[Progress in antibacterial coatings of titanium implants surfaces].

In recent years, bone implant materials such as titanium and titanium alloys have been widely used in the biomedical field due to their excellent mechanical properties and good biocompatibility. However, in clinical practice, bacterial adhesion to the material surface and postoperative infection issues may lead to implantation failure. Based on the antibacterial mechanism, this review elaborated on the antibacterial surface design of titanium implants from the aspects of anti-bacterial adhesion, contact sterilization and photocontrol sterilization. Surface modification of titanium or titanium-based alloy implants with different techniques can inhibit bacteria and promote osseointegration. Thus, the application range of multifunctional titanium-based implants in the field of orthopedics will be expanded.

[Progress in preparation and application of sodium alginate microspheres].

Sodium alginate (SA) is a kind of natural polymer material extracted from kelp, which has excellent biocompatibility, non-toxicity, biodegradability and abundant storage capacity. The formation condition of sodium alginate gel is mild, effectively avoiding the inactivation of active substances. After a variety of preparation methods, sodium alginate microspheres are widely used in the fields of biomaterials and tissue engineering. This paper reviewed the common methods of preparing alginate microspheres, including extrusion, emulsification, electrostatic spraying, spray drying and coaxial airflow, and discussed their applications in biomedical fields such as bone repair, hemostasis and drug delivery.

In vitro corrosion and cytocompatibility of Mg-Zn-Ca alloys coated with FHA.

In the field of orthopedics, it's crucial to effectively slow down the degradation rate of Mg alloys. This study aims to improve the degradation behavior of Mg-Zn-Ca alloys by electrodepositing fluorohydroxyapatite (FHA). We investigated the microstructure and bond strength of the deposition, as well as degradation and cellular reactions. After 15-30 days of degradation in Hanks solution, FHA deposited alloys showed enhanced stability and less pH change. The strong interfacial bond between FHA and the Mg-Zn-Ca substrate was verified through scratch tests (Critical loads: 10.73 ± 0.014 N in Mg-Zn-0.5Ca alloys). Cellular studies demonstrated that FHA-coated alloys exhibited good cytocompatibility and promoted the growth of MC3T3-E1 cells. Further tests showed FHA-coated alloys owed improved early bone mineralization and osteogenic properties, especially in Mg-Zn-0.5Ca. This research highlighted the potential of FHA-coated Mg-Zn-0.5Ca alloys in orthopedics applications.

Hydroxyapatite/Polyurethane Scaffolds for Bone Tissue Engineering.

Polyurethane (PU) and PU ceramic scaffolds are the principal materials investigated for developing synthetic bone materials due to their excellent biocompatibility and biodegradability. PU has been combined with calcium phosphate (such as hydroxyapatite [HA] and tricalcium phosphate) to prepare scaffolds with enhanced mechanical properties and biocompatibility. This article reviews the latest progress in the design, synthesis, modification, and biological attributes of HA/PU scaffolds for bone tissue engineering. Diverse HA/PU scaffolds have been proposed and discussed in terms of their osteogenic, antimicrobial, biocompatibility, and bioactivities. The application progress of HA/PU scaffolds in bone tissue engineering is predominantly introduced, including bone repair, bone defect filling, drug delivery, and long-term implants.

Improving osseointegration and antimicrobial properties of titanium implants with black phosphorus nanosheets-hydroxyapatite composite coatings for vascularized bone regeneration.

For decades, titanium implants have shown impressive advantages in bone repair. However, the preparation of implants with excellent antimicrobial properties as well as better osseointegration ability remains difficult for clinical application. In this study, black phosphorus nanosheets (BPNSs) were doped into hydroxyapatite (HA) coatings using electrophoretic deposition. The coatings' surface morphology, roughness, water contact angle, photothermal properties, and antibacterial properties were investigated. The BP/HA coating exhibited a surface roughness of 59.1 nm, providing an ideal substrate for cell attachment and growth. The water contact angle on the BP/HA coating was measured to be approximately 8.55°, indicating its hydrophilic nature. The BPNSs demonstrated efficient photothermal conversion, with a temperature increase of 42.2°C under laser irradiation. The BP/HA composite coating exhibited a significant reduction in bacterial growth, with inhibition rates of 95.6% and 96.1% against Staphylococcus aureus and Escherichia coli. In addition, the cytocompatibility of the composite coating was evaluated by cell adhesion, CCK8 and AM/PI staining; the effect of the composite coating in promoting angiogenesis was assessed by scratch assay, transwell assay, and protein blotting; and the osteoinductivity of the composite coating was evaluated by alkaline phosphatase assay, alizarin red staining, and Western blot. The results showed that the BP/HA composite coating exhibited superior performance in promoting biological functions such as cell proliferation and adhesion, antibacterial activity, osteogenic differentiation, and angiogenesis, and had potential applications in vascularized bone regeneration.

Calcium Phosphate Bone Cements Incorporated with Black Phosphorus Nanosheets Enhanced Osteogenesis.

For decades, calcium phosphate bone cements (CPCs) showed impressive advantages for their good biocompatibility, injectability, and osteoconductivity in the bone repair field. However, it is still difficult to prepare CPCs with outstanding antibacterial and self-curing properties, sufficient phosphorus release, and osteoinductivity for clinical application. Herein, we used partially crystallized calcium phosphate and dicalcium phosphate anhydrate particles incorporated with black phosphorous nanosheets to prepare calcium phosphate bone cements (CPCs). The curing time, compressive strength, photothermal properties, and degradation performance of BP/CPC were investigated. In addition, the cytocompatibility and osteoinductivity of BP/CPC were evaluated by cell adhesion, cytotoxicity, alkaline phosphatase detection, alizarin red staining, and western blot assay. The results indicated that BP/CPC showed adjustable curing time, good cytocompatibility, outstanding photothermal properties, and osteoinductivity, suggesting their potential application for bone regeneration.

Bifunctional electrospun poly (L-lactic acid) membranes incorporating black phosphorus nanosheets and nano-zinc oxide for enhanced biocompatibility and antibacterial properties in catheter materials.

For several decades, urinary tract infections caused by catheter-associated devices have negatively impacted not only medical device utilization, but also patient health. As such, the creation of catheter materials with both superior biocompatibility and antibacterial properties has become necessary. This study aimed to produce electrospun membranes based on polylactic acid (PLA) with the incorporation of black phosphorus nanosheets (BPNS) and nano-zinc oxide (nZnO) particles, as well as a mixture of both, in order to design bifunctional membranes with enhanced bioactivity and antibacterial features. The optimum spinning process was determined through examination of various PLA mass concentrations, spinning solution propelling speeds, and receiving drum rotating speeds, with emphasis on the mechanical properties of PLA membranes. Additionally, the antibacterial properties and cytocompatibility of the ZnO-BP/PLA antibacterial membranes were explored. Results demonstrated that the ZnO-BP/PLA antibacterial membranes displayed a rich porous structure, with uniform distribution of nZnO particles and BPNS. With the increase of polylactic acid concentration and the decrease of spinning solution advancing and drum rotation speeds, the mechanical properties of the fiber membrane were significantly improved. Furthermore, the composite membranes exhibited remarkable photothermal therapy (PTT) capabilities when aided by the synergistic effect of BP nanosheets and ZnO. This was achieved through near-infrared (NIR) irradiation, which not only dissipated the biofilm but also enhanced the release capability of Zn2+. Consequently, the composite membrane demonstrated an improved inhibitory effect on both Escherichia coli and Staphylococcus aureus. The results of cytotoxicity and adhesion experiments also indicated good cytocompatibility, with cells growing normally on the surface of the ZnO-BP/PLA antibacterial membrane. Overall, these findings validate the utilization of both BPNS and n-ZnO fillers in the creation of novel bifunctional PLA-based membranes, which possess both biocompatibility and antibacterial properties for interventional catheter materials.

Abundant tannic acid modified gelatin/sodium alginate biocomposite hydrogels with high toughness, antifreezing, antioxidant and antibacterial properties.

The acidity of high tannic acid (TA) content solution can destroy the structure of protein, such as gelatin (G). This causes a big challenge to introduce abundant TA into the G-based hydrogels. Here, the G-based hydrogel system with abundant TA as hydrogen bonds provider was constructed by a "protective film" strategy. The protective film around the composite hydrogel was first formed by the chelation of sodium alginate (SA) and Ca2+. Subsequently, abundant TA and Ca2+ were successively introduced into the hydrogel system by immersing method. This strategy effectively protected the structure of the designed hydrogel. After treatment with 0.3 w/v TA and 0.06 w/v Ca2+ solutions, the tensile modulus, elongation at break and toughness of G/SA hydrogel increased about 4-, 2-, and 6-fold, respectively. Besides, G/SA-TA/Ca2+ hydrogels exhibited good water retention, anti-freezing, antioxidant, antibacterial properties and low hemolysis ratio. Cell experiments showed that G/SA-TA/Ca2+ hydrogels possessed good biocompatibility and could promote cell migration. Therefore, G/SA-TA/Ca2+ hydrogels are expected to be used in the field of biomedical engineering. The strategy proposed in this work also provides a new idea for improving the properties of other protein-based hydrogels.

Electrospun polyamide-6/chitosan nanofibers reinforced nano-hydroxyapatite/polyamide-6 composite bilayered membranes for guided bone regeneration.

Periodontal defect poses a significant challenge in orthopedics. Guided Bone Regeneration (GBR) membrane is considered as one of the most successful methods applied to reconstruct alveolar bone and then to achieve periodontal defect repair/regeneration. In this paper, a novel polyamide-6/chitosan@nano-hydroxyapatite/polyamide-6 (PA6/CS@n-HA/PA6) bilayered tissue guided membranes by combining a solvent casting and an electrospinning technique was designed. The developed PA6/CS@n-HA/PA6 composites were characterized by a series of tests. The results show that n-HA/PA6 and electrospun PA6/CS layers are tightly bound by molecular interaction and chemical bonding, which enhances the bonding strength between two distinct layers. The porosity and adsorption average pore diameter of the PA6/CS@n-HA/PA6 membranes are 36.90 % and 22.61 nm, respectively. The tensile strength and elastic modulus of PA6/CS@n-HA/PA6 composites are 1.41 ± 0.18 MPa and 7.15 ± 1.09 MPa, respectively. In vitro cell culture studies demonstrate that PA6/CS@n-HA/PA6 bilayered scaffolds have biological safety, good bioactivity, biocompatibility and osteoconductivity.

Climbing-inspired twining electrodes using shape memory for peripheral nerve stimulation and recording.

Peripheral neuromodulation has been widely used throughout clinical practices and basic neuroscience research. However, the mechanical and geometrical mismatches at current electrode-nerve interfaces and complicated surgical implantation often induce irreversible neural damage, such as axonal degradation. Here, compatible with traditional 2D planar processing, we propose a 3D twining electrode by integrating stretchable mesh serpentine wires onto a flexible shape memory substrate, which has permanent shape reconfigurability (from 2D to 3D), distinct elastic modulus controllability (from ~100 MPa to ~300 kPa), and shape memory recoverability at body temperature. Similar to the climbing process of twining plants, the temporarily flattened 2D stiff twining electrode can naturally self-climb onto nerves driven by 37°C normal saline and form 3D flexible neural interfaces with minimal constraint on the deforming nerves. In vivo animal experiments, including right vagus nerve stimulation for reducing the heart rate and action potential recording of the sciatic nerve, demonstrate the potential clinical utility.