One-pot synthesis of α,β-unsaturated polyaldehyde of chondroitin sulfate

Abstract

Chondroitin sulfate (CS) was chemoselectively oxidized by Tempo/NaClO to C-6 aldehyde of a D-galactosamine subunit (GalNAc). The subsequent, spontaneous desulfatation of oxidized CS gave rise to α,β-unsaturated aldehyde. A new derivative of CS was fully characterized and a degree of oxidation was determined by spectroscopic analysis. The optimization of reaction conditions showed a proportional degree of oxidation to an amount of sodium hypochlorite. The utility of α,β-unsaturated aldehyde for crosslinking and conjugation was demonstrated by a seamless condensation with various N-nucleophiles. We also demonstrated pH-dependent release of biologically active agents from oxidized CS. A live-dead assay in the presence of α,β-unsaturated aldehyde revealed unaffected viability of NIH 3T3 fibroblasts, which made this precursor promising for several biomedical applications including drug delivery and tissue engineering.

Keywords: Chondroitin sulfate; Crosslinking; Hydrogel; Oxidation; Tissue engineering.