Xiao-Mei Wu

Preparation of core-shell PAN nanofibers encapsulated α-tocopherol acetate and ascorbic acid 2-phosphate for photoprotection

Magnesium l-ascorbic acid 2-phosphate (MAAP) and α-tocopherol acetate (α-TAc), as the stable vitamin C and vitamin E derivative, respectively, are often applied to skin care products for reducing UV damage. The encapsulation of MAAP (0.5%, g/mL) and α-TAc (5%, g/mL) together within the polyacrylonitrile (PAN) nanofibers was demonstrated using a coaxial electrospinning technique. The structure and morphology characterizations of the core-shell fibers MAAP/α-TAc-PAN were investigated by SEM, FTIR and XRD. As a negative control, the blend nanofibers MAAP/α-TAc/PAN were prepared from a normal electrospinning method. The results from SEM indicated that the morphology and diameter of the nanofibers were influenced by concentration of spinning solution, the polymer component of the shell, the carrying agent of the core and the fabricating methods, and the core-shell nanofibers obtained at the concentration of 8% had finer and uniform structure with the average diameters of 200 ± 15nm. From in vitro release studies it could be seen that both different fiber specimens showed a gradual increase in the amount of α-TAc or MAAP released from the nanofibers. Furthermore, α-TAc and MAAP released from the blend nanofibers showed the burst release at the maximum release of ∼15% and ∼40% during the first 6h, respectively, but their release amount from the core-shell nanofibers was only 10-12% during the initial part of the process. These results showed that core-shell nanofibers alleviated the initial burst release and gave better sustainability compared to that of the blend nanofibers. The present study would provide a basis for further optimization of processing conditions to obtain desired structured core-shell nanofibers and release kinetics for practical applications in dermal tissue.

Dual response surface-optimized process for feruloylated diacylglycerols by selective lipase-catalyzed transesterification in solvent free system.

Feruloylated diacylglycerol (FDAG) was synthesized using a selective lipase-catalyzed the transesterification between ethyl ferulate and triolein. To optimize the reaction conversion and purity of FDAG, dual response surface was applied to determine the effects of five-level-five-factors and their reciprocal interactions on product synthesis. A total of 32 individual experiments were performed to study reaction temperature, reaction time, substrate molar ratio, enzyme loading, and water activity. The highest reaction conversion and selectivity towards FDAG were 73.9% and 92.3%, respectively, at 55 degrees C, reaction time 5.3 day, enzyme loading 30.4 mg/ml, water activity 0.08, and a substrate molar ratio of 3.7. Moreover, predicted values showed good validation with the experimental values when experiments corresponding to selected points on the contour plots were carried out.

Preparation of Cellulose Acetate Fibers Loaded with Naproxen Ester Prodrug through Wet-Spinning

Cellulose acetate (CA) fibers loaded with naproxen ester prodrug, naproxen methyl ester, were prepared through a wet-spinning technique by using N, N-dimethylacetamide (DMAc) as a solvent. The chemical and morphological characterizations of the medicated fibers were investigated by means of scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR), as well as the studies of the drug release properties. It was observed that the surface and the cross section of the fibers were quite smooth and cylindrical respectively, whereas microcracks were present on the surface of the fibers. Naproxen methyl ester was successfully encapsulated into a monofilament fiber, and this system was stable in terms of high loading capacity and effectiveness in release. The in vitro release experiment indicated that constant drug release from the fiber was observed for a long duration of time. These findings demonstrate that controlled release of drugs from cellulose acetate fibers could be potentially useful in drug delivery systems.

The Deracemization of Secondary Alcohols via a Chemo-Enzymatic Process

Optically pure secondary alcohols were efficiently prepared via a two-step, one-pot process involving a chemical oxidative agent in combination with an enantioselective ketone reducase Rhodotorula sp. AS2.2241 in tandem. The reaction proceeded successfully with 88~99.5% enantiomeric excess in moderate to good conversions. A variety of substrates, including aromatic and aliphatic alcohols, could be tolerated.