Synthesis of biocompatible Ti-6Al-4V composite reinforced with ZrO2 and bioceramic produced by powder metallurgy: Morphological, structural, and biocompatibility analysis

In this experimental study, the initial phase involved preparing composite structures with various mix ratios using the Ti-6Al-4V alloy, widely used in clinical applications, in conjunction with ZrO2 and hydroxyapatite (HA) synthesized via the precipitation method, employing powder metallurgy techniques. Subsequently, the microstructures of the resultant hybrid composite materials were imaged, and x-ray diffraction (XRD) phase analyses were conducted. In the final phase of the experimental work, tests were performed to determine the biocompatibility properties of the hybrid composites. For this purpose, cytotoxicity and genotoxicity assays were carried out. The tests and examinations revealed that structures compatible both morphologically and elementally were obtained with no phase transformations that could disrupt the structure. The incorporation of ZrO2 into the Ti-6Al-4V alloy was observed to enhance cell viability values. The value of 98.25 ± 0.42 obtained by adding 20% ZrO2 gave the highest cell viability result. The addition of HA into the hybrid structures further increased the cell viability values by approximately 10%. All viability values for both HA-added and HA-free groups were obtained above the 70% viability level defined in the standard. According to the genotoxicity test results, the highest cytokinesis-block proliferation index values were obtained as 1.666 and 0.620 in structures containing 20% ZrO2 and 10% ZrO2 + 10% HA, respectively. Remarkably, all fabricated composite and hybrid composite materials surpassed established biocompatibility standards and exhibited nontoxic and nongenotoxic properties. This comprehensive study contributes vital insights for future biomechanical and other in vitro and in vivo experiments, as it meticulously addresses fundamental characterization parameters crucial for medical device development. RESEARCH HIGHLIGHTS: Support of optimum doping rates ions on hybrid composites and concentrations. Development of uniform surface appearance and distributions/orientations of microcrystals on ceramic compounds Improvement of cell viability and desired increase in biocompatibility with the doping of HA.

Augmented physical, mechanical, and cellular responsiveness of gelatin-aldehyde modified xanthan hydrogel through incorporation of silicon nanoparticles for bone tissue engineering

Bioactive scaffolds fabricated from a combination of organic and inorganic biomaterials are a promising approach for addressing defects in bone tissue engineering. In the present study, a self-crosslinked nanocomposite hydrogel, composed of gelatin/aldehyde-modified xanthan (Gel-AXG) is successfully developed by varying concentrations of porous silicon nanoparticles (PSiNPs). The effect of PSiNPs incorporation on physical, mechanical, and biological performance of the nanocomposite hydrogel is evaluated. Morphological analysis reveals formation of highly porous 3D microstructures with interconnected pores in all nanocomposite hydrogels. Increased content of PSiNPs results in a lower swelling ratio, reduced porosity and pore size, which in turn impeded media penetration and slowed down the degradation process. In addition, remarkable enhancements in dynamic mechanical properties are observed in Gel-AXG-8%Si (compressive strength: 0.6223 MPa at 90 % strain and compressive modulus: 0.054 MPa), along with improved biomineralization ability via hydroxyapatite formation after immersion in simulated body fluid (SBF). This optimized nanocomposite hydrogel provides a sustained release of Si ions at safe dose levels. Furthermore, in-vitro cytocompatibility studies using MG-63 cells exhibited remarkable performance in terms of cell attachment, proliferation, and ALP activity for Gel-AXG-8%Si. These findings suggest that the prepared nanocomposite hydrogel holds promising potential as a scaffold for bone tissue engineering.

Physio-Chemical and Biological Characterization of Novel HPC (Hydroxypropylcellulose):HAP (Hydroxyapatite):PLA (Poly Lactic Acid) Electrospun Nanofibers as Implantable Material for Bone Regenerative Application

The research on extracellular matrix (ECM) is new and developing area that covers cell proliferation and differentiation and ensures improved cell viability for different biomedical applications. Extracellular matrix not only maintains biological functions but also exhibits properties such as tuned or natural material degradation within a given time period, active cell binding and cellular uptake for tissue engineering applications. The principal objective of this study is classified into two categories. The first phase is optimization of various electrospinning parameters with different concentrations of HAP-HPC/PLA(hydroxyapatite-hydroxypropylcellulose/poly lactic acid). The second phase is in vitro biological evaluation of the optimized mat using MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) assay for bone regeneration applications. Conductivity and dielectric constant were optimized for the production of thin fiber and bead free nanofibrous mat. With this optimization, the mechanical strength of all compositions was found to be enhanced, of which the ratio of 70:30 hit a maximum of 9.53 MPa (megapascal). Cytotoxicity analysis was completed for all the compositions on MG63 cell lines for various durations and showed maximum cell viability on 70:30 composition for more than 48 hrs. Hence, this investigation concludes that the optimized nanofibrous mat can be deployed as an ideal material for bone regenerative applications. In vivo study confirms the HAP-HPC-PLA sample shows more cells and bone formation at 8 weeks than 4 weeks.

3D bioprinted poly(lactic acid)/mesoporous bioactive glass based biomimetic scaffold with rapid apatite crystallization and in-vitro Cytocompatability for bone tissue engineering

In the recent years, bone tissue engineering is regarded as the promising solution for treatment of bone defects which arises due to trauma, infection and surgical intervention. In view of this, several polymer or ceramic based constructs are envisaged for bone tissue engineering potential. However, scaffolds based on pure polymeric materials suffer from slow bioactivity characteristics. On the other hand, scaffolds based on ceramic materials do not offer sufficient strength for load bearing applications. In order to overcome these drawbacks, the current work aims to develop mixed matrix scaffolds based on poly (L-lactic acid)/mesoporous bioactive glass composite with the formulation of 30:70 weight ratio, which mimics the natural bone composition. In the current work, PLA/MBG (30:70) composite based bioink suitable for 3D bioprinting is indigenously developed and its rheological characteristics are evaluated. The 3D architecture for PLA/MBG composite scaffold is designed using Solidworks CAD 2015 and the scaffolds are fabricated using pneumatic based 3D bioprinting technology, which has not been documented earlier for this formulation in view of bone tissue engineering to the best of our knowledge. Followed by this, optimization of printing parameters in order to develop 3D PLA/MBG composite constructs with hierarchical pore architecture suitable for bone tissue engineering is performed. The SEM analysis confirmed that the pore size of the 3D printed PLA/MBG composite scaffolds falls in the range of 500-700 μm, which corresponds to the macroporous nature of the scaffolds useful for bone cell growth. The mechanical analysis confirmed the superior compressive modulus and yield strength for PLA/MBG composite scaffold in comparison to neat PLA. The in-vitro bioactivity assessment showed rapid apatite crystallization by attaining Ca/P ratio of 1.66 equivalent to natural bone mineral within 3rd day of SBF treatment for PLA/MBG composite scaffold, thus indicating the excellent bioactivity behaviour. The 3D bioprinted PLA/MBG composite scaffold showed promising response in terms of cell attachment and proliferation, mineralization as well as gene expression characteristics while assessed through of in-vitro biological assessment using MG-63 osteosarcoma cells. In this regard, the 3D bioprinted PLA/MBG scaffold could be applied as potential implant for bone tissue engineering application.

Artificial osteochondral interface of bioactive fibrous membranes mediating calcified cartilage reconstruction

Calcified cartilage is a mineralized osteochondral interface region between the hyaline cartilage and subchondral bone. There are few reported artificial biomaterials that could offer bioactivities for substantial reconstruction of calcified cartilage. Herein we developed new poly(L-lactide-co-caprolactone) (PLCL)-based trilayered fibrous membranes as a functional interface for calcified cartilage reconstruction and superficial cartilage restoration. The trilayered membranes were prepared by the electrospinning technique, and the fibrous morphology was maintained when the chondroitin sulfate (CS) or bioactive glass (BG) particles were introduced in the upper or bottom layer, respectively. Although 30% BG in the bottom layer led to a significant decrease in tensile resistance, the inorganic ion release was remarkably higher than that in the counterpart with 10% BG. The in vivo studies showed that the fibrous membranes as osteochondral interfaces exhibited different biological performances on superficial cartilage restoration and calcified cartilage reconstruction. All of the implanted host hyaline cartilage enabled a self-healing process and an increase in the BG content in the membranes was desirable for promoting the repair of the calcified cartilage with time. The histological staining confirmed the osteochondral interface in the 30% BG bottom membrane maintained appreciable calcified cartilage repair after 12 weeks. These findings demonstrated that such an integrated artificial osteochondral interface containing appropriate bioactive ions are potentially applicable for osteochondral interface tissue engineering.

The Impact of Bioceramic Scaffolds on Bone Regeneration in Preclinical In Vivo Studies: A Systematic Review

Bioceramic scaffolds are appealing for alveolar bone regeneration, because they are emerging as promising alternatives to autogenous and heterogenous bone grafts. The aim of this systematic review is to answer to the focal question: in critical-sized bone defects in experimental animal models, does the use of a bioceramic scaffolds improve new bone formation, compared with leaving the empty defect without grafting materials or using autogenous bone or deproteinized bovine-derived bone substitutes? Electronic databases were searched using specific search terms. A hand search was also undertaken. Only randomized and controlled studies in the English language, published in peer-reviewed journals between 2013 and 2018, using critical-sized bone defect models in non-medically compromised animals, were considered. Risk of bias assessment was performed using the SYRCLE tool. A meta-analysis was planned to synthesize the evidence, if possible. Thirteen studies reporting on small animal models (six studies on rats and seven on rabbits) were included. The calvarial bone defect was the most common experimental site. The empty defect was used as the only control in all studies except one. In all studies the bioceramic materials demonstrated a trend for better outcomes compared to an empty control. Due to heterogeneity in protocols and outcomes among the included studies, no meta-analysis could be performed. Bioceramics can be considered promising grafting materials, though further evidence is needed.

A Multimaterial Scaffold With Tunable Properties: Toward Bone Tissue Repair

Polyetheretherketone (PEEK)/β-tricalcium phosphate (β-TCP) scaffolds are expected to be able to combine the excellent mechanical strength of PEEK and the good bioactivity and biodegradability of β-TCP. While PEEK acts as a closed membrane in which β-TCP is completely wrapped after the melting/solidifying processing, the PEEK membrane degrades very little, hence the scaffolds cannot display bioactivity and biodegradability. The strategy reported here is to blend a biodegradable polymer with PEEK and β-TCP to fabricate multi-material scaffolds via selective laser sintering (SLS). The biodegradable polymer first degrades and leaves caverns on the closed membrane, and then the wrapped β-TCP is exposed to body fluid. In this study, poly(l-lactide) (PLLA) is adopted as the biodegradable polymer. The results show that large numbers of caverns form on the membrane with the degradation of PLLA, enabling direct contact between β-TCP and body fluid, and allowing for their ion-exchange. As a consequence, the scaffolds display the bioactivity, biodegradability and cytocompatibility. Moreover, bone defect repair studies reveal that new bone tissues grow from the margin towards the center of the scaffolds from the histological analysis. The bone defect region is completely connected to the host bone end after 8 weeks of implantation.

Biomineralization: From Material Tactics to Biological Strategy

Biomineralization is an important tactic by which biological organisms produce hierarchically structured minerals with marvellous functions. Biomineralization studies typically focus on the mediation function of organic matrices on inorganic minerals, which helps scientists to design and synthesize bioinspired functional materials. However, the presence of inorganic minerals may also alter the native behaviours of organic matrices and even biological organisms. This progress report discusses the latest achievements relating to biomineralization mechanisms, the manufacturing of biomimetic materials and relevant applications in biological and biomedical fields. In particular, biomineralized vaccines and algae with improved thermostability and photosynthesis, respectively, demonstrate that biomineralization is a strategy for organism evolution via the rational design of organism-material complexes. The successful modification of biological systems using materials is based on the regulatory effect of inorganic materials on organic organisms, which is another aspect of biomineralization control. Unlike previous studies, this study integrates materials and biological science to achieve a more comprehensive view of the mechanisms and applications of biomineralization.

Hydrothermally processed 1D hydroxyapatite: Mechanism of formation and biocompatibility studies

Recent developments in bone tissue engineering have led to an increased interest in one-dimensional (1D) hydroxyapatite (HA) nano- and micro-structures such as wires, ribbons and tubes. They have been proposed for use as cell substrates, reinforcing phases in composites and carriers for biologically active substances. Here we demonstrate the synthesis of 1D HA structures using an optimized, urea-assisted, high-yield hydrothermal batch process. The one-pot process, yielding HA structures composed of bundles of ribbons and wires, was typified by the simultaneous occurrence of a multitude of intermediate reactions, failing to meet the uniformity criteria over particle morphology and size. To overcome these issues, the preparation procedure was divided to two stages: dicalcium phosphate platelets synthesized in the first step were used as a precursor for the synthesis of 1D HA in the second stage. Despite the elongated particle morphologies, both the precursor and the final product exhibited excellent biocompatibility and caused no reduction of viability when tested against osteoblastic MC3T3-E1 cells in 2D culture up to the concentration of 2.6mg/cm(2). X-ray powder diffraction combined with a range of electron microscopies and laser diffraction analyses was used to elucidate the formation mechanism and the microstructure of the final particles. The two-step synthesis involved a more direct transformation of DCP to 1D HA with the average diameter of 37nm and the aspect ratio exceeding 100:1. The comparison of crystalline domain sizes along different crystallographic directions showed no signs of significant anisotropy, while indicating that individual nanowires are ordered in bundles in the b crystallographic direction of the P63/m space group of HA. Intermediate processes, e.g., dehydration of dicalcium phosphate, are critical for the formation of 1D HA alongside other key aspects of this phase transformation, it must be investigated in more detail in the continuous design of smart HA micro- and nano-structures with advanced therapeutic potentials.

Nano-hydroxyapatite/β-CD/chitosan nanocomposite for potential applications in bone tissue engineering

Herein, we report the synthesis of a novel tri-component nanocomposite system incorporating β-cyclodextrin (β-CD) with nano-hydroxyapatite (n-HA) and chitosan (CS), (n-HA/β-CD/CS) at three different temperatures via co-precipitation method. The chemical interactions and surface morphology have been evaluated by TEM, SEM and AFM techniques revealing the agglomerated nanoparticles in CS/n-HA-HA binary system whereas the ternary systems produced needle shaped nanoparticles dispersed homogeneously at low temperature with more porous and rougher surface. The addition of β-CD in CS/n-HA at low temperature decreased the particle size and raised the thermal stability as compared to CS/n-HA. The comparative hemolytic, protein adsorption and platelet adhesion studies confirmed the better hemocompatibility of n-HA/β-CD/CS-(RT,HT,LT) nanocomposites relative to CS/n-HA. The cell viability has been evaluated in vitro using MG-63 cell line which revealed superior non toxicity of n-HA/β-CD/CS-LT nanocomposite in comparison to n-HA/β-CD/CS-(RT,HT) and CS/n-HA nanocomposites. Thus it may be concluded that the orchestrated organic/inorganic n-HA/β-CD/CS-(RT,HT,LT) nanocomposites exhibited relatively higher cell viability of human osteoblast cells, stimulated greater osteogenesis, controlled biodegradation, enhanced antibacterial activity with excellent in-vitro biomineralization and remarkable mechanical parameters as compared to CS/n-HA nanocomposite and thus may provide opportunities for potential use as an alternative biomaterial for Bone tissue engineering applications.

Durable keratin-based bilayered electrospun mats for wound closure

A bilayered nanofibrous scaffold with rapid wound healing properties is found to be suitable for tissue regeneration applications. The objective of this study is to reveal the fabrication of a poly(3-hydroxybutyric acid) (P)-gelatin (G) nanofibrous mat through electrospinning, with a horn keratin-chitosan-based biosheet (KC) as a bilayered nanofibrous scaffold. The mupirocin (D)-loaded horn KC biosheet (KCD) acts as the primary layer over which PG nanofibers were electrospun to act as the secondary layer. It is shown that this engineered bilayered nanofibrous scaffold material (KC-PG) should fulfill the functions of the extracellular matrix (ECM) by elucidating its function in vitro and in vivo. The bilayered nanofibrous scaffold was designed to exhibit improved physiochemical, biological and mechanical properties, with better swelling and porosity for enhanced oxygen permeability, and it also exhibits an acceptable antibacterial property to prevent infection at the wound site. The bilayered nanofibrous scaffold assists in better biocompatibility towards fibroblast and keratinocyte cell lines. The morphology of the nanofibrous scaffold aids increased cell adhesion and proliferation with cell material interactions. This was elucidated with the help of in vitro fluorescence staining against both cell lines. The bilayered KCD-PG nanofibrous scaffold material gives accelerated wound healing efficiency during in vivo wound healing. The results showed the regulation of growth factors with enhanced collagen synthesis, thereby helping in faster wound healing.

Silk scaffolds for musculoskeletal tissue engineering

The musculoskeletal system, which includes bone, cartilage, tendon/ligament, and skeletal muscle, is becoming the targets for tissue engineering because of the high need for their repair and regeneration. Numerous factors would affect the use of musculoskeletal tissue engineering for tissue regeneration ranging from cells used for scaffold seeding to the manufacture and structures of materials. The essential function of the scaffolds is to convey growth factors as well as cells to the target site to aid the regeneration of the injury. Among the variety of biomaterials used in scaffold engineering, silk fibroin is recognized as an ideal material for its impressive cytocompatibility, slow biodegradability, and excellent mechanical properties. The current review describes the advances made in the fabrication of silk fibroin scaffolds with different forms such as films, particles, electrospun fibers, hydrogels, three-dimensional porous scaffolds, and their applications in the regeneration of musculoskeletal tissues.

Fabrication of a composite of nanocrystalline carbonated hydroxyapatite (cHAP) with polylactic acid (PLA) and its surface topographical structuring with direct laser writing (DLW)

The fabrication of a polylactic acid (PLA)–carbonated hydroxyapatite (cHAP) composite material from synthesised phase pure nano-cHAP and melted PLA by mechanical mixing at 220–235 °C has been developed in this study.

Fabrication and characterization of a collagen coated electrospun poly(3-hydroxybutyric acid)–gelatin nanofibrous scaffold as a soft bio-mimetic material for skin tissue engineering applications

The collagen coated nanofibrous scaffold mimics the function of the extra cellular matrix with good biocompatibility, cell adhesion, cell proliferation and aids to provide as a promising tool in skin tissue engineering application.

Fabrication of bioactive glass-introduced nanofibrous membranes with multifunctions for potential wound dressing

Bioactive glass-introduced gelatin/chitosan nanofibrous dressings were developedviaelectrospinning to endow improved antibacterial activity, adjustable bioactivity and water uptake capacity for enhancing chronic wound healing.