synthesis mechanism and antimicrobial effect of NM NMs and applications in food preservation.