Raman and quantitative-phase microscope with counter-propagating beams demonstrated on HeLa cells

Alejandro Diaz Tormo,Dmitry Khalenkow,Nicolas Le Thomas,Andre G Skirtach

doi:10.1364/osac.2.000797

Abstract

Raman spectroscopy probes the chemical composition of biological samples with sub-micron resolution, rendering it a powerful tool in the diagnosis of several diseases and the study unstained biological samples. However, the weak Raman signal leads to long acquisition times, unsuited to study dynamical processes or large samples. Quantitative phase microscopy can speed up the diagnosis, provide complementary data, and potentially link the Raman fingerprint of the sample with corresponding refractive indices. Here we demonstrate a 4$\pi$π microscope that records both the Raman and quantitative phase information from the same sample spot.

Highlights

Illnesses can present themselves in many different forms
To monitor morphology and biophysical parameters, Quantitative Phase Microscopy (QPM) can be employed. It has been used in the diagnosis of cancer [5] and in cell pathology studies [7,8,9,10]. These two techniques, Raman and QPM, have been used before to complement other microscopy techniques, for instance, Raman spectroscopy has been combined with fluorescence microscopy [11] and optical coherence tomography [12]
In this paper we propose a microscope with two complementary modalities —Raman and Quantitative Phase Microscopy— to study cell processes from two different points of view

Summary

Introduction

Illnesses can present themselves in many different forms. Changes in the morphology, chemical composition and biophysical parameters, such as matter density and cell dry mass, provide different windows through which the illnesses can be understood and diagnosed [1,2,3,4,5]. To monitor morphology and biophysical parameters, Quantitative Phase Microscopy (QPM) can be employed It has been used in the diagnosis of cancer [5] and in cell pathology studies [7,8,9,10]. These two techniques, Raman and QPM, have been used before to complement other microscopy techniques, for instance, Raman spectroscopy has been combined with fluorescence microscopy [11] and optical coherence tomography [12]. This microscope allows correlating the Raman and quantitative phase information [16] from the same spot of a HeLa cell, which has the potential to become a new tool in the diagnosis of disease

Experimental setup and methods

HeLa cell experiment

Conclusion