细菌生物被膜是大多数慢性和难治性感染的根源，对人类健康构成严重威胁。 生物被膜由细菌及其分泌的胞外多聚物（EPS）在组织或植入医疗器械表面聚集形 成，导致抗生素难以有效渗透并杀灭包埋细菌，进而诱导耐药性。因此，开发无 抗生素策略以治疗生物被膜相关感染是应对耐药性的重要途径。目前，活性氧 （ROS）生成策略，如光动力疗法（PDT）、化学动力学疗法（CDT）和声动力疗 法（SDT）等，已被用于治疗生物被膜相关感染。其中，PDT 和 CDT 联合应用产 生的 1 O2和·OH 等作为不同种类的高反应性 ROS，能够在生物大分子的不同靶部位 产生氧化损伤，兼具杀菌与 EPS 降解功能。然而，乏氧、有限 H2O2 和过度表达谷 胱甘肽（GSH）的生物被膜微环境，限制了基于 PDT/CDT 的 ROS 疗法的疗效。 为了解决生物被膜微环境对 PDT/CDT 联合疗法的限制问题，本研究将过氧化 钙（CaO2）和光敏剂黄连素（BBR）包载入含铁和锌的金属有机框架（MOF， FeZIF-8）中，构建了一种复合 ROS 纳米发生器（CBFZ）。CBFZ 能够在共递送 PDT 光敏剂和 CDT 催化剂的同时，将不利于产生 ROS 的细菌生物被膜微环境重塑 至具有丰富 O2、H2O2和低 GSH 浓度的状态，最终级联提高 PDT 和 CDT 联用的效 率。具体来讲，CBFZ 能够在低 pH 的生物被膜微环境中响应降解，并释放出 CaO2、 Fe3+、Fe2+和 BBR。其中 CaO2在水环境中分解成 O2和 H2O2以缓解乏氧，而 Fe3+能 够消耗生物被膜内的 GSH，实现对生物被膜微环境的重塑。随后，Fe²⁺催化高 H₂O₂水平下的芬顿反应，提升 CDT 效率；同时，O₂丰富环境增强了 BBR 介导的 PDT 效应。二者协同放大 ROS 生成，同时减少 GSH 介导的 ROS 清除，最终使生 物被膜中的 ROS 保持在较高水平，实现生物被膜高效清除。 研究结果表明，我们成功将 CaO2和 BBR 包载在 FeZIF-8 内，制备了直径约为 170 nm 的 ROS 纳米发生器 CBFZ。CBFZ 经光照后能够显著提升细菌生物被膜中的 ROS 水平，通过破坏 EPS 中的蛋白质和 DNA 组分降解生物被膜，同时杀死生物被 膜内的细菌，有效地清除生物被膜。体内研究结果表明，CBFZ 在小鼠皮下金黄色 葡萄球菌生物被膜感染模型中表现出了良好治疗效果，能够使生物被膜生物量降 低至 7%以下，并杀死超过 98%的细菌。总之，本论文利用双金属 MOF 材料通过 调控生物被膜微环境，高效增强 PDT/CDT 产生 ROS，为细菌生物被膜治疗提供了 一种新策略。

Bacterial biofilms are at the root of most chronic and intractable infections and pose a significant threat to human health. Biofilms are formed by the bacteria and their secreted extracellular polymeric substances (EPS) aggregating on the surface of tissues or implanted medical devices. This formation causes antibiotics to be unable to effectively penetrate and kill the embedded bacteria, thereby inducing drug resistance. Therefore, the development of antibiotic-free strategies to treat biofilm-associated infections is an important way to combat drug resistance. Currently, reactive oxygen species (ROS) therapies such as photodynamic therapy (PDT), chemodynamic therapy (CDT), and sonodynamic therapy (SDT) have been utilized for the treatment of biofilm-associated infections. Among them, the combined application of PDT and CDT generates 1 O2 and •OH as different types of highly reactive ROS, which can cause oxidative damage at different target sites of biomolecules, and achieving both sterilization and degradation of EPS. However, the microenvironment of biofilms with hypoxia, limited H2O2 and overexpressed glutathione (GSH) limits the efficacy of ROS-based therapies. To address the limitations of the biofilm microenvironment on the combined use of PDT/CDT, this study incorporated calcium peroxide (CaO₂) and the photosensitizer berberine (BBR) into an iron- and zinc-containing metal-organic framework (MOF, FeZIF-8) to construct a composite ROS nanogenerator (CBFZ). CBFZ can co-deliver PDT photosensitizers and CDT catalysts while remodeling the biofilm microenvironment of bacteria, which is not conducive to ROS production, to a state with abundant O2, H2O2 and low GSH concentrations, which ultimately cascades to enhance the efficiency of combined PDT and CDT. In detail, CBFZ can degrade in the acidic biofilm microenvironment and release CaO₂, Fe³⁺, Fe²⁺, and BBR. Among them, CaO2 decomposes into O2 and H2O2 in the aqueous environment to relieve hypoxia, and Fe3+ consumes glutathione (GSH) in the biofilm to remodel the biofilm microenvironment. Subsequently, Fe2+ catalyzed the Fenton reaction at high H2O2 levels to enhance the CDT efficiency. At the same time, the O2 enriched environment enhanced the BBR-mediated PDT effect. The two collaboratively amplified ROS generation while reducing GSH-mediated ROS scavenging, which ultimately maintained a high level of ROS in biofilm and achieved efficient biofilm clearance. The study demonstrated that we successfully incorporated CaO₂ and BBR into FeZIF-8 to create the composite ROS nanogenerator CBFZ with a diameter of about 170 nm. CBFZ significantly enhanced the ROS levels in bacterial biofilms with light exposure, degraded biofilms by disrupting the protein and DNA components in the EPS, and killed bacteria within biofilms, effectively eliminating biofilms. In vivo studies showed that CBFZ exhibited excellent therapeutic effects in a murine model with subcutaneous Staphylococcus aureus biofilm infection, reducing biofilm biomass to below 7% and killing over 98% of bacteria. In conclusion, this study provides a new strategy for bacterial biofilm treatment by using bimetallic MOF materials to efficiently enhance ROS production from PDT/CDT through regulating the biofilm microenvironment.