Polydopamine-Based Molecular Imprinting Polymer Electrochemical Sensor for Neopterin Detection

Neopterin, a low-molecular-weight pteridine, is a biomarker of pro-inflammatory immune activity. Its levels rise in viral infections, transplant rejection, autoimmune, cardiovascular, and neurodegenerative diseases, and cancer. In healthy human serum, neopterin concentration values are up to 10 nM. Detection is challenging due to its low concentration and limited solubility. In this work, a sensitive and selective electrochemical sensor for neopterin was developed using polydopamine molecularly imprinted polymers on a glassy carbon electrode. The polymer films were electro-polymerized directly on the electrode, varying the ratio of polymer to neopterin, while non-imprinted films were prepared without the template for comparison. Rebinding and template removal were monitored by cyclic voltammetry using ferricyanide as a redox probe. All imprinted films exhibited a concentration-dependent response from 1.2 nM to 1.2 mM, with a rapid increase at low concentrations up to 120 nM and a slower approach to a plateau at higher concentrations. The highest response was observed in films with the greatest neopterin content, consistent with increased binding site availability.