Porous scaffolds of alkaline-soluble collagen including nanocompositeparticles of chondroitin sulfate and low crystalline hydroxyapatite forcartilage regeneration were fabricated by freeze-drying and thermaldehydration treatments; porous collagen scaffolds were also synthesized as areference. The scaffolds were cross-linked using glutaraldehyde (GA) vaportreatment in order to enhance biodegradable resistance. Microstructuralobservation with scanning electron microscope indicated that the scaffoldswith and without GA cross-linkage had open pores between 130 to 200 μm indiameter and well-interconnected pores of 10 to 30 μm even aftercross-linkage. In vitro biodegradable resistance tocollagenase was significantly enhanced by GA cross-linking of the scaffolds.All these results suggest that the GA cross-linked scaffolds consisting ofcollagen, chondroitin sulfate, and low crystalline hydroxyapatite havesuitable microporous structures and long-term biochemical stability forcartilage tissue engineering.

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

The wrinkling of a 50:50 blend of a high molecular mass (Mn = 990kg/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 apparentmodulus of these PS blend films. The PS blend shows a modulus comparable tothe high molecular weight PS, ≈ 3.2 GPa for mechanical wrinkling at ambientand thermal wrinkling for T ≤ 50 °C. A sharp decrease in the apparentmodulus 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 belowthe modulus determined the neat PS for either Mn when thermallywrinkled at T > 60 °C. This behavior is attributed to a combination ofsurface segregation of the low molecular weight PS as well as the largedifference in bulk glass transition temperature (Tg) of eachcomponent. During thermal wrinkling, the high Mn PS vitrifiesfirst, while the surface containing primarily low Mn PS isrubbery; this leads to only the underlayer of PS wrinkling initially andselection of a shorter wavelength due to the effective thickness. Theincreased thermally induced stresses during cooling when the low Mn PS is vitrified do not change the selected wavelength andinstead only leads to an increase in the wrinkle amplitude. These resultsillustrate a potential method to modulate the wrinkle wavelength withoutchanging the overlayer, which could be useful for patterningapplications.

In recent years there has been a renewed interest in magnesium alloys forapplications as temporary biomedical implants because magnesium is bothbiocompatible and biodegradable. However, the rapid corrosion rate ofmagnesium in physiological environments has prevented its successful use fortemporary implants. Since alloying is one of the routes to slow downcorrosion, we report in this publication our investigation of Mg-Ti alloysfabricated by high-energy ball milling as possible materials forbiocompatible and biodegradable implants. Titanium was chosen mainly becauseof its proven biocompatibility and corrosion resistance. Corrosion testscarried out by immersing the Mg-Ti alloys in Hank’s Solution at 37°C showedsignificantly improved corrosion resistance of the alloy in comparison topure magnesium. Thus, Mg-Ti alloys are promising new biodegradable andbiocompatible materials for temporary implants.