Mechanical Properties of Artificial Materials for Bone Repair

Bone defect caused by injury, infection, tumor and congenital diseases is one of the most common diseases in clinical orthopaedics. Bone grafts are necessary when self-healing is not effective during the recovery.Preparation of ideal bone substitutes with good biocompatibility and biodegradability to repair bone defects has become the focus. So far artificial materials used in hard tissue repair and reconstruction most notably are metals and their alloys, then the ceramic materials and their composite materials. From the perspective of mechanical properties, metals have some advantages, but corrosion issue and stress shielding of metal have baffled scientists through the age and have been long searched for solution. The elastic modulus of ceramic is more close to the natural bone compared to metal while the improvement of brittleness has been always the emphasis for clinical use.Therefore, development of materials of proper mechanical properties without affecting biological compatibility has become a significant subject.     

Skin Penetration of Inorganic and Metallic Nanoparticles

Nanotechnology is a rapidly growing science of producing and utilizing nano-sized particles. These nanomaterials are already having an impact on health care. Nowadays we are using nanoproducts in various fields,and this leads to direct and indirect exposure in human. Skin is the largest organ of the body and functions as the first-line barrier between the external environment and the internal organs of the human body. Then people worry about the nanoparticle（NP） small enough to penetrate the skin. The potential of solid NPs to penetrate the stratum corneum and to diffuse into underlying structures raises a considerable health and safety issue for their topical use. We review the current state of knowledge on the potential risk to human health presented by skin penetration of NPs nanotechnologies, and explore the robustness of current research strategies and directions to ensure the development of ＂safe＂ and publicly accepted nano-based products and technologies.     

A simple screening method for analysis of cell adhesive strength cultured on zein microspheres

Cell adhesion plays an important role in the microcarrier culture. Therefore, it is necessary to find a simple method to evaluate the cell adhesive strength. By the glycerol method, we prepared zein microcarriers. Both microcarrier surface morphology and cells on the microcarriers could be observed clearly when the microcarriers and the cells were stained by acridine orange (AO). Pre-treatment of soaking and sterilizing processes was necessary for cell culture, but it did not alter the morphology of zein microcarriers. Three kinds of cells were cultured on zein microcarriers for 24 h. Vero cells showed the strongest adhesion, while L929 cells were easily detached from the microcarriers after a simple beating operation. The proliferation curve of Vero cells cultured on the microcarriers displayed no difference with that on Cytodex 1.