A promising eco-friendly and cost-effective photocatalytic rolled graphene oxide/poly(m-methylaniline) core-shell nanocomposite for antimicrobial action.

Abstract

A new and innovative rolled graphene oxide (roll-GO)/poly-m-methylaniline (PmMA) core-shell nanocomposite has been successfully synthesized using an in situ polymerization technique. This eco-friendly and cost-effective material shows great promise due to its antimicrobial properties. The characterization of the nanocomposite involved X-ray diffraction and Fourier transform infrared spectroscopy to analyze its structure and functional groups, whereas scanning electron microscopy and transmission electron microscopy (TEM) were utilized to examine its morphology. TEM analysis revealed the formation of roll-GO, forming multi-walled tubes with inner and outer diameters of 50 and 70 nm, respectively. Optical analysis demonstrated an enhanced bandgap in the nanocomposite, with bandgap values of 2.38 eV for PmMA, 2.67 eV for roll-GO, and 1.65 eV for roll-GO/PmMA. The antibacterial efficacy of the nanocomposite was tested against Gram-positive bacteria, including Bacillus subtilis and Staphylococcus aureus, as well as Gram-negative bacteria such as Escherichia coli and Salmonella sp. The well diffusion method was used to determine the inhibition zones, revealing that the nanocomposite demonstrated broad-spectrum antibacterial activity against all the pathogens tested. The largest inhibition zones were observed for B. subtilis, followed by S. aureus, E. coli, and Salmonella sp. Notably, the inhibition zones increased when the samples were exposed to light compared to dark conditions, with increases of 33 and 18 mm noted for B. subtilis. This enhanced activity under light exposure is attributed to the photocatalytic properties of the nanocomposite. The antibacterial mechanism is based on both adsorption and degradation processes. Moreover, antibacterial activity was found to increase with increasing concentrations of nanoparticles, ranging from 100 to 500 ppm. This suggests that the nanocomposite has potential as an alternative to antibiotics, especially considering the growing issue of bacterial resistance. The promising results obtained from the inhibition zones make these nanocomposites suitable for various applications. Currently, the research team is working on the development of a prototype utilizing these antimicrobial particles within commercial bottles for sterilization purposes in factories and companies.