Microfluidic Methods for Molecular Biology by Chang Lu & Scott S. Verbridge

Author:Chang Lu & Scott S. Verbridge
Language: eng
Format: epub
Publisher: Springer International Publishing, Cham

8.4.3 Other Biomolecules

While proteins and DNAs are two major classes of important biomarkers in blood or serum , other small molecules such as metabolites, lipids, and hormones regulate physiological and behavioral activities in human body. Microfluidic devices in combination with microbeads can be applied to detect small molecules using enzyme-based or fluorescent readouts with sensitive detection ranges. For example, a microfluidic device integrated with glass beads with enzymes was developed for the detection of glucose in the range of 1–10 mM. The hydrogen peroxide generated from the enzyme reaction between glucose in the sample and glucose oxidase immobilized on the surface of microbeads could be quantified by Amplex Red with fluorescent readout [129].

For small molecule analysis, it is necessary to utilize signal amplification strategies in order to detect trace amount of target analyte . Zhang et al. developed an aptamer-mediated microfluidic bead-based sensor for simultaneous detection of adenosine and cocaine using multienzyme-linked nanoparticle amplification and quantum dot labels [130]. Microbeads functionalized with the aptamers and modified electron-rich proteins were arrayed within a microfluidic channel and were connected with the horseradish peroxidases (HRP) and capture DNA probe derivative gold nanoparticles (AuNPs) via hybridization. The conformational transition of aptamer induced by target–aptamer complex contributes to the displacement of functionalized AuNPs and decreases the fluorescence signal of microbeads. In this approach, increased binding events of HRP on each nanosphere and enhanced mass transport capability inherent from microfluidics are integrated for enhancing the detection sensitivity of analytes. The developed aptamer-based microfluidic bead array sensor could discriminate as low as 0.1 pM of adenosine and 0.5 pM cocaine, and showed a 500-fold increase in detection limit of adenosine compared to the off-chip assay.

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