High-Performance Nanoscale Metallic Multilayer Composites: Techniques, Mechanical Properties and Applications.

Due to their exceptional properties and diverse applications, including to magnetic devices, thermoelectric materials, catalysis, biomedicine, and energy storage, nanoscale metallic multilayer composites (NMMCs) have recently attracted great attention. The alternating layers of two or more metals that make up NMMCs are each just a few nanometers thick. The difficulties in producing and synthesizing new materials can be overcome by using nanoscale multilayer architectures. By adjusting the layer thickness, composition, and interface structure, the mechanical properties of these materials can be controlled. In addition, NMMCs exhibit unusually high strength at thin layer thicknesses because the multilayers have exceptionally high strength, as the individual layer thicknesses are reduced to the nanoscale. The properties of NMMCs depend on the individual layers. This means that the properties can be tuned by varying the layer thickness, composition, and interface structure. Therefore, this review article aims to provide a comprehensive overview of the mechanical properties and the application of high-performance NMMCs. The paper briefly discusses the fabrication methods used to produce these composites and highlights their potential in various fields, such as electronics, energy storage, aerospace, and biomedical engineering. Furthermore, the electrical conductivity, mechanical properties, and thermal stability of the above composite materials are analyzed in detail. The review concludes with a discussion of the future prospects and challenges associated with the development of NMMCs.

Effect of Metal-Cored Filler Wire on Surface Morphology and Micro-Hardness of Regulated Metal Deposition Welded ASTM A387-Gr.11-Cl.2 Steel Plates.

Environmental and human-friendly welding is the need of the hour. In this context, this study explores the application of the regulated metal deposition (RMD) technique for ASTM A387-Gr.11-Cl.2 steel plates. To examine the effect of metal-cored filler wire (MCFW), MEGAFIL 237 M was employed during regulated metal deposition (RMD) welding of 6 mm thick ASTM A387-Gr.11-Cl.2 steel plates. The welding was carried out at an optimized current (A) of 100 A, voltage (V) of 13 V, and gas flow rate (GFR) of 21 L/min. Thereafter, the as-welded plates were examined for morphological changes using optical microscopy. Additionally, the micro-hardness of the as-welded plates was measured to make corroboration with the obtained surface morphologies. In addition to this, the as-welded plates were subjected to heat treatment followed by surface morphology and micro-hardness examination. A comparison was made between the as-welded and heat-treated plates for their obtained surface morphologies and microhardness values. During this, it was observed that the weld zone of as-welded plates has a dendritic surface morphology which is very common in fusion-based welding. Similarly, the weld zone of heat-treated plates has a finer and erratic arrangement of martensite. Moreover, the obtained surface morphologies in the weld zone of as-welded and heat-treated plates have been justified by their respective hardness values of 1588.6 HV and 227.3 HV.

Carfilzomib alleviated osteoporosis by targeting PSME1/2 to activate Wnt/ß-catenin signaling.

Osteoporosis (OP) is characterized by decreased bone mineral density and impaired bone strength. Carfilzomib (CFZ) is a new-generation proteasome inhibitor and has been found to affect bone metabolism. However, the effect and mechanism of CFZ on OP has not been investigated systematically. In this study, we found that protein levels of proteasome activator subunit 1/2 (PSME1/2) increased in OP, and accumulated mostly in osteoblasts and osteoclasts. Treatment with PSME1/2 recombinant protein inhibited osteogenesis and promoted osteoclast formation in vitro. Also, PSME1/2 inhibited the expression of ß-catenin protein, resulting in limitation of Wnt/ß-catenin signaling. CFZ inhibited PSME1 and PSME2 proteasome activities and increased ß-catenin protein level, resulting in the translocation of ß-catenin to the nucleus and activation of canonical Wnt/ß-catenin signaling, further promoting osteogenesis and inhibiting osteoclastic differentiation. In vivo, we conducted ovariectomy (OVX) to create a model of OVX-induced postmenopausal OP in mice. When analyzed by micro-CT scanning, enhancement of bone mineral density, bone volume, trabecular number, and thickness was seen in the CFZ-treated mice. Also, we noticed increased osteogenesis and decreased osteoclastogenesis, diminished expression of PSME1 and PSME2 and activated Wnt/ß-catenin signaling in bone sections from OP mice treated with CFZ. Overall, our data indicated that PSME1/2 may serve as new targets for the treatment of OP, and targeting PSME1/2 with CFZ provides a candidate therapeutic molecule for postmenopausal OP.

A Review on Design and Mechanical Properties of Additively Manufactured NiTi Implants for Orthopedic Applications.

NiTi alloy has a wide range of applications as a biomaterial due to its high ductility, low corrosion rate, and favorable biocompatibility. Although Young's modulus of NiTi is relatively low, it still needs to be reduced; one of the promising ways is by introducing porous structure. Traditional manufacturing processes, such as casting, can hardly produce complex porous structures. Additive manufacturing (AM) is one of the most advanced manufacturing technologies that can solve impurity issues, and selective laser melting (SLM) is one of the well-known methods. This paper reviews the developments of AM-NiTi with a particular focus on SLM-NiTi utilization in biomedical applications. Correspondingly, this paper aims to describe the three key factors, including powder preparation, processing parameters, and gas atmosphere during the overall process of porous NiTi. The porous structure design is of vital importance, so the unit cell and pore parameters are discussed. The mechanical properties of SLM-NiTi, such as hardness, compressive strength, tensile strength, fatigue behavior, and damping properties and their relationship with design parameters are summarized. In the end, it points out the current challenges. Considering the increasing application of NiTi implants, this review paper may open new frontiers for advanced and modern designs.

Hierarchical Microstructure Tailoring of Pure Titanium for Enhancing Cellular Response at Tissue-Implant Interface.

The main goal of this research is to scrutinize the effect of texture and grain size on the biological response of hierarchical structured pure titanium (Ti), examining the interrelation between grain refinement mechanisms with texture variation. The hierarchical structure was produced using two methods of severe plastic deformation (SPD). The Ti specimens were first processed up to six passes by equal channel angular pressing (ECAP) and subsequently treated at the top surface using surface mechanical attrition treatment (SMAT). Microstructure examination by Electron backscatter diffraction (EBSD) indicates that the SMAT-treated surface was categorized into three distinct microstructural regions based on the type of grain refinement process involved during SPD: twin induced dynamic recrystallization (TDRX) and geometric dynamic recrystallization (GDRX) in the topmost surface, and continuous (CDRX) and discontinuous dynamic recrystallization (DDRX) in the lower regions of the sample. The biological experiments showed meaningful improvement in the cellular response of SMATed and ECAPed samples. It was demonstrated that grain refinement could have the capability of improving the biological response of Ti surface. In this regard, SMATed + 2ECAPed sample showed the best result although it has not the smallest grain size and the highest texture intensity. It was observed that texture and grain orientation of planes have an important impact on the biological response of pure Ti and dominance of prismatic (1010) texture can improve the cell viability, adhesion and its differentiation. Therefore, microstructure and texture tailoring through combined SPD methods could be a promising strategy for the improvement of the next generation of medical implants.

3D Printing Technologies in Metallic Implants: A Thematic Review on the Techniques and Procedures.

Additive manufacturing (AM) is among the most attractive methods to produce implants, the processes are very swift and it can be precisely controlled to meet patient's requirement since they can be produced in exact shape, dimension, and even texture of different living tissues. Until now, lots of methods have emerged and used in this field with diverse characteristics. This review aims to comprehensively discuss 3D printing (3DP) technologies to manufacture metallic implants, especially on techniques and procedures. Various technologies based on their main properties are categorized, the effecting parameters are introduced, and the history of AM technology is briefly analyzed. Subsequently, the utilization of these AM-manufactured components in medicine along with their effectual variables is discussed, and special attention is paid on to the production of porous scaffolds, taking pore size, density, etc., into consideration. Finally, 3DP of the popular metallic systems in medical applications such as titanium, Ti6Al4V, cobalt-chromium alloys, and shape memory alloys are studied. In general, AM manufactured implants need to comply with important requirements such as biocompatibility, suitable mechanical properties (strength and elastic modulus), surface conditions, custom-built designs, fast production, etc. This review aims to introduce the AM technologies in implant applications and find new ways to design more sophisticated methods and compatible implants that mimic the desired tissue functions.

3D-printed HA15-loaded ß-Tricalcium Phosphate/Poly (Lactic-co-glycolic acid) Bone Tissue Scaffold Promotes Bone Regeneration in Rabbit Radial Defects.

In this study, a ß-tricalcium phosphate (ß-TCP)/poly (lactic-co-glycolic acid) (PLGA) bone tissue scaffold was loaded with osteogenesis-promoting drug HA15 and constructed by three-dimensional (3D) printing technology. This drug delivery system with favorable biomechanical properties, bone conduction function, and local release of osteogenic drugs could provide the basis for the treatment of bone defects. The biomechanical properties of the scaffold were investigated by compressive testing, showing comparable biomechanical properties with cancellous bone tissue. Furthermore, the microstructure, pore morphology, and condition were studied. Moreover, the drug release concentration, the effect of anti-tuberculosis drugs in vitro and in rabbit radial defects, and the ability of the scaffold to repair the defects were studied. The results show that the scaffold loaded with HA15 can promote cell differentiation into osteoblasts in vitro, targeting HSPA5. The micro-computed tomography scans showed that after 12 weeks of scaffold implantation, the defect of the rabbit radius was repaired and the peripheral blood vessels were regenerated. Thus, HA15 can target HSPA5 to inhibit endoplasmic reticulum stress which finally leads to promotion of osteogenesis, bone regeneration, and angiogenesis in the rabbit bone defect model. Overall, the 3D-printed ß-TCP/PLGA-loaded HA15 bone tissue scaffold can be used as a substitute material for the treatment of bone defects because of its unique biomechanical properties and bone conductivity.

Nano-Modified Titanium Implant Materials: A Way Toward Improved Antibacterial Properties.

Titanium and its alloys have superb biocompatibility, low elastic modulus, and favorable corrosion resistance. These exceptional properties lead to its wide use as a medical implant material. Titanium itself does not have antibacterial properties, so bacteria can gather and adhere to its surface resulting in infection issues. The infection is among the main reasons for implant failure in orthopedic surgeries. Nano-modification, as one of the good options, has the potential to induce different degrees of antibacterial effect on the surface of implant materials. At the same time, the nano-modification procedure and the produced nanostructures should not adversely affect the osteogenic activity, and it should simultaneously lead to favorable antibacterial properties on the surface of the implant. This article scrutinizes and deals with the surface nano-modification of titanium implant materials from three aspects: nanostructures formation procedures, nanomaterials loading, and nano-morphology. In this regard, the research progress on the antibacterial properties of various surface nano-modification of titanium implant materials and the related procedures are introduced, and the new trends will be discussed in order to improve the related materials and methods.

Surface Modification Techniques of Titanium and its Alloys to Functionally Optimize Their Biomedical Properties: Thematic Review.

Depending on the requirements of specific applications, implanted materials including metals, ceramics, and polymers have been used in various disciplines of medicine. Titanium and its alloys as implant materials play a critical role in the orthopedic and dental procedures. However, they still require the utilization of surface modification technologies to not only achieve the robust osteointegration but also to increase the antibacterial properties, which can avoid the implant-related infections. This article aims to provide a summary of the latest advances in surface modification techniques, of titanium and its alloys, specifically in biomedical applications. These surface techniques include plasma spray, physical vapor deposition, sol-gel, micro-arc oxidation, etc. Moreover, the microstructure evolution is comprehensively discussed, which is followed by enhanced mechanical properties, osseointegration, antibacterial properties, and clinical outcomes. Future researches should focus on the combination of multiple methods or improving the structure and composition of the composite coating to further enhance the coating performance.

The Toxicity Phenomenon and the Related Occurrence in Metal and Metal Oxide Nanoparticles: A Brief Review From the Biomedical Perspective.

Thousands of different nanoparticles (NPs) involve in our daily life with various origins from food, cosmetics, drugs, etc. It is believed that decreasing the size of materials up to nanometer levels can facilitate their unfavorable absorption since they can pass the natural barriers of live tissues and organs even, they can go across the relatively impermeable membranes. The interaction of these NPs with the biological environment disturbs the natural functions of cells and its components and cause health issues. In the lack of the detailed and comprehensive standard protocols about the toxicity of NPs materials, their control, and effects, this review study focuses on the current research literature about the related factors in toxicity of NPs such as size, concentration, etc. with an emphasis on metal and metal oxide nanoparticles. The goal of the study is to highlight their potential hazard and the advancement of green non-cytotoxic nanomaterials with safe threshold dose levels to resolve the toxicity issues. This study supports the NPs design along with minimizing the adverse effects of nanoparticles especially those used in biological treatments.

Multi-Scale Surface Treatments of Titanium Implants for Rapid Osseointegration: A Review.

The propose of this review was to summarize the advances in multi-scale surface technology of titanium implants to accelerate the osseointegration process. The several multi-scaled methods used for improving wettability, roughness, and bioactivity of implant surfaces are reviewed. In addition, macro-scale methods (e.g., 3D printing (3DP) and laser surface texturing (LST)), micro-scale (e.g., grit-blasting, acid-etching, and Sand-blasted, Large-grit, and Acid-etching (SLA)) and nano-scale methods (e.g., plasma-spraying and anodization) are also discussed, and these surfaces are known to have favorable properties in clinical applications. Functionalized coatings with organic and non-organic loadings suggest good prospects for the future of modern biotechnology. Nevertheless, because of high cost and low clinical validation, these partial coatings have not been commercially available so far. A large number of in vitro and in vivo investigations are necessary in order to obtain in-depth exploration about the efficiency of functional implant surfaces. The prospective titanium implants should possess the optimum chemistry, bionic characteristics, and standardized modern topographies to achieve rapid osseointegration.

Functionally graded titanium implants: Characteristic enhancement induced by combined severe plastic deformation.

Commercially pure titanium was processed by equal channel angular pressing (ECAP) and surface mechanical attrition treatment (SMAT) for the purpose of developing functionally graded titanium used for implants and a gradient structure including nanostructured, deformed and undeformed zones were produced on the samples. In particular, it was aimed to design the gradient-structure in the titanium with enhanced properties by applying 4 ECAP passes to form bulk structure of ultrafine-grains and subsequently subjecting SMAT to the surface of ECAPed samples to produce nanostructured surface region. Microstructural examination was made by electron back scatter diffraction (EBSD). Also, microhardness, nanoindentation, topography, roughness and wettability were evaluated. To examine the biological response, human osteosarcoma cells were cultured in contact with the samples in various time periods and morphology change, cell viability and alkaline phosphate activity were conducted also cell morphology was monitored. EBSD showed development of ultrafine-grained structure after 4 passes of ECAP with an average grain size of 500 nm. Applying SMAT resulted in additional refinement in the ECAP samples, particularly in the subsurface regions to a depth of 112 µm. Furthermore, the SMATed samples showed an enhancement in roughness, wettability and hardness magnitudes. Viability enhanced up to 7% in SMATed + ECAPed sample, although the acceptable cell adhesion, improved cell differentiation and mineralization were seen. The combined use of ECAP and SMAT has shown a good potential for optimizing the design of modern functionally graded medical devices and implants.