Synthesis, characterization of 2-(methacryloyloxy)ethyl-(di-) l-lactate and their application in dextran-based hydrogels

Abstract

This paper describes the synthesis and characterization of 2- (methacryloyloxy) ethyl-L-lactate and 2-(methacryloyloxy)ethyl-di-L-lactate. These compounds were obtained by reaction of L-lactide and 2-hydroxyethyl methacrylate (HEMA) at a molar ratio of 1:2 using stannous octoate as catalyst. After a purification step using preparative HPLC, the obtained products were characterized by 1 H-NMR, HPLC and mass spectrometry. 2- (Methacryloyloxy)ethyl-(di-)lactate as well as HEMA were grafted to dextran using 1,1'-carbonyldiimidazole as coupling agent resulting in dex- (lactate) 1,2 -HEMA and dex-HEMA, respectively. Hydrogels were obtained by radical polymerization of aqueous solutions of the methacrylated dextrans. Due to the presence of hydrolytically sensitive groups in the crosslinks, these hydrogels degraded when exposed to an aqueous solution (pH 7.2, 37 °C). For hydrogels with a fixed crosslink density, the degradation times were 30, 12 and 6 days for dex-HEMA, dex-lactate-HEMA and dex-(lactate) 2 - HEMA hydrogels, respectively. This demonstrates that the degradation rate and time of dextran hydrogels can be tailored by the length of the spacer in the crosslink of the hydrogels.