Rapid Redox-Response Featured Visual Ascorbic Acid Sensor Based on Simple-Assembled Europium Metal-Organic Frameworks

Abstract

A facile, fast and visible sensing platform for ascorbic acid (AA) detection has been developed based on self-assembled hydrangea-like europium metal-organic frameworks (HL-EuMOFs). HL-EuMOFs was synthesized through a simple one-step mixing process with Eu3+ and 1, 10-phenanthroline-2, 9-dicarboxylic acid (PCA) at room temperature, which exhibited excellent properties including strong red fluorescence, long decay lifetime (548.623 μs) and good luminescent stability. Based on the specific redox reaction between Fe3+ and AA, HL-EuMOFs@Fe3+ sensor was fabricated with “turn-off” response for AA, where the resulting Fe2+ displayed effective fluorescence quenching ability toward HL-EuMOFs. The sensor demonstrated low detection limit (31.94 nM), rapid response time (30 s) and high selectivity. Integrating smartphone-assisted RGB analysis application with HL-EuMOFs@Fe3+ achieved visible and quantitative determination of AA level. This approach also showed good detection performances in complex human serum and beverage samples, which could provide a valuable tool for AA detection in biomedical research and food industry.

Keywords: Simple-assembled europium metal-organic frameworks, Redox response, Fluorescent sensor, Visual detection, Ascorbic acid