Photodynamic therapy (PDT) is a minimally invasive treatment strategy that uses photosensitizers and light in combination with oxygen to generate cytotoxic singlet oxygen (¹O₂) to kill cancer cells by necrosis or apoptosis. However, the treatment effects are still not satisfactory because of the tumor hypoxia and the PDT-induced oxygen consumption. Here, we have successfully synthesized dendritic mesoporous organosilica nanoparticles (MONs) with large center-radial pore structure that can be used to simultaneously encapsulate indocyanine green (ICG, <1 nm) and macromolecule catalase (CAT, 2.0 nm × 6.0 nm × 9.0 nm) to overcome the tumor hypoxia. Upon 808 nm laser irradiation, ICG as the organic NIR dye can generate highly cytotoxic singlet oxygen (¹O₂) and other reactive oxygen species (ROS) to kill cancer cells and realize photoacoustic (PA) imaging. The catalase can decompose the endogenous H₂O₂ in malignant cancerous cells into O₂ bubble to simultaneously intensify the ultrasound (US) imaging signal and enhance PDT efficacy. These results indicate that the ICG-CAT@MONs holds great promise in multimodal photoacoustic / ultrasound image-guided tumor PDT therapy.

光动力疗法（PDT）是一种微创治疗策略，该技术使用光敏剂和光与氧气结合产生细胞毒性单线态氧（¹ O ₂），以通过坏死或凋亡杀死癌细胞。然而，由于肿瘤缺氧和PDT诱导的氧消耗，治疗效果仍然不能令人满意。在这里，我们成功地合成了具有大的中心径向孔结构的树枝状介孔有机硅纳米粒子（MONs），可用于同时封装吲哚菁绿（ICG，<1 nm）和大分子过氧化氢酶（CAT，2.0 nm×6.0 nm×9.0 nm） ）克服肿瘤的缺氧。在808 nm激光照射下，ICG作为有机NIR染料可产生高度细胞毒性的单线态氧（¹ O₂）和其他活性氧（ROS）杀死癌细胞并实现光声（PA）成像。过氧化氢酶可以将恶性癌细胞中的内源性H ₂ O ₂分解为O ₂气泡，从而同时增强超声（US）成像信号并增强PDT功效。这些结果表明，ICG-CAT @ MONs在多峰光声/超声图像引导的肿瘤PDT治疗中具有广阔的前景。