Ternary Core-Shell NiCoMnPB-Based Microneedle Sensor for Continuous Detection of Creatinine

Continuous creatinine monitoring is essential for the precise diagnosis, treatment, and personalized management of chronic kidney disease (CKD). However, existing diagnostic strategies suffer from invasive procedures and fail to capture dynamic profiles. In addition, the limited long-term stability of conventional enzymatic sensing interfaces remains a major challenge for wearable applications. To address these issues, this study developed a hollow microneedle-based (MN) creatinine sensor for in situ detection of creatinine. The hollow MN was modified with a multilayered core-shell structured Prussian blue analogue (PBA) NiCoMnPB, followed by the fabrication of a creatinine-specific recognition layer using a molecular imprinting polymer (MIP). The ternary core-shell NiCoMnPB can be synthesized via a one-step method, combining the structural stability of NiPB, the high electrochemical activity of CoPB, and the high capacity of MnPB, thereby significantly enhancing the sensor's conductivity and electrochemical stability. The sensor enables real-time, continuous monitoring of creatinine in interstitial fluid (ISF), exhibiting high sensitivity, selectivity, reproducibility, and long-term stability. Animal experiments using a kidney injury model demonstrate that the dynamic changes of creatinine levels in ISF measured by the sensor were in high agreement with those obtained using commercial kits, effectively distinguishing creatinine levels under normal, injured, and recovery states, confirming its feasibility for in vivo application. This study provides an innovative solution for continuous monitoring of creatinine, offers a promising route for clinical translation for dynamic assessment of kidney damage, highlighting the sensor's potential for personalized CKD management.