Near-infrared double-illumination optical-resolution photoacoustic microscopy

Area of Science:

• Biomedical Optics
• Photoacoustic Imaging
• Molecular Spectroscopy

Background:

• Label-free chemical bond imaging is crucial in biology and medicine.
• Photoacoustic imaging in the near-infrared-III window (1600-1870 nm) offers stable molecular vibrational imaging for lipid-rich tissues.
• Limitations include the lack of high-energy pulsed lasers at 1.7 μm and strong water absorption, reducing signal-to-noise ratio for lipid imaging.

Purpose of the Study:

• To develop a method for improving the sensitivity of label-free lipid imaging.
• To overcome the limitations of current near-infrared-III photoacoustic imaging for thin lipid tissues.

Main Methods:

• Development of near-infrared-III double-illumination optical-resolution photoacoustic microscopy (DIOR-PAM).
• Utilizing Monte Carlo simulations to predict sensitivity enhancement.
• Experimental validation on nonbiological and biological lipid-rich samples.

Main Results:

• DIOR-PAM enhances sensitivity by nearly 100% compared to single-illumination using the same laser, as confirmed by simulations.
• Experimental results showed 50%-100% sensitivity enhancements in lipid imaging.
• The technique effectively visualizes lipid-rich samples with improved signal.

Conclusions:

• Near-infrared-III DIOR-PAM significantly improves sensitivity for label-free lipid imaging.
• This technique addresses the limitations of existing methods, enabling better visualization of lipid-rich tissues.
• DIOR-PAM holds promise for advancing biological and medical diagnostic applications.