Jamun Seed-Derived Nitrogen-Doped Carbon Dots: A Novel Microwave-Assisted Synthesis for Ultra-Bright Fluorescence and Mn7+ Detection

Abstract

For the synthesis of heteroatom-doped carbon nanostructures, biomass is considered as a promising option. Utilizing the microwave-assisted method, we have demonstrated an easy and straightforward one-pot synthesis of nitrogen-doped luminous carbon dots (NCDs) from jamun seed powder and guanidine hydrochloride. Structural and morphological analyses were performed using various analytical techniques. Under ultraviolet light of 315 nm, NCDs emit a bright blue fluorescence, possess a high quantum yield of 26.90%, exhibit strong water dispersion, and demonstrated excellent stability. The average particle size of the NCDs was found to be 7.5±1.2 nm, with a spherical shape. NCDs exhibit high selectivity and sensitivity in fluorescence quenching when exposed to Mn⁷⁺ ions. Over a concentration range of 2-30 µM, the fluorescence response (F₀/F) shows a linear relationship with Mn⁷⁺ concentration, with a detection limit of 0.81 µM. The probe exhibited negligible interference and proved to be effective in accurately quantifying Mn⁷⁺ in spiked real-water samples.

Keywords: Guanidine hydrochloride; Jamun seed powder; Manganese (VII) detection; Microwave synthesis.