Effect of drying technique on some physical properties of cross-linked high amylose/pectin mixtures

Starch-based materials for drug delivery in the gastrointestinal tract-A review

Starch is a natural copolymer with unique physicochemical characteristics. Historically, it has been physically, chemically, or enzymatically modified to obtain ad-hoc functional properties for its use in different applications. In this context, the use of starch-based materials in drug delivery systems (DDSs) has gained great attention mainly because it is cheap, biodegradable, biocompatible, and renewable. This paper reviews the state of the art in starch-based materials design for their use in drug-controlled release with internal stimulus responsiveness; i.e., pH, temperature, colonic microbiota, or enzymes; specifically, those orally administered for its release in the gastrointestinal tract (GIT). Physical-chemical principles in the design of these materials taking into account their response to a particular stimulus are discussed. The relationship between the type of DDSs structure, starch modification routes, and the corresponding drug release profiles are systematically analyzed. Furthermore, the challenges and prospects of starch-based materials for their use in stimulus-responsive DDSs are also debated.

Effects of drying methods on the preparation of dexamethasone-loaded chitosan microspheres

The purpose of this study was to investigate the effects of drying methods on the preparation of dexamethasone- (Dex-) loaded chitosan microspheres. Two drying methods, namely, air drying and freeze drying, were adopted. The physical properties of the beads were first investigated and then the loading and release of Dex were characterized. Finally, the bioactivity of released Dex was evaluated. The data showed that, compared with freeze-dried beads, air-dried beads were denser and smaller, and had lower swelling ratios, slower degradation rate and greater Rockwell hardness. In terms of drug delivery, air-dried beads had lower encapsulation efficiency and a slower release rate of Dex. Regarding bioactivity, both groups prompted cell differentiation without significant differences. However, Dex released from freeze-dried beads inhibited cell proliferation, while Dex released from air-dried beads did not. Based on these results, we conclude that incorporation of Dex enhanced the osteogenic potential of chitosan microspheres and drying methods did affect the physical properties of the chitosan microspheres, which further influenced the drug loading and release. At the moment, the air-drying method is more appropriate to prepare Dex-loaded chitosan microspheres.