*Review* **Development Perspective of Bioelectrocatalysis-Based Biosensors**

#### **Taiki Adachi, Yuki Kitazumi, Osamu Shirai and Kenji Kano \*,**†

Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Sakyo, Kyoto 606-8502, Japan; adachi.taiki.62s@st.kyoto-u.ac.jp (T.A.); kitazumi.yuki.7u@kyoto-u.ac.jp (Y.K.); shirai.osamu.3x@kyoto-u.ac.jp (O.S.)


Received: 19 July 2020; Accepted: 25 August 2020; Published: 26 August 2020

**Abstract:** Bioelectrocatalysis provides the intrinsic catalytic functions of redox enzymes to nonspecific electrode reactions and is the most important and basic concept for electrochemical biosensors. This review starts by describing fundamental characteristics of bioelectrocatalytic reactions in mediated and direct electron transfer types from a theoretical viewpoint and summarizes amperometric biosensors based on multi-enzymatic cascades and for multianalyte detection. The review also introduces prospective aspects of two new concepts of biosensors: mass-transfer-controlled (pseudo)steady-state amperometry at microelectrodes with enhanced enzymatic activity without calibration curves and potentiometric coulometry at enzyme/mediator-immobilized biosensors for absolute determination.

**Keywords:** current–potential curve; multi-enzymatic cascades; multianalyte detection; mass-transfer-controlled amperometric response; potentiometric coulometry
