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An Electrochemical Immunoassay System for Measuring Circulating Protein Biomarkers of Pediatric Soft Tissue Sarcoma

The combination of simple, inexpensive 3D-printed flow cells with electrochemical biosensors has recently emerged a promising strategy for detecting molecular biomarkers of disease. In this study, we report a multiplex electrochemical immunoassay based on pencil graphite electrode arrays, 3D-printed flow cells and magnetic bead bioconjugates for simultaneous detection of three biomarker proteins (cancer antigen 125 (CA-125), midkine (MK) and osteopontin (OPN)) linked to pediatric soft tissue sarcoma (PSTS). Magnetic bead bioconjugates are functionalized with large amounts of antibody and enzyme labels according to a previously reported strategy,1 pencil graphite electrodes are modified with gold nanoparticles and antibodies for specific capture of bioconjugate-labeled biomarkers, and 3D-printed flow cells to facilitate amperometric detection. Using this immunoassay platform, detection limits for CA-125, MK and OPN that are 100 times lower than those obtained using commercial enzyme-linked immunosorbent assay (ELISA) can be achieved. The combination of low-cost pencil graphite electrode arrays with the convenience of multi-labeled magnetic bead bioconjugates and simplicity of 3D-printed flow-cells results in a promising electrochemical biosensing strategy for biomarker proteins CA-125, MK, and OPN in human serum samples.
 Reference
 (1) Malhotra, R.; Patel, V.; Chikkaveeraiah, B. v.; Munge, B. S.; Cheong, S. C.; Zain, R. B.; Abraham, M. T.; Dey, D. K.; Gutkind, J. S.; Rusling, J. F. Ultrasensitive Detection of Cancer Biomarkers in the Clinic by Use of a Nanostructured Microfluidic Array. Analytical Chemistry 
 2012, 84 (14), 6249–6255. https://doi.org/10.1021/ac301392g.