Label-free 3D molecular imaging of living tissues using Raman spectral projection tomography

Area of Science:

• Biomedical imaging
• Optical spectroscopy
• Biomolecular analysis

Background:

• Label-free molecular imaging is crucial for understanding tissue structure and function.
• Existing techniques often lack sufficient resolution or molecular specificity for mesoscale tissue analysis.

Purpose of the Study:

• To introduce and validate Raman spectral projection tomography (RSPT) for label-free 3D molecular imaging.
• To demonstrate RSPT's capability in visualizing molecular gradients and tissue heterogeneities.

Main Methods:

• Development of a novel RSPT imaging instrument for volumetric molecular contrast.
• Creation of a computational pipeline for multivariate reconstruction of Raman projection data.
• Application of RSPT to phantoms, tissue-engineered constructs, and native cartilage tissues.

Main Results:

• Successful 3D molecular imaging of complex phantoms with label-free contrast.
• Visualization of molecular gradients and extracellular matrix heterogeneities in biological tissues.
• Demonstration of a favorable balance between Raman spectroscopy's molecular specificity and imaging resolution.

Conclusions:

• RSPT provides a powerful tool for label-free volumetric molecular imaging at the optical sub-millimeter scale.
• The technique is suitable for analyzing both fixed and living tissues, including cartilage.
• RSPT opens new avenues for molecular monitoring in biological and biomedical applications.