Construction of bio-functional Mg/HA composite layered coating for orthopedic application

Magnesium was considered as a revolutionary biodegradable implant material for orthopedic application. Concerning the weakness of intrinsic strength and corrosion behavior, a novel strategy of Mg/metal hybrid system was proposed for extension of orthopedic application, especially at load-bearing site. In this work, an Mg and HA composite layered coating was constructed on titanium by means of chemical conversion and vapor deposition. The HA transition interlayer was introduced to enhance the bonding between Mg film and Ti substrate. Compared with the bare Mg coating, the Mg/HA coating presented good interface bonding, which avoided the occurrence of Mg film peeling off from the substrate. The Mg/HA coating showed a uniform degradation and kept integrity after immersion of 14 d. The Mg ions release by degradation played a crucial role in osteopromotion and antibacterial effect. Incubation of MC3T3-E1 osteoblasts with the Mg/HA coating showed significant promotion on osteogenic differentiation according to ALP activity and Alizarin Red staining assays. Meanwhile the degradation of Mg exhibited strong suppression of bacteria proliferation. It was believed that this novel Mg/HA composite layered coating could be potentially applied in further development of bio-functional hybrid orthopedic implants.

Progress in bioactive surface coatings on biodegradable Mg alloys:A critical review towards clinical translation

Mg and its alloys evince strong candidature for biodegradable bone implants,cardiovascular stents,and wound closing devices.However,their rapid degradation rate causes premature implant failure,constraining clinical applications.Bio-functional surface coatings have emerged as the most competent strategy to fulfill the diverse clinical requirements,besides yielding effective corrosion resistance.This article reviews the progress of biodegradable and advanced surface coatings on Mg alloys investigated in recent years,aiming to build up a comprehensive knowledge framework of coating techniques,processing parameters,performance measures in terms of corrosion resistance,adhesion strength,and biocompatibility.Recently developed conversion and deposition type surface coatings are thoroughly discussed by reporting their essential therapeutic responses like osteogenesis,angiogenesis,cytocompatibility,hemocompatibility,anti-bacterial,and controlled drug release towards in-vitro and in-vivo study models.The challenges associated with metallic,ceramic and polymeric coatings along with merits and demerits of various coatings have been illustrated.The use of multilayered hybrid coating comprising a unique combination of organic and inorganic components has been emphasized with future perspectives to obtain diverse bio-functionalities in a facile single coating system for orthopedic implant applications.

Construction of tantalum/poly(ether imide)coatings on magnesium implants with both corrosion protection and osseointegration properties

Poly(ether imide)(PEI)has shown satisfactory corrosion protection capability with good adhesion strength as a coating for magnesium(Mg),a potential candidate of biodegradable orthopedic implant material.However,its innate hydrophobic property causes insufficient osteoblast affinity and a lack of osseointegration.Herein,we modify the physical and chemical properties of a PEI-coated Mg implant.A plasma immersion ion implantation technique is combined with direct current(DC)magnetron sputtering to introduce biologically compatible tantalum(Ta)onto the surface of the PEI coating.The PEI-coating layer is not damaged during this process owing to the extremely short processing time(30 s),retaining its high corrosion protection property and adhesion stability.The Ta-implanted layer(roughly 10-nm-thick)on the topmost PEI surface generates long-term surface hydrophilicity and favorable surface conditions for pre-osteoblasts to adhere,proliferate,and differentiate.Furthermore,in a rabbit femur study,the Ta/PEI-coated Mg implant demonstrates significantly enhanced bone tissue affinity and osseointegration capability.These results indicate that Ta/PEI-coated Mg is promising for achieving early mechanical fixation and long-term success in biodegradable orthopedic implant applications.

DNA structure, binding mechanism and biology functions of polypyridyl complexes in biomedicine

There is considerable research interest and vigorous debate about the DNA binding of polypyridyl complexes including the electron transfer involving DNA. In this review, based on the fluorescence quenching experiments, it was proposed that DNA might serve as a conductor. From the time-interval CD spectra, the different binding rates of Δ- and Λ-enantiomer to calf thymus DNA were observed. The factors influencing the DNA-binding of polypyridyl complexes, and the potential bio-functions of the complexes are also discussed.