Rapid label-free electronic detection of biomarker using miniturized microfluidic system

The application of Lab-on-a-Chip or microfluidic technologies to perform protein assays is an emerging field and has a potential to be used for point-of-care device. In order to achieve this goal, the miniaturization of the biochip and high sensitivity is required. In this proposal, we addressed multiple novel solutions for biomarker detections in purified buffer, cancer cells and saliva sample using a micro sized biochip which includes sensor fabrication, sample preparation, theoretical consideration, impedance cytometry and data analysis. We started with detecting protein in purified buffer. We performed a sandwich immunoassay, where the complementary antibody pairs are immobilized on two different bead types, and the presence of target antigen results in bead aggregation, the amount of which depends on antigen quantity. When single beads or bead aggregates pass through the impedance sensor, differences in impedance change are detected. As for cancer cells, we focused on the rapid qualitative assessment of surface markers on cancer cells which can allow for point-of care prediction of patient response to various cancer drugs. Preclinical studies targeting cells with an antibody to “activated” matriptase conjugated to a potent toxin show promise as a selective treatment for a variety of solid tumors. We implemented a novel technique for electrical detection of proteins on surfaces of cancer cells using multi-frequency microfluidic impedance cytometry. The sensor is capable of differentiating between bare magnetic beads, cancer cells and bead-cell aggregates based on their various impedance and frequency responses. The use of saliva as a diagnostic fluid has always been appealing due to the ability for rapid and non-invasive sampling for monitoring health status and treatment progress. Saliva is rich in protein biomarkers and provides a wealth of information for diagnosis and prognosis of various disease conditions. Portable electronic tools that can monitor protein biomarkers rapidly can enable point-of-care diagnosis and monitoring of various health conditions. we have developed an electronic assay using impedance cytometry in conjunction with supervised machine learning, capable of quantifying immunoglobulins G and immunoglobulins A in saliva within two minutes.Ph.D.Includes bibliographical reference