Insulin smart drug delivery nanoparticles of aminophenylboronic acid-POSS molecule at neutral pH

Self-regulated "smart" insulin administration system that mimic pancreatic endocrine function would be highly desirable for diabetes management. Here, a glucose-responsive continuous insulin delivery system is developed, where novel polyhedral oligosilsesquioxane (POSS) modified with 3-aminophenylboronic acid (APBA) were used to encapsulate insulin (insulin entrapment efficiency: 73.2%) to prepare a fast response, high stability, good distribution, and excellent biocompatible system. Due to the strong hydrophobicity of POSS, the POSS moiety is located at the core in aqueous solution and combines with the boronic group of APBA and the diol generated in PEG-insulin to form a nanomicelle structure, that is, nanoparticles naturally. Micelles self-assembled from these molecules possess glucose-responsiveness at varying glucose concentrations. The interaction of the PBA and diol containing insulin via boronate ester bond and its interchange with glucose was investigated by FT-IR, ¹H NMR and XPS. Furthermore, the successful glucose-triggered release of insulin from the POSS-APBA micelles was investigated at neutral pH. A linear graph was plotted with the measured released insulin vs glucose concentrations, with a linear correlation coefficient (R2) value close to 1. Circular dichroism (CD) spectroscopy analysis was performed to measure insulin activity by comparing secondary structures of insulin, PEG-Insulin, and POSS-APBA@insulin. When confirming intracellular apoptosis signaling, cleaved caspase 3 and caspase 9 were not increased by 640 μg/ml POSS-APBA and POSS-APBA@insulin in HeLa, HDF and HUVE cells. Application in the biomedical field for controlled delivery of insulin appear to be promising.