A comparative study on two phenylboronic acid based glucose-sensitive hydrogels

Two phenylboronic acid based glucose-sensitive hydrogels, A•PBA-DMAPMA-EGDMA and A•PBA-PEG, were initially prepared by free-radical polymerization. Swelling properties of the gels were studied by determining the diameter changes in different buffer solutions, with or without glucose or fructose. The hydrogels were designed as "valves" to control the flow of glucose solutions. The results showed that gel A•PBA-DMAPMA-EGDMA was sensitive to pH and glucose, but not to fructose. It shrunk in weak basic solution and the addition of glucose made it shrink more. In this gel PBA moiety and glucose is supposed to form a 1:2 bis-bidentate complex. Hydrogel A•PBA-PEG was sensitive to pH, glucose and fructose, all of which made it swell in weak basic solution. A 1:1 complex is believed to form between PBA and glucose/fructose in this gel. All the stimuli-responses are reversible and the glucose-responses occurred in the range of the physiological/pathological glucose level. Both A•PBA-DMAPMA-EGDMA and A•PBA-PEG exhibited sufficient volume change to the alteration of glucose concentration and could be employed as a "valve" to control liquid flow in weak basic solution.