Visible light-mediated synthesis of metal-free molecularly imprinted polymers for highly selective creatinine detection.

Early and reliable monitoring of creatinine is essential for the timely diagnosis of chronic kidney disease; however, many existing electrochemical sensors are limited by enzyme instability, high fabrication cost, and concerns associated with metal-containing catalytic systems. Here, we report the fabrication of a hydroxypropyl cellulose (HPC)-based surface-imprinted macromolecular network through visible-light-mediated organocatalyzed atom transfer radical polymerization (O-ATRP) using a grafting-from strategy, yielding a fully metal-free molecularly imprinted polymer (MIP) for selective creatinine detection. Following template removal, the resulting poly(methacrylic acid)-based imprinted cavities generated a porous recognition layer capable of analyte-dependent modulation of interfacial charge transfer at the electrode surface. Electrochemical measurements demonstrated distinct responses of the MIP-modified electrode toward creatinine compared to the non-imprinted control, together with clear discrimination against structurally related interferents. Differential pulse voltammetry achieved sensitive creatinine detection with a limit of detection of 0.20 μg mL-1 within a physiologically relevant concentration range. In addition, impedance analysis revealed a concentration-dependent increase in charge-transfer resistance, supporting selective analyte binding within the imprinted cavities. These results demonstrate that visible-light-mediated O-ATRP can be employed to transform a cellulose-derived biological macromolecule into a functional surface-imprinted recognition platform, providing a promising metal-free strategy for selective electrochemical creatinine sensing.