title: Overcoming the Achilles' heel of photodynamic therapy.
abstract: Photodynamic therapy (PDT) has been applied to treat a wide range of medical conditions, including wet age-related macular degeneration psoriasis, atherosclerosis, viral infection and malignant cancers. However, the tissue penetration limitation of excitation light hinders the widespread clinical use of PDT. To overcome this "Achilles' heel", deep PDT, a novel type of phototherapy, has been developed for the efficient treatment of deep-seated diseases. Based on the different excitation sources, including near-infrared (NIR) light, X-ray radiation, and internal self-luminescence, a series of deep PDT techniques have been explored to demonstrate the advantages of deep cancer therapy over conventional PDT excited by ultraviolet-visible (UV-Vis) light. In particular, the featured applications of deep PDT, such as organelle-targeted deep PDT, hypoxic deep PDT and deep PDT-involved multimodal synergistic therapy are discussed. Finally, the future development and potential challenges of deep PDT are also elucidated for clinical translation. It is highly expected that deep PDT will be developed as a versatile, depth/oxygen-independent and minimally invasive strategy for treating a variety of malignant tumours at deep locations.
authors.affiliation: Guangdong Key Laboratory for Biomedical Measurements and Ultrasound Imaging, Department of Biomedical Engineering, School of Medicine, Shenzhen University, Shenzhen 518060, China. peng.huang@szu.edu.cn and Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China and Laboratory of Molecular Imaging and Nanomedicine, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, MD 20892, USA. shawn.chen@nih.gov.
authors.forename: Wenpei
authors.initials: W
authors.lastname: Fan
authors.affiliation: Guangdong Key Laboratory for Biomedical Measurements and Ultrasound Imaging, Department of Biomedical Engineering, School of Medicine, Shenzhen University, Shenzhen 518060, China. peng.huang@szu.edu.cn.
authors.forename: Peng
authors.initials: P
authors.lastname: Huang
authors.affiliation: Laboratory of Molecular Imaging and Nanomedicine, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, MD 20892, USA. shawn.chen@nih.gov.
authors.forename: Xiaoyuan
authors.identifier: 0000-0002-9622-0870
authors.initials: X
authors.lastname: Chen
mesh_terms: D000818:Animals; D006801:Humans; D000860:Hypoxia / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D008027:Light; D049449:Luminescence; D009369:Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D010100:Oxygen / Q000378:metabolism; D010778:Photochemotherapy / Q000379:methods*; D017319:Photosensitizing Agents / Q000737:chemistry / Q000627:therapeutic use*; D014466:Ultraviolet Rays; D014965:X-Rays
chemical_list: D017319:Photosensitizing Agents; D010100:Oxygen