Effect of Grape Seed Proanthocyanidin-Gelatin Colloidal Complexes on Stability and in Vitro Digestion of Fish Oil Emulsions.

The colloidal complexes composed of grape seed proanthocyanidin (GSP) and gelatin (GLT), as natural antioxidants to improve stability and inhibit lipid oxidation in menhaden fish oil emulsions, were evaluated. The interactions between GSP and GLT, and the chemical structures of GSP/GLT self-assembled colloidal complexes, were characterized by isothermal titration calorimetry (ITC), circular dichroism (CD), and Fourier transform infrared spectroscopic (FTIR) studies. Fish oil was emulsified with GLT to obtain an oil-in-water (o/w) emulsion. After formation of the emulsion, GLT was fixed by GSP to obtain the GSP/GLT colloidal complexes stabilized fish oil emulsion. Menhaden oil emulsified by GSP/GLT(0.4 wt %) colloidal complexes yielded an emulsion with smaller particles and higher emulsion stability as compared to its GLT emulsified counterpart. The GSP/GLT colloidal complexes inhibited the lipid oxidation in fish oil emulsions more effectively than free GLT because the emulsified fish oil was surrounded by the antioxidant GSP/GLT colloidal complexes. The digestion rate of the fish oil emulsified with the GSP/GLT colloidal complexes was reduced as compared to that emulsified with free GLT. The extent of free fatty acids released from the GSP/GLT complexes stabilized fish oil emulsions was 63.3% under simulated digestion condition, indicating that the fish oil emulsion was considerably hydrolyzed with lipase.

Preparation and characterization of dexamethasone-immobilized chitosan scaffold.

Chitosan film (CSF), 2-dimensional scaffold, was modified with dexamethasone (DEX) in the present work via amino-alcohol forming reaction between amino group of chitosan and carbonyl group of DEX. Successful immobilization was identified by ATR-FTIR spectroscopy and, the immobilized amounts were determined by weighting methods (WM) and integrated area analysis method (AM) of HPLC. For experiments of cell culture of osteogenic differentiation, our results showed that DEX immobilization has more efficiency than the other group (such as both groups of CSF and CSF with free DEX, CSF/fDEX), which was demonstrated as indicated by cell image analysis and ALP activity assay. The results show, as AD-MSCs cultured on DEX-CSF, its shape of cell transformed to polygonal or cubical. The ALP activity assay indicates that of DEX-CSF increase about 3.5 folds than that of CSF's. The results suggest that immobilization of DEX can make chitosan scaffolds to induce differentiation of AD-MSCs toward osteoblastic lineage for bone tissue engineering application.

Computational multiple steady states for enzymatic esterification of ethanol and oleic acid in an isothermal CSTR.

The capacity of complex biochemical reaction networks (consisting of 11 coupled non-linear ordinary differential equations) to show multiple steady states, was investigated. The system involved esterification of ethanol and oleic acid by lipase in an isothermal continuous stirred tank reactor (CSTR). The Deficiency One Algorithm and the Subnetwork Analysis were applied to determine the steady state multiplicity. A set of rate constants and two corresponding steady states are computed. The phenomena of bistability, hysteresis and bifurcation are discussed. Moreover, the capacity of steady state multiplicity is extended to the family of the studied reaction networks.

Enzymatic grafting of carboxyl groups on to chitosan--to confer on chitosan the property of a cationic dye adsorbent.

Chitosan (CTS) is a good adsorbent for dyes but lacks the ability to adsorb cationic dyes. In this study, chitosan was modified to possess the ability to adsorb cationic dyes from water. Four kinds of phenol derivatives: 4-hydroxybenzoic acid (BA), 3,4-dihydroxybenzoic acid (DBA), 3,4-dihydroxyphenyl-acetic acid (PA), hydrocaffeic acid (CA) were used individually as substrates of tyrosinase to graft onto chitosan. FTIR analysis provided supporting evidence of phenol derivatives being grafted. The grafting amounts of these phenol derivatives onto chitosan were examined by the adsorption of an anionic dye (amaranth) and reached a plateau value. The final contents of carboxyl groups in chitosan (mmol carboxyl groups per kg chitosan) were measured as 46.36 for BA, 70.32 for DBA, 106.44 for PA, and 113.15 for CA. These modified chitosans were used in experiments on uptake of the cationic dyes crystal violet (CV) and bismarck brown Y (BB) by a batch adsorption technique at pH 7 for CV and at pH 9 for BB and 30 degrees C. Langmuir type adsorption was found, and the maximum adsorption capacities for both dyes were increased with the following order CTS-CA>CTS-PA>CTS-DBA>CTS-BA.