Curcumin-Derived (3-Aminopropyl)trimethoxysilane-Functionalized Carbon Quantum Dots: A Fluorometric and Colorimetric Nanoprobe for Picric Acid Detection, Antioxidant Activity, and Liposome Encapsulation

Abstract

Creating an analytical probe to track extremely mutagenic picric acid (PA) is essential for human health and the environment. Here, we developed a straightforward and quick fluorescence analytical method utilizing 3-aminopropyltrimethoxysilane (3-APTMS)-functionalized curcumin carbon quantum dots (CQDs) for the fast and selective detection of PA. Solvothermal carbonization and functionalization of curcumin with 3-APTMS were used to create multifunctional CQDs, which were then characterized using UV−vis spectroscopy, Fourier transform infrared (FTIR), X-ray diffraction (XRD), ζ-potential, transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). Our CQDs, as synthesized with an average diameter of 3.4 nm, exhibited excitation-dependent emission behavior, demonstrating 63.85% yield, 1.59% quantum yield, and fluorescence lifetime decay broader than a single exponential. The addition of picric acid significantly reduced the fluorescence (FL) emission intensity of CQDs and caused a noticeable color shift in visible as well as UV light. Throughout the 0.1−2.5 μM range, the calibration curve of the suggested assay demonstrated favorable linearity between quenched FL emission intensity and PA concentration, with the lowest detection limit of 88.96 nM. The CQD shows antioxidant activity at low concentrations (<0.07 mg/mL), measured by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay (colorimetry and electrochemically). Further, we encapsulated our CQDs in the liposome to make it biocompatible for cell imaging for future study. The results indicate the efficacy of CQDs as a nanoprobe for the selective detection of PA, retaining a few of the primary properties of natural curcumin-like antioxidant activity while having significantly higher bioavailability and water solubility; they can be used as a modifier in semiconductors for photocatalytic application and can also be a promising fluorescence probe in cell imaging.