Vibration-enhanced disposable electroanalytical platform for selective analysis of tryptophan in fruits based on molecular imprinting

Although electrochemical detection based on molecular imprinting polymers (MIP) could dramatically improve the selectivity, the procedure is time-consuming because of the essential incubation step. In addition, current MIP electrochemical detections were not suitable for analysis of microliter-level sample solutions, limiting their applications for real samples. This investigation aims at applying vibration to enhance efficiency of MIP electrochemical detection of 20 μL sample solutions. MIP analysis of Tryptophan (Trp) was used as the model with disposable MIP electrodes prepared by electrochemical polymerization of o-phenylenediamine on carbon ink coated on stainless steel sheets. The MIP electrode was integrated in a 3D-printed analytical device for vibration-enhanced electrochemical detection of Trp. Our results showed that this vibration-enhanced strategy could significantly increase electrochemical responses of Trp at the same incubation time. Such improvement might be attributed to the enhanced mass transfer at the surface of the working electrode brought by vibration. It needs to be emphasized that this strategy is suitable for analysis of sample solutions with the volume of microliters, which is superior to normal stirring in MIP electrochemical detection. Our approach could be successfully utilized for differentiation of Trp in different fruits, opening more opportunities for MIP electrochemical detection of real samples. The enhanced efficiency by vibration could pave foundation for extensive practical MIP detection of sample solutions at the level of microliters.