Label-free biochemical quantitative phase imaging with mid-infrared photothermal effect

TL;DR

This paper introduces a unified, label-free imaging method combining quantitative phase imaging and molecular vibrational imaging using mid-infrared photothermal effect, enabling simultaneous morphological and biochemical analysis of single cells with low phototoxicity.

Contribution

It presents a novel integrated imaging scheme that captures both morphology and biochemistry of cells simultaneously in a label-free manner using mid-infrared photothermal effect.

Findings

Successful in-situ acquisition of MV-fingerprint contrasts in single cells

Demonstrates potential for studying fragile biological phenomena

Enables long-term observation with low phototoxicity

Abstract

Label-free optical imaging is valuable in biology and medicine with its non-destructive property and reduced optical and chemical damages. Quantitative phase (QPI) and molecular vibrational imaging (MVI) are the two most successful label-free methods, providing morphology and biochemistry, respectively, that have pioneered numerous applications along their independent technological maturity over the past few decades. However, the distinct label-free contrasts are inherently complementary and difficult to integrate due to the use of different light-matter interactions. Here, we present a unified imaging scheme that realizes simultaneous and in-situ acquisition of MV-fingerprint contrasts of single cells in the framework of QPI utilizing the mid-infrared photothermal effect. The fully label-free and robust integration of subcellular morphology and biochemistry would have important implications, especially for studying complex and fragile biological phenomena such as drug delivery, cellular diseases and stem cell development, where long-time observation of unperturbed cells are needed under low phototoxicity.