Biomass derived carbon quantum dots as a versatile platform for fluorescent sensing, catalytic reduction, fluorescent ink and anticancer agents

A simple and green hydrothermal approach was used to fabricate carbon quantum dots (CQDs) from the rhizomes of Acorus calamus with a quantum yield (QY) of 15 %. Designed CQDs were applied for four different applications, including the fluorescence detection of morin, the catalytic reduction of rhodamine B (Rh B) and sunset yellow (SY), fluorescent ink for writing and drawing, and anticancer and apoptosis studies on SKMEL-28 human skin cancer cell lines. Several characterization methods were performed to explore the optical, structural, and morphological properties. The average particle size of the CQDs was 6 nm, with a blue fluorescence emission when exposed to UV light under 360 nm. Based on the static and inner filter effects (IFE), the developed radiometric nanosensor showed high selectivity towards morin with a linear range of 0–2 μM and a detection limit of 96 nM. Using a NaBH₄-CQD mixture, the catalytic reduction of the ionic dyes Rh B and SY was achieved within seconds. A pseudo-first-order kinetics was followed by the reaction, with a rate constant of 0.0116 Min⁻¹. The cytotoxic studies revealed the anticancer ability of CQDs on SKMEL 28 cell lines with a low LD₅₀ value of 102 μg/mL. Besides the apoptosis studies using the double staining method show both viable and non-viable cells present in the medium. This study emphasizes the multiple practical uses of CQDs and demonstrates their versatility.