Duke University, Department of Biomedical Engineering, Durham, North Carolina, United States.
Brigham and Women's Hospital, Harvard Medical School, Division of Engineering in Medicine, Department of Medicine, Cambridge, Massachusetts, United States.
J Biomed Opt. 2023 Aug;28(8):082804. doi: 10.1117/1.JBO.28.8.082804. Epub 2023 Feb 16.
Based on acoustic detection of optical absorption, photoacoustic tomography (PAT) allows functional and molecular imaging beyond the optical diffusion limit with high spatial resolution. However, multispectral functional and molecular PAT is often limited by decreased spectroscopic accuracy and reduced detection sensitivity in deep tissues, mainly due to wavelength-dependent optical attenuation and inaccurate acoustic inversion.
Previous work has demonstrated that reversible color-shifting can drastically improve the detection sensitivity of PAT by suppressing nonswitching background signals. We aim to develop a new color switching-based PAT method using reversibly switchable thermochromics (ReST).
We developed a family of ReST with excellent water dispersion, biostability, and temperature-controlled color changes by surface modification of commercial thermochromic microcapsules with the hydrophilic polysaccharide alginate.
The optical absorbance of the ReST was switched on and off repeatedly by modulating the surrounding temperature, allowing differential photoacoustic detection that effectively suppressed the nonswitching background signal and substantially improved image contrast and detection sensitivity. We demonstrate reversible thermal-switching imaging of ReST and using three PAT modes at different length scales.
ReST-enabled PAT is a promising technology for high-sensitivity deep tissue imaging of molecular activity in temperature-related biomedical applications, such as cancer thermotherapy.
基于对光吸收的声学检测，光声断层扫描（PAT）允许具有高空间分辨率的超越光扩散限制的功能和分子成像。然而，多光谱功能和分子 PAT 通常受到深度组织中光谱准确性降低和检测灵敏度降低的限制，主要是由于波长相关的光衰减和不准确的声学反演。
先前的工作已经证明，可逆颜色变化可以通过抑制非开关背景信号来极大地提高 PAT 的检测灵敏度。我们旨在开发一种新的基于颜色切换的 PAT 方法，使用可逆可切换的热致变色材料（ReST）。
我们通过用亲水性多糖海藻酸钠对商业热致变色微胶囊进行表面修饰，开发了一系列具有出色水分散性、生物稳定性和温度控制颜色变化的 ReST。
通过调节周围温度，ReST 的光吸收率可以反复开关，从而实现差分光声检测，有效地抑制了非开关背景信号，并大大提高了图像对比度和检测灵敏度。我们展示了 ReST 以及 使用三种不同长度尺度的 PAT 模式进行的可逆热切换成像。
ReST 启用的 PAT 是一种有前途的技术，可用于与温度相关的生物医学应用中的分子活性的高灵敏度深层组织成像，例如癌症热疗。
