Polylactic Acid (PLA)-Based Persistent Room-Temperature Phosphorescence Polymer Nanoparticles for Bioimaging
Kaimin Zhang, Danman Guo, Tianyi Tang, Xuankun Fang, Faxu Lin, Long Xiang, Fangfang Ke, Xiaoyu Ji, Nipeng Chen, Zhen Zhang, Huahua Huang, Zhenguo Chi, Zhiyong Yang
Abstract
Recent advancements have focused on developing nanoscale persistent room-temperature phosphorescence (pRTP) structures to expand their applicability in biomedical fields. Traditional fabrication methods typically produce surface-coated core–shell pRTP nanoparticles composed of nonbiocompatible pRTP emitters at very high concentrations in the core. To overcome this limitation, polymeric pRTP nanosystems have been presented in this study as a promising alternative by embedding RTP molecules within the biocompatible polymer matrix, thereby significantly reducing the required concentration of RTP molecules. These polymer nanoparticles were fabricated using a biocompatible poly(lactic acid) (PLA) matrix by an effective microemulsion-based method. They exhibited similar pRTP properties to the traditional nanoparticles, showing comparable long-lasting phosphorescence with a lifetime of 118 ms even when the phosphorescent molecule content is below 2%. Moreover, the pRTP polymer nanoparticles with excellent biocompatibility and stability demonstrate interesting reversible photoactivated pRTP properties. They have been successfully applied for in vivo imaging with a high signal-to-noise ratio (SBR) of 2061, maintaining strong and long-lived phosphorescent emissions even for 20 min. These results highlight a viable approach to advancing the pRTP technology for biological applications.