Label-Free Detection and Spectrometrically Quantitative Analysis of the Cancer Biomarker CA125 Based on Lyotropic Chromonic Liquid Crystal.

Hassanein Shaban,Wei Lee,Mon-Juan Lee

doi:10.3390/bios11080271

Abstract

Compared with thermotropic liquid crystals (LCs), the biosensing potential of lyotropic chromonic liquid crystals (LCLCs), which are more biocompatible because of their hydrophilic nature, has scarcely been investigated. In this study, the nematic phase, a mesophase shared by both thermotropic LCs and LCLCs, of disodium cromoglycate (DSCG) was employed as the sensing mesogen in the LCLC-based biosensor. The biosensing platform was constructed so that the LCLC was homogeneously aligned by the planar anchoring strength of polyimide, but was disrupted in the presence of proteins such as bovine serum albumin (BSA) or the cancer biomarker CA125 captured by the anti-CA125 antibody, with the level of disturbance (and the optical signal thus produced) predominated by the amount of the analyte. The concentration- and wavelength-dependent optical response was analyzed by transmission spectrometry in the visible light spectrum with parallel or crossed polarizers. The concentration of CA125 can be quantified with spectrometrically derived parameters in a linear calibration curve. The limit of detection for both BSA and CA125 of the LCLC-based biosensor was superior or comparable to that of thermotropic LC-based biosensing techniques. Our results provide, to the best of our knowledge, the first evidence that LCLCs can be applied in spectrometrically quantitative biosensing.

Highlights

Most liquid crystal (LC)-based biosensing techniques reported to date employ thermotropic liquid crystals (LCs), especially the rod-like nematic 4-cyano-40 -pentylbiphenyl (5CB), as the predominant sensing medium [1,2,3,4]
At an optimized immobilization concentration of 10−9 g/mL anti-cancer antigen 125 (CA125) antibody, both the sensitivity and limit of detection (LOD) of the lyotropic chromonic liquid crystals (LCLCs)-based CA125 immunoassay were improved in comparison with those obtained at 10−10 g/mL anti-CA125 antibody, without compromising the signal-to-noise ratio
A quantitative label-free biosensor for bovine serum albumin (BSA) protein assay and CA125 immunoassay was developed based on the spectrometric analysis of LCLCs

Summary

Introduction

Most liquid crystal (LC)-based biosensing techniques reported to date employ thermotropic LCs, especially the rod-like nematic 4-cyano-40 -pentylbiphenyl (5CB), as the predominant sensing medium [1,2,3,4]. The biosensing application of lyotropic LCs is relatively scarce due possibly to the concentration-dependent polymorphic phase transitions and the lack of effective signal transduction approaches. Lyotropic chromonic liquid crystals (LCLCs) are a unique class of lyotropic LCs most frequently investigated in biosensing. When the drug disodium cromoglycate (DSCG) is dissolved in water, the nematic LCLC phase can be observed at room temperature (23 ◦ C) at concentrations ranging from 12 to 17 wt%, with the viscosity strongly dependent on the DSCG content [13]

Methods

Results

Conclusion