Antibacterial properties of starch-reduced graphene oxide-polyiodide nanocomposite

Graphene-based nanocomposites with superior antibacterial activity are highly sought after by the food packaging industries. Here, we report for the first time a method that utilizes soluble starch biopolymer as a functionalizing and reducing agent for the preparation of starch-reduced graphene oxide (SRGO), whereby polyiodide binds to the helical structures of amylose units of the starch (chromophore) to form a SRGO-polyiodide nanocomposite (SRGO-PI NC). UV-visible spectroscopy, X-ray diffraction, Raman spectroscopy, scanning electron microscopy, and energy-dispersive spectroscopy confirmed the presence of polyiodide in SRGO. SRGO-PI NC exhibited good antibacterial activities against pathogenic Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) microbes with minimum inhibitory concentrations (MICs) and minimum bactericidal concentration (MBC) values (as determined by a broth-dilution method) of 2.5 and 5 mg/ml, respectively, for both E. coli and S. aureus. PrestoBlue viability assays showed half-maximal inhibitory concentration (IC50) values of 0.45 and 0.41 mg/ml for E. coli and S. aureus, respectively. Time-kill kinetic and live/dead bacterial viability assays revealed the antimicrobial activities of SRGO-PI NC against both E. coli and S. aureus. The study provides new insights regarding the utilization of graphene-polyiodide NCs as high-efficacy antibacterial starch-based nanomaterials for food packaging applications.

Automated summary

The development of graphene-polyiodide nanocomposites by utilizing soluble starch biopolymer as a functionalizing and reducing agent has shown to be effective in creating nanomaterials with superior antibacterial properties for food packaging applications. The nanocomposites exhibited good antibacterial activities against E. coli and S. aureus, showcasing potential as high-efficacy antibacterial starch-based nanomaterials.UV-visible spectroscopy, X-ray diffraction, Raman spectroscopy, scanning electron microscopy, and energy-dispersive spectroscopy were used to confirm the presence of polyiodide in the starch-reduced graphene oxide.