Biocompatibility of Biomaterials for Tissue Regeneration or Replacement

Mitochondria-engine with self-regulation to restore degenerated intervertebral disc cells via bioenergetic robust hydrogel design

Previous studies have confirmed that intervertebral disc degeneration (IDD) is closely associated with inflammation-induced reactive oxygen species (ROS) and resultant cell mitochondrial membrane potential (MMP) decline. Clearance of ROS in an inflammatory environment is essential for breaking the vicious cycle of MMP decline. Additionally, re-energizing the mitochondria damaged in the inflammatory milieu to restore their function, is equally important. Herein, we proposed an interesting concept of mitochondrion-engine equipped with coolant, which enables first to "cool-down" the inflammatory environment, next to restore the MMP, finally to allow cells to regain normal energy metabolism through materials design. As such, we developed a multi-functional composite composed of a reactive oxygen species (ROS)-responsive sodium alginate/gelatin hydrogel infused into a rigid 3D-printed thermoplastic polyurethane (TPU) scaffold. The TPU scaffold was coated with conductive polypyrrole (PPy) to electrophoretically deposit l-arginine, which could upregulate the Mammalian target of rapamycin (mTOR) pathway, thus increasing MMP and energy metabolism to stimulate extracellular matrix synthesis for IVD repair. While the ROS-responsive hydrogel acting as the "mito-engine coolant" could scavenge the excessive ROS to create a favorable environment for IVD cells recovery. Demonstrated by in vitro and in vivo evaluations, the mito-engine system markedly promoted the proliferation and collagen synthesis of nucleus pulposus cells while enhancing the mitochondrial respiration and MMP under oxidative stress. Radiological and histological assessments in vivo revealed the efficacy of this system in IVD repair. This unique bioinspired design integrated biomaterial science with mitochondrial biology, presents a promising paradigm for IDD treatment.

A novel injectable thermo/photo dual-crosslinking hydrogel based on modified chitosan for fast sealing open globe injury

Open globe injuries (OGIs) demand immediate attention to prevent further complications and improve vision prognosis. Herein, we developed a thermo/photo dual-crosslinking injectable hydrogel, HBC_m_Arg, for rapidly sealing OGIs in emergency ophthalmic cases. HBC_m_Arg was prepared with arginine and methacrylic anhydride modified hydroxybutyl chitosan (HBC). HBC_m_Arg was initially in liquid form at 25 °C, enabling easy injection at the injury site. After reaching the ocular surface temperature, it underwent reversible heat-induced gelation to achieve in situ transformation. Further, HBC_m_Arg was capable of rapid photocrosslinking under UV light, forming a dual network structure to bolster mechanical strength, thereby facilitating effective OGI closure. Biocompatibility assessments, including in vitro studies with three ocular cell types and in vivo experiments on rabbit eyes, confirmed the safety profile of HBC_m_Arg. Ex vivo and in vivo burst pressure tests demonstrated the hydrogel's ability to promptly restore intraocular pressure and withstand elevated pressures, underscoring its potential for OGI stabilization. Additionally, the suitable degradation of HBC_m_Arg within ocular tissues, coupled with its stability in ex vivo assessments, presented a delicate balance between stability and biodegradability. In conclusion, HBC_m_Arg holds promise for improving emergency ophthalmic care by providing a rapid, effective, and safe way to seal OGIs in critical situations.

Multifunctional Injectable Hydrogel Microparticles Loaded with miR-29a Abundant BMSCs Derived Exosomes Enhanced Bone Regeneration by Regulating Osteogenesis and Angiogenesis

The study investigated whether both the osteogenic and angiogenic potential of Exos (Exosomes) can be enhanced by overexpression of exosomal miRNA (microRNA) and to confirm whether Exos loaded in HMPs (Hydrogel microparticles) exert long-term effects during new bone formation. BMSCs and Exos are successfully obtained. In vitro and in vivo experiments confirmed that HDAC4 (Histone deacetylase 4) is inhibited by miR-29a overexpression accompanied by the upregulation of RUNX2 (Runt-related transcription factor 2) and VEGF (Vascular Endothelial Growth Factor), thereby enhancing osteogenic and angiogenic capabilities. The HMP@Exo system is synthesized from HB-PEGDA (Hyperbranched Poly Ethylene Glycol Diacrylate)- and SH-HA (Sulfhydryl-Modified Hyaluronic Acid)-containing Exos using a microfluidic technique. The HMP surface is modified with RGD (Arg-Gly-Asp) peptides to enhance cell adhesion. The system demonstrated good injectability, remarkable compatibility, outstanding cell adhesion properties, and slow degradation capacity, and the sustained release of Agomir-29a-Exos (Exosomes derived from Agomir-29a transfected BMSCs) from HMPs enhanced the proliferation and migration of BMSCs and HUVECs (Human Umbilical Vein Endothelial Cells) while promoting osteogenesis and angiogenesis. Overall, the findings demonstrate that the HMP@Exo system can effectively maintain the activity and half-life of Exos, accompanied by overexpression of miR-29a (microRNA-29a). The injectable system provides an innovative approach for accelerating fracture healing by coupling osteogenesis and angiogenesis.

Localized trans-browning and pro-angiogenesis inductive self-assembled collagen resveratrol bio-matrix for tissue repair and regeneration in obese conditions

The present study probes into the complexities of wound management in obesity by proposing a novel biomaterial designed to reprogram the altered skin physiology prevalent in obese conditions. The strategy involves the development of a multifunctional biomaterial addressing issues such as excessive exudate, pressure ulcers, and reduced vascularity. The bio-matrix demonstrates the localized transformation of white adipocytes through trans-browning, coupled with the simultaneous induction of angiogenesis at obese wound sites, resulting in expedited wound closure. The collagen bio-matrices, stabilized with Resveratrol (Rsv), exhibit remarkable thermal, mechanical, and biological stability. The porous 3D microstructure of the Rsv-stabilized collagen bio-matrix closely resembled the natural extracellular matrix, facilitating effective cell adhesion. The bio-matrix exhibited the unique capability to induce localized thermogenesis in the subcutaneous fat layer while concurrently activating angiogenesis. In vivo wound healing studies conducted on DIO-C57BL6 mice demonstrated complete healing within 10 days, showcasing accelerated tissue regeneration, blood vessel formation, robust collagen deposition, and significant activation of browning in the subcutaneous adipose layer. This study introduces the concept of tailored regenerative biomaterials with the ability to reprogram the challenging wound environment associated with obesity. This innovative approach opens up new avenues for enhanced wound care strategies, particularly for bariatric patients.

Apigenin Self-Assembled Collagen Biomatrix for Reprogramming the Obese Wound Microenvironment for Its Management and Repair

Wound management in obesity is complicated by excessive exudates from wounded areas, pressure ulcerations due to stacking of the fat layer, and vascular rarefaction. The current study explored the development of biomaterials for reprogramming the altered wound microenvironment under obese conditions. Self-assembled collagen biomatrix with trans and de novo browning activator, apigenin, was fabricated as a soft tissue regenerative wound dressing material. The as-synthesized self-assembled collagen biomatrix exhibited excellent thermal, mechanical, and biological stability with a superior wound exudate absorption capacity. The apigenin self-assembled collagen biomatrix exhibited porous 3-D microstructure that mimicked the extracellular matrix that promoted cell adhesion and proliferation. The apigenin self-assembled collagen multifunctional biomatrix triggered adaptive localized thermogenesis in the subcutaneous fat layer, resulting in the activation of angiogenesis and fibroblast spreading and migration. The in vivo wound healing assay performed in DIO-C57BL6 mice showed faster tissue regeneration within 9 days, with well-defined neo-epidermis, blood vessel formation, thick collagen deposition, minimal inflammation, and significant activation of browning in the subcutaneous adipose layer. This study paves the way forward for the development of specialized regenerative biomatrices that reprogram the obese wound bed for faster tissue regeneration.

Bone Cements Used in Vertebral Augmentation: A State-of-the-art Narrative Review

Vertebral compression fractures (VCFs) are common in osteoporotic patients, with a frequency projected to increase alongside a growing geriatric population. VCFs often result in debilitating back pain and decreased mobility. Cement augmentation, a minimally invasive surgical technique, is widely used to stabilize fractures and restore vertebral height. Acrylic-based cements and calcium phosphate cements are currently the two primary fill materials utilized for these procedures. Despite their effectiveness, acrylic bone cements and calcium phosphate cements have been associated with various intraoperative and postoperative incidents impacting VCF treatment. Over the past decade, discoveries in the field of biomedical engineering and material science have shown advancements toward addressing these limitations. This narrative review aims to assess the potential pitfalls and barriers of the various types of bone cements.

Investigation of background, novelty and recent advance of iron (II,III) oxide- loaded on 3D polymer based scaffolds as regenerative implant for bone tissue engineering: A review

Bone tissue engineering had crucial role in the bone defects regeneration, particularly when allograft and autograft procedures have limitations. In this regard, different types of scaffolds are used in tissue regeneration as fundamental tools. In recent years, magnetic scaffolds show promising applications in different biomedical applications (in vitro and in vivo). As superparamagnetic materials are widely considered to be among the most attractive biomaterials in tissue engineering, due to long-range stability and superior bioactivity, therefore, magnetic implants shows angiogenesis, osteoconduction, and osteoinduction features when they are combined with biomaterials. Furthermore, these scaffolds can be coupled with a magnetic field to enhance their regenerative potential. In addition, magnetic scaffolds can be composed of various combinations of magnetic biomaterials and polymers using different methods to improve the magnetic, biocompatibility, thermal, and mechanical properties of the scaffolds. This review article aims to explain the use of magnetic biomaterials such as iron (II,III) oxide (Fe2O3 and Fe3O4) in detail. So it will cover the research background of magnetic scaffolds, the novelty of using these magnetic implants in tissue engineering, and provides a future perspective on regenerative implants.

Hydrogels for the Treatment of Myocardial Infarction: Design and Therapeutic Strategies

Cardiovascular diseases (CVDs) have become the leading global burden of diseases in recent years and are the primary cause of human mortality and loss of healthy life expectancy. Myocardial infarction (MI) is the top cause of CVDs-related deaths, and its incidence is increasing worldwide every year. Recently, hydrogels have garnered great interest from researchers as a promising therapeutic option for cardiac tissue repair after MI. This is due to their excellent properties, including biocompatibility, mechanical properties, injectable properties, anti-inflammatory properties, antioxidant properties, angiogenic properties, and conductive properties. This review discusses the advantages of hydrogels as a novel treatment for cardiac tissue repair after MI. The design strategies of various hydrogels in MI treatment are then summarized, and the latest research progress in the field is classified. Finally, the future perspectives of this booming field are also discussed at the end of this review.

Harnessing Natural Polymers for Nano-Scaffolds in Bone Tissue Engineering: A Comprehensive Overview of Bone Disease Treatment

Numerous surgeries are carried out to replace tissues that have been harmed by an illness or an accident. Due to various surgical interventions and the requirement of bone substitutes, the emerging field of bone tissue engineering attempts to repair damaged tissues with the help of scaffolds. These scaffolds act as template for bone regeneration by controlling the development of new cells. For the creation of functional tissues and organs, there are three elements of bone tissue engineering that play very crucial role: cells, signals and scaffolds. For the achievement of these aims, various types of natural polymers, like chitosan, chitin, cellulose, albumin and silk fibroin, have been used for the preparation of scaffolds. Scaffolds produced from natural polymers have many advantages: they are less immunogenic as well as being biodegradable, biocompatible, non-toxic and cost effective. The hierarchal structure of bone, from microscale to nanoscale, is mostly made up of organic and inorganic components like nanohydroxyapatite and collagen components. This review paper summarizes the knowledge and updates the information about the use of natural polymers for the preparation of scaffolds, with their application in recent research trends and development in the area of bone tissue engineering (BTE). The article extensively explores the related research to analyze the advancement of nanotechnology for the treatment of bone-related diseases and bone repair.

Shaping the Future of Cardiovascular Disease by 3D Printing Applications in Stent Technology and its Clinical Outcomes

Cardiovascular disease (CVD) is a leading cause of death worldwide. In recent years, 3D printing technology has ushered in a new era of innovation in cardiovascular medicine. 3D printing in CVD management encompasses various aspects, from patient-specific models and preoperative planning to customized medical devices and novel therapeutic approaches. In-stent technology, 3D printing has revolutionized the design and fabrication of intravascular stents, offering tailored solutions for complex anatomies and individualized patient needs. The advantages of 3D-printed stents, such as improved biocompatibility, enhanced mechanical properties, and reduced risk of in-stent restenosis. Moreover, the clinical trials and case studies that shed light on the potential of 3D printing technology to improve patient outcomes and revolutionize the field has been comprehensively discussed. Furthermore, regulatory considerations, and challenges in implementing 3D-printed stents in clinical practice are also addressed, underscoring the need for standardization and quality assurance to ensure patient safety and device reliability. This review highlights a comprehensive resource for clinicians, researchers, and policymakers seeking to harness the full potential of 3D printing technology in the fight against CVD.

Polymethylmethacrylate Microspheres are Immunologically Inert in Mouse Tissues

Nowadays, aesthetic concerns have gained attention, especially by patients looking for a less invasive alternative to minor facial corrections. Polymethylmethacrylate (PMMA) is widely used as a soft tissue filler; the demand for this polymer has increased, and along with it, there are some reports of adverse reactions. Such adverse reactions stem from consequences of immune and inflammatory reactions to PMMA. Some animal models have been used to unravel the causes of these reactions, among other factors involving the management of PMMA. The aim of this study was to determine the immunogenic profile of PMMA implantation in different anatomical planes of mice, over up to 360 experimental days. In this study, BALB/c mice were divided into 30 groups for immune evaluation of the interaction between the organism and the polymer; 2% PMMA was implanted subcutaneously, 10% intramuscularly and 30% in periosteal juxtaposition and followed during five experimental days (7, 30, 90, 180 and 360 days after implantation-DAI). Pro- and anti-inflammatory cytokines (IL-2, IL-4, IL-6, IFN-gamma, TNF, IL-17A, IL-10 and TGF-beta) were quantified in all experimental days. There was no statistical difference between the groups analyzed considering the evaluated parameters. Therefore, at all implanted depths, PMMA behaved inertly in a murine model.No Level Assigned This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Hybrid 3D-Printed and Electrospun Scaffolds Loaded with Dexamethasone for Soft Tissue Applications

BACKGROUND

To make the regenerative process more effective and efficient, tissue engineering (TE) strategies have been implemented. Three-dimensional scaffolds (electrospun or 3D-printed), due to their suitable designed architecture, offer the proper location of the position of cells, as well as cell adhesion and the deposition of the extracellular matrix. Moreover, the possibility to guarantee a concomitant release of drugs can promote tissue regeneration.

METHODS

A PLA/PCL copolymer was used for the manufacturing of electrospun and hybrid scaffolds (composed of a 3D-printed support coated with electrospun fibers). Dexamethasone was loaded as an anti-inflammatory drug into the electrospun fibers, and the drug release kinetics and scaffold biological behavior were evaluated.

RESULTS

The encapsulation efficiency (EE%) was higher than 80%. DXM embedding into the electrospun fibers resulted in a slowed drug release rate, and a slower release was seen in the hybrid scaffolds. The fibers maintained their nanometric dimensions (less than 800 nm) even after deposition on the 3D-printed supports. Cell adhesion and proliferation was favored in the DXM-loading hybrid scaffolds.

CONCLUSIONS

The hybrid scaffolds that were developed in this study can be optimized as a versatile platform for soft tissue regeneration.

Biomaterial based implants caused remote liver fatty deposition through activated blood-derived macrophages

Understanding the biocompatibility of biomaterials is a prerequisite for the prediction of its clinical application, and the present assessments mainly rely on in vitro cell culture and in situ histopathology. However, remote organs responses after biomaterials implantation is unclear. Here, by leveraging body-wide-transcriptomics data, we performed in-depth systems analysis of biomaterials - remote organs crosstalk after abdominal implantation of polypropylene and silk fibroin using a rodent model, demonstrating local implantation caused remote organs responses dominated by acute-phase responses, immune system responses and lipid metabolism disorders. Of note, liver function was specially disturbed, defined as hepatic lipid deposition. Combining flow cytometry analyses and liver monocyte recruitment inhibition experiments, we proved that blood derived monocyte-derived macrophages in the liver underlying the mechanism of abnormal lipid deposition induced by local biomaterials implantation. Moreover, from the perspective of temporality, the remote organs responses and liver lipid deposition of silk fibroin group faded away with biomaterial degradation and restored to normal at end, which highlighted its superiority of degradability. These findings were further indirectly evidenced by human blood biochemical ALT and AST examination from 141 clinical cases of hernia repair using silk fibroin mesh and polypropylene mesh. In conclusion, this study provided new insights on the crosstalk between local biomaterial implants and remote organs, which is of help for future selecting and evaluating biomaterial implants with the consideration of whole-body response.

Cell-Tissue Interaction: The Biomimetic Approach to Design Tissue Engineered Biomaterials

The advancement achieved in Tissue Engineering is based on a careful and in-depth study of cell-tissue interactions. The choice of a specific biomaterial in Tissue Engineering is fundamental, as it represents an interface for adherent cells in the creation of a microenvironment suitable for cell growth and differentiation. The knowledge of the biochemical and biophysical properties of the extracellular matrix is a useful tool for the optimization of polymeric scaffolds. This review aims to analyse the chemical, physical, and biological parameters on which are possible to act in Tissue Engineering for the optimization of polymeric scaffolds and the most recent progress presented in this field, including the novelty in the modification of the scaffolds' bulk and surface from a chemical and physical point of view to improve cell-biomaterial interaction. Moreover, we underline how understanding the impact of scaffolds on cell fate is of paramount importance for the successful advancement of Tissue Engineering. Finally, we conclude by reporting the future perspectives in this field in continuous development.

Incorporation of strontium borosilicate bioactive glass in calcium aluminate biocement: Physicomechanical, bioactivity and antimicrobial properties

Strontium borosilicate bioactive glass (SrBG) and calcium aluminate cement (CA) composites have been synthesized. The primary goal of this work is to evaluate how SrBG affects the bioactivity and physico-mechanical characteristics of CA. To fulfill this aim, SrBG was prepared by melt-quenching method and utilized as a substitute for CA by 5, 10, 15, and 20 wt%. To estimate the biological behavior of the prepared specimens, hydrᴏxyapatite layer (HA) establishment on the surface of cement paste was followed; after their immersion in a solution resembles human blood plasma (simulated body fluid solution (SBF)) at a temperature of about37 ± 0.5 °C for 4 weeks. The variations of pH, Ca and P ions concentrations in the SBF solution after soaking were determined. Compressive strength, apparent porosity, and bulk density were also measured. Via Fourier transform IR spectroscopy and X-ray diffraction analyses, the main components had been analyzed. Using scanning electron microscope (SEM) attached to energy dispersive spectroscopy, morphology of the samples was investigated. Additionally, the antimicrobial property was also assessed. The results proved that the hydrᴏxyapatite layer (HA) was developed on the surface of the prepared samples after soaking in the biological solution (SBF). It was also found that increasing SrBG percent in synthesized samples promotes the physico-mechanical characteristics and also the bioactivity performance of CA cement. Finally, these materials also showed good inhibition behavior towards bacterial biᴏfilms, against S. aureus and E. coli. after 48h. This makes these materials excellent candidates for preventing growth of bacteria after their implantation in teeth or bone.

Preparation of Gelatin-Quaternary Ammonium Salt Coating on Titanium Surface for Antibacterial/Osteogenic Properties

Titanium (Ti) and its alloys are widely used in medical treatment, engineering, and other fields because of their excellent properties including biological activity, an elastic modulus similar to that of human bones, and corrosion resistance. However, there are still many defects in the surface properties of Ti in practical applications. For example, the biocompatibility of Ti with bone tissue can be greatly reduced in implants due to a lack of osseointegration as well as antibacterial properties, which may lead to osseointegration failure. To address these problems and to take advantage of the amphoteric polyelectrolyte properties of gelatin, a thin layer of gelatin was prepared by electrostatic self-assembly technology. Diepoxide quaternary ammonium salt (DEQAS) and maleopimaric acid quaternary ammonium salt (MPA-N⁺) were then synthesized and grafted onto the thin layer. The cell adhesion and migration experiments demonstrated that the coating has excellent biocompatibility, and those grafted with MPA-N⁺ promoted cell migration. The bacteriostatic experiment showed that the mixed grafting with two ammonium salts had excellent bacteriostatic performance against Escherichia coli and Staphylococcus aureus, with bacteriostasis rates of 98.1 ± 1.0% and 99.2 ± 0.5%, respectively.

An Eco-Friendly Process to Extract Hydroxyapatite from Sheep Bones for Regenerative Medicine: Structural, Morphologic and Electrical Studies

Hydroxyapatite (HA) promotes excellent bone regeneration in bone-tissue engineering, due to its similarity to bone mineral and its ability to connect to living tissues. These factors promote the osteointegration process. This process can be enhanced by the presence of electrical charges, stored in the HA. Furthermore, several ions can be added to the HA structure to promote specific biological responses, such as magnesium ions. The main objective of this work was to extract hydroxyapatite from sheep femur bones and to study their structural and electrical properties by adding different amounts of magnesium oxide. The thermal and structural characterizations were performed using DTA, XRD, density, Raman spectroscopy and FTIR analysis. The morphology was studied using SEM, and the electrical measurements were registered as a function of frequency and temperature. Results show that: (i) an increase of MgO amount indicates that the solubility of MgO is below 5%wt for heat treatments at 600 °C; (ii) the rise of MgO content increases the capacity for electrical charge storage; (iii) sheep hydroxyapatite presents itself as a natural source of hydroxyapatite, environmentally sustainable and low cost, and promising for applications in regenerative medicine.

Antioxidant Biomaterials in Cutaneous Wound Healing and Tissue Regeneration: A Critical Review

Natural-based biomaterials play an important role in developing new products for medical applications, primarily in cutaneous injuries. A large panel of biomaterials with antioxidant properties has revealed an advancement in supporting and expediting tissue regeneration. However, their low bioavailability in preventing cellular oxidative stress through the delivery system limits their therapeutic activity at the injury site. The integration of antioxidant compounds in the implanted biomaterial should be able to maintain their antioxidant activity while facilitating skin tissue recovery. This review summarises the recent literature that reported the role of natural antioxidant-incorporated biomaterials in promoting skin wound healing and tissue regeneration, which is supported by evidence from in vitro, in vivo, and clinical studies. Antioxidant-based therapies for wound healing have shown promising evidence in numerous animal studies, even though clinical studies remain very limited. We also described the underlying mechanism of reactive oxygen species (ROS) generation and provided a comprehensive review of ROS-scavenging biomaterials found in the literature in the last six years.

A New Mass Spectroscopy-Based Method for Assessing the Periodontal-Endodontic Interface after Intracanal Placement of Biomaterials In Vitro

Optimizing the interface between biomaterials and dental hard tissues can prevent leakage of bacteria or inflammatory mediators into periapical tissues and thus avoid alveolar bone inflammation. In this study, an analysis system for testing the periodontal-endodontic interface using gas leakage and subsequent mass spectrometry was developed and validated using the roots of 15 single-rooted teeth in four groups: (I) roots without root canal filling, (II) roots with an inserted gutta-percha post without sealer, (III) roots with gutta-percha post and sealer, (IV) roots filled with sealer only, and (V) adhesively covered roots. Helium was used as the test gas, and its leakage rate was found by measuring the rising ion current using mass spectrometry. This system made it possible to differentiate between the leakage rates of tooth specimens with different fillings. Roots without filling showed the highest leakage values (p < 0.05). Specimens with a gutta-percha post without sealer showed statistically significantly higher leakage values than groups with a filling of gutta-percha and sealer or sealer alone (p < 0.05). This study shows that a standardized analysis system can be developed for periodontal-endodontic interfaces to prevent biomaterials and tissue degradation products from affecting the surrounding alveolar bone tissue.

The Impact of Hydroxyapatite Sintering Temperature on Its Microstructural, Mechanical, and Biological Properties

Hydroxyapatite (HA), the principal mineral of bone tissue, can be fabricated as an artificial calcium phosphate (CaP) ceramic and potentially used as bioceramic material for bone defect treatment. Nevertheless, the production method (including the applied sintering temperature) of synthetic hydroxyapatite directly affects its basic properties, such as its microstructure, mechanical parameters, bioabsorbability, and osteoconductivity, and in turn influences its biomedical potential as an implantable biomaterial. The wide application of HA in regenerative medicine makes it necessary to explain the validity of the selection of the sintering temperature. The main emphasis of this article is on the description and summarization of the key features of HA depending on the applied sintering temperature during the synthesis process. The review is mainly focused on the dependence between the HA sintering temperature and its microstructural features, mechanical properties, biodegradability/bioabsorbability, bioactivity, and biocompatibility.

A Review of Biomimetic and Biodegradable Magnetic Scaffolds for Bone Tissue Engineering and Oncology

Bone defects characterized by limited regenerative properties are considered a priority in surgical practice, as they are associated with reduced quality of life and high costs. In bone tissue engineering, different types of scaffolds are used. These implants represent structures with well-established properties that play an important role as delivery vectors or cellular systems for cells, growth factors, bioactive molecules, chemical compounds, and drugs. The scaffold must provide a microenvironment with increased regenerative potential at the damage site. Magnetic nanoparticles are linked to an intrinsic magnetic field, and when they are incorporated into biomimetic scaffold structures, they can sustain osteoconduction, osteoinduction, and angiogenesis. Some studies have shown that combining ferromagnetic or superparamagnetic nanoparticles and external stimuli such as an electromagnetic field or laser light can enhance osteogenesis and angiogenesis and even lead to cancer cell death. These therapies are based on in vitro and in vivo studies and could be included in clinical trials for large bone defect regeneration and cancer treatments in the near future. We highlight the scaffolds' main attributes and focus on natural and synthetic polymeric biomaterials combined with magnetic nanoparticles and their production methods. Then, we underline the structural and morphological aspects of the magnetic scaffolds and their mechanical, thermal, and magnetic properties. Great attention is devoted to the magnetic field effects on bone cells, biocompatibility, and osteogenic impact of the polymeric scaffolds reinforced with magnetic nanoparticles. We explain the biological processes activated due to magnetic particles' presence and underline their possible toxic effects. We present some studies regarding animal tests and potential clinical applications of magnetic polymeric scaffolds.

Two dimensional (2D) materials and biomaterials for water desalination; structure, properties, and recent advances

BACKGROUND

An efficient solution to the global freshwater dilemma is desalination. MXene, Molybdenum Disulfide (MoS₂), Graphene Oxide, Hexagonal Boron Nitride, and Phosphorene are just a few examples of two-dimensional (2D) materials that have shown considerable promise in the development of 2D materials for water desalination. However, other promising materials for desalinating water are biomaterials. The benefits of bio-materials are their wide distribution, lack of toxicity, and superior capacity for water desalination.

METHODS

For the rational use of water and the advancement of sustainable development, it is of the utmost importance to research 2D-dimensional materials and biomaterials that are effective for water desalination. The scientific community has concentrated on wastewater remediation using bio-derived materials, such as nanocellulose, chitosan, bio-char, bark, and activated charcoal generated from plant sources, among the various endeavors to enhance access to clean water. Moreover, the 2D-materials and biomaterials may have ushered in a new age in the production of desalination materials and created a promising future.

RESULTS

The present review article focuses on and reviews the progress of 2D materials and biomaterials for water desalination. Their properties, surface, and structure, combined with water desalination applications, are highlighted. Further, the practicability and potential future directions of 2D materials and biomaterials are proposed. Thus, the current work provides information and discernments for developing novel 2D materials and biomaterials for wastewater desalination. Moreover, it aims to promote the contribution and advancement of materials for water desalination, fabrication, and industrial production.

From Basic Science to Clinical Perfection: What Defines the Orthopedic Biocompatible Implant?

The general improvement in life expectancy and standard of living makes it easier for patients to get access to routine medical exams and is anticipated to increase the prevalence of several degenerative joint illnesses. In addition, it is anticipated that their incidence will increase both nationally and internationally, which will raise the demand for novel and long-lasting implantable devices in the field of orthopedics. The current review’s goals are to define what constitutes a biocompatible orthopedic implant in terms of in vitro biocompatibility testing and to clarify important concepts and definitions that are already in use. The demand for materials and implants made of various tissues is now increasing, and the ongoing advancement of in vitro cell culture studies is a reliable practical tool for examining the biocompatibility of potential implantable materials. In vitro biocompatibility research has been reduced and, in most cases, diminished to laboratory studies that no longer or drastically reduce animal sacrifice as a response to the well-known three “Rs” (“reduction”, “refinement”, and “replacement”) introduced to literature by English academics in the 1960s. As technology advances at an astounding rate, a new generation of gene-activating biomaterials tailored for specific people and disease conditions might emerge in the near future.

Static and photoresponsive dynamic materials to dissect physical regulation of cellular functions

Recent progress in mechanobiology has highlighted the importance of physical cues, such as mechanics, geometry (size), topography, and porosity, in the determination of cellular activities and fates, in addition to biochemical factors derived from their surroundings. In this review, we will first provide an overview of how such fundamental insights are identified by synchronizing the hierarchical nature of biological systems and static materials with tunable physical cues. Thereafter, we will explain the photoresponsive dynamic biomaterials to dissect the spatiotemporal aspects of the dependence of biological functions on physical cues.

Albumin as a Biomaterial and Therapeutic Agent in Regenerative Medicine

Albumin is a constitutional plasma protein, with well-known biological functions, e.g., a nutrient for stem cells in culture. However, albumin is underutilized as a biomaterial in regenerative medicine. This review summarizes the advanced therapeutic uses of albumin, focusing on novel compositions that take advantage of the excellent regenerative potential of this protein. Albumin coating can be used for enhancing the biocompatibility of various types of implants, such as bone grafts or sutures. Albumin is mainly known as an anti-attachment protein; however, using it on implantable surfaces is just the opposite: it enhances stem cell adhesion and proliferation. The anticoagulant, antimicrobial and anti-inflammatory properties of albumin allow fine-tuning of the biological reaction to implantable tissue-engineering constructs. Another potential use is combining albumin with natural or synthetic materials that results in novel composites suitable for cardiac, neural, hard and soft tissue engineering. Recent advances in materials have made it possible to electrospin the globular albumin protein, opening up new possibilities for albumin-based scaffolds for cell therapy. Several described technologies have already entered the clinical phase, making good use of the excellent biological, but also regulatory, manufacturing and clinical features of serum albumin.

Biocompatibility and antioxidant activity of a novel carrageenan based injectable hydrogel scaffold incorporated with Cissus quadrangularis: an in vitro study

Background

Over the past years, polysaccharide-based scaffolds have emerged as the most promising material for tissue engineering. In the present study, carrageenan, an injectable scaffold has been used owing to its advantage and superior property. Cissus quadrangularis, a natural agent was incorporated into the carrageenan scaffold. Therefore, the present study aimed to assess the antioxidant activity and biocompatibility of this novel material.

Methods

The present in vitro study comprised of four study groups each constituting a sample of 15 with a total sample size of sixty (n = 60). The carrageenan hydrogel devoid of Cissus quadrangularis acted as the control group (Group-I). Based on the concentration of aqueous extract of Cissus quadrangularis (10% w/v, 20% w/v and 30% w/v) in carrageenan hydrogel, respective study groups namely II, III and IV were considered. Antioxidant activity was assessed using a 1,1-diphenyl-2-picrylhydrazyl radical scavenging assay, whereas the biocompatibility test was performed using a brine shrimp lethality assay. The microstructure and surface morphology of the hydrogel samples containing different concentrations of Cissus quadrangularis aqueous extract was investigated using SEM. One-way ANOVA with the post hoc tukey test was performed using SPSS software v22.

Results

A significant difference (P < 0.05) in the antioxidant activity was observed among the study groups. Group III reported the highest activity, whereas the control group showed the least antioxidant activity. Additionally, a significant (P < 0.01) drop in the antioxidant activity was observed in group IV when compared with group III. While assessing the biocompatibility, a significant (P < 0.001) dose-dependent increase in biocompatibility was observed with the increasing concentration of aqueous extract of Cissus quadrangularis. SEM analysis in group III showed even distribution throughout the hydrogel although the particles are close and densely arranged. Reduced antioxidant activity in group IV was probably due to clumping of the particles, thus reducing the active surface area.

Conclusion

Keeping the limitations of in vitro study, it can be assumed that a carrageenan based injectable hydrogel scaffold incorporated with 20% w/v Cissus quadrangularis can provide a favourable micro-environment as it is biocompatible and possess better antioxidant property.

Inflammation Self-Limiting Electrospun Fibrous Tape via Regional Immunity for Deep Soft Tissue Repair

Overexpression of inflammatory cytokines and chemokines occurs at deep soft tissue injury sites impeding the inflammation self-limiting and impairing the tissue remodeling process. Inspired by the electrostatically extracellular matrix (ECM) binding property of the inflammatory signals, an inflammation self-limiting fibrous tape is designed by covalently modifying the thermosensitive methacrylated gelatin (GelMA) and negatively charged methacrylated heparin (HepMA) hydrogel mixture with proper ratio onto the electrospun fibrous membrane by mild alkali hydrolysis and carboxyl-amino condensation reaction to restore inflammation self-limiting and promote tissue repair via regional immunity regulation. While the GelMA guarantees cell compatibility, the negatively charged HepMA successfully adsorbs the inflammatory cytokines and chemokines by electrostatic interactions and inhibits immune cell migration in vitro. Furthermore, in vivo inflammation self-limiting and regional immunity regulation efficacy is evaluated in a rat abdominal hernia model. Reduced local inflammatory cytokines and chemokines in the early stage and increased angiogenesis and ECM remodeling in the later phase confirm that the tape is an approach to maintain an optimal regional immune activation level after soft tissue injury. Overall, the reported electrospun fibrous tape will find its way into clinical transformation and solve the challenges of deep soft tissue injury.

Insights into the use of genetically modified decellularized biomaterials for tissue engineering and regenerative medicine

Various modifications have been performed on biomaterials to improve their applications in tissue engineering and regenerative medicine. However, the challenges of immunogenicity and biocompatibility existed since the application of biomaterials. As a method to solve this problem, the decellularization process removes most living cells from biomaterials to minimize their immunogenicity; and preserves the native structures and compositions that favour cell growth and the subsequent construction of functional tissue. On the other hand, genetic modification of biomaterials aims to achieve specific functions (low immunogenicity, osteogenesis, etc.) or analyse the genetic mechanisms underlying some diseases (cardiac dysfunction, liver fibrosis, etc.). The combination of decellularization and gene modification is highly superior to biomaterials; thus, we must obtain a deeper understanding of these novel biomaterials. In this review, we summarize the fabrication approaches and current applications of genetically modified decellularized biomaterials and then discuss their disadvantages and corresponding future perspectives.

Citric acid cross-linked chitosan for inhibiting oxidative stress after nerve injury

Scaffold design is particularly important and necessary for soft tissue repair such as nerve tissue repair. In this article, we designed and manufactured a macroporous chitosan-based hydrogel with excellent cell compatibility and antioxidant properties. Here, the chitosan (CS) based hydrogel is obtained by repeated freezing and thawing using citric acid (CA) as a cross-linking agent. We have evaluated the effects of citric acid content on the physical and chemical properties of hydrogels through mechanical properties and scanning electron microscopy. CA-CS hydrogel shows a macroporous structure, as the citric acid increases, the mechanical strength increases and the pore size decreases. In vitro cell experiments show that CA-CS hydrogel partakes positive effects on cell survival, adhesion and proliferation, as well as antioxidant properties. All results provide a basis for the construction of porous chitosan-based hydrogels, while demonstrating a promising approach to deal with oxidative stress in nerve injury.

Surface Modification of Sponge-like Porous Poly(3-hydroxybutyrate-co-4-hydroxybutyrate)/Gelatine Blend Scaffolds for Potential Biomedical Applications

In this study, we described the preparation of sponge-like porous scaffolds that are feasible for medical applications. A porous structure provides a good microenvironment for cell attachment and proliferation. In this study, a biocompatible PHA, poly(3-hydroxybutyrate-co-4-hydroxybutyrate) was blended with gelatine to improve the copolymer’s hydrophilicity, while structural porosity was introduced into the scaffold via a combination of solvent casting and freeze-drying techniques. Scanning electron microscopy results revealed that the blended scaffolds exhibited higher porosity when the 4HB compositions of P(3HB-co-4HB) ranged from 27 mol% to 50 mol%, but porosity decreased with a high 4HB monomer composition of 82 mol%. The pore size, water absorption capacity, and cell proliferation assay results showed significant improvement after the final weight of blend scaffolds was reduced by half from the initial 0.79 g to 0.4 g. The pore size of 0.79g-(P27mol%G10) increased three-fold while the water absorption capacity of 0.4g-(P50mol%G10) increased to 325%. Meanwhile, the cell proliferation and attachment of 0.4g-(P50mol%G10) and 0.4g-(P82mol%G7.5) increased as compared to the initial seeding number. Based on the overall data obtained, we can conclude that the introduction of a small amount of gelatine into P(3HB-co-4HB) improved the physical and biological properties of blend scaffolds, and the 0.4g-(P50mol%G10) shows great potential for medical applications considering its unique structure and properties.

Multiscale Mechanical Performance of Wood: From Nano- to Macro-Scale across Structure Hierarchy and Size Effects

This review describes methods and results of studying the mechanical properties of wood at all scales: from nano- to macro-scale. The connection between the mechanical properties of material and its structure at all these levels is explored. It is shown that the existing size effects in the mechanical properties of wood, in a range of the characteristic sizes of the structure of about six orders of magnitude, correspond to the empirical Hall-Petch relation. This “law” was revealed more than 60 years ago in metals and alloys and later in other materials. The nature, as well as the particular type of the size dependences in different classes of materials can vary, but the general trend, “the smaller the stronger”, remains true both for wood and for other cellulose-containing materials. The possible mechanisms of the size effects in wood are being discussed. The correlations between the mechanical and thermophysical properties of wood are described. Several examples are used to demonstrate the possibility to forecast the macromechanical properties of wood by means of contactless thermographic express methods based on measuring temperature diffusivity. The research technique for dendrochronological and dendroclimatological studies by means of the analysis of microhardness and Young’s modulus radial dependences in annual growth rings is described.

3D Printed Multiphasic Scaffolds for Osteochondral Repair: Challenges and Opportunities

Osteochondral (OC) defects are debilitating joint injuries characterized by the loss of full thickness articular cartilage along with the underlying calcified cartilage through to the subchondral bone. While current surgical treatments can provide some relief from pain, none can fully repair all the components of the OC unit and restore its native function. Engineering OC tissue is challenging due to the presence of the three distinct tissue regions. Recent advances in additive manufacturing provide unprecedented control over the internal microstructure of bioscaffolds, the patterning of growth factors and the encapsulation of potentially regenerative cells. These developments are ushering in a new paradigm of 'multiphasic' scaffold designs in which the optimal micro-environment for each tissue region is individually crafted. Although the adoption of these techniques provides new opportunities in OC research, it also introduces challenges, such as creating tissue interfaces, integrating multiple fabrication techniques and co-culturing different cells within the same construct. This review captures the considerations and capabilities in developing 3D printed OC scaffolds, including materials, fabrication techniques, mechanical function, biological components and design.

Toughening of Bioceramic Composites for Bone Regeneration

Bioceramics are widely considered as elective materials for the regeneration of bone tissue, due to their compositional mimicry with bone inorganic components. However, they are intrinsically brittle, which limits their capability to sustain multiple biomechanical loads, especially in the case of load-bearing bone districts. In the last decades, intense research has been dedicated to combining processes to enhance both the strength and toughness of bioceramics, leading to bioceramic composite scaffolds. This review summarizes the recent approaches to this purpose, particularly those addressed to limiting the propagation of cracks to prevent the sudden mechanical failure of bioceramic composites.

Electrophoretic Deposition of Biocompatible and Bioactive Hydroxyapatite-Based Coatings on Titanium

Current trends in biomaterials science address the issue of integrating artificial materials as orthopedic or dental implants with biological materials, e.g., patients' bone tissue. Problems arise due to the simple fact that any surface that promotes biointegration and facilitates osteointegration may also provide a good platform for the rapid growth of bacterial colonies. Infected implant surfaces easily lead to biofilm formation that poses a major healthcare concern since it could have destructive effects and ultimately endanger the patients' life. As of late, research has centered on designing coatings that would eliminate possible infection but neglected to aid bone mineralization. Other strategies yielded surfaces that could promote osseointegration but failed to prevent microbial susceptibility. Needless to say, in order to assure prolonged implant functionality, both coating functions are indispensable and should be addressed simultaneously. This review summarizes progress in designing multifunctional implant coatings that serve as carriers of antibacterial agents with the primary intention of inhibiting bacterial growth on the implant-tissue interface, while still promoting osseointegration.

Methylcellulose-Cellulose Nanocrystal Composites for Optomechanically Tunable Hydrogels and Fibers

Chemical modification of cellulose offers routes for structurally and functionally diverse biopolymer derivatives for numerous industrial applications. Among cellulose derivatives, cellulose ethers have found extensive use, such as emulsifiers, in food industries and biotechnology. Methylcellulose, one of the simplest cellulose derivatives, has been utilized for biomedical, construction materials and cell culture applications. Its improved water solubility, thermoresponsive gelation, and the ability to act as a matrix for various dopants also offer routes for cellulose-based functional materials. There has been a renewed interest in understanding the structural, mechanical, and optical properties of methylcellulose and its composites. This review focuses on the recent development in optically and mechanically tunable hydrogels derived from methylcellulose and methylcellulose-cellulose nanocrystal composites. We further discuss the application of the gels for preparing highly ductile and strong fibers. Finally, the emerging application of methylcellulose-based fibers as optical fibers and their application potentials are discussed.

Surface engineering of biomaterials in orthopedic and dental implants: Strategies to improve osteointegration, bacteriostatic and bactericidal activities

BACKGROUND

The success of biomedical implants in orthopedic and dental applications is usually limited due to insufficient bone-implant integration, and implant-related infections. Biointerfaces are critical in regulating their interactions and the desirable performance of biomaterials in biological environment. Surface engineering has been widely studied to realize better control of the interface interaction to further enhance the desired behavior of biomaterials.

PURPOSE AND SCOPE

This review aims to investigate surface coating strategies in hard tissue applications to address insufficient osteointegration and implant-related infection problems.

SUMMARY

We first focused on surface coatings to enhance the osteointegration and biocompatibility of implants by emphasizing calcium phosphate-related, nanoscale TiO₂ -related, bioactive tantalum-based and biomolecules incorporated coatings. Different coating strategies such as plasma spraying, biomimetic deposition, electrochemical anodization and LENS are discussed. We then discussed techniques to construct anti-adhesive and bactericidal surface while emphasizing multifunctional surface coating techniques that combine potential osteointegration and antibacterial activities. The effects of nanotopography via TiO₂ coatings on antibacterial performance are interesting and included. A smart bacteria-responsive titanium dioxide nanotubes coating is also attractive and elaborated.

CONCLUSION

Developing multifunctional surface coatings combining osteogenesis and antimicrobial activity is the current trend. Surface engineering methods are usually combined to obtain hierarchical multiscale surface structures with better biofunctionalization outcomes.

A Comparative Review of Natural and Synthetic Biopolymer Composite Scaffolds

Tissue engineering (TE) and regenerative medicine integrate information and technology from various fields to restore/replace tissues and damaged organs for medical treatments. To achieve this, scaffolds act as delivery vectors or as cellular systems for drugs and cells; thereby, cellular material is able to colonize host cells sufficiently to meet up the requirements of regeneration and repair. This process is multi-stage and requires the development of various components to create the desired neo-tissue or organ. In several current TE strategies, biomaterials are essential components. While several polymers are established for their use as biomaterials, careful consideration of the cellular environment and interactions needed is required in selecting a polymer for a given application. Depending on this, scaffold materials can be of natural or synthetic origin, degradable or nondegradable. In this review, an overview of various natural and synthetic polymers and their possible composite scaffolds with their physicochemical properties including biocompatibility, biodegradability, morphology, mechanical strength, pore size, and porosity are discussed. The scaffolds fabrication techniques and a few commercially available biopolymers are also tabulated.