Evaluation of layer-by-layer assembly systems for drug delivery and antimicrobial properties in orthopaedic application.

Layer-by-layer self-assembly systems were developed using monolayer and multilayer carriers to prevent infections and improve bone regeneration of porous Ti-6Al-4V scaffolds. These polymeric carriers incorporated (Gel/Alg-IGF-1 + Chi-Cef) and (4Gel/Alg-IGF-1 + Chi-Cef) on the surface of porous implants produced via electron beam melting (EBM). The results showed that the drug release from multilayer carriers was higher than that of monolayers after 14 days. However, the carrier containing Gel/Alg-IGF-1 + Chi-Cef exhibited more sustained behavior. Cell morphology was characterized, revealing that multilayer carriers had higher cell adhesion than monolayers. Additionally, cell differentiation was significantly greater for (Gel/Alg-IGF-1) + Chi-Cef, and (4Gel/Alg-IGF-1) + Chi-Cef multilayer carriers than for the monolayer groups after 7 days. Notably, the drug dosage was effective and did not interfere, and the cell viability assay showed safe results. Antibacterial evaluations demonstrated that both multilayer carriers had a greater effect on Staphylococcus aureus during treatment. The carriers containing lower alginate had notably less effect than the other studied carriers. This study aimed to test systems for controlling drug release, which will be applied to improve MG63 cell behavior and prevent bacterial accumulation during orthopaedic applications.

Influence of Proteins and Building Direction on the Corrosion and Tribocorrosion of CoCrMo Fabricated by Laser Powder Bed Fusion.

Cobalt-chromium-molybdenum (CoCrMo) alloys are common wear-exposed biomedical alloys and are manufactured in multiple ways, increasingly using additive manufacturing processes such as laser powder bed fusion (LPBF). Here, we investigate the effect of proteins and the manufacturing process (wrought vs LPBF) and building orientation (LPBF-XY and XZ) on the corrosion, metal release, tribocorrosion, and surface oxide composition by means of electrochemical, mechanical, microscopic, diffractive, and spectroscopic methods. The study was conducted at pH 7.3 in 5 g/L NaCl and 5 mM 2-(N-morpholino) ethanesulfonic acid (MES) buffer, which was found to be necessary to avoid metal phosphate and metal-protein aggregate precipitation. The effect of 10 g/L bovine serum albumin (BSA) and 2.5 g/L fibrinogen (Fbn) was studied. BSA and Fbn strongly enhanced the release of Co, Cr, and Mo and slightly enhanced the corrosion (still in the passive domain) for all CoCrMo alloys and most for LPBF-XZ, followed by LPBF-XY and the wrought CoCrMo. BSA and Fbn, most pronounced when combined, significantly decreased the coefficient of friction due to lubrication, the wear track width and severity of the wear mechanism, and the tribocorrosion for all alloys, with no clear effect of the manufacturing type. The wear track area was significantly more oxidized than the area outside of the wear track. In the reference solution without proteins, a strong Mo oxidation in the wear track surface oxide was indicative of a pH decrease and cell separation of the anodic and cathodic areas. This effect was absent in the presence of the proteins.

Surface modification of additive manufactured Ti6Al4V scaffolds with gelatin/alginate- IGF-1 carrier: An effective approach for healing bone defects.

The study investigates the potential of porous scaffolds with Gel/Alg-IGF-1 coatings as a viable candidate for orthopaedic implants. The scaffolds are composed of additively manufactured Ti6Al4V lattices, which were treated in an alkali solution to obtain the anatase and rutile phases. The treated surface exhibited hydrophilicity of <11.5°. A biopolymer carrier containing Insulin-like growth factor 1 was coated on the samples using immersion treatment. This study showed that the surface-modified porous Ti6Al4V scaffolds increased cell viability and proliferation, indicating potential for bone regeneration. The results demonstrate that surface modifications can enhance the osteoconduction and osteoinduction of Ti6Al4V implants, leading to improved bone regeneration and faster recovery. The porous Ti6Al4V scaffolds modified with surface coating of Gel/Alg-IGF-1 exhibited a noteworthy increase in cell viability (from 80.7 to 104.1%viability) and proliferation. These results suggest that the surface modified scaffolds have potential for use in treating bone defects.

Biological Performance of Duplex PEO + CNT/PCL Coating on AZ31B Mg Alloy for Orthopedic and Dental Applications.

To regulate the degradation rate and improve the surface biocompatibility of the AZ31B magnesium alloy, three different coating systems were produced via plasma electrolytic oxidation (PEO): simple PEO, PEO incorporating multi-walled carbon nanotubes (PEO + CNT), and a duplex coating that included a polycaprolactone top layer (PEO + CNT/PCL). Surfaces were characterized by chemical content, roughness, topography, and wettability. Biological properties analysis included cell metabolism and adhesion. PEO ± CNT resulted in an augmented surface roughness compared with the base material (BM), while PCL deposition produced the smoothest surface. All surfaces had a contact angle below 90°. The exposure of gFib-TERT and bmMSC to culture media collected after 3 or 24 h did not affect their metabolism. A decrease in metabolic activity of 9% and 14% for bmMSC and of 14% and 29% for gFib-TERT was observed after 3 and 7 days, respectively. All cells died after 7 days of exposure to BM and after 15 days of exposure to coated surfaces. Saos-2 and gFib-TERT adhered poorly to BM, in contrast to bmMSC. All cells on PEO anchored into the pores with filopodia, exhibited tiny adhesion protrusions on PEO + CNT, and presented a web-like spreading with lamellipodia on PEO + CNT/PCL. The smooth and homogenous surface of the duplex PEO + CNT/PCL coating decreased magnesium corrosion and led to better biological functionality.

Electrophoretic deposition of Bioactive glass - Chitosan nanocomposite coatings on Ti-6Al-4V for orthopedic applications.

Chitosan-Bioactive glass (CS-BG) nanocomposite coatings were developed on the Ti-6Al-4 V alloy to investigate the effect of the BG content on the adhesion strength, bioactivity, bio-corrosion, wettability and roughness. For this purpose, BG nanoparticles were synthesized using a sol-gel process. Three nanocomposite coatings with different concentrations of BG (0.5, 1 and 1.5 g/L) were fabricated through cathodic electrophoretic deposition (EPD). The surface morphology and composition of the coatings revealed the formation of compact coatings with a uniform distribution of BG nanoparticles. Increasing the BG content enhanced the deposition rate of CS-BG nanocomposite coatings and raised the coating thickness. Moreover, the CS-BG coating containing 1.5 g/L BG showed the best corrosion performance owing to the more uniform distribution of BG nanoparticles and its higher thickness. Also, increasing the BG concentration improved the adhesion strength, raised the roughness, and promoted wettability. Further, in-vitro bioactivity evaluation of the coated and uncoated specimens in SBF revealed that the formation of bone-like apatite was significantly encouraged on the surface of CS-BG coatings, as compared to the Ti-6Al-4 V uncoated sample. So, the apatite-forming ability of the coatings was improved by increasing the BG content. For in vitro investigation, osteoblast-like cell line MG63 were cultured on Ti-6Al-4 V substrate coated with CS-BG and cellular behavior was evaluated. Results demonstrated good cell attachment with no significant levels of cytotoxicity during 5 days of culture. Therefore, the electrophoretic deposition of the CS-1.5 g/L BG coating could successfully enhance the adhesion strength, bioactivity, corrosion and cellular performance of the substrate.