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 (Dh) 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.