Specific “light-up” sensor made easy: An aggregation induced emission monomer for molecular imprinting

Development of a specific "light-up" sensor for detection of psychoactive drug has been a great challenge in forensic analysis. To achieve this goal, an aggregation induced emission (AIE) functional monomer containing both phenylboronic group and double bond was synthesized for construction of molecularly imprinted polymers (MIPs) based fluorescent sensor. In this AIE-MIP sensor, the AIE fluorophore could vibrate freely in the absence of the target analyte (cathinone, CAT), while this vibration was restricted after the specific molecular recognition, leading to "light-up" character of the corresponding sensor. FT-IR and LC-MS characterizations proved the AIE monomer was successfully introduced onto AIE-MIPs. SEM analysis indicated the AIE-MIPs was ∼140 nm in diameter. Binding experiments indicated the AIE-MIPs owned high specificity towards CAT. Fluorescent studies confirmed that the "light-up" capability of the AIE-MIPs was highly selective. On this basis, the AIE-MIP sensor was applied in detecting CAT in forensic samples. The sensor reached a detection limit of 0.32 μmol L-1 and exhibited a linear range of 2-12 μmol L-1. Compared to previously reported MIPs based electrochemical sensors and fluorescent sensors for measurement of CAT drug and its analogue, the present AIE-MIP sensor showed much higher sensitivity. To the best of our knowledge, this is the first time that an AIE functional monomer was synthesized for molecular imprinting, and also the first "light-up" AIE-MIP sensor to be reported. We believe that this versatile design of the specific "light-up" sensor can be used as a general protocol for construction of advanced sensor in various fields.