Photoacoustic molecular imaging with functional nanoparticles

Abstract

Photoacoustic imaging (PAI) breaks through the optical di®usion limit by making use of the PA e®ect. By converting incident photons into ultrasonic waves, PAI combines high contrast of optical imaging and high spatial resolution in depth tissue of ultrasound imaging in a single imaging modality. This imaging modality has now shown potential for molecular imaging, which enables visualization of biological processes with systemically introduced functional nanoparticles. In the current review, the potentials of di®erent optical nanoprobes as PAI contrast agents were elucidated and discussed.

Copolymerized carbon nitride nanoparticles for near-infrared II photoacoustic-guided synergistic photothermal/radiotherapy

“…Photoacoustic (PA) imaging-guided photothermal therapy (PTT), which combines diagnosis with treatment in a single system, has attracted worldwide attention in recent years (Li et al, 2015;Sun et al, 2017;Cao et al, 2019). Specifically, owing to the reasonable sensitivity, high resolution up to the micrometers scale and deep tissue penetration up to the centimeter scale, PA imaging has great potential for biomedical diagnosis in clinical application (Wang, 2009;Zhang et al, 2010a;Hui et al, 2016;Liu and Qin, 2017). PTT utilizes photosensitizers to produce hyperthermia without oxygen under near-infrared (NIR) light irradiation, leading to hypoxia tumor ablation, which has spatiotemporal controllability to realize precise treatment (Huang et al, 2006).…”

W-doped TiO2 nanoparticles with strong absorption in the NIR-II window for photoacoustic/CT dual-modal imaging and synergistic thermoradiotherapy of tumors

“…By detecting the ultrasound caused by laser pulses, PAI combines the advantages of traditional ultrasound and optical imaging and has deeper tissue penetration and enhanced spatial resolution 41, 42. Due to its excellent imaging capabilities, PAI has been applied in molecular, cellular, vascular and tumor imaging 43-46. Moreover, the specificity and penetration depth of PAI could be further improved through exogenous contrast agents, including small molecule dyes 47-49, inorganic NPs 35, 50-52, and organic NPs 53-55.…”

Recent progress in photoacoustic molecular imaging

“…We also overview the opportunities that may lead to future advances. Readers are referred to recent review articles to gain a more comprehensive knowledge of the principles of PAT [40, 41], the molecular contrast agents [34, 37, 42–44], and the biomedical applications [6, 16, 45–47]. …”