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Open AccessArticle

Label-Free Multi-Microfluidic Immunoassays with Liquid Crystals on Polydimethylsiloxane Biosensing Chips

1
School of Biomedical Engineering, Taipei Medical University, 250 Wuxing St., Taipei 11031, Taiwan
2
International PhD Program for Biomedical Engineering, Taipei Medical University, 250 Wuxing St., Taipei 11031, Taiwan
3
Graduate Institute of Biomedical Optomechatronics, College of Biomedical Engineering, Taipei Medical University, 250 Wuxing St., Taipei 11031, Taiwan
4
Division of Infectious Diseases, Department of Internal Medicine, Wan Fang Hospital, Taipei Medical University, No.111, Sec. 3, Xinglong Rd., Wenshan Dist., Taipei 116, Taiwan
5
Department of Internal Medicine, School of Medicine, College of Medicine, Taipei Medical University, 250 Wuxing St., Taipei 11031, Taiwan
6
Department of Engineering Science, University of Oxford, Parks Road, Oxford OX1 3PJ, UK
*
Author to whom correspondence should be addressed.
These authors contributed equally to this work.
Polymers 2020, 12(2), 395; https://doi.org/10.3390/polym12020395
Received: 16 January 2020 / Revised: 29 January 2020 / Accepted: 30 January 2020 / Published: 10 February 2020
(This article belongs to the Special Issue Medical Application of Polymer-Based Composites)
We developed a new format for liquid crystal (LC)-based multi-microfluidic immunoassays, hosted on a polydimethylsiloxane substrate. In this design, the orientations of the LCs were strongly affected by the interface between the four microchannel walls and surrounding LCs. When the alignment layer was coated inside a microchannel, the LCs oriented homeotropically and appeared dark under crossed polarizers. After antigens bound to the immobilized antibodies on the alignment layer were coated onto the channel walls, the light intensity of the LC molecules changed from dark to bright because of disruption of the LCs. By employing pressure-driven flow, binding of the antigen/antibody could be detected by optical signals in a sequential order. The multi-microfluidic LC biosensor was tested by detecting bovine serum albumin (BSA) and an immunocomplex of BSA antigen/antibody pairs, a protein standard commonly used in labs. We show that this multi-microfluidic immunoassay was able to detect BSA and antigen/antibody BSA pairs with a naked-eye detection limitation of −0.01 µg/mL. Based on this new immunoassay design, a simple and robust device for LC-based label-free microfluidic immunodetection was demonstrated. View Full-Text
Keywords: polydimethylsiloxane; microfluidic; bovine serum albumin polydimethylsiloxane; microfluidic; bovine serum albumin
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MDPI and ACS Style

Fan, Y.-J.; Chen, F.-L.; Liou, J.-C.; Huang, Y.-W.; Chen, C.-H.; Hong, Z.-Y.; Lin, J.-D.; Hsiao, Y.-C. Label-Free Multi-Microfluidic Immunoassays with Liquid Crystals on Polydimethylsiloxane Biosensing Chips. Polymers 2020, 12, 395.

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