随着光声成像技术和纳米材料的发展,多功能纳米探针的设计和制备在光声成像领域受到了广泛的关注。基于此,主要总结了近年来纳米光声探针在生物医学成像中的应用。根据纳米探针固有的理化性质,将其分成两大类:一类是具有强光吸收性能的光声成像探针,主要包括金基纳米探针、碳基纳米探针、金属硫/硒/碳化物、黑磷、有机小分子吲哚菁绿(ICG)及黑色素等,这类纳米探针通过高通透性和滞留(EPR)效应富集到肿瘤部位,固有的强光吸收性能有利于光声成像指引的光热治疗;另外一类是肿瘤微环境触发的光声成像探针,这些探针本身没有近红外吸收性能,经微环境的酸性pH值、内源双氧水(H2O2)或过表达的谷胱甘肽(GSH)激活后,探针具有很强的近红外吸收性能,实现了肿瘤的光声成像介导光学治疗。将光声成像和光学治疗相结合以实时监测肿瘤治疗效果,有利于推进纳米探针的诊疗一体化。

With the development of photoacoustic (PA) imaging and nanomaterials, the design and preparation of multifunctional photoacoustic nanoprobes has attracted increasing attentions in the field of PA imaging. In this review, we mainly summarize the recent application of photoacoustic nanoprobes in biomedical imaging. According to the inherent physical and chemical properties, these photoacoustic nanoprobes are divided into two main categories. One is the nanoprobes for PA imaging with strong near-infrared (NIR) absorption, which includes gold-based nanoprobes, carbon-based nanoprobes, metal sulfide/ selenide/ carbide, black phosphorus, indocyanine green (ICG), melanin, and so on. Due to the enhanced permeation and retention (EPR) effect, these nanoprobes could be highly accumulated in tumor sites, and the inherent strong NIR absorption could be helpful to PA imaging-guided photothermal therapy (PTT). The other category is the tumor microenvironment (TME)-triggered nanoprobes for PA imaging. These nanoprobes themselves have not absorption, but after TME-triggering using acidic pH values, endogenous hydrogen peroxide (H₂O₂), or over-expressed glutathione (GSH), they would exhibit strong NIR absorption, and thus the PA imaging-guided phototherapy is achieved. In addition, the combination of PA imaging and phototherapy can monitor the therapeutic effects in real time and promote the application of nanoprobes in cancer theranostics.