Regulation Mechanism of Special Functional Groups Contained in Polymer Molecular Chains on the Tribological Properties of Modified Ti6Al4V

Polymer coatings can effectively improve the surface tribological properties of human implant materials, thereby increasing their service life. In this study, poly(vinylsulfonic acid, sodium salt) (PVS), poly(acrylic acid) (PAA) and poly(vinylphosphonic acid) (PVPA) were used to modify Ti6Al4V surfaces. Experimental analyses were combined with molecular simulation to explore the regulation mechanism of special functional groups contained in polymer molecular chains on the tribological properties of modified surfaces. In addition, the bearing capacities and velocity dependence of different polymer modified surfaces during friction were also explored. The PVS coating, due to physical adsorption, can have an anti-friction effect under NaCl solution lubrication, but is not durable under long-term or repeated usage. Both PAA and PVPA molecular chains can form chemical bonds with Ti6Al4V. Phosphate acid groups can firmly bind to the substrate, and the adsorption of salt ions and water molecules can form a hydrated layer on the PVPA coating surface, achieving ultra-low friction and wear. The adsorption of salt ions would aggravate the surface wear of the PAA-modified Ti6Al4V due to the unfirm binding of carboxyl groups to the substrate, resulting in a high friction coefficient. This study can provide effective guidance for the design of modified polymer coatings on metals.

A Versatile Hydrophilic and Antifouling Coating Based on Dopamine Modified Four-Arm Polyethylene Glycol by One-Step Synthesis Method

A versatile hydrophilic and antifouling coating was designed and prepared based on catechol-modified four-arm polyethylene glycol. The dopamine (DA) molecules were grafted onto the end of the four-arm polyethylene glycol carboxyl (4A-PEG-COOH) through the amidation reaction, which was proven by ¹H NMR and FTIR analysis, assisting the strong adhesion of PEG on the surface of various types of materials, including metallic, inorganic, and polymeric materials. The reduction of the water contact angle and the bacteria-repellent and protein-repellent effects indicated that the coating had good hydrophilicity and antifouling performance. Raman spectroscopy analysis demonstrated the affinity between the polymeric surface and water, which further confirmed the hydrophilicity of the coating. Finally, in vitro cytotoxicity assay demonstrated good biocompatibility of the coating layer.

[Research progress of antibacterial modification of orthopaedic implants surface]

OBJECTIVE

To summarize the related research progress of antibacterial modification of orthopaedic implants surface in recent years.

METHODS

The domestic and foreign related literature in recent years was extensively consulted, the research progress on antibacterial modification of orthopaedic implants surface was discussed from two aspects of characteristics of infection in orthopedic implants and surface anti-infection modification.

RESULTS

The orthopaedic implants infections are mainly related to aspects of bacterial adhesion, decreased host immunity, and surface biofilm formation. At present, the main antimicrobial coating methods of orthopaedic implants are antibacterial adhesion coating, antibiotic coating, inorganic antimicrobial coating, composite antimicrobial coating, nitric oxide coating, immunomodulation, three-dimensional printing, polymer antimicrobial coating, and "smart" coating.

CONCLUSION

The above-mentioned antibacterial coating methods of orthopedic implants can not only inhibit bacterial adhesion, but also solve the problems of low immunity and biofilm formation. However, its mechanism of action and modification are still controversial and require further research.

Bacterial Inhibition and Osteoblast Adhesion on Ti Alloy Surfaces Modified by Poly(PEGMA- r-Phosmer) Coating

We have synthesized and immobilized PEGMA₅₀₀-Phosmer to Ti6Al4V surfaces by a simple procedure to reduce bacteria-associated infection without degrading the cell response. Adhered bacteria coverage was lessened to 1% on polymer-coated surfaces when exposed to Escherichia coli, Staphylococcus epidermidis, and Streptococcus mutans. Moreover, PEGMA₅₀₀-Phosmer and homoPhosmer coatings presented better responses to MC3T3-E1 preosteoblast cells when compared with the results for PEGMA₂₀₀₀-Phosmer-coated and raw Ti alloy surfaces. The behavior of balancing bacterial inhibition and cell attraction of the PEGMA₅₀₀-Phosmer coating was explained by the grafted phosphate groups, with an appropriate PEG brush length facilitating greater levels of calcium deposition and further fibronectin adsorption when compared with that of the raw Ti alloy surface.

Site-specific grafting on titanium surfaces with hybrid temporin antibacterial peptides

Controlled orientation of silylated hybrid-temporins on titanium surfaces improved antibacterial activity.

A microporous Mg2+ MOF with cation exchange properties in a single-crystal-to-single-crystal fashion

A microporous Mg²⁺ MOF shows single-crystal-to-single-crystal exchange of Mg²⁺ by Cu²⁺ ions.

Dopamine-assisted deposition and zwitteration of hyaluronic acid for the nanoscale fabrication of low-fouling surfaces

In this study, we proposed a bioinspired approach for the deposition and zwitteration of hyaluronic acid (HA) with a reduced glutathione (GSH) to form a composite layer that functions as a low fouling coating.

Antifouling property of monothiol-terminated bottle-brush poly(methylacrylic acid)-graft-poly(2-methyl-2-oxazoline) copolymer on gold surfaces

A series of well-controlled bottle-brush poly(methylacrylic acid)-graft-poly(2-methyl-2-oxazoline) copolymers were grafted to gold surfaces through an in situ aminolysis reaction to reduce protein adsorption and platelet adhesion.

Pseudopeptide polymer coating for improving biocompatibility and corrosion resistance of 316L stainless steel

The coating formed by electrochemical assembly of hydrolyzed poly(2-methyl-2-oxazoline) and dopamine could improve the migration and proliferation of HUVECs.