过氧化氢酶-纤维素基气凝胶-PPIX Janus界面结构的构建及其酶促/光促协同作用机制

光敏剂、光源、氧气是光动力疗法(PDT)的三个重要因素，氧气的供应过于依赖环境中的氧浓度，限制了PDT在缺氧组织中的应用，过氧化氢酶(CAT)与光敏剂协同作用有望打破这一瓶颈。然而，既往研究发现光动力产生的单线态氧或光照可能导致CAT失活。本课题提出利用细菌纤维素/多壁碳纳米管(BC/MWCNT)复合气凝胶作为固定化基材，在其两侧界面分别负载原卟啉IX (PPIX)和CAT，得到CAT-(BC/MWCNT)-PPIX Janus界面功能材料，利用载体对光源以及单线态氧的阻隔效应来保证CAT的活性。本课题拟探讨光照及单线态氧对固定化CAT的基本酶学性质、不同氧分压下固定化PPIX的光动力疗效、不同酶促底物浓度对Janus界面材料光动力疗效的影响，阐明该材料的酶促/光促协同作用机制。本项目将进一步深化低氧条件下的光动力反应理论，为PDT在深度炎性伤口及乏氧肿瘤细胞的临床治疗提供实验依据。

Photosensitizer, light and oxygen are three important elements in photodynamic therapy (PDT). However, the supply of oxygen largely depends on the oxygen content in the air, hindering its application in hypoxia tissue. The synergic effect of catalase and photosensitizer can overcome this difficulty. Nevertheless, previous research reported that singlet oxygen produced by PDT and the light itself can denaturalize catalase. In this work, we propose that bacterial cellulose/multi-wall carbon nanotubes (BC/MWCNT) composite aerogel be used as the carrier to immobilize protoporphyrin IX (PPIX) and catalase (CAT) respectively on its opposite interfaces to obtain the CAT-(BC/MWCNT)-PPIX Janus interfaces functional material, within which the barrier effect of the light and singlet oxygen by BC/MWCNT matrix to guarantee the enzyme activity. This work will investigate the basic enzymatic properties of CAT-(BC/MWCNT) under the conditions with/without light exposure as well as the presence of singlet oxygen, the singlet oxygen yield and the anti-bacterial and anti-tumor effect by (BC/MWCNT)-PPIX under different oxygen concentration, and the anti-bacterial and anti-tumor effect of CAT-(BC/MWCNT)-PPIX with different concentration of H2O2. The synergistic mechanism between enzymatic/photocatalytic effect will be clarified. The project will enrich and deepen the theory of PDT under hypoxic conditions, and lay the experimental foundation for future clinical application in the area of PDT techniques in inflammatory wounds and hypoxia tumor cells treatment.