The significant drawbacks and lack of success associated with current methods to treat critically sized nerve defects have led to increased interest in neural tissue engineering. Conducting polymers show great promise due to their electrical properties, and in the case of polypyrrole (PPY), its cell compatibility as well. Thus, the goal of this study is to synthesize a conducting composite nerve conduit with PPY and poly(D, L-lactic acid) (PDLLA), assess its ability to support the differentiation of rat pheochromocytoma 12 (PC12) cells in vitro, and determine its ability to promote nerve regeneration in vivo. Different amounts of PPY (5%, 10%, and 15%) are used to synthesize the conduits resulting in different conductivities (5.65, 10.40, and 15.56 ms/cm, respectively). When PC12 cells are seeded on these conduits and stimulated with 100 mV for 2 h, there is a marked increase in both the percentage of neurite-bearing cells and the median neurite length as the content of PPY increased. More importantly, when the PPY/PDLLA nerve conduit was used to repair a rat sciatic nerve defect it performed similarly to the gold standard autologous graft. These promising results illustrate the potential that this PPY/PDLLA conducting composite conduit has for neural tissue engineering.

Hydroxyapatite (HAP), similar to inorganic phase in bones, shows good biocompatibility and bioactivity as bone defect repairing material. Recently, nanoscaled HAP shows the special properties differing from bulk HAP in physics, chemistry and biology. This paper demonstrates that HAP nanoparticle (nHAP) possesses the ability for inhibiting cancer cell growth in vitro and in vivo. In vitro, after treatment with nHAP for 3 days, proliferation of human cancer cells are inhibited by more than 65% and by less than 30% for human normal cells. In vivo, injection of nHAP in transplanted tumor results in significant reduction (about 50%) of tumor size. The anticancer effect of nHAP is mainly attributed to high amount by endocytosis in cancer cells and inhibition on protein synthesis in cells. The abundant nHAP internalized in cancer cells around endoplasmic reticulum may inhibit the protein synthesis by decreasing the binding of mRNA to ribosome due to its high adsorption capacity for ribosome and arrest cell cycle in G0/G1 phase. nHAP shows no ROS-involved cytotoxicity and low cytotoxicity to normal cells. These results strongly suggest that nHAP can inhibit cancer cell proliferation and have a potential application in cancer treatment.

In order to enhance the bioavailability of poorly water-soluble curcumin, solution-enhanced dispersion by supercritical carbon dioxide (CO 2 ) (SEDS) was employed to prepare curcumin nanoparticles for the first time. A 2 4 full factorial experiment was designed to determine optimal processing parameters and their influence on the size of the curcumin nanoparticles. Particle size was demonstrated to increase with increased temperature or flow rate of the solution, or with decreased precipitation pressure, under processing conditions with different parameters considered. The single effect of the concentration of the solution on particle size was not significant. Curcumin nanoparticles with a spherical shape and the smallest mean particle size of 325 nm were obtained when the following optimal processing conditions were adopted: P =20 MPa, T =35°C, flow rate of solution =0.5 mL·min −1 , concentration of solution =0.5%. Fourier transform infrared (FTIR) spectroscopy measurement revealed that the chemical composition of curcumin basically remained unchanged. Nevertheless, X-ray powder diffraction (XRPD) and thermal analysis indicated that the crystalline state of the original curcumin decreased after the SEDS process. The solubility and dissolution rate of the curcumin nanoparticles were found to be higher than that of the original curcumin powder (approximately 1.4 μg/mL vs 0.2 μg/mL in 180 minutes). This study revealed that supercritical CO 2 technologies had a great potential in fabricating nanoparticles and improving the bioavailability of poorly water-soluble drugs.

A facile and bioinspired synthesis of ZnO hierarchical architectures, including prismlike and flowerlike structures and crytalline and noncrystalline hollow microspheres, has been developed using the amino acid histidine as the directing and assembling agent. The histidine molecules play different roles in the formation of ZnO hierarchical architectures due to the competitive coordination between histidine and OHto Zn 2+ when the reactant molar ratios are adjusted. The resulting architectures are characterized using field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and high-resolution TEM (HRTEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectoscopy, and thermogravimetric analysis (TGA). Morphology-and phase-dependent photoluminescence of the ZnO architectures has been shown. In particularly, a novel photocatalytic activity of the ZnO hierarchical architectures for the reaction of the formaldehyde and carbon dioxide has been demonstrated, probably through mechanisms involving an oxidative coupling reaction and hydrolyzation process.