Rapid Characterization of Biomolecules’ Thermal Stability in a Segmented Flow-Through Optofluidic Microsystem

• Published in: Scientific reports Vol. 10; no. 1; p. 6925
• Main Authors: Fohlerova, Zdenka, Zhu, Hanliang, Hubalek, Jaromir, Ni, Sheng, Yobas, Levent, Podesva, Pavel, Otahal, Alexandr, Neuzil, Pavel
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 24.04.2020; Nature Publishing Group
• Subjects: 631/1647; 631/45; 639/925; Deoxyribonucleic acid; DNA; Fluorescein isothiocyanate; Fluorescence; Heat transfer; Humanities and Social Sciences; Lab-on-a-chip; Lasers; Light sources; Melting; Melting curve; Microfluidics; multidisciplinary; Optics; Physical properties; Protein folding; Proteins; Science; Science (multidisciplinary); Signal processing; Temperature gradients; Thermal stability
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-020-63620-5

Optofluidic devices combining optics and microfluidics have recently attracted attention for biomolecular analysis due to their high detection sensitivity. Here, we show a silicon chip with tubular microchannels buried inside the substrate featuring temperature gradient (∇ T ) along the microchannel. We set up an optical fluorescence system consisting of a power-modulated laser light source of 470 nm coupled to the microchannel serving as a light guide via optical fiber. Fluorescence was detected on the other side of the microchannel using a photomultiplier tube connected to an optical fiber via a fluorescein isothiocyanate filter. The PMT output was connected to a lock-in amplifier for signal processing. We performed a melting curve analysis of a short dsDNA – SYBR Green I complex with a known melting temperature ( T M ) in a flow-through configuration without gradient to verify the functionality of the proposed detection system. We then used the segmented flow configuration and measured the fluorescence amplitude of a droplet exposed to ∇ T of ≈ 2.31 °C mm −1 , determining the heat transfer time as ≈ 554 ms. The proposed platform can be used as a fast and cost-effective system for performing either MCA of dsDNAs or for measuring protein unfolding for drug-screening applications.