Circular intensity differential scattering (CIDS) scanning microscopy to image chromatin-DNA nuclear organization

Alberto Diaspro,Giulia Zanini,Luca Pesce,Michele Oneto,Aymeric Le Gratiet,Riccardo Marongiu,Paolo Bianchini

doi:10.1364/osac.1.001068

Alberto Diaspro, Giulia Zanini + Show 5 more

Open Access

https://doi.org/10.1364/osac.1.001068

Copy DOI

Journal: OSA Continuum	Publication Date: Nov 13, 2018
Citations: 24	License type: cc-by

Affiliation: Italian Institute of Technology

Abstract

Circular dichroism imaging has proved a powerful and simple method for extracting information on chiral molecules without specific fluorescent labels. Numerous mathematical models show that outside the absorption band, the circular dichroism signal comes from the scattering interaction and brings additional information about the organization of biopolymers. With this article, we propose a fast method to control the polarization states without moving parts, by means of a photoelastic modulator. We implemented the technique on a modified commercial confocal microscope realizing a multimodal configuration. We demonstrate its imaging capabilities by studying the organization of chromatin DNA inside isolated cell nuclei.

Highlights

Optical scanning microscopy techniques based on the polarization control of the light are powerful label-free methods capable of extracting supplementary information from a medium, which has shown numerous applications for biomedical studies such as early cancer diagnosis [1,2] and ophthalmology [3,4]
If this device is coupled with a demodulation detection scheme using a Lock-in Amplifier (LA) at the reference frequency of the photo-elastic modulator (PEM), it is possible to analyze the difference of intensities between the right and left circular polarization states in few microseconds
We expect to see a strong contrast in the Circular Intensity Differential Scattering (CIDS) signal inside the nucleus induced by the presence of chromatin DNA

Summary

Introduction

Optical scanning microscopy techniques based on the polarization control of the light are powerful label-free methods capable of extracting supplementary information from a medium, which has shown numerous applications for biomedical studies such as early cancer diagnosis [1,2] and ophthalmology [3,4]. Among these techniques, it was shown that Circular Dichroism (CD) microscopy gives access to the structural organization and concentration of chiral molecules in a sample [5,6]. Most of the recent works reporting CIDS scanning or wide-field microscopy are mainly focused on the study of the molecular organization of thin layers [23,24] or metamaterials [25]

Methods

Results

Conclusion