Rational design of niobium carbide MXene quantum dots decorated with arginine for the fluorescence sensing of superoxide anion in Saccharomyces cerevisiae cells

In this work, arginine functionalized niobium carbide MXene quantum dots (arginine-Nb2C MQDs) were synthesized using Nb2AlC, NaOH and arginine as reagents. The as-synthesized probe showed bluish-green fluorescence under UV light at 365 nm. The structural and morphological changes of as-synthesized arginine-Nb2C MQDs were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Raman spectroscopy and high-resolution transmittance electron microscopy (HR-TEM). The synthesized fluorescent arginine-Nb2C MQDs were stable, with an average size of 1.92 ± 0.52 nm. As-synthesized arginine-Nb2C MQDs act as a sensor for detecting superoxide anion (O2•−) via a fluorescence “turn-off” mechanism with the detection limit of 31.89 nM. The fluorescence of arginine-Nb2C MQDs is quenched by O2•− via Förster resonance energy transfer (FRET) mechanism. Fascinatingly, the synthesized arginine-Nb2C MQDs showed negligible cytotoxicity on HeLa cells and acted as promising candidates for sensing of O2•− in Saccharomyces cerevisiae cells.