Self healing and release behaviour of HEMA based supramolecular hydrogels

In supramolecular polymeric hydrogels based on hydrogen bonding, multiple hydrogen bonding motifs such as ureidopyrimidinone (UPy) are employed as physical cross-linking units to form reversible networks.In this study, we synthesized HEMA copolymers based on UPy-substituted HEMA (HU) with hexamethylene spacer that linked to the UPy moieties to discover effect of UPy moieties as pending groups on the hydrogel behavior of PHEMA such as swelling and healing behavior as well as controlled release of metronidazole. The results showed that HEMA homopolymer absorbed water very fast until underwent complete deformation. Meanwhile, the HEMA-HU copolymers could act as hydrogels and their swelling ratios increased with time and after 5 days, the equilibrium swelling was reached. Self healing behavior of the hydrogels was investigated and the results showed the supramolecular zerogels could heal immediately upon spray of water. The hydrogels were loaded with metronidazole and the hydrogel with 10 mol % HU showed a large burst, while the hydrogel with 6% mol HU exhibited a slower release rate and relatively small burst (about 50%). Noticeable that release continued for about 5 days for both the hydrogels. Meanwhile, the chemical hydrogel based on HEMA showed a large burst effect (about 90% within the first 15 minutes) and release continued for 3 hours only. Our results demonstrated that substitution of HEMA with UPy groups and subsequent copolymerization with HEMA, results in hydrogels with adjustable swelling and release properties. The hydrogels are promising candidates for potential application as drug carrier.

Keywords:

Self healing , Ureidopyrimidinone , HEMA , Supramolecular hydrogel