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The mineralization of collagen scaffolds can improve their mechanical properties and biocompatibility, thereby providing an appropriate microenvironment for bone regeneration. The primary purpose of the present study is to fabricate a synergistically intra- and extrafibrillar mineralized collagen scaffold, which has many advantages in terms of biocompatibility, biomechanical properties, and further osteogenic potential. In this study, mineralized collagen scaffolds were fabricated using a traditional mineralization method (ie, immersed in simulated body fluid) as a control group and using a biomimetic method based on the polymer-induced liquid precursor process as an experimental group. In the polymer-induced liquid precursor process, a negatively charged polymer, carboxymethyl chitosan (CMC), was used to stabilize amorphous calcium phosphate (ACP) to form nanocomplexes of CMC/ACP. Collagen scaffolds mineralized based on the polymer-induced liquid precursor process were in gel form such that nanocomplexes of CMC/ACP can easily be drawn into the interstices of the collagen fibrils. Scanning electron microscopy and transmission electron microscopy were used to examine the porous micromorphology and synergistic mineralization pattern of the collagen scaffolds. Compared with simulated body fluid, nanocomplexes of CMC/ACP significantly increased the modulus of the collagen scaffolds. The results of in vitro experiments showed that the cell count and differentiated degrees in the experimental group were higher than those in the control group. Histological staining and micro-computed tomography showed that the amount of new bone regenerated in the experimental group was larger than that in the control group. The biomimetic mineralization will assist us in fabricating a novel collagen scaffold for clinical applications.

Surface microstructure and chemical composition of the implant are very important for its osseointegration in vivo. In this paper, a hierarchical micropattern covered with calcium phosphate (Ca/P phase) was obtained on titanium (Ti) implant surface by femtosecond lasers (FSL) irradiation in hydroxyapatite suspension. The hierachical micropattern as well as Ca/P phase increased osteoblastic cell adhesion. Higher expression of osteogenic markers (osteocalcin, osteopontin, and runt related transcription factor-2) on the surface treated by FSL of 2.55 J/cm(2) indicated the favorable effect of laser treatment on cell differentiation. In vivo studies were carried out to evaluate the effect of laser treatment and Ca/P deposition on the osseointegration. It showed that the binding capacity between bone and FSL-treated Ti implants was obviously stronger than that between bone and polished or sand blasting and acid etching (SLA) Ti implants. Bone trabecula surrounded the FSL-treated implants without fibrous tissue after 8-week implantation. Also, higher bone mineral density was seen surrounding the FSL-treated implants. Our in vitro and in vivo studies demonstrated that the FSL induced micropattern and Ca/P phase had positive effects on the acceleration of early osseointegration of Ti implants with bone tissue.

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Current dental implant research aims at seeking an innovative surface able to promote a more favorable biological response to the cells and tissues at the bone-implant interface and to accelerate osseointegration. Anodic oxidation is a promising method for acquiring nanotube structures on the implant surface. In this paper, we modified the titanium surface using anodic oxidation to form nanotube structures on the surface and observed the surface by scanning electron microscopy (SEM). The bioactivity of the Ti implants was evaluated by simulated body fluid soaking test. We further sought to characterize the cellular and molecular responses of murine preosteoblast MC3T3-E1 cells to anodic oxidation modified titanium surface with a nanotube-texture. Gene expression of osteoprotegrin (OPG) was also evaluated by reverse transcription-polymerase chain reaction (RT-PCR) and quantitative real-time PCR. SEM showed that the inner diameter of the nanotubes was about 70nm, the wall thickness was around 20nm, and the depth was about 200nm. The simulated body fluid soaking test displayed that bone-like apatite was formed on the nanotube-textured Ti surface after immersion in simulated body fluid for two weeks, but not on the smooth surface Ti surface. The biocompatibility was investigated by an in vitro cell culture test. Cell morphology exhibited a more differentiated characteristic, and gene expression of osteogenic markers OPG was also remarkably upregulated by anodic oxidation modification. Based on these results, it can be concluded that bioactivity and osteogenic responses to the nanotube-structured Ti surface were better than to the smooth surface, and gene expression indicates that OPG activation may be responsible for this increased osteogenic differentiation.

Although titanium material is currently widely used in dental and orthopedic application, the bio-inertness of Ti impairs its further use. We previously reported the good bioactivity and biocompatibility of TiO 2 nanotube layer fabricated by anodic oxidation technique using in vitro tests. In the present work, we further clarify the cell adhesion and osseointegration properties of anodized surface through both in vitro and in vivo tests. After anodic oxidation (AO), the structure of nanotubes was confirmed by scanning electron microscopy. The surface roughness and hydrophilic properties of the AO and pristine Ti surfaces were evaluated by atomic force microscopy and contact angle measurement test, respectively. It was found that the AO surface displayed moderately higher surface roughness and obviously increased wettability, compared to the original Ti surface. In vitro cellular activity tests demonstrated that osteoblast cells cultured on the AO surface exhibited a much well-spread cytoskeleton organization with more stretched actin filaments, compared to those cultured on the Ti surface. The adherent cell number was also higher on the AO surface than the pure Ti substrate. In addition, we explore the molecular basis of mechanism by analyzing gene expression levels of adhesion and osteogenesis-related genes in MC3T3-E1 cells cultured on different surfaces using quantitative real-time PCR. Increased mRNA levels of vinculin, collagen type 1, osteopontin and osteocalcin were found on the AO surface, compared with the control group. Furthermore, in vivo animal experiment using a rat model revealed that anodized implant surface promotes osseointegration and demonstrated higher bone bonding strength compared to the pure Ti substrate. Our study revealed the superior cell adhesion property, increased adherent and osteogenesis-related gene expressions and enhanced osseointegration by anodized surface, thus implying its enlarged application in future.

The objective of this study was to investigate the effects of cryo-treatment on the microstructure, corrosion behavior, and mechanical properties of Ti before and after laser welding. The microstructure was studied by optical microscopy. It was found that the grain size for Ti became smaller after cryo-treatment. Cryo-treatment could also refine and stabilize the crystal lattice structure and distribute precipitate particles throughout the material in the welded metal. Potentiodynamic polarization measurements were employed to investigate the corrosion behavior in an artificial saliva solution. Electrochemical results showed that the laser-welded Ti after cryo-treatment exhibited the most obvious passivation behavior of all the specimens. The mechanical properties of Ti, cryo-treated Ti (C-Ti), laser-welded Ti (W-Ti), and cryo-treated, laser-welded Ti (CW-Ti) were characterized by tensile tests. It was found that the tensile strength and elongation could be improved for Ti and laser-welded Ti by cryo-treatment without impairing its corrosion resistance.