Release of Ftorafur from pH-sensitive hydrogels with hyperbranched poly(4-vinylbenzyl chloride) moieties

Drug release behavior of a hydrogel is related to its transport mechanism, which is dominated by structure of the hydrogel. Therefore, we prepared pH-sensitive poly(4-vinylpyridine) (P4VP) hydrogels with hyperbranched poly(4-vinylbenzyl chloride) (PVBC; M _n = 2391 g/mol, PDI = 1.87, the minimum percent linearity = 12.4%) moieties (P4VP-PVBC) by atom transfer radical polymerizations (ATRP) in two steps. A PVBC moiety provides the hydrogel with a microenvironment, which may encapsulate guest molecules like drug. The presence of the microenvironment could affect drug transport in the hydrogel matrices. To understand this, we used Ftorafur as drug molecule, and investigated release behavior of the P4VP-based hydrogels. Diffusion and transport mechanism of Ftorafur in the P4VP-based hydrogels was analyzed by early-time and late-time approximation diffusion coefficients. It was found that the transport behavior of Ftorafur was related to the presence of the PVBC moiety and external pH. The presence of the PVBC moiety could sustain release of Ftorafur.