Recrystallization kinetics of starch microspheres prepared by temperature cycling in aqueous two-phase system

Enzymatic Synthesis of α-Glucan Microparticles Using Amylosucrases from Bifidobacterium Species and Its Physicochemical Properties

α-Glucan microparticles (GMPs) have significant potential as high-value biomaterials in various industries. This study proposes a bottom-up approach for producing GMPs using four amylosucrases from Bifidobacterium sp. (BASs). The physicochemical characteristics of these GMPs were analyzed, and the results showed that the properties of the GMPs varied depending on the type of enzymes used in their synthesis. As common properties, all GMPs exhibited typical B-type crystal patterns and poor colloidal dispersion stability. Interestingly, differences in the physicochemical properties of GMPs were generated depending on the synthesis rate of linear α-glucan by the enzymes and the degree of polymerization (DP) distribution. Consequently, we found differences in the properties of GMPs depending on the DP distribution of linear glucans prepared with four BASs. Furthermore, we suggest that precise control of the type and characteristics of the enzymes provides the possibility of producing GMPs with tailored physicochemical properties for various industrial applications.

Preparation of cassava starch-gelatin yolk-shell microspheres by water-in-water emulsion method

This paper reports the preparation and characterization of gelatin-cassava starch microspheres using the water-in-water emulsion technique. The effects of different weight ratios (10: 0, 9: 1, 8: 2, 7: 3, 6: 4, 5: 5) of starch to gelatin on the morphology, structure, thermal properties, and stability of microspheres were investigated. The morphology results showed that most microspheres had spherical shapes and smooth surfaces. When the weight ratio of starch to gelatin was 5: 5, the prepared microspheres formed a stable yolk-shell structure. The swelling capacity of the microspheres increased with the proportion of gelatin, up to 682.3 %. The gelatin and starch in the microspheres were compatible but not miscible. Compared with the native starch, the crystalline structure of microspheres changed from A-type to a mixture of B-type and V-type, and the relative crystallinity decreased. Differential scanning calorimetry results showed that the melting of microspheres involved both gelatin dissolution and starch gelatinization. Due to the formation of composite microspheres, the starch content decreased, and the release of reducing sugars from the microspheres upon hydrolysis was reduced. The gelatin-cassava starch microspheres are simple to prepare, biocompatible, and can be used as a potential material for microencapsulation.

Injectable hydroxypropyl chitin hydrogels embedded with carboxymethyl chitin microspheres prepared via a solvent-free process for drug delivery

Microspheres and injectable hydrogels derived from natural biopolymers have been extensively investigated as controlled local drug delivery systems. In this study, we prepared carboxymethyl chitin microspheres (CMCH-Ms) with a diameter of 10-100 μm through physical crosslinking by increasing temperature in an aqueous two-phase system without using organic solvents, surfactants and crosslinking agents. The stable microspheres keeping spherical shape with porous microstructure in different pH environments were embeded in thermosensitive hydroxypropyl chitin (HPCH) hydrogels. The morphology, gelation rate, swelling, rheological and mechanical properties, in vitro degradation and cytotoxicity, drug loading and drug release of the CMCH-Ms/HPCH gel scaffolds were examined. In vitro degradation and cytotoxicity test indicated that CMCH-Ms/HPCH gel scaffolds were biodegradable and non-cytotoxic. Moreover, no organic solvent was used in the preparation and drug loading process of CMCH-Ms/HPCH gel scaffold. Importantly, less burst drug release and long-term sustained-release from the CMCH-Ms/HPCH composite hydrogel was observed than those from only CMCH-Ms or HPCH hydrogel. Thus, the composite CMCH-Ms/HPCH hydrogel exhibited great potential application for loading different drugs and sustained drug release in controlled local drug delivery systems.