Chemical Design of Activatable Photoacoustic Probes for Precise Biomedical Applications

Abstract

Photoacoustic (PA) imaging technology, a three-dimensional hybrid imaging modality that integrates the advantage of optical and acoustic imaging, has great application prospects in molecular imaging due to its high imaging depth and resolution. To endow PA imaging with the ability for real-time molecular visualization and precise biomedical diagnosis, numerous activatable molecular PA probes which can specifically alter their PA intensities upon reacting with the targets or biological events of interest have been developed. This review highlights the recent developments of activatable PA probes for precise biomedical applications including molecular detection of the biotargets and imaging of the biological events. First, the generation mechanism of PA signals will be given, followed by a brief introduction to contrast agents used for PA probe design. Then we will particularly summarize the general design principles for the alteration of PA signals and activatable strategies for developing precise PA probes. Furthermore, we will give a detailed discussion of activatable PA probes in molecular detection and biomedical imaging applications in living systems. At last, the current challenges and outlooks of future PA probes will be discussed. We hope that this review will stimulate new ideas to explore the potentials of activatable PA probes for precise biomedical applications in the future.

Looking deep inside tissue with photoacoustic molecular probes: a review

“…The most common type is activable probes, 230 which only respond to specific biomarkers, such as low pH in tumor microenvironments. Activable PA probes have been used for in vivo imaging of a variety of biomarkers and biological metabolites and therefore imaging of aberrant tissues in recent years.…”

“…The selection processes and design considerations for targeted and activatable probes have been recently reviewed. 230 , 243 , 244 In this section, we will review some of the recent molecular PAI applications with PA probes.…”

Biomedical Photoacoustic Imaging for Molecular Detection and Disease Diagnosis: “Always‐On” and “Turn‐On” Probes

“…First, we evaluated the benefits and drawbacks of “always‐on” PA contrast agents. Then, we classified “turn‐on” PA contrast agents into “single‐wavelength detection” and “ratiometric detection” PA contrast agents, and the “ratiometric detection” PA contrast agents were categorized as “internal reference detection” or “seesaw detection.” [ 18 ] Finally, the current state and future prospects for PA contrast agents were presented to generate innovative ideas for the future of PA imaging in semiquantitative and quantitative methods for disease diagnosis and progression monitoring in vitro or in vivo.…”

Single-molecule photosensitizers for NIR-II fluorescence and photoacoustic imaging guided precise anticancer phototherapy

“…25,26 Meanwhile, photoacoustic imaging (PAI), as another photodiagnosis mode, is a non-invasive and non-ionizing biomedical 3D imaging method that combines the advantages of optical and ultrasound imaging without the influence of photo-scattering, centimeter-level penetration depth, and high spatiotemporal resolution. 27,28 Therefore, the development of sm-PS with SIT features in phototherapy guided by NIR-II FLI and PAI is of great significance, but there is no relevant report so far.…”