# Liquid Crystal-Based Optical Biosensor for Quantitative, Highly Sensitive Detection of Proteins

## TL;DR

This paper introduces a highly sensitive optical biosensor using liquid crystals to detect proteins and antibodies at extremely low concentrations.

## Contribution

The paper presents a novel experimental strategy achieving a detection limit of 10−13 g/mL for proteins using liquid crystal-based biosensing.

## Key findings

- The biosensor achieves a detection limit of 10−13 g/mL, significantly better than existing similar biosensors.
- Protein concentration shows a specific and well-defined dependence on cell birefringence, enabling rapid quantitative analysis.
- The method is also applicable for the detection of antibodies.

## Abstract

We report a highly sensitive label-free optical biosensor based on nematic liquid crystals, for the detection of proteins. The principles of biosensing are based on the change in the liquid crystal alignment induced by biomolecules adsorbed on the cell inner surface, which can be easily detected with a polarizing optical microscope. Although this approach is well-known, we propose here an experimental strategy that allows us to reach a detection limit of the order of 10−13 g/mL, orders of magnitude higher than the one reported in the literature for similar biosensors. Furthermore, our method leads to assessing a well-defined, specific dependence of protein concentration on cell birefringence, for rapid quantitative biosensing. The proposed biosensor can additionally be used for the detection of antibodies.