Since diseases result from alterations or abnormalities in typical biochemical processes, much emphasis has been placed on the measurement of biomolecules in patient samples. Such data may not only indicate a patient's health state, but may also hold the key to predicting the efficacy of different care options for an individual patient. However, simultaneous measurement of multiple biomarker proteins in patient samples often requires expensive and/or complicated instrumentation and time-consuming techniques. There is great need for multiplex assays that are rapid and inexpensive, exhibit a wide dynamic range in complex media (e.g. patient serum), and require minimal sample volume, little or no special technical expertise, and inexpensive, durable instrumentation. Our research group recently developed a multiplex sandwich-type immunoassay based on electrochemical detection on a nanostructured electrode array platform in a microfluidic channel. Target antigens are captured from the sample onto magnetic beads that are modified with a large number of enzyme label molecules and a specific antibody. The magnetic particles with bound antigen are introduced into the microfluidic channel, and subsequently captured onto the electrodes, which are modified with specific antibodies. The electrochemical signal generated by the enzyme label molecules on the particles is measured at each electrode through use of a multi-potentiostat, and the large number of enzyme labels present on the beads leads to excellent signal enhancement, typically resulting in detection limits in the low femtogram per milliliter range. The combination of the electrode array platform in the microfluidic channel with the massively labeled magnetic particles also results in minimal sample consumption (= 20 �L). Through use of this strategy, we have achieved simultaneous measurement of up to four biomarker proteins for cancer in patient serum with assay times as little as 8 minutes and good correlation to data obtained with traditional enzyme-linked immunosorbent assay (ELISA) methods.

Ultrasensitive electrochemical detection of cancer biomarker proteins through use of a microfluidic nanostructured electrode array with enzyme and antibody dual-labeled magnetic beads

246th National Meeting (2013)

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