Micrometric Wrinkled Patterns Spontaneously Formed on Hydrogel Thin Films via Argon Plasma Exposure

Controlled Release of Insulin Based on Temperature and Glucose Dual Responsive Biomicrocapsules

The treatment of diabetes lies in developing novel functional carriers, which are expected to have the unique capability of monitoring blood glucose levels continuously and dispensing insulin correctly and timely. Hence, this study is proposing to create a smart self-regulated insulin delivery system according to changes in glucose concentration. Temperature and glucose dual responsive copolymer microcapsules bearing N-isopropylacrylamide and 3-acrylamidophenylboronic acid as main components were developed by bottom-spray coating technology and template method. The insulinoma β-TC6 cells were trapped in the copolymer microcapsules by use of temperature sensitivity, and then growth, proliferation, and glucose-responsive insulin secretion of microencapsulated cells were successively monitored. The copolymer microcapsules showed favorable structural stability and good biocompatibility against β-TC6 cells. Compared with free cells, the biomicrocapsules presented a more effective and safer glucose-dependent insulin release behavior. The bioactivity of secreted and released insulin did not differ between free and encapsulated β-TC6 cells. The results demonstrated that the copolymer microcapsules had a positive effect on real-time sensing of glucose and precise controlled release of insulin. The intelligent drug delivery system is supposed to mimic insulin secretion in a physiological manner, and further provide new perspectives and technical support for the development of artificial pancreas.

Microwrinkled pH-sensitive hydrogel films and their role on the cell adhesion/proliferation

In this work, hydrogels based on HEMA and DMAEMA (pH-sensitive monomer) were used to form biocompatible films which present microwrinkled patterns in their surface, with the focus of exploring the role of chemical composition on cell adhesion and proliferation. Three different pH (5.4, 7.4, and 8.3) were employed to prepare these hydrogels. The pre-polymerized hydrogel mixtures were deposited via spin coating, then exposed to vacuum for deswelling the films and finally, to UV-light to spontaneously generate the wrinkled pattern. By following this procedure, is possible to form a thin rigid layer on the top of the soft and incompletely polymerized hydrogel film which generates, in turn, a wrinkled pattern due to strain mismatch in the interface. FE-SEM and AFM micrographs allowed us to characterize the wrinkled pattern dimensions. The results evidenced that chemical composition is directly related to the surface pattern morphologies obtained, not so in the case of pH variation, which does not generate relevant changes in the pattern morphology. Interestingly, these pH variations resulted in significant alterations on the interface-cell interactions. More precisely, a premyoblastic cell monolayer was cultured over the wrinkled pattern, showing an optimal cell proliferation at neutral pH. Also, the variation of DMAEMA amount on the monomer feed composition employed for the preparation of the wrinkle surfaces revealed that a certain amount is required to favor cell attachment and growth.