Yeast-Derived Carbon Dots as Fluorescent Probes for Selective Detection of Methylene Blue Dye: A Combined Experimental and Computational Study

The excessive use of synthetic dyes in textile industries has raised significant environmental and human health concerns. Methylene blue (MB) dye, being widely used in industrial and medical applications, poses a risk to “ONE” health at elevated concentrations. Herein, we have developed an environmentally friendly and robust synthetic route for preparing bright blue carbon dots using yeast powder via a hydrothermal approach. The resulting C-dots were characterized by various analytical methods, wherein the fluorescence spectroscopy exhibited an excitation-dependent emission, with a prominent red shift between 360 and 460 nm. Subsequently, the C-dots were employed as a fluorescence-based sensing probe for rapid and selective detection of MB dye. Intriguingly, the particles exhibited a strong decrement in emission intensity with LOD and LOQ equivalent to 73.9 and 246.4 ppb, respectively. Finally, theoretical investigations revealed that the quenching mechanism was governed by π–π stacking and hydrogen bonding, which likely enhanced the sensitivity and specificity of C-dots toward MB.