Label-free multimodal coherent anti-Stokes Raman scattering analysis of microparticles in unconstrained microfluidics

Area of Science:

• Biomedical Optics
• Microfluidics
• Chemical Analysis

Background:

• Label-free optical methods are crucial for liquid biopsy and disease diagnostics.
• Microfluidic devices offer platforms for analyzing biological samples.
• Coherent Anti-Stokes Raman Scattering (CARS) and Linear Scattering (LS) are advanced optical techniques.

Purpose of the Study:

• To develop a method for fast, label-free detection of biomolecules in microfluidic systems.
• To overcome optical challenges in analyzing microparticles in fluid flow.
• To demonstrate the utility of multimodal CARS for liquid biopsy.

Main Methods:

• Utilized an optical microscope capable of simultaneous non-linear CARS and linear LS.
• Probed microparticles in aqueous solutions within microfluidic channels.
• Co-analyzed CARS and LS signals to identify in-focus microparticles.

Main Results:

• Demonstrated unambiguous detection of individual microparticles.
• Overcame challenges posed by out-of-focus particles and water CARS background.
• Showcased chemical discrimination of microscale features in realistic flow conditions.

Conclusions:

• Multimodal CARS platforms are relevant for liquid biopsy.
• Co-analysis of CARS and LS enhances microparticle detection in microfluidics.
• This technique supports advanced diagnostics through label-free optical identification.