Characterization of 3-Ester and 3-Carbamate Derivatives of N-Acetyl-D-Glucosamine and Their Use in Controlled Drug Delivery

Low molecular weight gelators (LMWGs) are a class of compounds which reversibly form a network that traps solvents to form gels. Gelation by LMWGs is driven solely by non-covalent interactions such as hydrogen bonding, π - π stacking, and hydrophobic interactions. LMWGs can be designed such that the gel-sol and sol-gel transitions happen as a response to a specific stimulus. These stimulus responsive gels or “smart” gels can be used in a wide variety of applications including tissue regeneration, biosensing, and controlled drug delivery. Among the different types of compounds that are LMWGs, carbohydrate based systems are especially interesting. Carbohydrates are abundant, renewable, biocompatible, and have numerous hydroxyl groups which can be readily functionalized. Our group has previously found that organogelators and hydrogelators can be obtained from D-glucose and D-glucosamine by selectively functionalization of the hydroxyl groups. Various C-2 acyl derivatives including esters and carbamates are found to be effective LMWGs for both water and organic solvents. In this study, the functionalization at the C-3 position of glucosamine derivative was carried out. Two types of C-3 derivatives including esters and carbamates were synthesized and characterized by 1H and 13C NMR spectroscopy and LCMS. These compounds were then analyzed for gelation properties in a series of selected solvents. Several compounds were found to be effective organogelators, the resulting gels were characterized using IR, rheology, optical microscopy, etc. The use of these gelators for controlled drug delivery was tested and it was found that the gels loaded with naproxen sodium or chloramphenicol released the drug in an acidic environment