Electrochemical ELISA-based Platform for Bladder Cancer Protein Biomarker Detection in Urine

A novel fluidic-based electrochemical ELISA platform is descried for estimation of the bladder cancer protein markers nuclear mitotic apparatus protein 1 (NUMA1) and complement factor H-related 1 (CFHR1). The platform uses an off-site chamber for a sandwich immunoassay and performs the electrochemistry on-chip in a separate chamber. The off-site matrices were connected to the sensor chip in a manner that the sensors were exposed only to the final electroactive product for signal detection, thus avoiding interference from other molecules present in the sample. Two off-site matrices using 3D polymethyl methacrylate (PMMA) sheets and 2D polycarbonate (PC) membranes modified with the desired antibodies were investigated. Antibodies for NUMA1 and CFHR1 were utilized for the immunoassay and hair comb structured gold electrodes were used for sensing. Results in 10% synthetic urine reveal that the system can detect NUMA1 and CFHR1 in the 1-100 ng/ml range with high sensitivities of 260 nA/(ng/ml) and 310 nA/(ng/ml), for NUMA1 and CFHR1, respectively; negligible interference from the diluted urine and other molecules has been observed. A fully automated fluidic prototype has also been developed to demonstrate that automation of the process and multiplexing of detection can be achieved in a small footprint benchtop device. The use of off-site matrix-based platforms paves the way towards a new generation of electrochemical immunosensors for biomarker estimation with negligible non-specific interactions and false signals in complex samples.