Colon-targeting drug delivery systems (CDDSs) are employed to improve the bioavailability of protein and peptide drugs through the oral route. So it is important to prepare the drug carriers for oral CDDS. In this study, the Enzyme-Resistant starch (RS) was studied for use as a vehicle in oral colon-targeting drug delivery. The characteristics of RS powders were investigated by X-ray diffraction, polarizing microscopy, DSC and SEM, and their film were examined by enzymatic digestion test. The results showed that RS could be a promising film-former for pharmaceutical coatings, having good stability to enzymatic digestion. Furthermore, a novel peroral formulation using RS coating and bovine serum albumin as a model drug was studied for colon-specific drug delivery in vitro. Drug release studies have shown that RS coating could delivery the drug to the colon and the release rate in simulated colonic fluids was dependent on the biodegradation of RS and its coatings. It is indicated that the RS coated tablet is a potential system for oral CDDS.

The process, thermodynamical isotherm and mechanism of Cr(III) uptake by Spirulina platensis were investigated in this paper. At the beginning of Cr uptake, Cr is physically adsorbed to the surface of algal cell by electrostatic attraction. Finally, chemical complexation through ion-exchange with K+, Mn2+, Ca2+, Mg2+, Na+, Fe3+, Zn2+, H+, etc. ions by reversible or irreversible strategies plays the main role in Cr uptake. Most of the absorbed Cr are steadily bound to proteins, polysaccharides, lipids, etc. Biological ligands, whereas only a very small part of Cr are loosely adsorbed on the algal surface. Langmuir isotherm model seems to be suitable for describing Cr uptake than Freundlich isotherm model. pH is the most important factor influencing Cr uptake as well as anions, cell concentration, Cr concentration, temperature, light. Scatchard analysis and isotherm analysis indicate multi types binding sites for Cr and multi interactions between Cr and alga. Bioaccumulation strategy is suggested to be involved in Cr uptake besides biosorption e.g. adsorption and chemical complexation. S. platensis is of efficiently capable in the uptake of Cr(III), consequently high-value Spirulina can be produced.

The eVects of covalent cross-linking of microbial transglutaminase (MTGase) on the thermal properties of soy protein isolates (SPI), including the thermal denaturation and glass transition were investigated by conventional and modulated diverential scanning calorimetry (DSC). The MTGase treatment signiWcantly increased the thermal denaturation temperatures (including the on-set temperature of denaturation, Tm and the peak temperature of denaturation, Td) of glycinin and-conglycinin components of SPI (P60.05), and the thermal pretreatment of SPI further increased the extent of this improvement. The MTGase treatment also improved the ability of SPI to resist the urea-induced denaturation. Modulated DSC analysis showed that there were two glass transition temperatures (Tg) in the reversible heat Xow signals of native SPI (about 5% moisture content), approximately corresponding to 45 and 180

The influence of different denaturants on the phosphorescence spectrum and lifetime decay of Escherichia coli alkaline phosphatase (AP) was investigated. Phosphorescence intensity and lifetime of tryptophan residue (Trp-109) decrease upon addition of guanidine hydrochloride, ethylene diamine tetraacetic acid, and urea or decreasing acidity. The experiments show that AP undergoes different pathways with different denaturants and that the activation energy data, DS8" and DH8" further confirm that there is a stable intermediate state between the folded and unfolded AP states in solution.

In this study, the effects of acetylation on the swelling and enzymatic degradation of maize starch as well as the release rate of drug from tablets coated with starch-based polymer were examined. Maize starch acetates (SA) were prepared by acetyl esterification with a degree of substitution from 1.31 to 2.40, and bovine serum albumin was used as a model drug. For in-vitro drug release assays, the starch based polymer was incubated in simulated gastric fluid, simulated intestinal fluid and simulated colonic fluid, respectively. The resistant starch content and swelling property of maize starch were increased by acetylation, which retarded its enzymatic degradation. Drug release studies have shown that SA-coated tablets could deliver the drug to the colon. These results suggest that the SA can be used for a potential drug delivery carrier for colon-targeting biomacromolecule drugs.