Coordination-induced and tunable layered rare-earth hydroxide-complex intercalated nanohybrid phosphorescent photosensitizer and therapy

Abstract

Hydrotalcite intercalated nanohybrid has served as a vital phosphorescent photosensitizer owing to remarkable ¹O₂ quantum yield and high cell mortality performance. However, it is rather difficult for potential large or complex guest phosphors to directly intercalate into the hydrotalcite gallery. Hence, it is necessary to regulate the interlayer microenvironment of hydrotalcites firstly for outstanding photosensitive properties. Herein, two isomers, 5,5′BDA and 4,4′BDA, with distinctive dual coordinative features were selected to modify the layer microenvironment of the LGdH gallery and induce the introduction of prospective Gd(HPhN)₃ phosphorescent complexes into hydrotalcite through two different coordination effects successively. A LGdH-BDA-Gd(HPhN)₃ intercalated nanohybrid phosphorescent photosensitizer was successfully obtained. The results indicated that the more efficient improvement was observed from 5,5′BDA due to offering a more spacious and stable space. Specifically, LGdH-5,5′BDA-Gd(HPhN)₃ showed significantly better room temperature phosphorescence properties than LGdH-4,4′BDA-Gd(HPhN)₃, whose lifetime was nearly 15 times longer than the latter. Additionally, the LGdH-5,5′BDA-Gd(HPhN)₃ system displayed superior singlet oxygen generation in vitro under 460 nm irradiation (the quantum yield Φ = 0.48) and outstanding photodynamic therapy performance in tumor cells. LGdH presented more remarkable enhancement performance on the RTP properties of the luminescent molecules. This work provides a novel platform for designing a high-performance hydrotalcite intercalated nanohybrid phosphorescent photosensitizer through coordination induction to regulate the layer microenvironment.