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Journal of Biomedical Optics

Surface modification of alignment layer by ultraviolet irradiation to dramatically improve the detection limit of liquid-crystal-based immunoassay for the cancer biomarker CA125
Author(s): Hui-Wen Su; Mon-Juan Lee; Wei Lee
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Paper Abstract

Liquid crystal (LC)-based biosensing has attracted much attention in recent years. We focus on improving the detection limit of LC-based immunoassay techniques by surface modification of the surfactant alignment layer consisting of dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride (DMOAP). The cancer biomarker CA125 was detected with an array of anti-CA125 antibodies immobilized on the ultraviolet (UV)-modified DMOAP monolayer. Compared with a pristine counterpart, UV irradiation enhanced the binding affinity of the CA125 antibody and reproducibility of immunodetection in which a detection limit of 0.01  ng/ml for the cancer biomarker CA125 was achieved. Additionally, the optical texture observed under a crossed polarized microscope was correlated with the analyte concentration. In a proof-of-concept experiment using CA125-spiked human serum as the analyte, specific binding between the CA125 antigen and the anti-CA125 antibody resulted in a distinct and concentration-dependent optical response despite the high background caused by nonspecific binding of other biomolecules in the human serum. Results from this study indicate that UV modification of the alignment layer, as well as detection with LCs of large birefringence, contributes to the enhanced performance of the label-free LC-based immunodetection, which may be considered a promising alternative to conventional label-based methods.

Paper Details

Date Published: 22 May 2015
PDF: 9 pages
J. Biomed. Opt. 20(5) 057004 doi: 10.1117/1.JBO.20.5.057004
Published in: Journal of Biomedical Optics Volume 20, Issue 5
Show Author Affiliations
Hui-Wen Su, National Chiao Tung Univ. (Taiwan)
Mon-Juan Lee, Chang Jung Christian Univ. (Taiwan)
Wei Lee, National Chiao Tung Univ. (Taiwan)

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