Cellulosic schiff base hydrogel biosensor for bacterial detection with pH/thermo-responsitivity: DFT calculations and molecular docking.

A facile green hydrothermal method was developed for the preparation of fluorescent carbon dots (CDs) using sugarcane bagasse (SB) as a raw material. The incorporation of CDs within the hydroxyethyl cellulose-acrylamide hydrogel (HEC-AM) in the presence of glutardehyde (GA) as a crosslinking agent showed bright red emission under fluorescence microscope. The hydroxyethyl cellulose-N-CDs-acrylamide hydrogel (HEC-AM@N-CDs) were used as alternative biocompatible fluorescent probes for imaging and suppression of Gram-negative bacteria such as Escherichia coli (with inhibition zones 13 mm for HEC-AM to 17 mm for HEC-AM@N-CDs) & Helicobacter pylori (with inhibition zones 16 mm for HEC-AM to 13 mm for HEC-AM@N-CDs) and Gram-positive bacteria such as Micrococcus luteus (with inhibition zones 15 mm for HEC-AM to 16 mm for HEC-AM@N-CDs) & Staphylococcus aureus (with inhibition zones 13 mm for HEC-AM to 14 mm for HEC-AM@N-CDs). The N-CDs promote bacterial binding and internalization, leading to differential fluorescence emission depending on the bacteria's cell wall composition. DFT calculations support strong interactions between the bacteria and HEC-AM@N-CDs.