Improved Biocompatible, Flexible Mesh Composites for Implant Applications via Hydroxyapatite Coating with Potential for 3-Dimensional Extracellular Matrix Network and Bone Regeneration

Biosurfactant-Assisted Cu Doping of Brushite Coatings: Enhancing Structural, Electrochemical, and Biofunctional Properties

Stainless steel (316L SS) has been widely used in orthopedic, cardiovascular stents, and other biomedical implant applications due to its strength, corrosion resistance, and biocompatibility. To address the weak interaction between steel implants and tissues, it is a widely adopted strategy to enhance implant performance through the application of bioactive coatings. In this study, Cu-doped brushite coatings were deposited successfully through pulse electrodeposition on steel substrates facilitated with a biosurfactant (BS) (i.e., surfactin). Further, the combined effect of various concentrations of Cu ions and BS on the structural, electrochemical, and biological properties was studied. The X-ray diffraction (XRD) confirms brushite composition with Cu substitution causing lattice contraction and a reduced crystallite size. The scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) studies reveal the morphological changes of the coatings with the incorporation of Cu, which is confirmed by X-ray photoelectron spectroscopy (XPS) and elemental mapping. The Fourier transform infrared (FTIR) and Raman spectroscopy confirm the brushite and Cu doping in the coatings, respectively. Increased surface roughness and mechanical properties of Cu-doped coatings were analyzed by using atomic force microscopic (AFM) and nanohardness tests, respectively. Electrochemical assessments demonstrate corrosion resistance enhancement in Cu-doped coatings, which is further improved with the addition of biosurfactants. In vitro biomineralization studies show the Cu-doped coating's potential for osseointegration, with added stability. The cytocompatibility of the coatings was analyzed using live/dead and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assays; cell adhesion, proliferation, and migration studies were evaluated using SEM. Antibacterial assays highlight significant improvement in the antibacterial properties of Cu-doped coatings with BS. Thus, the developed Cu-doped brushite coatings with BS demonstrate their potential in the realm of biomedical implant technologies, paving the way for further exploration.

Electroconductivity, a regenerative engineering approach to reverse rotator cuff muscle degeneration

Muscle degeneration is one the main factors that lead to the high rate of retear after a successful repair of rotator cuff (RC) tears. The current surgical practices have failed to treat patients with chronic massive rotator cuff tears (RCTs). Therefore, regenerative engineering approaches are being studied to address the challenges. Recent studies showed the promising outcomes of electroactive materials (EAMs) on the regeneration of electrically excitable tissues such as skeletal muscle. Here, we review the most important biological mechanism of RC muscle degeneration. Further, the review covers the recent studies on EAMs for muscle regeneration including RC muscle. Finally, we will discuss the future direction toward the application of EAMs for the augmentation of RCTs.

Accelerated Bone Regeneration on the Metal Surface through Controllable Surface Potential

Surface potential is rarely investigated as an independent factor in influencing tissue regeneration on the metal surface. In this work, the surface potential on the titanium (Ti) surface was designed to be tailored and adjusted independently, which arises from the ferroelectricity and piezoelectricity of poled poly(vinylidene fluoride-trifluoroethylene) (PVTF). Notably, it is found that such controllable surface potential on the metal surface significantly promotes osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) in vitro as well as bone regeneration in vivo. In addition, the intracellular calcium ion (Ca2+) concentration measurement further proves that such controllable surface potential on the metal surface could activate the transmembrane calcium channels and allow the influx of extracellular Ca2+ into the cytoplasm. That might be the reason for improved osteogenic differentiation of BMSCs and bone regeneration. These findings reveal the potential of the metal surface with improved bioactivity for stimulation of osteogenesis and show great prospects for fabricable implantable medical devices with adjustable surface potential.

Bone-mimicking scaffold based on silk fibroin incorporated with hydroxyapatite and titanium oxide as enhanced osteo-conductive material for bone tissue formation: fabrication, characterization, properties, andin vitrotesting

Bone-mimicking scaffolds based on silk fibroin (SF) mixed with hydroxyapatite nanoparticles (HA NPs) and titanium oxide (TiO2) nanoparticles were created as materials for bone formation. Six scaffold groups were fabricated: S1 (SF), S2 (Silk + (HA: TiO2; 100: 0)), S3 (Silk, (HA: TiO2; 70: 30)), S4 (Silk + (HA NPs: TiO2; 50: 50)), S5 (Silk + (HA: TiO2; 30: 70)), and S6 (Silk + (HA NPs: TiO2; 0:100)). Scaffolds were characterized for molecular formation, structure, and morphology by Fourier transform infrared spectroscopy, element analysis, and X-ray diffraction. They were tested for physical swelling and compressive modulus. Scaffolds were cultured with MC3T3 and testedin vitroto evaluate their biological performance. The results showed that scaffolds with HA and TiO2demonstrated molecular interaction via amide I and phosphate groups. These scaffolds had smaller pore sizes than those without HA and TiO2. They showed more swelling and higher compressive modulus than the scaffolds without HA and TiO2. They exhibited better biological performance: cell adhesion, viability, proliferation, alkaline phosphatase activity, and calcium content than the scaffolds without HA and TiO2. Their porous walls acted as templates for cell aggregation and supported synthesis of calcium secreted from cells. S3 were the most suitable scaffolds. With their enhanced osteo-conductive function, they are promising for bone augmentation for oral and maxillofacial surgery.

Titanium Membranes with Hydroxyapatite/Titania Bioactive Ceramic Coatings: Characterization and In Vivo Biocompatibility Testing

Titanium membranes and meshes are used for the repair of trauma, tumors, and hernia in dentistry and maxillofacial and abdominal surgery. But such membranes demonstrate the limited effectiveness of integration in recipients due to their bioinertness. In this study, we prepared titania oxide (by microarc oxidation) and/or HAp (by electrophoresis deposition) coatings with alginate soaking. We used annealing at 700 °C for 2.5 h for HAp crystallinity increasing with achievement of an acceptable Ca²⁺ release rate. The feedstock HAp and prepared coatings were characterized by X-ray diffraction, IR spectroscopy, electron and optical confocal microscopy, and thermal analysis, as well as the in vitro study of solubility in saline and in vivo tests with the animal model of subcutaneous implantation (with Wistar rats). Biocompatible compounds were found for all deposited coatings. We noted that the best biological response was detected for the annealed Ca-P/TiO₂ bilayer with alginate binding. In this case, the coating crystallinity was ≈40.5-50.0%. The Ca²⁺ release rate was 2.042 ± 0.058%/mm² at 168 h after immersion in saline. Thin and mature tissue capsules with minimal inflammation and vascularization were found in histological sections. We did not detect any unwanted responses around the implants, including inflammation infiltration, suppuration, bacterial infections, tissue lyses, and, finally, implant rejection. This information is expected to be useful for understanding the properties of bioactive ceramic coatings and improving the quality of medical care in dentistry and maxillofacial surgery and other applications of titanium membranes in medicine.

Multi-objective Shape Optimization of Bone Scaffolds: Enhancement of Mechanical Properties and Permeability

Porous scaffolds have recently attracted attention in bone tissue engineering. The implanted scaffolds are supposed to satisfy the mechanical and biological requirements. In this study, two porous structures named MFCC-1 (modified face centered cubic-1) and MFCC-2 (modified face centered cubic-2) are introduced. The proposed porous architectures are evaluated, optimized, and tested to enhance mechanical and biological properties. The geometric parameters of the scaffolds with porosities ranging from 70% to 90% are optimized to find a compromise between the effective Young's modulus and permeability, as well as satisfying the pore size and specific surface area requirements. To optimize the effective Young's modulus and permeability, we integrated a mathematical formulation, finite element analysis, and computational fluid dynamics simulations. For validation, the optimized scaffolds were 3D-printed, tested, and compared with two different orthogonal cylindrical struts (OCS) scaffold architectures. The MFCC designs are preferred to the generic OCS scaffolds from various perspectives: a) the MFCC architecture allows scaffold designs with porosities up to 96%; b) the very porous architecture of MFCC scaffolds allows achieving high permeabilities, which could potentially improve the cell diffusion; c) despite having a higher porosity compared to the OCS scaffolds, MFCC scaffolds improve mechanical performance regarding Young's modulus, stress concentration, and apparent yield strength; d) the proposed structures with different porosities are able to cover all the range of permeability for the human trabecular bones. The optimized MFCC designs have simple architectures and can be easily fabricated and used to improve the quality of load-bearing orthopedic scaffolds. STATEMENT OF SIGNIFICANCE: Porous scaffolds are increasingly being studied to repair large bone defects. A scaffold is supposed to withstand mechanical loads and provide an appropriate environment for bone cell growth after implantation. These mechanical and biological requirements are usually contradicting; improving the mechanical performance would require a reduction in porosity and a lower porosity is likely to reduce the biological performance of the scaffold. Various studies have shown that the mechanical and biological performance of bone scaffolds can be improved by internal architecture modification. In this study, we propose two scaffold architectures named MFCC-1 and MFCC-2 and provide an optimization framework to simultaneously optimize their stiffness and permeability to improve their mechanical and biological performances.

Titanium Nanosurface with a Biomimetic Physical Microenvironment to Induce Endogenous Regeneration of the Periodontium

The periodontium supports the teeth by dentoalveolar fibrous joints that serve unique oral functions. Endogenous regeneration of the periodontium around artificial teeth (dental implants) provides a cost-effective solution for the extension of healthy life expectancy but remains a challenge in regenerative medicine. Biomimetics can create smart biomaterials that tune endogenous cells at a tissue-material interface. Here, we created a smart titanium nanosurface mimicking the surface nanotopography and micromechanical properties of the tooth root cementum (TRC), which is essential for the induction of dentoalveolar fibrous joints to regenerate the periodontium. After transplantation into the rat renal capsule, only the titanium artificial tooth with the TRC-mimetic nanosurface formed a complex dentoalveolar fibrous joint structure, with bone tissue, periodontal ligament (PDL), and TRC, in the decellularized jawbone matrix. TRC-mimetic titanium implants induce the formation of functional periodontium, even in a jawbone implantation model, which generally causes osseointegration (ankyloses). In human PDL cells, TRC analogousness in the surface mechanical microenvironment regulates matrix mineralization through bone sialoprotein expression and phosphorus metabolism, which are critical for cementogenesis. Therefore, the titanium nanosurfaces with nanotopographical and mechanical microenvironments mimicking the TRC surface induce dentoalveolar fibrous joints for periodontal regeneration by interfacial tuning of endogenous cells.