Programmable bio-nano-chip immunosensor for multiplexed detection of ovarian cancer biomarkers
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Ovarian cancer is a high mortality disease where early stage detection may have significant survival benefits. Promising next-generation non-invasive, biomarker-based screening modalities involve longitudinal monitoring of serum biomarkers and multi-marker panel detection. Here, rapid, sensitive, precise and multiplexable diagnostic platforms can facilitate biomarker validation along with early detection and screening, and this work attempts to exploit the programmable bio-nano-chip (p-BNC) immunosensor to address these specific translational needs in ovarian cancer. First, the p-BNC was adapted for Cancer Antigen 125 (CA125) quantitation, the current FDA standard, with prominent implications in novel early detection and screening modalities. Antibody pairs binding to distinct epitopes on CA125 were identified and the p-BNC operating variables (incubation times, flow rates and reagent concentrations) were attuned to deliver optimal analytical performance (inter- and intra-assay precision of 1.2% and 1.9% and Limit-of-Detection (LOD) 1.0 U/mL), competitive with current gold standards, but with a short analysis time of 43 minutes. Further validation of the system with advanced stage patient sera (n=20) demonstrated good correlation with 'gold standard' ELISA (R² = 0.97). Next, the p-BNC was adapted for concomitant analysis of CA125 and Human Epididymis Protein 4 (HE4), a novel multiplexed biomarker panel for early detection and screening. The HE4 immunoassay was developed to perform optimally with the 'rate determining' CA125 assay. Cross-reactivity analysis demonstrated high specificity multiplexing. The dose-response curves for the multiplexed CA125 and HE4 immunoassays were congruous with their singleplex counterparts with respective LODs of 0.51 U/mL and 4.18 pM and a total analysis time of 44 minutes. A small pilot scale clinical study was conducted to discriminate between surgically confirmed patient sera (n=8) and corresponding age-matched healthy controls (n=8) utilizing the multiplexed p-BNC, interpreted with a risk of ovarian malignancy algorithm. Successful discrimination was achieved between the groups with Receiver Operating Characteristic (ROC) curve AUC (Area Under the Curve) values of 1.00, 0.984 and 1.00 respectively for CA125, HE4 and the composite marker combination. Taken together, the analytical and clinical performance, multiplexing capabilities and the short turn-around times on the p-BNC offer methodological advancements over current gold standard techniques, indicating strong promise for ovarian cancer diagnostics.