Structural Characterization Of Polysaccharides_based Cryogels And Potential Application As Carriers Of Active Molecules: A Case Study Through NMR Spectroscopy

Polysaccharides (PS's) are natural and environmentally friendly polymers that have been used as starting materials for the production of the "new generation" of biobased materials because biocompatible, biodegradable, and nontoxic.[1] In the present study, PS_based materials, (from starch and polygalactomannans) were obtained after enzymatic modification, with the Laccase/(2,2,6,6-tetramethylpiperidin-1-yl)oxyl TEMPO system, in aqueous solution. The structural characterization of the modified polysaccharides by solution NMR spectroscopy showed partial conversion of the primary hydroxyl groups versus aldehyde and carboxyl groups, and successive creation of hemiacetal and ester bonds able to generate, upon lyophilisation, stable cryogels.[2,3] The presence of pores of dimensions ranging from 200 nm to few microns, evidenced by Scanning Electron (SEM) Microscopy, supports their potential use for tuning the absorption/release of active molecules. Therefore, PS_based cryogels were loaded with caffeine, as model molecule, and release profiles were determined by proton NMR studies during time. Results demonstrated that synthesized cryogels are good candidates to act as drug carriers due to their stability and prolonged residence times of loaded molecules.