Mingjing Tu

A thermosensitive hydrogel based on biodegradable amphiphilic poly(ethylene glycol)–polycaprolactone–poly(ethylene glycol) block copolymers

A series of low molecular weight poly(ethylene glycol)–polycaprolactone–poly(ethylene glycol) (PEG–PCL–PEG) biodegradable block copolymers were successfully synthesized using isophorone diisocyanate (IPDI) as the coupling agent, and were characterized using 1H NMR and Fourier transform infrared spectroscopy. The aqueous solutions of the PEG–PCL–PEG copolymers displayed a special thermosensitive gel–sol transition when the concentration was above the corresponding critical gel concentration. Gel–sol phase diagrams were recorded using the test-tube-inversion method; they depended on the hydrophilic/hydrophobic balance in the macromolecular structure, as well as some other factors, including the heating history, volume, and the ageing time of the copolymer aqueous solutions and dissolution temperature of the copolymers. As a result, the gel–sol transition temperature range could be altered, which might be very useful for application in injectable drug delivery systems.

A novel near-ultraviolet (NUV) converting blue-violet Ca2−xAlMg0.5Si1.5O7:xCe3+ phosphor for white light-emitting-diodes (w-LEDs)

Ce3+ doped aluminosilicate phosphors (Ca2−xAlMg0.5Si1.5O7:xCe3+, x = 0.015–0.075) for white NUV w-LEDs were synthesized by a solid-state reaction method at 1250 °C. The as-prepared samples were characterized by XRD and fluorescence spectrophotometry; the obtained XRD results show that the target phase was synthesized and doping with Ce3+ did not result in an impurity phase. The as-prepared phosphors exhibit a strong blue-violet emission under the near-ultraviolet radiation excitation. Corresponding fitting results show the emission spectra contain two distinct single bands, which come from the transition of 2D3/2 → 2F7/2 and 2F5/2 of the Ce3+ ion. The colorimetric coordinates of the sample with x = 0.03 are (0.1574, 0.0359), located in the blue-violet region. In addition, the sample exhibits high external quantum efficiency (EQE = 37.3%) and excellent thermal stability (T50 = 230 °C). We obtained bright blue-violet light by pumping the sample with NUV light (λ ≈ 365 nm), which suggests that this material has the potential for application as a NUV converting blue-violet phosphor for the NUV w-LEDs.

Uptake and cytotoxicity of Ce(IV) doped TiO 2 nanoparticles in human hepatocyte cell line L02

Ce(IV) doped anatase TiO2 nanoparticles (CDTs) were prepared and the underlying mechanism by which CDT nanoparticle enters into cell and its cytotoxicity were investigated in a human hepatocellular line L02 cell. The results showed that CDTs can enter into cytoplasm of L02 cell via endocytosis and nonendocytic ways. Large aggregation of CDTs went into cell by endocytosis and finally formed an endocytic vesicle with membrane boundary. Tiny aggregation of CDTs entered into cell cytoplasm via channels similar to that for lung-blood substance exchange in the alveolar-airway barrier. In addition, tiny aggregation of CDTs was observed in nucleus, and maybe CDTs could pass through the nucleus envelope via the channels provided by nuclear pore complexes (NPCs). Results from MTT assay, fluorescence microscope, and TEM observations showed that the cell viability, cell morphology, cell growth, and cell division periods could not be obviously impaired when cells were exposed to CDTs of different concentration from30 to 150 µgmL-1 without UV irradiation. However, large vacuoles containing CDTs were found in cytoplasm, some structure changes were observed in mitochondria, and smooth envelope around the nucleus was shrank and deformed.

Ce(IV) Doped TiO2 Nanoparticles and the Effect on Proliferation of BEL7402 Human Hepatoma Cells

To investigate nanoparticles’ antitumor effect, a globose 30~35nm Ce(IV) doped Titanium dioxide nanoparticles (CDT) were prepared by impregnation method and characterized by X-ray diffraction (XRD) and transmission electron microscopy(TEM). Proliferation of BEL7402 human Hepatoma cells was studied in vitro by using fluorescence microscopy and Flow Cytometry. The results show that cerium elements doping enhanced thermal stability of nano-size titanium dioxide to 800°C. With UV irradiated for 8min, BEL7402 were induced a dose-dependent apoptosis by CDT, about 28.2% , 41.5% and 88.3% cells were induced apoptosis after 24h at concentration of 60, 120 and 180ug/ml respectively, relative to 3.9% of that of control group cell just only in the presence of UV.