Visible light-absorbing biocompatible polymers based on L-lactide and aminosugars: Preparation and characterization

Two series of polymers with low-molecular-weight L-lactide side-arms were prepared by ring-opening polymerization using D-glucosamine and N-acetyl-D-glucosamine as polymer core molecules, and methanesulfonic acid as solvent and catalyst. This simple synthetic route does not rely on the use of organometallic catalysts, and has also proven useful to the authors for chitosan grafting with lactones. NMR spectroscopy reveals a high degree of substitution (>3), and Fourier transform infrared/NMR spectra suggest the existence of three different lactate tautomers likely to be responsible for coloration. These D-glucosamine-based polymers also display glass transition temperatures approximately 10 °C above that of the human body, which points to the potential of these lactone-grafted aminosugars with tunable amphiphilic character in the design of submicrometer-sized drug delivery vehicles. They are also viewed as interesting hydrophobic chelating agents for catalytic transition metal centers.