10.1021/acsami.9b01615.s001 Huifang Shi Huifang Shi Liang Zou Liang Zou Kaiwei Huang Kaiwei Huang He Wang He Wang Chen Sun Chen Sun Shan Wang Shan Wang Huili Ma Huili Ma Yarong He Yarong He Jianpu Wang Jianpu Wang Haidong Yu Haidong Yu Wei Yao Wei Yao Zhongfu An Zhongfu An Qiang Zhao Qiang Zhao Wei Huang Wei Huang A Highly Efficient Red Metal-free Organic Phosphor for Time-Resolved Luminescence Imaging and Photodynamic Therapy American Chemical Society 2019 particle size design principle phosphor Efficient Red Metal-free Organic Phosphor photodynamic anticancer therapy Photodynamic Therapy background fluorescence interference application metal-free RTP materials Time-Resolved Luminescence Imaging metal-free PNDs 5 nm time-resolved luminescence imaging 2019-04-30 00:00:00 Journal contribution https://acs.figshare.com/articles/journal_contribution/A_Highly_Efficient_Red_Metal-free_Organic_Phosphor_for_Time-Resolved_Luminescence_Imaging_and_Photodynamic_Therapy/8091113 Developing highly efficient red metal-free organic phosphors for biological applications is a formidable challenge. Here, we report a novel molecular design principle to obtain red metal-free organic phosphors with long emission lifetime (504.6 μs) and high phosphorescence efficiency (14.6%) from the isolated molecules in the crystal. Furthermore, the well-dispersed phosphorescent nanodots (PNDs) with the particle size around 5 nm are prepared through polymer-encapsulation in an aqueous solution, which show good biocompatibility and low cytotoxicity. The metal-free PNDs are successfully applied to time-resolved luminescence imaging to eliminate background fluorescence interference both in vitro and vivo as well as effective photodynamic anticancer therapy for the first time. This work will not only pave a pathway to develop highly efficient metal-free RTP materials but also expand the scope of their applications to biomedical fields.