# 3D correlative single-cell imaging utilizing fluorescence and refractive index tomography

## TL;DR

This paper introduces a novel 3D imaging technique combining fluorescence and refractive index tomography with optofluidic rotation, enabling detailed intracellular analysis without markers and revealing new cellular insights.

## Contribution

The study presents RAFTOR, a new method for 3D correlative imaging of cells that integrates RI and fluorescence tomography with optofluidic rotation, enhancing cellular biophysical understanding.

## Key findings

- Confirmed lower nuclear RI in HL60 cells
- Observed nuclear inversion in mouse photoreceptor cells
- Validated technique with cell phantoms

## Abstract

Cells alter the path of light, a fact that leads to well-known aberrations in single cell or tissue imaging. Optical diffraction tomography (ODT) measures the biophysical property that causes these aberrations, the refractive index (RI). ODT is complementary to fluorescence imaging and does not require any markers. The present study introduces RI and fluorescence tomography with optofluidic rotation (RAFTOR) of suspended cells, quantifying the intracellular RI distribution and colocalizing it with fluorescence in 3D. The technique is validated with cell phantoms and used to confirm a lower nuclear RI for HL60 cells. Furthermore, the nuclear inversion of adult mouse photoreceptor cells is observed in the RI distribution. The applications shown confirm predictions of previous studies and illustrate the potential of RAFTOR to improve our understanding of cells and tissues.