Label-free self-referenced sensing of living cells by terahertz metamaterial-based reflection spectroscopy.

Xiang Zhao,Weiling Fu,Zhongquan Lin,Jia Peng,Yunxia Wang,Liqun Zhang,Xiang Yang,Ke Yang,Marc Lamy De La Chapelle,Yang Zhang

doi:10.1364/boe.10.001196

Abstract

Terahertz (THz) metamaterial-based reflection spectroscopy is proposed for label-free sensing of living cells by a self-referenced method. When sensing the living Madin-Darby canine kidney cell monolayer and phosphate buffered saline solution, self-referenced signals showed significant differences in peak intensity because of inherent discrepancy in the imaginary part of their complex refractive indices, as confirmed by 3D-FDTD simulations. The resonance peak intensity was unaffected by cell monolayer thickness variation, demonstrating feasibility for sensing various cells. Simulations and experiments showed that saponin-induced changes in cell permeability could be monitored in real-time. The self-referenced signal was linearly dependent on the adherent cell density, illustrating a label-free in situ THz metamaterial-based cell sensor.

Highlights

Cells, the fundamental unit of life, determine the structure and function of all living organisms
We introduced the application of THz metamaterial-based reflection spectroscopy to extract the response of adherent living Madin–Darby canine kidney (MDCK) cells in phosphate buffered saline (PBS) solution
THz metamaterial-based reflection spectroscopy was used for living cell sensing in a self-referenced method

Summary

Introduction

The fundamental unit of life, determine the structure and function of all living organisms. To comprehensively understand the proliferation, differentiation, interaction, and apoptosis of cells will further boost the development of research in bioscience and biomedicine. The biophysical properties of cells, including their mechanical [1], electrical [2] and optical properties [3], could provide a comprehensive perspective about how they function. A widely used non-invasive method, utilizes the passing of light through cells and measures the absorption, reflection, and scattering coefficient, which helps obtain information about intracellular biomolecules [3]. THz spectroscopy could be a unique method to characterize the intracellular hydration dynamics, which is closely related to cell biology and pathology processes [7,8]. The energy of THz photons (i.e., ≈1–10 meV) is far below that of X-rays and cannot cause any ionization damage to organisms

Methods

Results

Conclusion