In the lignin biosynthesis aryloxy groups act like radical propagating species during a radical polymerization. We take advantage of this special chemistry to use catechol as the cross-linking species in a radical polymerization to form robust polyethylene glycol (PEG) hydrogels. Hydrogels are prepared by the radical co-polymerization of poly(ethylene glycol) methyl ether methacrylate and a methacrylamide catechol derivative monomer. The crosslinking results from the catechol groups, through the generation of aryloxy radicals that react with the CC monomer double bonds. These lignin-mimicking hydrogels display a high swelling degree (near 2400%), good mechanical properties in their swollen state (up to 390 Pa) and free catechol groups that can be used for further functionalization. These hydrogels can therefore be used as a platform for the preparation of a more advanced multifunctional material by incorporating magnetite nanoparticles and cyclodextrin macrorings (CD). The magnetic-CD- functionalized PEG hydrogel exhibits a high water-swelling capability, robust mechanical properties (G' ≈ 1900 Pa in the swollen state), magnetic behavior, a great Doxorubicin loading capacity (ca. 0.6 mg Doxorubicin per gram of dried gel) and highly controlled temporal drug release. As a result, this hydrogel shows high potential as an advanced drug delivery system.
Lignin inspired PEG hydrogels for drug delivery
G. Marcelo, M. López-González, I. Trabado, M.M. Rodrigo, M. Valiente, F. Mendicuti.
Materials Today Communications, 7 2016, 73-80