Development of silver/titanium dioxide/chitosan adipate nanocomposite as an antibacterial coating for fruit storage

- A novel nanocomposite Ag/TiO2/CS was developed through photochemical reduction.
- Multiple characterization technologies confirmed the formation of the nanocomposite.
- The nanocomposite attained higher antimicrobial activity than AgNO3 or AgNP.

A novel nanocomposite of silver/titanium dioxide/chitosan adipate (Ag/TiO2/CS) was developed through photochemical reduction using a chitosan adipate template. Chitosan served as a reducing agent anchoring the metal ions through Ag-N coordination bonds and electrostatic attractions, thus stabilizing the Ag/TiO2/CS product observed by Fourier transform infrared spectroscopy and X-ray diffraction patterns. Scanning electron microscopy observations revealed that the nanocomposite particles (50-100 nm) were deposited onto the chitosan adipate layer. The product exhibited high ζ-potentials from 30.1 mV to 33.0 mV during 60 days of storage. In addition, the nanocomposite demonstrated higher antimicrobial activity than AgNO3 or nano-Ag particles at similar concentrations, as evidenced by the inhibition zone, minimum inhibitory concentrations (MIC), and growth curve. The nanocomposite reduced the Escherichia coli population by 6 logs after 24 h of incubation, and had an MIC value of 0.38 μg Ag/mL. These results suggest that Ag/TiO2/CS has the potential to be used as an antibacterial protective coating for fruit storage.