A facile strategy to fabricate glucose-responsive vesicles via a template of thermo-sensitive micelles

A facile strategy toward the construction of glucose-responsive polymer vesicles at physiological pH is reported. A thermo-sensitive phenylboronic acid (PBA)-containing block copolymer PNIPAM-b-P(Asp-co-AspPBA) was self-assembled into core-shell (CS) micelles with a PNIPAM core and a P(Asp-co-AspPBA) shell above the LCST of PNIPAM. The addition of a glucosamine (GA)-containing block copolymer PEG-b-P(Asp-co-AspGA) resulted in the formation of core-shell-corona (CSC) complex micelles because of the crosslinking between PBA- and GA-containing blocks. Polymer vesicles with a swollen PNIPAM core, a cross-linked P(Asp-co-AspPBA)/P(Asp-co-AspGA) vesicular membrane, and a PEG corona were obtained simply by storing the CSC complex micelles below the LCST of PNIPAM. A combination of transmission electron microscopy (TEM) and dynamic light scattering (DLS) in terms of the variations of hydrodynamic diameter (D-h) and light scattering intensity (LSI) was applied to characterize the polymer vesicles in PBS solution with glucose. The polymer vesicles had a hydrophilic vesicular membrane which was favorable for the penetration of water-soluble substances and exhibited prominent glucose-responsiveness at physiological pH 7.4. FITC-insulin as a model protein was encapsulated in the polymer vesicles and the glucose-triggered insulin release was investigated.