Probing the organisation and function of structured starch materials by advanced NMR techniques

Hydrogels have a complex and heterogeneous structure and organisation, making them promising candidates for applications in the biomedical, pharmaceutical and cosmetics industry. Starch is a particularly attractive material for producing hydrogels due to its low cost and biocompatibility, but the structural dynamics of polymer chains within starch hydrogels are not well understood, which has limited their development and utilisation. We employed a range of NMR methodologies to probe the structural organisation of these systems on various length scales, investigating the internal dynamics and intercomponent interactions within these heterogeneous systems. We report on a new level of structural organisation within starch gels – namely, highly dynamic solvated starch chains. Our findings provide new insights into the rationalisation of structure-function relationships governing the micro- and macroscopic properties of hydrogel assemblies. Physiologically, starch hydrolysis by a-amylase occurs in several places in the human body and involves host’s salivary and pancreatic a-amylase enzymes, as well as amylolytic enzymes of bacterial origin. There has been some research on the impact of starch on the gut microbiota, but not much is known about the structure-function relationships governing starch hydrogels’ interaction and impact on the full extent of the gastrointestinal tract (GIT). We demonstrate a quick and easy method for the preparation of pharmaceutical excipients from easily accessible materials, and their ability to provide targeted release of orally administrable physiologically relevant small molecules in the colon, with minimal to no release in the upper GIT. Our work provides important insights into the role and function of starch hydrogel structure on its drug delivery properties, probing guest-host interactions, and elucidating starch gels’ interaction with the human GIT. These insights provide important knowledge for the development of superior orally administrable targeted drug delivery systems with auxiliary physiologically relevant properties