Imaging-Guided Drug Release from Glutathione-Responsive Supramolecular Porphysome Nanovesicles

Drug delivery systems that can be employed to load anticancer drugs and release them triggered by a specific stimulus, such as glutathione, are of great importance in cancer therapy. In this study, supramolecular porphysome nanovesicles that were self-assembled by amphiphilic porphyrin derivatives were successfully constructed, mainly driven by the π–π stacking, hydrogen bonding, and hydrophobic interactions, and were used as carriers of anticancer drugs. The nanovesicles are monodispersed in shape and uniform in size. The drug loading and in vitro drug release investigations indicate that these nanovesicles are able to encapsulate doxorubicin (DOX) to achieve DOX-loaded nanovesicles, and the nanovesicles could particularly release the loaded drug triggered by a high concentration of glutathione (GSH). More importantly, the drug release in cancer cells could be monitored by fluorescent recovery of the porphyrin derivative. Cytotoxicity experiments show that the DOX-loaded nanovesicles possess comparable therapeutic effect to cancer cells as free DOX. This study presents a new strategy in the fabrication of versatile anticancer drug nanocarriers with stimuli-responsive properties. Thus, the porphysome nanovesicles demonstrated here might offer an opportunity to bridge the gap between intelligent drug delivery systems and imaging-guided drug release

Regulating Phosphorescence Lifetime of Organic Cocrystals by Alkyl Engineering

Phosphorescent cocrystal is one of the emerging room-temperature phosphorescence (RTP) materials. However, it remains a great challenge to understand the relationship between the phosphorescent properties and molecular aggregation. Herein, we prepared a series of organic cocrystals with RTP features composed of different alkyl chain lengths. It is worth noting that the phosphorescent lifetime varied by the different lengths of alkyl chains. For melamine–succinic acid cocrystal, the phosphorescence lifetime can reach up to 512 ms. From the single-crystal analysis, the longer lifetime was mainly attributed to the shorter distance of molecular stacking between phosphorescent chromophores resulting in smaller free volume. This study not only provides a simple method to prepare RTP materials but also explores the relationship between phosphorescent properties and molecular stacking in organic phosphorescent cocrystals

Twisted Molecular Structure on Tuning Ultralong Organic Phosphorescence

Compared to planar carbazole, the molecular conjugation of iminodibenzyl (Id) was destroyed by a C–C bond and a twisted structure was formed, which exhibited blue-shifted ultralong phosphorescence with a lifetime of 402 ms in a crystal under ambient conditions. For the presence of an oscillating C–C bond between the two benzene rings in Id, more than one molecular configuration in the crystal was discovered by X-ray single-crystal analysis. Moreover, its ultralong phosphorescence color changed from blue to green by varying the excitation wavelength in solution at 77 K. Theoretical calculations also confirmed that different molecular configurations had certain impact on the phosphorescent photophysical properties. This result will allow a major step forward in expanding the scope of ultralong organic phosphorescent (UOP) materials, building a bridge to realize the relationship between molecular structure and UOP property

Enhancing Organic Phosphorescence by Manipulating Heavy-Atom Interaction

Achieving highly efficient phosphorescence in metal-free materials under ambient conditions remains a major challenge in organic optoelectronics. Herein, we report a concise approach to obtaining pure organic phosphorescence with high quantum efficiency of up to 21.9% and millisecond-scale lifetime by manipulating heavy-atom interaction based on a class of dibromobenzene derivatives in the solid state under ambient conditions. By comparing two pairs of the organic compounds designed, the one with two more bromine atoms on the alky terminals (PhBr₂C₆Br₂/PhBr₂C₈Br₂) showed higher luminescence efficiency than the other one (PhBr₂C₆/PhBr₂C₈). From the single-crystal analysis, it was proposed that the enhancement of phosphorescence resulted from increased intermolecular heavy-atom interaction in the organic crystals. Furthermore, a temperature sensor was demonstrated by using a model probe of this kind of organic phosphorescent crystals. This work not only provides a concise alternative to enhance phosphorescence in metal-free materials but also extends the scope of pure organic phosphorescent materials with high luminescent efficiency in a single component