Biocompatibility and osteogenic potential of choline phosphate chitosan-coated biodegradable Zn1Mg.

Zinc alloys have demonstrated considerable potentials as implant materials for biodegradable vascular and orthopedic applications. However, the high initial release of Zn2+ can trigger intense immune responses that impede tissue healing. To address this challenge and enhance the osteogenic capacity of zinc alloys, the surface of Zn1Mg was subjected to CO2 plasma modification (Zn1Mg-PP) followed by grafting with choline phosphate chitosan (Zn1Mg-PP-PCCs). This study aims to investigate the in vitro and in vivo biocompatibility of the surface-modified Zn1Mg. The effect of the surface modification on the inflammatory response and osteogenic repair process was investigated. Compared with unmodified Zn1Mg, the degradation rate of Zn1Mg-PP-PCCs was significantly decreased, avoiding the cytotoxicity triggered by the release of large amounts of Zn2+. Moreover, PCCs significantly enhanced the cell-material adhesion, promoted the proliferation of osteoblasts (MC3T3-E1) and upregulated the expression of key osteogenic factors in vitro. Notably, the in vivo experiments revealed that the surface modification of Zn1Mg suppressed inhibited the expression of inflammatory cytokines, promoting the secretion of anti-inflammatory factors, thereby reducing inflammation and promoting bone tissue repair. Furthermore, histological analysis of tissue sections exhibited strong integration between the material and the bone, along with well-defined new bone formation and reduced osteoclast aggregation on the surface. This was attributed to the improved immune microenvironment by PCCs, which promoted osteogenic differentiation of osteoblasts. These findings highlight that the preparation of PCCs coatings on zinc alloy surfaces effectively inhibited ion release and modulated the immune environment to promote bone tissue repair. STATEMENT OF SIGNIFICANCE: Surface modification of biodegradable Zn alloys facilitates the suppression of intense immune responses caused by excessive ion release concentrations from implants. We modified the surface of Zn1Mg with choline phosphate chitosan (PCCs) and investigated the effects of surface modification on the inflammatory response and osteogenic repair process. In vitro results showed that the PCCs coating effectively reduced the degradation rate of Zn1Mg to avoid cytotoxicity caused by high Zn2+ concentration, favoring the proliferation of osteoblasts. In addition, in vivo results indicated that Zn1Mg-PP-PCCs attenuated inflammation to promote bone repair by modulating the release of inflammation-related factors. The surface-modified Zn1Mg implants demonstrated strong osseointegration, indicating that the PCCs coating effectively modulated the immune microenvironment and promoted bone healing.

Effects of Zr Addition on the Microstructural Evolution, Mechanical Properties, and Corrosion Behavior of Novel Biomedical Ti-Zr-Mo-Mn Alloys.

ß-Type Ti alloys have been widely investigated as implant materials owing to their excellent mechanical properties, corrosion resistance, and biocompatibility. In the present work, the effects of Zr on the microstructure, mechanical properties, and corrosion behaviors of Ti-Zr-Mo-Mn alloys were systematically studied. With the increase of Zr content, the phase composition gradually changed from intragranular-α + ß of (TZ)5:1MM alloy to grain-boundary-α + ß of (TZ)2:1MM alloy and finally transferred to a single ß phase structure of (TZ)1:1MM alloy. The (TZ)1:1MM alloy exhibited a good mechanical combination with a yield strength of 750.8 MPa, an elastic modulus of 61.3 GPa, and a tensile ductility of 14.6%. Moreover, the addition of Zr can effectively stabilize the passivation film and reduce the sensitivity of microgalvanic corrosion in simulated body fluid, leading to enhanced corrosion resistance in the TZMM alloys. X-ray photoelectron spectroscopy analysis together with the ion-sputtering technique revealed that the passivation films formed on TZMM alloys possessed a bilayered structure (outer Ti+Zr mixed-oxide layer and inner Zr-oxide-rich layer), in which the inner Zr oxide layer plays an important role in the corrosion resistance of the TZMM alloys. In vitro biocompatibility evaluations demonstrated that the TZMM alloys can support cell adhesion and proliferation with high biocompatibility comparable to that of CP-Ti, while in vivo biocompatibility evaluations validated the bone osteointegration ability of TZMM alloys after long-term implantation. The above results indicate that novel TZMM alloys are promising candidates for implant material.

Cartilage-inspired terpolymer hydrogel with excellent mechanical properties and superior lubricating ability.

Osteoarthritis (OA), the most common degenerative joint disorder, seriously affects patients' daily activities. Recently, hydrogels, due to their similar structure to articular cartilage, have shown great potential as cartilage-repairing materials. In the present work, we developed a simple process for fabricating terpolymer [P(acrylamide-co-acrylic acid-co-2-acrylamido-2-methyl-1-propanesulfonic acid)/Fe3+] hydrogel [P(AAm-co-AAc-co-AMPS)/Fe3+]. The content of AMPS was found to show a crucial effect on the mechanical and tribological performance of the terpolymer hydrogel. When the content of AMPS was 0.45 mol L-1, the compressive strength, modulus, and friction coefficient of the terpolymer hydrogel were 66.60 ± 1.79 MPa, 2.10 ± 0.16 MPa, and 0.032, respectively. In addition, the hydrogel showed high wear durability and the friction coefficient was as low as 0.038 after 3.6 × 105 sliding cycles.

Carboxymethyl chitosan-zinc coating for prevention of pin tract infection: An animal model.

BACKGROUND: Pin tract infection is a common problem in orthopedic and traumatology surgery. The aim of this study was to investigate the efficacy of an implant coated with carboxymethyl chitosan-zinc (CMC-Zn2+) in prevention of pin tract infection. MATERIALS AND METHODS: Twenty-four male New Zealand White rabbits were randomized into two equal groups ( n = 12, uncoated and CMC-Zn2+). The implants were colonized with 1 × 106 colony forming units of Staphylococcus aureus and inserted into the lateral right proximal tibia in each rabbit. In each group, at 2 and 4 weeks post-surgery, five and seven rabbits were killed, respectively, to harvest the soft tissues around the implant as well as the hard tissue for histological analysis. The bone cross-sectional view, X-ray, and micro-computed tomography (µCT) were performed. RESULTS: The surgical sites in each animal were evaluated individually at both time points. No evident signs of infections were found in the CMC-Zn2+ group, while a high rate of infection was observed in the uncoated group where minor infections were 85.71% ( n = 12) and major infections 14.29% ( n = 12). The radiography, µCT, and histological analysis showed no evident signs of infection in both groups at 2 weeks post-surgery. However, at 4 weeks, signs of infection were found in all the animals in the uncoated group, whereas in the CMC-Zn2+ group, no infections were observed. The difference between the two groups was highly significant ( p = 0.00). CONCLUSIONS: Our study showed that CMC-Zn2+-coated implants were effective in preventing pin tract infection.

Study on machinable glass-ceramic containing fluorophlogopite for dental CAD/CAM system.

The glass-ceramic mainly containing fluorophlogopite is one of widely used dental ceramics. In the K2O-CaO-MgO-Al2O3-SiO2-F system, a new-type glass-ceramic containing fluorophlogopite Ca-mica has been synthesized. Its crystalline was studied by XRD and EDS. The fluorophlogopite whose formula postulated K(1 - X )Ca( X/2)Mg(3)AlSi(3)O(10)F(2) was its main crystalline. The microstructure of the glass-ceramic displayed typical machinable microstructure with lath like crystals isolated and interlocking with different aspect ratio. The material also showed better bending strength (228.11 +/- 7.55 MPa). It took less than 12 minutes to fabricate a whole crown by dental CAD/CAM system with the glass-ceramic.