Solid-state tailored silver nanocomposites from chitosan: Synthesis, antimicrobial evaluation and molecular docking.

Area of Science:

• Materials Science
• Biotechnology
• Organic Chemistry

Background:

• Chitosan is a biocompatible polymer with inherent antimicrobial properties.
• Developing novel chitosan derivatives with enhanced efficacy is crucial for combating microbial infections.
• Silver nanoparticles are known for their broad-spectrum antimicrobial activity.

Purpose of the Study:

• To synthesize and characterize novel alpha-aminophosphonate-chitosan derivatives and their silver nanocomposites.
• To evaluate the antimicrobial efficacy of these compounds against various bacterial and fungal strains.
• To investigate the structure-activity relationship for optimizing antimicrobial mechanisms.

Main Methods:

• Synthesis of alpha-aminophosphonate-chitosan (α-AP-Cs) derivatives using chitosan, triphenyl-phosphite, and carbamide-glutaraldehyde crosslinkers.
• Preparation of α-AP-Cs silver nanocomposites (Ag0NPs) via a solid-state approach.
• Characterization using CHNS/P/O, FT-IR, XRD, TEM, EDX, XPS, and UV-visible spectroscopy.
• Antimicrobial evaluation including MIC, dose-killing assays, growth kinetics, protein leakage, and antibiofilm activity.

Main Results:

• Successful synthesis and characterization of three α-AP-Cs derivatives (CU, CT, CSC) and their corresponding Ag0NPs.
• Spectroscopic and elemental analyses confirmed the phosphonation and crosslinking.
• XPS and XRD confirmed metallic silver with FCC structure; UV-Vis showed peak at ~399 nm.
• TEM revealed semi-spherical Ag0NPs with an average size of 30.4 nm.
• Enhanced antimicrobial efficacy against Streptococcus mutans, Pseudomonas aeruginosa, Candida albicans, and Rhizopus oryzae, particularly against biofilms.

Conclusions:

• The synthesized α-aminophosphonate-chitosan-silver nanocomposites exhibit significantly improved antimicrobial and antibiofilm activity compared to bare chitosan.
• The combination of α-aminophosphonate functionalization and silver nanoparticles potentiates the antimicrobial effects.
• These novel materials hold promise for developing advanced antimicrobial agents and coatings.