A high-performance wearable microneedle sensor based on CNT/CCNT@Cu-ZIF-67 composites for simultaneous detection of uric acid and dopamine

With hyperuricemia and gout affecting approximately 930 million people worldwide and Parkinson's disease impacting around 2 % of individuals over 65, the ability to monitor uric acid (UA) and dopamine (DA) levels daily is essential for disease management. Sensing biomarkers in human subcutaneous interstitial fluid (SISF) has emerged as a promising method. However, current electrochemical sensors for UA and DA face challenges in simultaneously achieving the required linear range and high sensitivity, and research on their simultaneous detection in SISF remains limited. Here, an electrochemical microneedle sensor based on multiwalled carbon nanotubes/carboxylated carbon nanotubes@copper-doped Zeolitic Imidazolate Frameworks-67 (CNT/CCNT@Cu-ZIF-67) composites for simultaneous DA and UA detection was developed. Cu-doped ZIF-67 was in-situ grown on CCNT, then mixed with CNT to fabricate CNT/CCNT@Cu-ZIF-67. The large specific surface area, dual microporous-mesoporous structure, and the synergistic effects of carboxyl groups and Cu-Co bimetallic catalytic centers of CNT/CCNT@Cu-ZIF-67 significantly enhance sensing performance. The sensor achieves a wide linear range for UA (1 μM − 800 μM) with high sensitivity (9.87 μA μM⁻¹ cm⁻²), and a wide linear range for DA (0.5 μM − 300 μM) with high sensitivity (19.2 μA μM⁻¹ cm⁻²) demonstrating leading performance in current UA and DA detection. The sensor achieves simultaneous detection of DA and UA in artificial ISF and remaining unaffected by ascorbic acid. Theoretical calculations revealed that Cu doping in ZIF-67 enhances both the adsorption energies and charge transfer for UA/DA. Finally, the sensor successfully detects UA levels in hyperuricemia patients, demonstrating its potential for practical applications.