Aminoalkyl functionalization of dextran for coupling of bioactive molecules and nanostructure formation

Aminopropyl dextrans and mixed aminopropyl cyanoethyl dextrans were prepared from cyanoethyl precursors by full or partial reduction with CoCl2/NaBH4. Coupling of various aldehydes to the glucan backbone by reductive amination was accomplished with 4-hydroxy-3-methoxybenzaldehyde (vanillin), 3,5-di-tert-butyl-4-hydroxy-benzaldehyde (BHT-CHO), maltose and maltotriose, and picoline borane as reducing agent. Successful coupling of these representatives for aroma compounds, antioxidants and sugar side-chains were verified by ESI-MS after hydrolysis and by 1D and 2D NMR spectroscopy. Degree of conversion (molar ratio of coupled aldehydes) was estimated from 1H NMR spectra. Formation of secondary and tertiary amines was detectd by ESI-MS. Applying a solvent exchange process, new nanoparticles based on these modified dextrans were prepared with and without addition of iron oxide nanoparticles.