Objective To research in vitro biocompatibility of silicon containing micro-arc oxidation (MAO) coated magnesium alloy ZK60 with osteoblasts. Methods The surface microstructure of silicon containing MAO coated magnesium alloy ZK60 was observed by a scanning electron microscopy (SEM), and chemical composition of the coating surface was determined by energy dispersive spectrum analysis. The experiments were divided into 4 groups: silicon containing MAO coated magnesium alloy ZK60 group (group A), uncoated magnesium alloy ZK60 group (group B), titanium alloy group (group C), and negative control group (group D). Extracts were prepared respectively with the surface area to extraction medium ratio (1.25 cm2/ mL) according to ISO 10993-12 standard in groups A, B, and C, and were used to culture osteoblasts MC3T3-E1. The α-MEM medium supplemented with 10% fetal bovine serum was used as negative control in group D. The cell morphology was observed by inverted phase contrast microscopy. MTT assay was used to determine the cell viability. The activity of alkaline phosphatase (ALP) was detected. Cell attachment morphology on the surface of different samples was observed by SEM. The capability of protein adsorption of the coating surface was assayed, then DAPI and calcein-AM/ethidium homodimer 1 (calcein-AM/EthD-1) staining were carried out to observe cell adhesion and growth status. Results The surface characterization showed a rough and porous layer with major composition of Mg, O, and Si on the surface of silicon containing MAO coated magnesium alloy ZK60 by SEM. After cultured with the extract, cells grew well and presented good shape in all groups by inverted phase contrast microscopy, group A was even better than the other groups. At 5 days, MTT assay showed that group A presented a higher cell proliferation than the other groups (P lt; 0.05). Osteoblasts in groups A and C presented a better cell extension than group B under SEM, and group A exhibited better cell adhesion and affinity. Protein adsorption in group A [ (152.7 ± 6.3) µg/mL] was significantly higher than that of group B [(96.3 ± 3.9) µg/mL] and group C [ (96.1 ± 8.7) µg/mL] (P lt; 0.05). At each time point, the adherent cells on the sample surface of group A were significantly more than those of groups B and C (P lt; 0.05). The calcein-AM/EthD-1 staining showed that groups A and C presented better cell adhesion and growth status than group B. The ALP activities in groups A and B were 15.55 ± 0.29 and 13.75 ± 0.44 respectively, which were significantly higher than those in group C (10.43 ± 0.79) and group D (10.73 ± 0.47) (P lt; 0.05), and group A was significantly higher than group B (P lt; 0.05). Conclusion The silicon containing MAO coated magnesium alloy ZK60 has obvious promoting effects on the proliferation, adhesion, and differentiation of osteoblasts, showing a good biocompatibility, so it might be an ideal surface modification method on magnesium alloys.
Objective To investigate the antibacterial and osteogenic capabil ities in vivo of hydroxyapatite (HA)/silver (Ag) coating. Methods HA/Ag coating (Ag qual ity percentage was 3%) and HA coating were deposited to external fixator Schanz screws. The tibial fracture model was establ ished in right hindl imb of 18 adult male Beagle dogs (weighing 15-20 kg). Thetibia was stabil ized with an external fixator and 2 Schanz screws of HA coating at proximal tibia (control group, n=18) and HA/Ag coating at distal tibia (experimental group, n=18), and every screw incision was infected with Staphylococcus aureus. Infection in screw holes and the changes of bone-screw interface were observed by wound grading and X-ray films. Results In control group, wounds infection became worse with time (χ2=13.492, P=0.001), while in experimental group, no obvious change was observed (χ2=0.208, P=0.901). The wound grading of experimental group was significantly better than that of the control group at 1, 2, and 3 weeks (P lt; 0.05). Laser scanning confocal microscope showed that there was bacterial adhesion on the surface of screws in 2 groups, viable becteria mainly in control group and non-viable becteria mainly in experimental group. The scanning electron microscope (SEM) observation results of the fractured sclerous tissue section showed that an obvious transparent boundary between screw and bone in control group, but no obvious boundary in experimental group. The osseointegration ratios were 76.23% ± 15.54% in control group and 93.42% ± 5.53% in experimental group, showing significant difference (t=8.843, P=0.000). The SEM observation showed that HA/Ag coating integrated with new bone and the surface of implant was filled with new bone in experimental group; obvious interspace was seen between the HA coating and new bone in control group. Conclusion HA/Ag coating has good antibacterial and osteogenic capabil ities, so it can take effects in preventing infection in screw holes and loosening of implants.
Objective Surface modification of nitinol (NiTi) shape memory alloy is an available method to prevent nickel ion release and coating with titanium-niobium (TiNb) alloy will not affect the superelasticity and shape memory of NiTi. To evaluate the bone histocompatibil ity of NiTi shape memory alloy implants coated by TiNb in vivo. Methods NiTi memory alloy columns which were 4 mm in diameter and 12 mm in length were coated with Ti (Ti-coating group) and TiNb alloy (TiNb-coating group) respectively by magnetron sputtering technique. And NiTi group were not coated on the surface. Fifteen mongrel dogs were divided into 3 groups randomly with 5 dogs in each group. NiTi, Ti-coating and TiNb-coating columns were implanted into the lateral femoral cortex of each group, respectively. There were 10 columns embedded in eachdog’s femur whose distance was 1.0 cm to 1.5 cm from each other. The materials were obtained 12 months after operation. After X-ray photography, only those columns which were perpendicular to the cortex of the femur shaft were selected for subsequent analysis. Push-out tests were performed to attain the maximum shear strength (the number of specimens of TiNi group, Ticoating group, and TiNb-coating group were 12, 10, and 14, respectively). Undecalcified sections were used for histological observation and the calculation of osseointegration rate (the number of specimens of TiNi group, Ti-coating group, and TiNb-coating group were 8, 5, and 10, respectively). Results The maximum shear strength of Ti-coating group (95.10 ± 10.03) MPa, and TiNb-coating group (91.20 ± 15.42) MPa were significantly higher than that of NiTi group (71.60 ± 14.24) MPa (P lt; 0.01). Gimesa staining showed that no obvious macrophage and inflammation cell was observed in 3 groups. The osseointegration rates of NiTi group, Ti-coating group, and TiNb-coating group were (21.30% ± 0.23%), (32.50% ± 0.31%), and (38.60% ± 0.58%), respectively; there were significant differences among 3 groups (P lt; 0.01). Conclusion The implants of 3 groups all have good bone histocompatabil ity. But the osseointegration rate and the shear strength in the Ti-coating group and the TiNb-coating group were better than those in the NiTi group, the TiNb-coating group is the best among them.
Objective To prepare silver-containing hydroxyapatite coating (hydroxyapatite/Ag, HA/Ag) and investigate its antibacterial property and biocompatibil ity in vitro. Methods Vacuum plasma spraying technique was adopted to prepare HA/Ag coating on titanium alloy substrate (3% Ag). After incubating the HA/Ag and the HA coating under staphylococcus aureus and pseudomonas aeruginosa suspensions of 2% tryptic soy broth (TBS) medium for 2, 4 and 7 days, respectively, the biofilm on the coatings was examined by confocal laser scanning microscope, and the bacterial density and viable bacterial percentage of bacterial biofilm were calculated. Meanwhile, the micro-morphology of bacterial biofilm was observed by SEM, the cytotoxicity was detected via MTT and the biocompatibil ity of biofilm was evaluated by acute aemolysis test. Results Compared with HA coating, the bacterial biofilm’s thickness on the surface of HA/Ag coating witnessed no significant difference at 2 days after culture (Pgt; 0.05), but decreased obviously at 4 and 7 days after culture (P lt; 0.01). The bacterial density of the biofilm increased with time, but there was no significant difference between two coatings (P gt; 0.05) at 2, 4 and 7 days after culture. The viable bacterial percentage of the biofilms on the surface of HA/Ag coating decreased obviously compared with that of HA coating at 2, 4 and 7 days after cultureP lt; 0.01). The MTT notified the cytotoxic grade of both coatings was zero. The acute haemolysis assay showed that the hemolytic rate of HA/Ag and HA coating was 0.19% and 0.12%, respectively. Conclusion With good biocompatibil ity, significant antibacterial property against staphylococcus aureus and pseudomonas aeruginosa, no obvious cytotoxicity and no erythrocyte destruction, the vacuum plasma sprayed HA/Ag coating is a promising candidate for the surface of orthopedic metal implants to improve their osseointegration and antibacterial property.
Objective To understand the value of pre-coating in artificial vessel endothelialization. Methods Literature concerning precoating in artificial vessel endothelialization was extensively reviewed. Results Pre-coating included chemical coatings(collagen, fibronectin, laminin, poly-l-lysin, gelatin andextracellular matrix), pre-clotting(plasma, blood, serum and fibrin glue), chemical bonding (heparin, RGD and lectins) and surface modification. Most of them could enhance the adhesion of the endothelial cells. Conclusion Pre-coating couldimprove endothelialization, but further research is needed to search for the appropriate concentration and incubation time.
An oxide ceramic coating can be formed on the surface of magnesium alloy by micro-arc oxidation so that the corrosion resistance of the magnesium alloy can be enhanced. In this paper, a general overview of the surface treatment of micro-arc oxidation on the surface of magnesium alloy is presented, the related research on the treatment of several kinds of magnesium alloys is introduced in detail, and a brief introduction of biological activity of magnesium alloy due to micro-arc oxidation is given. Finally, the technical advantages and existing problems are summarized.
Objective To investigate the research progress of drug-loaded antibacterial coating of orthopedic metal implants in recent years. Methods The recent literature on the drug-loaded antibacterial coating of orthopedic metal implants were reviewed. The research status, classification, and development trend of drug-loaded antibacterial coating were summarized. Results The drug-loaded antibacterial coating of orthopedic metal implants can be divided into passive release type and active release type according to the mode of drug release. Passive drug release coating can release the drug continuously regardless of whether the presence of bacteria around the implants. Active drug release coating do not release the drug unless the presence of bacteria around the implants. Conclusion The sustained and stable release of drugs is a key problem to be solved in various antibacterial coatings research. The intelligent antibacterial coating which release antibiotics only in the presence of bacteria is the future direction of development.
A diblock copolymer, poly(ethylene glycol) methacrylate-block-glycidyl methacrylate (PEGMA-GMA), was prepared on glass substrate by surface-initiated atom transfer radical polymerization (SI-ATRP), and endothelial specific peptide Arg-Glu-Asp-Val (REDV) was immobilized at the end of the PEGMA-GMA polymer brush by ring opening reaction through the rich epoxy groups in the GMA. The structure and hydrophilicity of the polymer brushes were characterized by static water contact angle, X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The results showed that the REDV modified copolymer brushes were successfully constructed on the glass substrates. The REDV peptide immobilized onto surface was quantitatively characterized by ultraviolet–visible spectroscopy (UV-VIS). The blood compatibility of the coating was characterized by recalcification time and platelet adhesion assay. The results showed that the polymer coating had good blood compatibility. The multifunctional active polymer coating with PEGMA and peptide produced an excellent prospect in surface construction with endothelial cells selectivity.
ObjectiveThe antibacterial properties of porous medical implant materials were reviewed to provide guidance for further improvement of new medical implant materials.MethodsThe literature related to the antibacterial properties of porous medical implant materials in recent years was consulted, and the classification, characteristics and applications, and antibacterial methods of porous medical implant materials were reviewed.ResultsPorous medical implant materials can be classified according to surface pore size, preparation process, degree of degradation in vivo, and material source. It is widely used in the medical field due to its good biocompatibility and biomechanical properties. Nevertheless, the antibacterial properties of porous medical implant materials themselves are not obvious, and their antibacterial properties need to be improved through structural modification, overall modification, and coating modification.ConclusionAt present, coating modification as the mainstream modification method for improving the antibacterial properties of porous medical materials is still a research hotspot. The introduction of new antibacterial substances provides a new perspective for the development of new coated porous medical implant materials, so that the porous medical implant materials have a more reliable antibacterial effect while taking into account biocompatibility.
Objective To investigate the physicochemical properties of pure titanium surface grafted with chlorhexidine (CHX) by phenolamine coating, and to evaluate its antibacterial activity and osteoblast-compatibility in vitro. MethodsControl group was obtained by alkali and thermal treatment, and then immersed in the mixture of epigallocatechin-3-gallate/hexamethylene diamine (coating group). Phenolamine coating was deposited on the surface, and then it was immersed in CHX solution to obtain the grafted surface of CHX (grafting group). The surface morphology was observed by scanning electron microscope, the surface element composition was analyzed by X-ray photoelectron spectroscopy, and the surface hydrophilicity was measured by water contact angle test. Live/dead bacterial staining, nephelometery, and inhibition zone method were executed to evaluate the antibacterial property. Cytotoxicity was evaluated by MTT assay and cell fluorescence staining. Bacteria-MC3T3-E1 cells co‐culture was conducted to evaluate the cell viability on the samples under the circumstance with bacteria. Results Scanning electron microscope observation results showed that deposits of coating group and grafting group increased successively and gradually covered the porous structure. X-ray photoelectron spectroscopy results showed the peak of N1s enhanced and the peak of Cl2p appeared in grafting group. Water contact angle test results showed that the hydrophilic angle of three groups increased in turn, and there was significant difference between groups (P<0.05). Live/dead bacteria staining results showed that the grafting group had the least amount of bacteria adhered to the surface and the proportion of dead bacteria was high. The grafting group had a transparent inhibition zone around it and the absorbance (A) value did not increase, showing significant difference when compared with control group and coating group (P<0.05). MTT assay and cell fluorescence staining results showed that the number of adherent cells on the surface of the grafting group was the least, but the adherent cells had good proliferation activity. Bacteria-cell co-culture results showed that there was no bacteria on the surface of grafting group but live cells adhered well. ConclusionCHX-grafted phenolamine coating has the ability to inhibit bacterial adhesion and proliferation, and effectively protect cell adhesion and proliferation in a bacterial environment.