Multiscale photoacoustic tomography using reversibly switchable thermochromics.

Area of Science:

• Biomedical Optics
• Medical Imaging
• Materials Science

Background:

• Photoacoustic tomography (PAT) enables deep tissue imaging but faces challenges in sensitivity and spectroscopic accuracy.
• Wavelength-dependent optical attenuation and acoustic inversion errors limit multispectral PAT in deep tissues.

Purpose of the Study:

• To develop a novel color-switching based PAT method utilizing reversibly switchable thermochromics (ReST).
• To enhance detection sensitivity and image contrast in deep tissue PAT.

Main Methods:

• Developed ReST by surface modifying commercial thermochromic microcapsules with alginate for improved water dispersion and biostability.
• Utilized temperature-controlled color changes of ReST for differential photoacoustic detection, switching optical absorbance on and off.

Main Results:

• Demonstrated effective suppression of nonswitching background signals through differential photoacoustic detection.
• Achieved substantial improvements in image contrast and detection sensitivity using ReST.
• Showcased reversible thermal-switching imaging of ReST in vitro and in vivo across multiple PAT modes and length scales.

Conclusions:

• ReST-enabled PAT offers a promising approach for high-sensitivity molecular imaging in deep tissues.
• This technology is particularly relevant for temperature-related biomedical applications, including cancer thermotherapy monitoring.