Comparative analysis of the physicochemical and anti-biofilm properties of iota and lambda carrageenan-capped silver nanocomposites synthesized using response surface methodology

Abstract

Antimicrobial resistance of microbes due to the formation of biofilms is a global industrial, environmental, and health concern. The current study presents the synthesis, characterization, and functional assessment of two carbohydrate/sulfated polysaccharide (ι-carrageenan and λ-carrageenan)-capped silver nanocomposites (ι-CrgAgNPs and λ-CrgAgNPs). The nanocomposite syntheses were designed and optimized using RSM-based FCCCD. The synthesized nanocomposites were characterized using an array of physicochemical techniques to study their morphological, structural, compositional, and molecular interaction features. Spherically shaped nanoparticles of sizes 12 ± 5 nm and 62 ± 10 nm were obtained for ι-CrgAgNPs and λ-CrgAgNPs. As evident from FTIR, silver nanocomposites were stabilized by various functional groups present in carrageenans. Antibacterial and anti-biofilm studies performed using the Gram-negative strain Pseudomonas aeruginosa and Gram-positive strain Staphylococcus aureus suggested that both the nanocomposites were potent in inhibiting and eradicating the bacterial biofilms; however, their potency for eradicating the P. aeruginosa biofilm is much higher as compared to the S. aureus biofilm. Furthermore, within the nanocomposites, λ-CrgAgNPs was observed to be more stable, while ι-CrgAgNPs exhibited enhanced biofilm inhibition/eradication properties. These results confirm the broad-spectrum anti-biofilm features of the synthesized carrageenan nanocomposites, which can be further developed as functional industrial formulations as potent antimicrobial agents.