Bioactive chitosan-citral Schiff base zinc complex: A pH-responsive platform for potential therapeutic applications

Area of Science:

• Materials Science
• Green Chemistry
• Biotechnology

Background:

• Supercritical fluid (SCF) technology offers a non-toxic, environmentally friendly, and safe approach for nano-material synthesis.
• SCF technology enhances reaction speed, controllability, and repeatability in material preparation.
• Chitosan derivatives are widely explored for their biocompatibility and functional properties.

Purpose of the Study:

• To synthesize a novel pH-responsive complex agent using carboxymethyl chitosan sodium salt (CCS), citral (CT), p-coumaric acid (CA), and ZnSO4 via supercritical fluid technique.
• To characterize the coordination structure and morphology of the prepared CCS-CT-CA-Zn complex.
• To evaluate the antioxidant, antibacterial, and anti-biofilm activities of the complex and its acid-decomposed form.

Main Methods:

• Utilized CO2 supercritical fluid technique for the synthesis of the CCS-CT-CA-Zn complex.
• Employed techniques to verify the coordination structure (e.g., Schiff base/OH) and morphology of the complex.
• Assessed pH-responsive release, antioxidant activity, anti-vibrio efficacy, and inhibition of *Vibrio parahaemolyticus* motility and biofilm formation.

Main Results:

• The CCS-CT-CA-Zn complex exhibited good dispersion and uniformity with a mean size of 852 ± 202 nm, PdI of 0.301, and zeta potential of -31 ± 6 mV.
• The complex demonstrated effective pH-responsive release in an acidic environment.
• Both the complex (DS-B) and its acid-decomposed form (DS-A) showed significant antioxidant and anti-vibrio activity, inhibiting *V. parahaemolyticus* biofilm formation and motility.

Conclusions:

• The synthesized CCS-CT-CA-Zn complex is a promising pH-responsive agent with notable antioxidant and antibacterial properties.
• Supercritical fluid technology provides an efficient and green method for developing such functional complex agents.
• This research lays the groundwork for designing natural product-derived antibacterial-antioxidant agents for applications as food and feed additives.