Micropipet Tip-Based Miniaturized Electrochemical Device Combined with Ultramicroelectrode and Its Application in Immobilization-Free Enzyme Biosensor

In this study, a simple miniaturized microliter electrochemical device was constructed using a disposable micropipet tip and a reproducible carbon fiber ultramicroelectrode. The novel electrochemical device set the electrochemical reaction in a micropipet tip containing an ultramicroelectrode. We investigated the feasibility of the designed electrochemical device by cyclic voltammetric measurements of redox probe. Its application in an immobilization-free enzyme electrochemical biosensor was also evaluated. Horse-radish peroxidase and glucose oxidase were selected to test sensor feasibility. Our results showed that the micropipet tip-based electrochemical device could detect low substrate or enzyme concentration or enzymatic reaction rate. The electrochemical device was applied to analyze the glucose content in human blood samples. With the advantages of low cost, easy operation, rapid detection and high reproducibility, this design provides a new approach in immobilization-free enzyme biosensor construction. Integrated with an ultramicroelectrode, our micropipet tip-based electrochemical device could replace most normal electrodes and electrochemical cells in common laboratories for electroanalysis.