Highly sensitive and selective determination of nuclear matrix protein 22 based on an epitope imprinted electrochemical biosensor

Nuclear matrix protein 22 (NMP22) is a well-recognized biomarker for bladder cancer; however, conventional detection methods often suffer from insufficient sensitivity, high-cost and time-consuming. In this work, a novel epitope molecularly imprinted polymer (EMIP)-based electrochemical biosensor was constructed for highly selective and sensitive determination of NMP22. The EMIP biosensor was fabricated by electro-polymerization with C-terminal dodecapeptide (GATPRAKGKAKH, named as epitope) of NMP22 as template and o -phenylenediamine ( o -PD) as functional monomer on the gold electrode (AuE) which was previously self-assembled with thiolated graphene (G-SH) and gold nanoparticles (AuNPs). The use of G-SH and AuNPs can supply synergistic effects for enhancing detection sensitivity and epitope imprinting of C-terminal dodecapeptide of NMP22 can provide high selectivity for NMP22 detection. To obtain the superior sensitivity, several experimental parameters affecting the performance of the EMIP electrochemical sensor were investigated, including the molar ratio of template to functional monomer, electropolymerization cycle, elution time and incubation time. Under the optimal experiment, this EMIP electrochemical biosensor exhibited a good linear relationship for NMP22 in the concentration range from 0.1 pg mL −1 to 1.0 μg mL −1 , with a limit of detection (LOD) of 0.077 pg mL −1 . Finally, the EMIP electrochemical biosensor was successfully used for the determination of NMP22 in human urine with the recovery rates ranging from 96.92 % to 100.88 %. Compared with conventional ELISA, the proposed EMIP biosensor displayed shorter detection time, improved reproducibility and comparable analytical reliability. These findings highlight that the developed EMIP biosensor holds strong potentials for early bladder cancer diagnosis and broader clinical applications.