Porous scaffolds of alkaline-soluble collagen including nanocomposite particles of chondroitin sulfate and low crystalline hydroxyapatite for cartilage regeneration were fabricated by freeze-drying and thermal dehydration treatments; porous collagen scaffolds were also synthesized as a reference. The scaffolds were cross-linked using glutaraldehyde (GA) vapor treatment in order to enhance biodegradable resistance. Microstructural observation with scanning electron microscope indicated that the scaffolds with and without GA cross-linkage had open pores between 130 to 200 μm in diameter and well-interconnected pores of 10 to 30 μm even after cross-linkage. In vitro biodegradable resistance to collagenase was significantly enhanced by GA cross-linking of the scaffolds. All these results suggest that the GA cross-linked scaffolds consisting of collagen, chondroitin sulfate, and low crystalline hydroxyapatite have suitable microporous structures and long-term biochemical stability for cartilage tissue engineering.

In this study, the morphological changes of chemically treated (or preserved) with aqueous solutions of 1) a sodium chloride (NaCl) and 2) a compound containing sodium silicate, so called “wasserglass”, and untreated I-type collagen fibers of Mongolian goatskin are investigated by atomic force microscopy in ambient condition and at room temperature. The experimental results show that the difference between D period for both chemically treated and untreated collagen fibers are a relatively stable for morphological behavior. However, we find that the width of collagen fibers treated with the NaCl solution is more increasing with approximately 112 nm than those of samples (untreated and treated with wasserglass solution) for the range 93.4-94.8 nm. We also observe that a typically structure of the collagen fibers generally, a dense packing of the untreated and treated by wasserglass collagen fibers in bundles in a nearly parallel arrangement, with little changes in orientation can be seen. The collagen fibers treated by NaCl are a more destructive than untreated and treated by wasserglass for collagen fibers.

The wrinkling of a 50:50 blend of a high molecular mass (Mn = 990 kg/mol) and low molecular mass (Mn = 1.3 kg/mol) polystyrene (PS) film is studied as a function of annealing temperature and film thickness. Both thermal and mechanical wrinkling are utilized to elucidate the apparent modulus of these PS blend films. The PS blend shows a modulus comparable to the high molecular weight PS, ≈ 3.2 GPa for mechanical wrinkling at ambient and thermal wrinkling for T ≤ 50 °C. A sharp decrease in the apparent modulus of the film occurs when thermal wrinkling occurs at 60 °C or higher. The calculated modulus in this case is 0.5 GPa, which is significantly below the modulus determined the neat PS for either Mn when thermally wrinkled at T > 60 °C. This behavior is attributed to a combination of surface segregation of the low molecular weight PS as well as the large difference in bulk glass transition temperature (Tg) of each component. During thermal wrinkling, the high Mn PS vitrifies first, while the surface containing primarily low Mn PS is rubbery; this leads to only the underlayer of PS wrinkling initially and selection of a shorter wavelength due to the effective thickness. The increased thermally induced stresses during cooling when the low Mn PS is vitrified do not change the selected wavelength and instead only leads to an increase in the wrinkle amplitude. These results illustrate a potential method to modulate the wrinkle wavelength without changing the overlayer, which could be useful for patterning applications.

In recent years there has been a renewed interest in magnesium alloys for applications as temporary biomedical implants because magnesium is both biocompatible and biodegradable. However, the rapid corrosion rate of magnesium in physiological environments has prevented its successful use for temporary implants. Since alloying is one of the routes to slow down corrosion, we report in this publication our investigation of Mg-Ti alloys fabricated by high-energy ball milling as possible materials for biocompatible and biodegradable implants. Titanium was chosen mainly because of its proven biocompatibility and corrosion resistance. Corrosion tests carried out by immersing the Mg-Ti alloys in Hank’s Solution at 37°C showed significantly improved corrosion resistance of the alloy in comparison to pure magnesium. Thus, Mg-Ti alloys are promising new biodegradable and biocompatible materials for temporary implants.