Ultrasonic-assisted molecular probe for turn-on electrochemical and fluorescence dual-mode detection of GSH in human serum.

A molecular probe, 3-oxo-3H-phenoxazin-7-yl thiophene-2-carboxylate (RD), was synthesized using resorufin (Re) as the substrate for the specific recognition of glutathione (GSH). Ultrasonic waves were employed to enhance the reaction efficiency between the molecular probe and GSH. The molecular probe was designed to exhibit specific recognition ability for GSH. In the absence of GSH, the probe's fluorescence is quenched; in the presence of GSH, a specific reaction restores the fluorescence intensity, achieving "turn-on" fluorescence detection. The detection limit for GSH was 5.52 μM, with a linear range of 5 μM to 1.2 mM. Additionally, an electrochemical detection method was integrated. The interaction between GSH and the modified electrode surface induces a change in the electrochemical signal, which can be used for the quantitative determination  of GSH. The detection limit for GSH using this method was 8 μM, with a linear range of 10 μM to 1.2 mM. By combining these two detection modes, the reliability and accuracy of glutathione detection were significantly improved. Furthermore, the practical application of this method in human serum samples demonstrated its good selectivity and anti-interference ability, providing a reliable dual-mode analysis platform for clinical GSH detection.