Thermal–mechanical behaviour of chitosan–cellulose derivative thermoreversible hydrogel films

Once damaged, articular cartilage has very little capacity for spontaneous healing because of the avascular nature of the tissue. Although many repair techniques have been proposed over the past four decades, none has sucessfully regenerated long-lasting hyaline cartilage tissue to replace damaged cartilage. Tissue engineering approaches, such as transplantation of isolated chondrocytes, have recently demonstrated tremendous clinical potential for regeneration of hyaline-like cartilage tissue and treatment of chondral lesions. As such a new approach emerges, new important questions arise. One of such questions is: what kinds of biomaterials can be used with chondrocytes to tissue-engineer articular cartilage? The success of chondrocyte transplantation and/or the quality of neocartilage formation strongly depend on the specific cell-carrier material. The present article reviews some of those biomaterials, which have been suggested to promote chondrogenesis and to have potentials for tissue engineering of articular cartilage. A new biomaterial, a chitosan-based polysaccharide hydrogel, is also introduced and discussed in terms of the biocompatibility with chondrocytes.

Uniform, spherical-shaped TiO2:Eu nanoparticles with different doping concentrations have been synthesized through controlled hydrolysis of titanium tetrabutoxide under appropriate pH and temperature in the presence of EuCl3·6H2O. Through air annealing at 500°C for 2 h, the amorphous, as-grown nanoparticles could be converted to a pure anatase phase. The morphology, structural, and optical properties of the annealed nanostructures were studied using X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy [EDS], and UV-Visible diffuse reflectance spectroscopy techniques. Optoelectronic behaviors of the nanostructures were studied using micro-Raman and photoluminescence [PL] spectroscopies at room temperature. EDS results confirmed a systematic increase of Eu content in the as-prepared samples with the increase of nominal europium content in the reaction solution. With the increasing dopant concentration, crystallinity and crystallite size of the titania particles decreased gradually. Incorporation of europium in the titania particles induced a structural deformation and a blueshift of their absorption edge. While the room-temperature PL emission of the as-grown samples is dominated by the 5D0 - 7F j transition of Eu+3 ions, the emission intensity reduced drastically after thermal annealing due to outwards segregation of dopant ions.