Microwave assisted synthesis of blue fluorescent molybdenum nanoclusters with maltose-cysteine Schiff base for detection of myoglobin and γ-aminobutyric acid in biofluids.

The fabrication of stable fluorescent MoNCs in aqueous media is quite challenging as it is not much explored yet. Herein, we report a facile and efficient strategy for assembling MoNCs using 2,3 dialdehyde maltose-cysteine Schiff base (DAM-cysteine) as a ligand for detecting myoglobin and γ-aminobutyric acid (GABA) in biofluids with high selectivity and sensitivity. The DAM-cysteine-MoNCs displayed fluorescence of bright blue color under a UV light at 365 nm with peak of emission at 444 nm after exciting at 370 nm. The synthesized DAM-cysteine-MoNCs were homogeneously distributed with a mean size of 2.01 ± 0.98 nm as confirmed by the high-resolution transmission electron microscopy (HR-TEM). Further, X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FT-IR techniques are utilized to confirm the elemental oxidation states, and surface functional groups of the DAM-cysteine-MoNCs. After the addition of myoglobin and GABA the emission peak of DAM-cysteine-MoNCs at 444 nm was significantly quenched. This resulted in the development of a quantitative assay for the recognition of myoglobin (0.1 - 0.5 μM) and GABA (0.125-2.5 μM) with the lower limit of detection as 56.48 and 112.75 nM for myoglobin and GABA, respectively.