Phenylboronic acid and geraniol co-modified chitosan oligosaccharide derivatives boost antibacterial efficacy by targeting bacteria

Chitosan oligosaccharide (COS) derivatives present significant potential as antimicrobial agents. Our previously developed geraniol (Ger) grafted Chitosan oligosaccharide (COS-Ger) has demonstrated commendable solubility and antibacterial activity. To further improve its effectiveness, exploring methods for bacterial targeting could be a beneficial approach. Therefore, we herein report a novel dual-functional derivative, phenylboronic acid (PBA) and Ger co-modified COS, by strategically integrating PBA into the COS-Ger framework. The molecular structure of the derivative has been validated through several characterization techniques. Biological evaluations demonstrated that PBA incorporation synergistically enhanced the compound's bacterial targeting, resulting in markedly improved antibacterial performance. PBA incorporation synergistically enhanced the compound's bacterial targeting. Specifically, at a low concentration of 0.2 mg/mL, the inhibition rate of PBA–COS–Ger against Staphylococcus aureus (S. aureus) reached 73.10%, significantly outperforming that of COS-Ger (30.61%). Moreover, it achieved nearly 100% inhibition against both S. aureus and Escherichia coli (E. coli) at 1.0 mg/mL. These results clearly indicate that the grafting of PBA greatly enhanced the antibacterial ability of COS-Ger. The practical potential of this derivative was preliminarily verified through a preservation experiment on cherry tomatoes. This approach establishes a conceptual platform for the rational design of highly efficient, bio-based antimicrobial agents.