The combination of photodynamic therapy (PDT) and enzyme therapy is a highly desirable approach in malignant tumor therapies as it takes advantage of the spatial-controlled PDT and the effective enzyme-catalyzed bioreactions. However, it is a challenge to co-encapsulate hydrophilic enzymes and hydrophobic photosensitizers, and these two agents often interfere with each other. In this work, a protocell-like nanoreactor (GOx-MSN@MnPc-LP) has been designed for synergistic starvation therapy and PDT. In this nanoreactor, the hydrophilic glucose oxidase (GOx) is loaded in the pore of mesoporous silica nanoparticles (MSNs), while the hydrophobic manganese phthaleincyanide (MnPc) is loaded in the membrane layer of liposome. This spatial separation of two payloads protects GOx and MnPc from the cellular environment and avoids interference with each other. GOx catalyzes the oxidation of glucose, which generates hydrogen peroxide and gluconic acid, leading to the starvation therapy via glucose consumption in cancer cells, as well as the disruption of cellular redox balance. MnPc produces cytotoxic singlet oxygen under 730 nm laser irradiation, achieving PDT. The antitumor effects of the nanoreactor have been verified on tumor cells and tumor-bearing mice models. GOx-MSN@MnPc-LP efficiently inhibits tumor growth in vivo with a single treatment, indicating the robust synergy of starvation therapy and PDT treatment. This work also offers a versatile strategy for delivering hydrophilic enzymes and hydrophobic photosensitizers using a protocell-like nanoreactor for effective cancer treatment.
Keywords: glucose oxidases; mesoporous silica nanoparticles; nanoreactors; photodynamic therapy; starvation therapy.