Glucose-responsive insulin microneedle patches for long-acting delivery and release visualization.

Limited drug loading and incomplete drug release are two major obstacles that traditional polymeric microneedles (MNs) have to overcome. For smart controlled-release MNs, since drug release duration is uncertain, a clear indication of the finish of drug release is also important for patient guidance on the timing of the next dose. In this study, MN with a triple structure of a glucose-responsive shell, loaded insulin powders and a colored propelling inner core (inspired by the mechanism of osmotic pump) was innovatively constructed. The MN patch could release insulin according to blood glucose levels (BGLs) and had excellent drug loading, more complete drug release, and good drug stability, which significantly prolonged the normoglycemic time. An approximately 0.3 cm2 patch has a hypoglycemic effect on diabetic mice for up to 24 h. Moreover, the fading of the inner core could indicate the release process of the loaded drug and can help to facilitate uninterrupted closed loop therapy for patients. The designed triple MN structure is also suitable, and can be used in the design of other smart MN drug delivery systems to further improve their drug loading capacity and simultaneously achieve more complete, smart controlled and visualized drug release.

A universal powder-laden crosslinked chitosan microneedle patch for high-dose controllable drug delivery.

In this study, we constructed a novel powder-laden core-shell crosslinked chitosan microneedle patch for high-dose and controllable delivery of various drugs, including both macromolecular biological drugs and small-molecule chemical drugs. Direct loading of drug powders greatly improved drug loading capacity and minimized degradation. The results of the in vitro drug release study suggested that the release behaviors of the most tested drugs (both macromolecular drugs and small-molecule drugs) can be tuned by adjusting the crosslink density of the microneedle shell to achieve either rapid or sustained release of the loaded drug. The in vivo hypoglycemic efficacy test in streptozotocin-induced diabetic mice further proved that the onset and duration of the insulin-laden patch can be customized by adjusting the crosslink density. Furthermore, a combination of microneedle patches with different crosslink densities not only rapidly reduced blood glucose levels to normoglycemic levels (within 1 h) but also maintained normoglycemia for up to 36 h. The insulin loaded in the patch also showed good stability during storage at 40 °C for 6 months. Our results suggest that this powder-laden patch represents a strong candidate for addressing the multiple challenges in the preparation and application of polymeric microneedles and shows promise in clinical applications.

Approaches and materials for endocytosis-independent intracellular delivery of proteins.

The intracellular delivery of proteins is of great significance. For diseases such as cancer, heart disease and neurodegenerative diseases, many important pharmacological targets are located inside cells. For genetic engineering and cell engineering, various functional proteins need to be delivered into cells for gene editing or cell state regulation. However, most existing protein delivery strategies involve endosomal escape (endocytosis-dependent), resulting in inefficient delivery due to endosome trapping. In contrast, endocytosis-independent intracellular delivery, which refers to the directly delivery of proteins across the cell membrane to the cytoplasm, will bypass the low efficiency of early endosomal escape, avoid protein inactivation caused by late endosome/lysosome, fundamentally improve the intracellular delivery efficiency, and open up a new way for intracellular protein delivery. In this review, the latest advances in direct intracellular delivery of proteins through membrane perforation, membrane translocation, and membrane fusion were summarized. The mechanisms, related materials and potential therapeutic in living cells/in vivo for each approach were discussed in detail, and the future development in this promising field was briefly presented.