A novel synthesis of hybrid graphene oxide as a dual-functional fluorescent chemosensor for Ti4+ ion detection and antibacterial performance via simultaneous oxidation and functionalization

Abstract

Functionalized graphene oxide (GO), a versatile two-dimensional material, is synthesized by surface modification and exhibits remarkable physical and chemical properties, making it attractive for a wide range of applications. In this work, we present a unique one-step approach that simultaneously oxidizes and functionalizes graphite using Calotropis gigantea latex as a natural reagent. The latex functions as an oxidizing and functionalizing agent, introducing bioactive compounds and oxygen- and nitrogen-rich functional groups onto the GO surface under ambient conditions (Bio@HGO). This method minimizes the use of hazardous reagents and introduces a high density of surface functional groups on GO sheets suitable for metal ion interactions. The synthesized material was characterized using PXRD, FE-SEM, XPS, Raman, FTIR, and BET analyses to confirm the successful functionalization by using natural latex. The introduction of oxygenated and nitrogen-containing groups from Calotropis gigantea latex is found to improve dispersion stability and enhance the affinity for Ti⁴⁺ metal ion detection. Electrochemical investigations have confirmed that the material exhibits high sensitivity and selectivity towards Ti⁴⁺ ions, with a distinguishable and measurable response in the given experimental concentration range. This work highlights the potential of Calotropis gigantea latex-derived materials for the development of graphene-based sensors, offering a sustainable route for environmental monitoring of toxic metals such as Ti⁴⁺. In addition, the potential antibacterial activity of Bio@HGO was also confirmed against Pseudomonas aeruginosa and Escherichia coli bacteria, with zones of inhibition of 0.95, 1.57, and 1.90 mm and 1.25, 1.45, and 2.15 mm at 20, 40, and 80 μg mL⁻¹ concentrations of Bio@HGO, respectively.