Wireless Bipolar Electrochromic Sensor Based on Metal–Organic Framework-Derived NiCo Bimetallic Carbon Nanocomposite for Visual Detection of Uric Acid

Abstract

Electrochromic sensors offer compelling advantages in health monitoring owing to their ability to convert electrochemical signals into visual outputs. However, achieving interference-free and highly sensitive detection of biomolecules remains challenging, mainly due to the challenges of integrating electrochromic materials with (enzymatic) catalysts while preserving anti-interference performance. In this work, a closed bipolar electrochromic (cBPEC) sensor for wireless and visual detection of uric acid (UA) is presented, utilizing a NiCo bimetallic embedded nitrogen-doped carbon (NiCo@NC) nanocomposite. In the cBPEC configuration, the polarized anode, modified with NiCo@NC, enables the electrocatalytic oxidation of UA. The generated electrons are then transferred to the physically separated polarized cathode, modified with a Prussian blue (PB) film, where PB reduction produces a color change quantitatively correlated with UA concentration. The cBPEC sensor exhibits excellent reproducibility, reusability, and selectivity, with a linear range for UA concentration ranging from 50 to 800 μM and a detection limit of 38 μM. The practical utility of the sensor is successfully validated by detecting UA in fetal bovine serum samples, yielding recoveries of 98.3–102.6% (relative standard deviations ≤3.37%), thus demonstrating its potential for biomedical applications in UA monitoring.