(11e) Ultra-Low Fouling Zwitterionic Carboxybetaine Antibody Microarrays for Cancer Diagnostics Directly From Human Blood

Cancer biomarkers play a vital role in early disease diagnostics, monitoring the therapeutic response, and improving patient stratification for treatment. The extreme complexity and heterogeneity of cancer both between patients and between cells within a patient has lead to a continued push for discovering more of these biological indicators. This has resulted in the use of high-throughput antibody-based biosensor platforms which can detect multiple disease biomarkers simultaneously in order to enhance the sensitivity and accuracy of diagnostic assays. However, the presence of non-specific protein adsorption on biosensors has been the major culprit preventing the highly sensitive detection of these target analytes (at or below nanogram/milliliter quantities) from the complex environment of human blood serum or plasma. In this work, antibody arrays were created using a simple yet robust zwitterionic poly(carboxybetaine acrylamide) (pCBAA) surface platform. The functionalization capabilities combined with the ultra-low protein fouling properties both before and after effective immobilization of biorecognition elements made pCBAA highly desirable. Using standard pin-spotting techniques on the pCBAA films, arrays containing antibodies to multiple cancer biomarkers were analyzed using a highly sensitive self-referencing surface plasmon resonance (SPR) imaging sensor with polarization contrast. Successful antibody immobilization and subsequent reduced biofouling properties of the functionalized surfaces resulted in a dynamic detection range with high sensitivity and reproducibility for the simultaneous detection of multiple cancer biomarkers directly from undiluted human blood plasma. The lack of cross reactivity and high selectivity enabled these coatings to be used with actual cancer patient samples illustrating the great potential of this new biosensing platform.