A Review of Bioactive Glass/Natural Polymer Composites: State of the Art

Bioglass and nano bioglass: A next-generation biomaterial for therapeutic and regenerative medicine applications

Biomaterials are an indispensable component in tissue engineering that primarily functions to resemble the extracellular matrix of any tissue targeted for regeneration. In the last five decades, bioglass has been extensively used in the field of therapeutic and tissue engineering. The doping of metal components into bioglass and the synthesizing of nano bioglass particles have found remarkable implications, both in vivo and in vitro. These include various medical and biological applications such as rejuvenating tissues, facilitating regeneration, and delivering biomolecules into cells and therapy, etc. Therefore, the current review discusses the various techniques used in synthesizing bioglass particles, trends of various ion-doped nano bioglass, and their applications in therapy as well as in regenerative medicine, specifically in the fields of dentistry, cardiovascular, skin, nervous, and respiratory systems. Apart from these, this review also emphasizes the bioglass combined with diverse natural polymers (like collagen, chitosan, etc.) and their applications. Furthermore, we discuss the effectiveness of bioglass properties such as antibacterial effects, biomolecular delivery systems, tissue compatibility, and regenerative material. Finally, the prospects and limitations are elaborated.

Nano-Micron Combined Hydrogel Microspheres: Novel Answer for Minimal Invasive Biomedical Applications

Hydrogels, key in biomedical research for their hydrophilicity and versatility, have evolved with hydrogel microspheres (HMs) of micron-scale dimensions, enhancing their role in minimally invasive therapeutic delivery, tissue repair, and regeneration. The recent emergence of nanomaterials has ushered in a revolutionary transformation in the biomedical field, which demonstrates tremendous potential in targeted therapies, biological imaging, and disease diagnostics. Consequently, the integration of advanced nanotechnology promises to trigger a new revolution in the realm of hydrogels. HMs loaded with nanomaterials combine the advantages of both hydrogels and nanomaterials, which enables multifaceted functionalities such as efficient drug delivery, sustained release, targeted therapy, biological lubrication, biochemical detection, medical imaging, biosensing monitoring, and micro-robotics. Here, this review comprehensively expounds upon commonly used nanomaterials and their classifications. Then, it provides comprehensive insights into the raw materials and preparation methods of HMs. Besides, the common strategies employed to achieve nano-micron combinations are summarized, and the latest applications of these advanced nano-micron combined HMs in the biomedical field are elucidated. Finally, valuable insights into the future design and development of nano-micron combined HMs are provided.

Recent Advances in Bioactive Carbon Nanotubes Based on Polymer Composites for Biosensor Applications

Recent breakthroughs in the field of carbon nanotubes (CNTs) have opened up unprecedented opportunities for the development of specialized bioactive CNT-polymers for a variety of biosensor applications. The incorporation of bioactive materials, including DNA, aptamers and antibodies, into CNTs to produce composites of bioactive CNTs has attracted considerable attention. In addition, polymers are essential for the development of biosensors as they provide biocompatible conditions and are the ideal matrix for the immobilization of proteins. The numerous applications of bioactive compounds combined with the excellent chemical and physical properties of CNTs have led to the development of bioactive CNT-polymer composites. This article provides a comprehensive overview of CNT-polymer composites and new approaches to encapsulate bioactive compounds and polymers in CNTs. Finally, biosensor applications of bioactive CNT-polymer for the detection of glucose, H2O2 and cholesterol were investigated. The surface of CNT-polymer facilitates the immobilization of bioactive molecules such as DNA, enzymes or antibodies, which in turn enables the construction of state-of-the-art, future-oriented biosensors.

Biodegradable Polymers in Veterinary Medicine-A Review

During the past two decades, tremendous progress has been made in the development of biodegradable polymeric materials for various industrial applications, including human and veterinary medicine. They are promising alternatives to commonly used non-degradable polymers to combat the global plastic waste crisis. Among biodegradable polymers used, or potentially applicable to, veterinary medicine are natural polysaccharides, such as chitin, chitosan, and cellulose as well as various polyesters, including poly(ε-caprolactone), polylactic acid, poly(lactic-co-glycolic acid), and polyhydroxyalkanoates produced by bacteria. They can be used as implants, drug carriers, or biomaterials in tissue engineering and wound management. Their use in veterinary practice depends on their biocompatibility, inertness to living tissue, mechanical resistance, and sorption characteristics. They must be designed specifically to fit their purpose, whether it be: (1) facilitating new tissue growth and allowing for controlled interactions with living cells or cell-growth factors, (2) having mechanical properties that address functionality when applied as implants, or (3) having controlled degradability to deliver drugs to their targeted location when applied as drug-delivery vehicles. This paper aims to present recent developments in the research on biodegradable polymers in veterinary medicine and highlight the challenges and future perspectives in this area.

Rapidly derived equimolar Ca: P phasic bioactive glass infused flexible gelatin multi-functional scaffolds - A promising tissue engineering

The study aims to design and fabricate an ultra-easier multi-functional biomedical polymeric scaffold loaded with unique equimolar Ca:P phasic bioactive glass material (BG). Gelatin (G) - 45S5 bioactive glass (BG) scaffolds were synthesized via a simple laboratory refrigerator with higher biocompatibility and cytocompatibility. The results proved that BG has enhanced bio-mineralization of the scaffolds and results support that the G: BG (1:2) ratio is the more appropriate composition. Brunauer-Emmett-Teller (BET) study confirms the higher surface area for pure Gelatin and G: BG (1:2). Scanning Electron Microscopic images display the precipitation of hydroxycarbonate apatite layer over the scaffolds on immersing it in simulated body fluid. Alkaline phosphate activity proved that G: BG (1:2) scaffold could induce mitogenesis in MG-63 osteoblast cells, thus helping in hard tissue regeneration. Sirius red collagen deposition showed that higher content bioactive glass incorporated Gelatin polymeric scaffold G: BG (1:2) could induce rapid collagen secretion of NIH 3T3 fibroblast cell line that could help in soft tissue regeneration and earlier wound healing. The scaffolds were also tested for cell viability using NIH 3T3 fibroblast cell lines and MG 63 osteoblastic cell lines through methyl thiazolyl tetrazolium (MTT) assay. Thus, the study shows a scaffold of appropriate composition G: BG (1:2) can be a multifunctional material to regenerate hard and soft tissues.

Effect of Silicon Dioxide and Magnesium Oxide on the Printability, Degradability, Mechanical Strength and Bioactivity of 3D Printed Poly (Lactic Acid)-Tricalcium Phosphate Composite Scaffolds

BACKGROUND

Poly (lactic acid) (PLA) is a biodegradable polyester that has been exploited for a variety of biomedical applications, including tissue engineering. The incorporation of β-tricalcium phosphate (TCP) into PLA has imparted bioactivity to the polymeric matrix.

METHODS

We have modified a 90%PLA-10%TCP composite with SiO2 and MgO (1, 5 and 10 wt%), separately, to further enhance the material bioactivity. Filaments were prepared by extrusion, and scaffolds were fabricated using 3D printing technology associated with fused filament fabrication.

RESULTS

The PLA-TCP-SiO2 composites presented similar structural, thermal, and rheological properties to control PLA and PLA-TCP. In contrast, the PLA-TCP-MgO composites displayed absence of crystallinity, lower polymeric molecular weight, accelerated degradation ratio, and decreased viscosity within the 3D printing shear rate range. SiO2 and MgO particles were homogeneously dispersed within the PLA and their incorporation increased the roughness and protein adsorption of the scaffold, compared to a PLA-TCP scaffold. This favorable surface modification promoted cell proliferation, suggesting that SiO2 and MgO may have potential for enhancing the bio-integration of scaffolds in tissue engineering applications. However, high loads of MgO accelerated the polymeric degradation, leading to an acid environment that imparted the composite biocompatibility. The presence of SiO2 stimulated mesenchymal stem cells differentiation towards osteoblast; enhancing extracellular matrix mineralization, alkaline phosphatase (ALP) activity, and bone-related genes expression.

CONCLUSION

The PLA-10%TCP-10%SiO2 composite presented the most promising results, especially for bone tissue regeneration, due to its intense osteogenic behavior. PLA-10%TCP-10%SiO2 could be used as an alternative implant for bone tissue engineering application.

Bioinspired synthesis of bioactive glass nanocomposites for hyaluronic acid delivery to bone and skin

In this study, we present nanocomposites of bioactive glass (BG) and hyaluronic acid (HA) (nano-BGHA) for effective delivery of HA to skin and bone. The synthesis of the nanocomposites has been carried out through the bio-inspired method, which is a modification of the traditional Stober's synthesis as it avoids using ethanol, ammonia, synthetic surfactants, or high-temperature calcination. This environmentally friendly, bio-inspired route allowed the synthesis of mesoporous nanocomposites with an average hydrodynamic radius of ∼190 nm and an average net surface charge of ∼-21 mV. Most nanocomposites are amorphous and bioactive in nature with over 70 % cellular viability for skin and bone cell lines even at high concentrations, along with high cellular uptake (90-100 %). Furthermore, the nanocomposites could penetrate skin cells in a transwell set-up and artificial human skin membrane (StratM®), thus depicting an attractive strategy for the delivery of HA to the skin. The purpose of the study is to develop nanocomposites of HA and BG that can have potential applications in non-invasive treatments that require the delivery of high molecular weight HA such as in the case of osteoarthritis, sports injury treatments, eye drops, wound healing, and some anticancer treatments, if further investigated. The presence of BG further enhances the range to bone-related applications. Additionally, the nanocomposites can have potential cosmeceutical applications where HA is abundantly used, for instance in moisturizers, dermal fillers, shampoos, anti-wrinkle creams, etc.

Injectable smart stimuli-responsive hydrogels: pioneering advancements in biomedical applications

Hydrogels have established their significance as prominent biomaterials within the realm of biomedical research. However, injectable hydrogels have garnered greater attention compared with their conventional counterparts due to their excellent minimally invasive nature and adaptive behavior post-injection. With the rapid advancement of emerging chemistry and deepened understanding of biological processes, contemporary injectable hydrogels have been endowed with an "intelligent" capacity to respond to various endogenous/exogenous stimuli (such as temperature, pH, light and magnetic field). This innovation has spearheaded revolutionary transformations across fields such as tissue engineering repair, controlled drug delivery, disease-responsive therapies, and beyond. In this review, we comprehensively expound upon the raw materials (including natural and synthetic materials) and injectable principles of these advanced hydrogels, concurrently providing a detailed discussion of the prevalent strategies for conferring stimulus responsiveness. Finally, we elucidate the latest applications of these injectable "smart" stimuli-responsive hydrogels in the biomedical domain, offering insights into their prospects.

Rheology in Product Development: An Insight into 3D Printing of Hydrogels and Aerogels

Rheological characterisation plays a crucial role in developing and optimising advanced materials in the form of hydrogels and aerogels, especially if 3D printing technologies are involved. Applications ranging from tissue engineering to environmental remediation require the fine-tuning of such properties. Nonetheless, their complex rheological behaviour presents unique challenges in additive manufacturing. This review outlines the vital rheological parameters that influence the printability of hydrogel and aerogel inks, emphasising the importance of viscosity, yield stress, and viscoelasticity. Furthermore, the article discusses the latest developments in rheological modifiers and printing techniques that enable precise control over material deposition and resolution in 3D printing. By understanding and manipulating the rheological properties of these materials, researchers can explore new possibilities for applications such as biomedicine or nanotechnology. An optimal 3D printing ink requires strong shear-thinning behaviour for smooth extrusion, forming continuous filaments. Favourable thixotropic properties aid viscosity recovery post-printing, and adequate yield stress and G' are crucial for structural integrity, preventing deformation or collapse in printed objects, and ensuring high-fidelity preservation of shapes. This insight into rheology provides tools for the future of material design and manufacturing in the rapidly evolving field of 3D printing of hydrogels and aerogels.

Opportunities for Bioactive Glass in Gastrointestinal Conditions: A Review of Production Methodologies, Morphology, Composition, and Performance

Bioactive glasses (BGs) are widely used in orthopedic and dental applications for their ability to stimulate endogenous bone formation and regeneration. BG applications more recently broadened to include soft tissue conditions, based on their ability to stimulate angiogenesis, soft tissue regeneration, and wound healing. Sol-gel synthesis has helped facilitate this expansion, allowing formulators to tailor the morphological characteristics of the BG matrix. The effectiveness of BGs in skin wound healing is viewed as a gateway for their use as both a therapeutic and drug delivery platform in other soft tissue applications, notably gastrointestinal (GI) applications, which form the focus of this review. Recent changes in international guidelines for GI conditions shifted clinical objectives from symptom management to mucosal wound healing. The additional scrutiny of proton pump inhibitor (PPI) safety, increasing burden of disease, and financial costs associated with gastroesophageal reflux disease (GERD), peptic ulcer disease (PUD), and inflammatory bowel disease (IBD) open new clinical possibilities for BG. This narrative literature review intersects materials engineering, formulation science, and clinical practice, setting it apart from prior literature. Broadly, current evidence for BG applications in GI conditions is sparse and under-developed, which this review directly addresses. It explores and synthesizes evidence that supports the potential use of sol-gel-derived BG for the efficacious treatment of soft tissue applications, with specific reference to GI conditions. An overview with comparative analysis of current BG synthesis techniques and associated challenges is presented, and influences of composition, biologically active ions, and morphological characteristics in soft tissue applications are explored. To contextualize this, sol-gel-derived BGs are proposed as a dual, tailorable therapeutic and drug delivery platform for upper and lower GI conditions. Future directions for this largely untapped area of translational research are also proposed, based on extant literature.

3D Printing Assisted Fabrication of Copper-Silver Mesoporous Bioactive Glass Nanoparticles Reinforced Sodium Alginate/Poly(vinyl alcohol) Based Composite Scaffolds: Designed for Skin Tissue Engineering

Additive manufacturing (also known as 3D printing) is a promising method for producing patient-specific implants. In the present study, sodium alginate (Na-ALG)/poly(vinyl alcohol) (PVA) polymer blends of varying ratios (1:0, 3:1, 1:1, and 1:3) were used to produce tailored-designed skin scaffolds using a 3D bioprinter. Samples of skin scaffolds were printed at 20 layers with a layer height of 0.15 mm using a needle with an inner diameter of 330 μm while maintaining the extrusion speed, extrusion width, and fill density at 10 mm/s, 0.2 mm, and 85%, respectively. The Na-ALG/PVA blend with a 3:1 ratio showed the best printability due to its good viscosity and minimal nozzle leakage, allowing for the fabrication of skin scaffolds with high fidelity and the desired morphological characteristics. Then, copper-silver doped mesoporous bioactive glass nanoparticles (Cu-Ag MBGNs) were incorporated into the Na-ALG/PVA blend (which had already been prepared by using a Na-ALG:PVA ratio of 3:1) in order to obtain therapeutic (angiogenic and antibacterial) effects. The fabricated Na-ALG/PVA/Cu-Ag MBGNs biocomposite scaffolds with dimensions of 20 mm× 20 × 3 mm3 and pore size of 400 ± 60 μm exhibited a promising fidelity. The presence of chemical bonds attributed to Na-ALG, PVA, and Cu-Ag MBGNs and the uniform distribution of Na, C, and O elements within the microstructure of the scaffolds were confirmed by EDX, SEM, and FTIR analyses. The scaffolds were hydrophilic and exhibited proper swelling and degradation behavior for skin tissue engineering. According to the inhibition halo test, the scaffolds exhibited strong antibacterial activity against Staphylococcus aureus and Escherichia coli. The cytocompatibility to human-derived fibroblast cells was confirmed by the WST-8 assay and in vivo Chorioallantoic Membrane Assay. In addition, Na-ALG/PVA/Cu-Ag MBGNs showed angiogenic potential, exhibiting favorable wound healing properties.

A better roadmap for designing novel bioactive glasses: effective approaches for the development of innovative revolutionary bioglasses for future biomedical applications

The introduction of bioactive glasses (BGs) precipitated a paradigm shift in the medical industry and opened the path for the development of contemporary regenerative medicine driven by biomaterials. This composition can bond to live bone and can induce osteogenesis by the release of physiologically active ions. 45S5 BG products have been transplanted effectively into millions of patients around the world, primarily to repair bone and dental defects. Over the years, many other BG compositions have been introduced as innovative biomaterials for repairing soft tissue and delivering drugs. When research first started, many of the accomplishments that have been made today were unimaginable. It appears that the true capacity of BGs has not yet been realized. Because of this, research involving BGs is extremely fascinating. However, to be successful, it requires interdisciplinary cooperation between physicians, glass chemists, and bioengineers. The present paper gives a picture of the existing clinical uses of BGs and illustrates key difficulties deserving to be faced in the future. The challenges range from the potential for BGs to be used in a wide variety of applications. We have high hopes that this paper will be of use to both novice researchers, who are just beginning their journey into the world of BGs, as well as seasoned scientists, in that it will promote conversation regarding potential additional investigation and lead to the discovery of innovative medical applications for BGs.

Wound healing performance of electrospun PVA/70S30C bioactive glass/Ag nanoparticles mats decorated with curcumin: In vitro and in vivo investigations

Biocompatible fibrous scaffold containing polyvinyl alcohol (PVA), 70S30C bioactive glass (BG), silver (Ag) nanoparticles and curcumin (Cur) was fabricated through electrospinning method. Scanning electron microscope (SEM) and Field emission scanning electron microscopy (FESEM) were employed to investigate the morphological characteristics of the scaffolds. In addition, biodegradability, hydrophilicity, and contact angle were studied as criteria for evaluating physical properties of the scaffolds. Tensile strength was reported to be 0.971 ± 0.093 MPa. Also, the viability of fibroblasts after 7 days of cell culture was 93.58 ± 1.36 %. The antibacterial activity against Escherichia coli and Staphylococcus aureus bacteria was illustrated using inhibition zones of 13.12 ± 0.69 and 14.21 ± 1.37 mm, respectively. Histological results revealed that tissue regeneration after 14 days of surgery was much higher for the dressing group compared to the blank group. According to the obtained results, the authors introduce the PVA-BG-Ag-Cur scaffold as a promising candidate for skin tissue engineering applications.

Resorbable Membranes for Guided Bone Regeneration: Critical Features, Potentials, and Limitations

Lack of horizontal and vertical bone at the site of an implant can lead to significant clinical problems that need to be addressed before implant treatment can take place. Guided bone regeneration (GBR) is a commonly used surgical procedure that employs a barrier membrane to encourage the growth of new bone tissue in areas where bone has been lost due to injury or disease. It is a promising approach to achieve desired repair in bone tissue and is widely accepted and used in approximately 40% of patients with bone defects. In this Review, we provide a comprehensive examination of recent advances in resorbable membranes for GBR including natural materials such as chitosan, collagen, silk fibroin, along with synthetic materials such as polyglycolic acid (PGA), polycaprolactone (PCL), polyethylene glycol (PEG), and their copolymers. In addition, the properties of these materials including foreign body reaction, mechanical stability, antibacterial property, and growth factor delivery performance will be compared and discussed. Finally, future directions for resorbable membrane development and potential clinical applications will be highlighted.

Kaempferol-loaded bioactive glass-based scaffold for bone tissue engineering: in vitro and in vivo evaluation

Due to the increasing prevalence of bone disorders among people especially in average age, the future of treatments for osseous abnormalities has been illuminated by scaffold-based bone tissue engineering. In this study, in vitro and in vivo properties of 58S bioactive glass-based scaffolds for bone tissue engineering (bare (B.SC), Zein-coated (C.SC), and Zein-coated containing Kaempferol (KC.SC)) were evaluated. This is a follow-up study on our previously published paper, where we synthesized 58S bioactive glass-based scaffolds coated with Kaempferol-loaded Zein biopolymer, and characterized from mostly engineering points of view to find the optimum composition. For this aim, in vitro assessments were done to evaluate the osteogenic capacity and biological features of the scaffolds. In the in vivo section, all types of scaffolds with/without bone marrow-derived stem cells (BMSC) were implanted into rat calvaria bone defects, and potential of bone healing was assessed using imaging, staining, and histomorphometric analyses. It was shown that, Zein-coating covered surface cracks leading to better mechanical properties without negative effect on bioactivity and cell attachment. Also, BMSC differentiation proved that the presence of Kaempferol caused higher calcium deposition, increased alkaline phosphatase activity, bone-specific gene upregulation in vitro. Further, in vivo study confirmed positive effect of BMSC-loaded KC.SC on significant new bone formation resulting in complete bone regeneration. Combining physical properties of coated scaffolds with the osteogenic effect of Kaempferol and BMSCs could represent a new strategy for bone regeneration and provide a more effective approach to repairing critical-sized bone defects.

Additive Manufacturing of Bioactive Glass and Its Polymer Composites as Bone Tissue Engineering Scaffolds: A Review

Bioactive glass (BG) and its polymer composites have demonstrated great potential as scaffolds for bone defect healing. Nonetheless, processing these materials into complex geometry to achieve either anatomy-fitting designs or the desired degradation behavior remains challenging. Additive manufacturing (AM) enables the fabrication of BG and BG/polymer objects with well-defined shapes and intricate porous structures. This work reviewed the recent advancements made in the AM of BG and BG/polymer composite scaffolds intended for bone tissue engineering. A literature search was performed using the Scopus database to include publications relevant to this topic. The properties of BG based on different inorganic glass formers, as well as BG/polymer composites, are first introduced. Melt extrusion, direct ink writing, powder bed fusion, and vat photopolymerization are AM technologies that are compatible with BG or BG/polymer processing and were reviewed in terms of their recent advances. The value of AM in the fabrication of BG or BG/polymer composites lies in its ability to produce scaffolds with patient-specific designs and the on-demand spatial distribution of biomaterials, both contributing to effective bone defect healing, as demonstrated by in vivo studies. Based on the relationships among structure, physiochemical properties, and biological function, AM-fabricated BG or BG/polymer composite scaffolds are valuable for achieving safer and more efficient bone defect healing in the future.

Nanoscale borosilicate bioactive glass for regenerative therapy of full-thickness skin defects in rabbit animal model

Bioactive glass (BG) occupies a significant position in the field of hard and soft tissue regeneration. Different processing techniques and formulas have been introduced to expand their regenerative, angiogenic, and antibacterial properties. In the present study, a new formula of bborosilicate bioactive glass nanofibers was prepared and tested for its wound-healing efficacy in a rabbit animal model. The glass formula ((1-2) mol% of B₂O₃ (68-69) mol% of SiO2, and (29-30) mol% of CaO) was prepared primarily by the sol-gel technique followed by the electrospinning technique. The material was characterized for its ultrastructure using scanning electron microscopy, chemical composition using FTIR, and its dynamic in vitro biodegradability using ICP-AES. Twelve rabbits were subjected to surgical induction of full-thickness skin defects using a 1 cm² custom-made stainlessteel skin punch. The bioactive glass nanofibers were used as a grafting material in 6 experimental rabbits, while the defects in the remaining rabbits were considered as the negative control samples. All defects were assessed clinically for the decrease in wound size and clinical signs of healing and histologically for angiogenesis, collagen density, inflammatory response, cell recruitment, epithelial lining, and appendages at 1,2 and 3 weeks following the intervention. Structural analysis of the glass fibers confirmed their nano-size which ranged from 150 to 700 nm. Moreover, the chemical analysis confirmed the presence of SiO₂ and B₂O₃ groups within the structure of the nanofibers. Additionally, dynamic biodegradation analysis confirmed the rapid degradation of the material starting from the first 24 h and rapid leaching of calcium, silicon, and boron ions confirming its bioactivity. The wound healing study of the nanofibrous scaffold confirmed its ability to accelerate wound healing and the closure rate in healthy rabbits. Histological analysis of the defects confirmed the angiogenic, regenerative and antibacterial ability of the material throughout the study period. The results unveil the powerful therapeutic properties of the formed nanofibers and open a new gate for more experimental and clinical applications.

Microspheres with 2D rGO/Alginate Matrix for Unusual Prolonged Release of Cefotaxime

A synergistic interaction between reduced graphene oxide (rGO) and a biodegradable natural polymer, sodium alginate, was developed to create unique microspheres with protruding spiky features at the surface (spiky microspheres) that act as a super encapsulation and sustained release system for the highly effective antibiotic cefotaxime. Three forms of microspheres, namely alginate (Alg), alginate-cefotaxime (Alg-CTX), and alginate-cefotaxime-reduced graphene (Alg-CTX-rGO) composites, were prepared using calcium chloride as a cross-linking agent. The microspheres were characterized using field emission scanning electron microscopy (FESEM), Fourier-transform infrared (FT-IR) spectroscopy, and X-ray diffraction to investigate their pores, roughness, surface morphology, functional groups, phase formation, purity, and structural properties. The membrane diffusion method was employed to determine the release profile of Cefotaxime from the fabricated microspheres. The antibacterial activities of CTX solution, Alg microspheres, Alg-CTX microspheres, and Alg-CTX-rGO microspheres were investigated against gram-negative bacteria (Escherichia coli) using the agar diffusion method on Muller-Hinton agar. The prepared samples exhibited excellent results, suggesting their potential for enhanced antibiotic delivery. The results demonstrated the potential of the microsphere 2D rGO/alginate matrix for enhancing cefotaxime delivery with an unusual, prolonged release profile.

A 3D-Printed Biomaterial Scaffold Reinforced with Inorganic Fillers for Bone Tissue Engineering: In Vitro Assessment and In Vivo Animal Studies

This research aimed to substantiate the potential practicality of utilizing a matrix-like platform, a novel 3D-printed biomaterial scaffold, to enhance and guide host cells' growth for bone tissue regeneration. The 3D biomaterial scaffold was successfully printed using a 3D Bioplotter^® (EnvisionTEC, GmBH) and characterized. Osteoblast-like MG63 cells were utilized to culture the novel printed scaffold over a period of 1, 3, and 7 days. Cell adhesion and surface morphology were examined using scanning electron microscopy (SEM) and optical microscopy, while cell viability was determined using MTS assay and cell proliferation was evaluated using a Leica microsystem (Leica MZ10 F). The 3D-printed biomaterial scaffold exhibited essential biomineral trace elements that are significant for biological bone (e.g., Ca-P) and were confirmed through energy-dispersive X-ray (EDX) analysis. The microscopy analyses revealed that the osteoblast-like MG63 cells were attached to the printed scaffold surface. The viability of cultured cells on the control and printed scaffold increased over time (p < 0.05); however, on respective days (1, 3, and 7 days), the viability of cultured cells between the two groups was not significantly different (p > 0.05). The protein (human BMP-7, also known as growth factor) was successfully attached to the surface of the 3D-printed biomaterial scaffold as an initiator of osteogenesis in the site of the induced bone defect. An in vivo study was conducted to substantiate if the novel printed scaffold properties were engineered adequately to mimic the bone regeneration cascade using an induced rabbit critical-sized nasal bone defect. The novel printed scaffold provided a potential pro-regenerative platform, rich in mechanical, topographical, and biological cues to guide and activate host cells toward functional regeneration. The histological studies revealed that there was progress in new bone formation, especially at week 8 of the study, in all induced bone defects. In conclusion, the protein (human BMP-7)-embedded scaffolds showed higher regenerative bone formation potential (week 8 complete) compared to the scaffolds without protein (e.g., growth factor; BMP-7) and the control (empty defect). At 8 weeks postimplantation, protein (BMP-7) significantly promoted osteogenesis as compared to other groups. The scaffold underwent gradual degradation and replacement by new bones at 8 weeks in most defects.

Biomedical applications of chitosan/silk fibroin composites: A review

Natural polymers have been used in the biomedical fields for decades, mainly derived from animals and plants with high similarities with biomacromolecules in the human body. As an alkaline polysaccharide, chitosan (CS) attracts much attention in tissue regeneration and drug delivery with favorable biocompatibility, biodegradation, and antibacterial activity. However, to overcome its mechanical properties and degradation behavior drawbacks, a robust fibrous protein-silk fibroin (SF) was introduced to prepare the CS/SF composites. Not only can CS be combined with SF via the amide and hydrogen bond formation, but also their functions are complementary and tunable with the blending ratio. To further improve the performances of CS/SF composites, natural (e.g., hyaluronic acid and collagen) and synthetic biopolymers (e.g., polyvinyl alcohol and hexanone) were incorporated. Also, the CS/SF composites acted as slow-release carriers for inorganic non-metals (e.g., hydroxyapatite and graphene) and metal particles (e.g., silver and magnesium), which could enhance cell functions, facilitate tissue healing, and inhibit bacterial growth. This review presents the state-of-the-art and future perspectives of different biomaterials combined with CS/SF composites as sponges, hydrogels, membranes, particles, and coatings. Emphasis is devoted to the biological potentialities of these hybrid systems, which look rather promising toward a multitude of applications.

Zinc and Strontium-Substituted Bioactive Glass Nanoparticle/Alginate Composites Scaffold for Bone Regeneration

The global population is growing older and entering an aging society. Aging results in severe tissue disorder and organ dysfunction. Bone-related injuries are particularly significant. The need for alternative bone replacement materials for human implants has grown over the past few decades. Alginate has the potential for use as a cell scaffold for bone tissue engineering due to its high bio-compatibility. To improve the bioactivity of alginate scaffolds, zinc- and strontium-containing sol-gel-derived bioactive glass nanoparticles (Zn-Sr-BGNPs) with sizes ranging from 100 to l40 nm were incorporated. Zn-Sr-BGNPs synthesized through the sol-gel process have a high sur-face-to-volume ratio, homogeneity, and purity, resulting in faster degradation. The therapeutic bivalent ions released from Zn-Sr-BGNPs strengthen the cell scaffold and improve the stimulation of the production and development of bone cells. Zn-Sr-BGNPs with different Zn to Si nominal ratios of 0, 1, and 1.5 were mixed with alginate in this research. The ratio of Zn in Zn-Sr-BGNPs and the ratio of Zn-Sr-BGNPs in scaffolds impact the pore size, swelling, and biological properties of synthesized composite scaffolds. The surface area and pore volume of a 1:1 1Zn-Sr-BGNP:Alg composite scaffold were 22.58 m²/g and 0.055 cm³/g, respectively. The incorporation of Zn-Sr-BGNPs improved the mechanical performance of the scaffolds up to 4.73 ± 0.48 MPa. The swelling rate decreased slightly from 2.12 (pure Alg) to 1.50 (1Zn-Sr-BGNP:Alg (1:1)). The 1Zn-Sr-BGNP:Alg (1:1) composite scaffold promoted bioactivity through apatite layer formation, increased bone cell proliferation via the dissolution products released from the scaffold, enhanced calcium deposition, and facilitated cell attachment. Thus, 1Zn-Sr-BGNP:Alg (1:1) composite scaffold is proposed as a possible artificial bone scaffold in bone tissue regeneration.

Biomimetic biphasic scaffolds in osteochondral tissue engineering: Their composition, structure and consequences

Approaches to the design and construction of biomimetic scaffolds for osteochondral tissue, show increasing advances. Considering the limitations of this tissue in terms of repair and regeneration, there is a need to develop appropriately designed scaffolds. A combination of biodegradable polymers especially natural polymers and bioactive ceramics, shows promise in this field. Due to the complicated architecture of this tissue, biphasic and multiphasic scaffolds containing two or more different layers, could mimic the physiology and function of this tissue with a higher degree of similarity. The purpose of this review article is to discuss the approaches focused on the application of biphasic scaffolds for osteochondral tissue engineering, common methods of combining layers and the ultimate consequences of their use in patients were discussed.

Biodegradable Biopolymeric Nanoparticles for Biomedical Applications-Challenges and Future Outlook

Biopolymers are polymers obtained from either renewable or non-renewable sources and are the most suitable candidate for tailor-made nanoparticles owing to their biocompatibility, biodegradability, low toxicity and immunogenicity. Biopolymeric nanoparticles (BPn) can be classified as natural (polysaccharide and protein based) and synthetic on the basis of their origin. They have been gaining wide interest in biomedical applications such as tissue engineering, drug delivery, imaging and cancer therapy. BPn can be synthesized by various fabrication strategies such as emulsification, ionic gelation, nanoprecipitation, electrospray drying and so on. The main aim of the review is to understand the use of nanoparticles obtained from biodegradable biopolymers for various biomedical applications. There are very few reviews highlighting biopolymeric nanoparticles employed for medical applications; this review is an attempt to explore the possibilities of using these materials for various biomedical applications. This review highlights protein based (albumin, gelatin, collagen, silk fibroin); polysaccharide based (chitosan, starch, alginate, dextran) and synthetic (Poly lactic acid, Poly vinyl alcohol, Poly caprolactone) BPn that has recently been used in many applications. The fabrication strategies of different BPn are also being highlighted. The future perspective and the challenges faced in employing biopolymeric nanoparticles are also reviewed.

Multifunctional, Adhesive, and PDA-Coated Bioactive Glass Reinforced Composite Hydrogel for Regenerative Wound Healing

Effective wound management imposes several challenges in clinical outcomes due to the complexity of the wound microenvironment, bacterial infections, impaired angiogenesis, aggravated inflammation, and enduring pain. In addition, adhesion on wet biological tissue is another extremely challenging task. Addressing all the issues is necessary for an effective wound healing process. Herein, we developed a unique multifunctional, adhesive composite hydrogel composed of gelatin, chitosan, polydopamine-coated bioactive glass (BG), and curcumin-capped silver nanoparticles (Cur-AgNPs) to target the multifaceted complexity of the wound. The PDA-coated BG serves multiple purposes: (1) adhesivity: catechol groups of PDA and Ca ion released from BG chelate the group present in the hydrogel network and surrounding tissues, (2) angiogenesis: promotes vascularization due to the release of Si from BG, and (3) BG also serves as the "reservoir" for the pain-relieving diclofenac sodium drug with a sustained-release behavior. Cur-AgNPs provide excellent bactericidal and anti-inflammatory properties to the composite hydrogel. In situ application of the composite hydrogel could serve the purpose of a "skin biomimetic" and work as a barrier along with bactericidal properties to inhibit the microbial growth. The multifunctional composite hydrogel (MCH) targeted multiple aspects of wound repair including pain alleviation, elimination of microbes (up to 99%), reduced inflammation, high adhesivity, and increased angiogenesis for effective skin regeneration. The MCH showed excellent wound healing potential as significant wound closure was observed at day 7 and also significantly upregulated the expression of crucial genes involved in the skin regeneration process along with increasing vascularization in the wound area.

Synthesis and Characterizations of Bioactive Glass Nanoparticle-Incorporated Triblock Copolymeric Injectable Hydrogel for Bone Tissue Engineering

Recently, injectable hydrogels have attracted much interest in tissue engineering (TE) applications because of their controlled flowability, adaptability, and easy handling properties. This work emphasizes the synthesis and characterizations of bioactive glass (BAG) nanoparticle-reinforced poly(ethylene glycol) (PEG)- and poly(N-vinylcarbazole) (pNVC)-based minimally invasive composite injectable hydrogel suitable for bone regeneration. First, the copolymer was synthesized from a combination of PEG and pNVC through reversible addition-fragmentation chain-transfer (RAFT) polymerization and nanocomposite hydrogel constructs were subsequently prepared by conjugating BAG particles at varying loading concentrations. Gel permeation chromatography (GPC) analysis confirmed the controlled nature of the polymer. Various physicochemical characterization results confirmed the successful synthesis of copolymer and nanocomposite hydrogels that showed good gelling and injectability properties. Our optimal nanocomposite hydrogel formulation showed excellent swelling properties in comparison to the copolymeric hydrogel due to the presence of hydrophilic BAG particles. The bone cell proliferation rate was found to be evidently higher in the nanocomposite hydrogel than in the copolymeric hydrogel. Moreover, the enhanced level of ALP activity and apatite mineralization for the nanocomposite in comparison to that for the copolymeric hydrogel indicates accelerated in vitro osteogenesis. Overall, our study findings indicate BAG particle-conjugated nanocomposite hydrogels can be used as promising grafting materials in orthopedic reconstructive surgeries complementary to conventional bone graft substitutes in cancellous bone defects due to their 3D porous framework, minimal invasiveness, and ability to form any desired shape to match irregular bone defects.

Carboxymethyl chitosan-alginate enhances bone repair effects of magnesium phosphate bone cement by activating the FAK-Wnt pathway

There is a continuing need for artificial bone substitutes for bone repair and reconstruction, Magnesium phosphate bone cement (MPC) has exceptional degradable properties and exhibits promising biocompatibility. However, its mechanical strength needs improved and its low osteo-inductive potential limits its therapeutic application in bone regeneration. We functionally modified MPC by using a polymeric carboxymethyl chitosan-sodium alginate (CMCS/SA) gel network. This had the advantages of: improved compressive strength, ease of handling, and an optimized interface for bioactive bone in-growth. The new composites with 2% CMCS/SA showed the most favorable physicochemical properties, including mechanical strength, wash-out resistance, setting time, injectable time and heat release. Biologically, the composite promoted the attachment and proliferation of osteoblast cells. It was also found to induce osteogenic differentiation in vitro, as verified by expression of osteogenic markers. In terms of molecular mechanisms, data showed that new bone cement activated the Wnt pathway through inhibition of the phosphorylation of β-catenin, which is dependent on focal adhesion kinase. Through micro-computed tomography and histological analysis, we found that the MPC-CMCS/SA scaffolds, compared with MPC alone, showed increased bone regeneration in a rat calvarial defect model. Overall, our study suggested that the novel composite had potential to help repair critical bone defects in clinical practice.

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CMCS/SA improves the mechanical strength of MPC while minimizing tissue damage.

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The MPC-CMCS/SA composite is easily manipulable for clinical application.

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MPC-CMCS/SA has good biocompatibility, and is easier for cell adhesion and proliferation.

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The MPC-CMCS/SA composite enhances osteogenic differentiation in vitro through the integrin-FAK-Wnt axis.

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The MPC-CMCS/SA composite enhances critical bone defect repair in vivo.

Application of Polymer Hydrogels in the Prevention of Postoperative Adhesion: A Review

Postoperative adhesion is a common post-surgery complication formed between the surface of the body cavity, ranging from a layer of connective tissue to a fibrous bridge containing blood vessels and nerve tissue. Despite achieving a lot of progress, the mechanisms of adhesion formation still need to be further studied. In addition, few current treatments are consistently effective in the prevention of postoperative adhesion. Hydrogel is a kind of water-expanding crosslinked hydrophilic polymer network generated by a simple reaction of one or more monomers. Due to the porous structure, hydrogels can load different drugs and control the drug release kinetics. Evidence from existing studies has confirmed the feasibility and superiority of using hydrogels to counter postoperative adhesions, primarily due to their outstanding antifouling ability. In this review, the current research status of hydrogels as anti-adhesion barriers is summarized, the character of hydrogels in the prevention of postoperative adhesion is briefly introduced, and future research directions are discussed.

Gelatin and Bioactive Glass Composites for Tissue Engineering: A Review

Nano-/micron-sized bioactive glass (BG) particles are attractive candidates for both soft and hard tissue engineering. They can chemically bond to the host tissues, enhance new tissue formation, activate cell proliferation, stimulate the genetic expression of proteins, and trigger unique anti-bacterial, anti-inflammatory, and anti-cancer functionalities. Recently, composites based on biopolymers and BG particles have been developed with various state-of-the-art techniques for tissue engineering. Gelatin, a semi-synthetic biopolymer, has attracted the attention of researchers because it is derived from the most abundant protein in the body, viz., collagen. It is a polymer that can be dissolved in water and processed to acquire different configurations, such as hydrogels, fibers, films, and scaffolds. Searching "bioactive glass gelatin" in the tile on Scopus renders 80 highly relevant articles published in the last ~10 years, which signifies the importance of such composites. First, this review addresses the basic concepts of soft and hard tissue engineering, including the healing mechanisms and limitations ahead. Then, current knowledge on gelatin/BG composites including composition, processing and properties is summarized and discussed both for soft and hard tissue applications. This review explores physical, chemical and mechanical features and ion-release effects of such composites concerning osteogenic and angiogenic responses in vivo and in vitro. Additionally, recent developments of BG/gelatin composites using 3D/4D printing for tissue engineering are presented. Finally, the perspectives and current challenges in developing desirable composites for the regeneration of different tissues are outlined.

Preparation and In Vitro Osteogenic Evaluation of Biomimetic Hybrid Nanocomposite Scaffolds Based on Gelatin/Plasma Rich in Growth Factors (PRGF) and Lithium-Doped 45s5 Bioactive Glass Nanoparticles

Bone tissue engineering is an emerging technique for repairing large bone lesions. Biomimetic techniques expand the use of organic-inorganic spongy-like nanocomposite scaffolds and platelet concentrates. In this study, a biomimetic nanocomposite scaffold was prepared using lithium-doped bioactive-glass nanoparticles and gelatin/PRGF. First, sol-gel method was used to prepare bioactive-glass nanoparticles that contain 0, 1, 3, and 5%wt lithium. The lithium content was then optimized based on antibacterial and MTT testing. By freeze-drying, hybrid scaffolds comprising 5, 10, and 20% bioglass were made. On the scaffolds, human endometrial stem cells (hEnSCs) were cultured for adhesion (SEM), survival, and osteogenic differentiation. Alkaline phosphatase activity and osteopontin, osteocalcin, and Runx2 gene expression were measured. The effect of bioactive-glass nanoparticles and PRGF on nanocomposites' mechanical characteristics and glass-transition temperature (T _g) was also studied. An optimal lithium content in bioactive glass structure was found to be 3% wt. Nanoparticle SEM examination indicated grain deformation due to different sizes of lithium and sodium ions. Results showed up to 10% wt bioactive-glass and PRGF increased survival and cell adhesion. Also, Hybrid scaffolds revealed higher ALP-activity and OP, OC, and Runx2 gene expression. Furthermore, bioactive-glass has mainly increased ALP-activity and Runx2 expression, whereas PRGF increases the expression of OP and OC genes. Bioactive-glass increases scaffold modulus and T _g continuously. Hence, the presence of both bioactive-glass and nanocomposite scaffold improves the expression of osteogenic differentiation biomarkers. Subsequently, it seems that hybrid scaffolds based on biopolymers, Li-doped bioactive-glass, and platelet extracts can be a good strategy for bone repair.

Obtaining and Characterizing Composite Biomaterials of Animal Resources with Potential Applications in Regenerative Medicine

Raw materials, such as collagen and chitosan, obtained from by-products from the food industry (beef hides and crustacean exoskeletons), can be used to obtain collagen–chitosan composite biomaterials, with potential applications in regenerative medicine. Functionalization of these composite biomaterials is a possibility, thus, resulting in a molecule with potential applications in regenerative medicine, namely clotrimazole (a molecule with antibacterial, antifungal, and antitumor activity), at a mass ratio (collagen–chitosan–clotrimazole) of 1:1:0.1. This functionalized composite biomaterial has great potential for application in regenerative medicine, due to the following properties: (1) it is porous, and the pores formed are interconnected, due to the use of a mass ratio between collagen and chitosan of 1:1; (2) the size of the formed pores is between 500–50 μm; (3) between collagen and chitosan, hydrogen bonds are formed, which ensure the unity of composite biomaterial; (4) the functionalized bio-composite exhibits in vitro antimicrobial activity for Candida albicans, Staphylococcus aureus, and Staphylococcus aureus MRSA; for the latter microorganism, the antimicrobial activity is equivalent to that of the antibiotic Minocycline; (5) the proliferation tests performed on a standardized line of normal human cells with simple or composite materials obtained by lyophilization do not show cytotoxicity in the concentration range studied (10–500) μg/mL.

Chitosan-Based Biomaterials for Bone Tissue Engineering Applications: A Short Review

Natural bone tissue is composed of calcium-deficient carbonated hydroxyapatite as the inorganic phase and collagen type I as the main organic phase. The biomimetic approach of scaffold development for bone tissue engineering application is focused on mimicking complex bone characteristics. Calcium phosphates are used in numerous studies as bioactive phases to mimic natural bone mineral. In order to mimic the organic phase, synthetic (e.g., poly(ε-caprolactone), polylactic acid, poly(lactide-co-glycolide acid)) and natural (e.g., alginate, chitosan, collagen, gelatin, silk) biodegradable polymers are used. However, as materials obtained from natural sources are accepted better by the human organism, natural polymers have attracted increasing attention. Over the last three decades, chitosan was extensively studied as a natural polymer suitable for biomimetic scaffold development for bone tissue engineering applications. Different types of chitosan-based biomaterials (e.g., molded macroporous, fiber-based, hydrogel, microspheres and 3D-printed) with specific properties for different regenerative applications were developed due to chitosan's unique properties. This review summarizes the state-of-the-art of biomaterials for bone regeneration and relevant studies on chitosan-based materials and composites.

Protein-based nanomaterials: a new tool for targeted drug delivery

Protein nanomaterials are well-defined, hollow protein nanoparticles comprised of virus capsids, virus-like particles, ferritin, heat shock proteins, chaperonins and many more. Protein-based nanomaterials are formed by the self-assembly of protein subunits and have numerous desired properties as drug-delivery vehicles, including being optimally sized for endocytosis, nontoxic, biocompatible, biodegradable and functionalized at three separate interfaces (external, internal and intersubunit). As a result, protein nanomaterials have been intensively investigated as functional entities in bionanotechnology, including drug delivery, nanoreactors and templates for organic and inorganic nanomaterials. Several variables influence efficient administration, particularly active targeting, cellular uptake, the kinetics of the release and systemic elimination. This review examines the wide range of medicines, loading/release processes, targeted therapies and treatment effectiveness.

Cerium-Containing Mesoporous Bioactive Glasses (MBGs)-Derived Scaffolds with Drug Delivery Capability for Potential Tissue Engineering Applications

Finding innovative solutions to improve the lives of people affected by trauma, bone disease, or aging continues to be a challenge worldwide. Tissue engineering is the most rapidly growing area in the domain of biomaterials. Cerium-containing MBG-derived biomaterials scaffolds were synthesized using polymethyl methacrylate (PMMA) as a sacrificial template. The obtained scaffolds were characterized by X-ray powder diffraction (XRPD), infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The Ce4+/Ce3+ ratio in the scaffolds was estimated. In vitro testing revealed good cytocompatibility of the investigated scaffolds in mouse fibroblast cell line (NCTC clone L929). The results obtained regarding bioactivity, antibacterial activity, and controlled drug delivery functions recommend these scaffolds as potential candidates for bone tissue engineering applications.

Recent Advancements in Materials and Coatings for Biomedical Implants

Metallic materials such as stainless steel (SS), titanium (Ti), magnesium (Mg) alloys, and cobalt-chromium (Co-Cr) alloys are widely used as biomaterials for implant applications. Metallic implants sometimes fail in surgeries due to inadequate biocompatibility, faster degradation rate (Mg-based alloys), inflammatory response, infections, inertness (SS, Ti, and Co-Cr alloys), lower corrosion resistance, elastic modulus mismatch, excessive wear, and shielding stress. Therefore, to address this problem, it is necessary to develop a method to improve the biofunctionalization of metallic implant surfaces by changing the materials’ surface and morphology without altering the mechanical properties of metallic implants. Among various methods, surface modification on metallic surfaces by applying coatings is an effective way to improve implant material performance. In this review, we discuss the recent developments in ceramics, polymers, and metallic materials used for implant applications. Their biocompatibility is also discussed. The recent trends in coatings for biomedical implants, applications, and their future directions were also discussed in detail.

New and Efficient Bioactive Glass Compositions for Controlling Endodontic Pathogens

Endodontic treatment aims to conserve teeth through removing infected tissue, disinfecting, and filling/sealing the root canal. One of the most important treatment steps is the removal of microorganisms to avoid reinfection and consequent tooth loss. Due to increased resistance to intracanal medications, new alternative procedures are needed. Thus, an intracanal medication is suggested using three bioactive glass (BG) compositions (BG1, BG2, and BG3) produced by the sol–gel method, with different molar contents of bactericidal oxides. The BGs were morphologically and physically characterized. Their ability to inhibit the growth of two oral pathogens responsible for the failure of endodontic treatments (E. faecalis and C. albicans) was also studied. The results suggest that BG2 and BG3 can inhibit the growth of E. faecalis after 48 h of incubation, and all BG samples have a significant effect on C. albicans survival.

Improved 3D Printing and Cell Biology Characterization of Inorganic-Filler Containing Alginate-Based Composites for Bone Regeneration: Particle Shape and Effective Surface Area Are the Dominant Factors for Printing Performance

The use of organic-inorganic 3D printed composites with enhanced properties in biomedical applications continues to increase. The present study focuses on the development of 3D printed alginate-based composites incorporating inorganic fillers with different shapes (angular and round), for bone regeneration. Reactive fillers (bioactive glass 13-93 and hydroxyapatite) and non-reactive fillers (inert soda-lime glass) were investigated. Rheological studies and the characterization of various extrusion-based parameters, including material throughput, printability, shape fidelity and filament fusion, were carried out to identify the parameters dominating the printing process. It was shown that the effective surface area of the filler particle has the highest impact on the printing behavior, while the filler reactivity presents a side aspect. Composites with angular particle morphologies showed the same high resolution during the printing process, almost independent from their reactivity, while composites with comparable amounts of round filler particles lacked stackability after printing. Further, it could be shown that a higher effective surface area of the particles can circumvent the need for a higher filler content for obtaining convincing printing results. In addition, it was proven that, by changing the particle shape, the critical filler content for the obtained adequate printability can be altered. Preliminary in vitro biocompatibility investigations were carried out with the bioactive glass containing ink. The 3D printed ink, forming an interconnected porous scaffold, was analyzed regarding its biocompatibility in direct or indirect contact with the pre-osteoblast cell line MC3T3-E1. Both kinds of cell tests showed increased viability and a high rate of proliferation, with complete coverage of the 3D scaffolds' surface already after 7 d post cell-seeding.

Inorganic Nanoparticles in Bone Healing Applications

Modern biomedicine aims to develop integrated solutions that use medical, biotechnological, materials science, and engineering concepts to create functional alternatives for the specific, selective, and accurate management of medical conditions. In the particular case of tissue engineering, designing a model that simulates all tissue qualities and fulfills all tissue requirements is a continuous challenge in the field of bone regeneration. The therapeutic protocols used for bone healing applications are limited by the hierarchical nature and extensive vascularization of osseous tissue, especially in large bone lesions. In this regard, nanotechnology paves the way for a new era in bone treatment, repair and regeneration, by enabling the fabrication of complex nanostructures that are similar to those found in the natural bone and which exhibit multifunctional bioactivity. This review aims to lay out the tremendous outcomes of using inorganic nanoparticles in bone healing applications, including bone repair and regeneration, and modern therapeutic strategies for bone-related pathologies.

3D-Printed, Dual Crosslinked and Sterile Aerogel Scaffolds for Bone Tissue Engineering

The fabrication of bioactive three-dimensional (3D) hydrogel scaffolds from biocompatible materials with a complex inner structure (mesoporous and macroporous) and highly interconnected porosity is crucial for bone tissue engineering (BTE). 3D-printing technology combined with aerogel processing allows the fabrication of functional nanostructured scaffolds from polysaccharides for BTE with personalized geometry, porosity and composition. However, these aerogels are usually fragile, with fast biodegradation rates in biological aqueous fluids, and they lack the sterility required for clinical practice. In this work, reinforced alginate-hydroxyapatite (HA) aerogel scaffolds for BTE applications were obtained by a dual strategy that combines extrusion-based 3D-printing and supercritical CO₂ gel drying with an extra crosslinking step. Gel ageing in CaCl₂ solutions and glutaraldehyde (GA) chemical crosslinking of aerogels were performed as intermediate and post-processing reinforcement strategies to achieve highly crosslinked aerogel scaffolds. Nitrogen adsorption–desorption (BET) and SEM analyses were performed to assess the textural parameters of the resulting alginate-HA aerogel scaffolds. The biological evaluation of the aerogel scaffolds was performed regarding cell viability, hemolytic activity and bioactivity for BTE. The impact of scCO₂-based post-sterilization treatment on scaffold properties was also assessed. The obtained aerogels were dual porous, bio- and hemocompatible, as well as endowed with high bioactivity that is dependent on the HA content. This work is a step forward towards the optimization of the physicochemical performance of advanced biomaterials and their sterilization.

Bioactive Glasses in Periodontal Regeneration: Existing Strategies and Future Prospects-A Literature Review

The present review deals with bioactive glasses (BGs), a class of biomaterials renowned for their osteoinductive and osteoconductive capabilities, and thus widely used in tissue engineering, i.e., for the repair and replacement of damaged or missing bone. In particular, the paper deals with applications in periodontal regeneration, with a special focus on in vitro, in vivo and clinical studies. The study reviewed eligible publications, identified on the basis of inclusion/exclusion criteria, over a ranged time of fifteen years (from 1 January 2006 to 31 March 2021). While there are many papers dealing with in vitro tests, only a few have reported in vivo (in animal) research, or even clinical trials. Regardless, BGs seem to be an adequate choice as grafts in periodontal regeneration.

Polymeric Hydrogels for Controlled Drug Delivery to Treat Arthritis

Rheumatoid arthritis (RA) and osteoarthritis (OA) are disabling musculoskeletal disorders that affect joints and cartilage and may lead to bone degeneration. Conventional delivery of anti-arthritic agents is limited due to short intra-articular half-life and toxicities. Innovations in polymer chemistry have led to advancements in hydrogel technology, offering a versatile drug delivery platform exhibiting tissue-like properties with tunable drug loading and high residence time properties This review discusses the advantages and drawbacks of polymeric materials along with their modifications as well as their applications for fabricating hydrogels loaded with therapeutic agents (small molecule drugs, immunotherapeutic agents, and cells). Emphasis is given to the biological potentialities of hydrogel hybrid systems/micro-and nanotechnology-integrated hydrogels as promising tools. Applications for facile tuning of therapeutic drug loading, maintaining long-term release, and consequently improving therapeutic outcome and patient compliance in arthritis are detailed. This review also suggests the advantages, challenges, and future perspectives of hydrogels loaded with anti-arthritic agents with high therapeutic potential that may alter the landscape of currently available arthritis treatment modalities.

Dual-Drug Delivery via Zein In Situ Forming Implants Augmented with Titanium-Doped Bioactive Glass for Bone Regeneration: Preparation, In Vitro Characterization, and In Vivo Evaluation

In situ forming implants (IFIs) are non-surgical approach using biodegradable polymers to treat bone fractures. The study aimed at preparing dual-drug-loaded IFIs to deliver pitavastatin (osteogenic drug) and tedizolid (antibiotic) using zein as the implant matrix via solvent-induced phase inversion method. At first, several investigations were done on pitavastatin-loaded zein IFIs, where three concentrations of zein were used (10, 20, and 30% w/v). IFIs were evaluated for their solidification time, rheological properties, injectability, and in vitro release. IFIs containing bioactive glass nanoparticles were prepared by the addition of non-doped bioactive glass nanoparticles (BGT₀; 1, 3, 5, and 10% w/v) or titanium-doped bioactive glass nanoparticles (BGT₅; 1% w/v) to the selected concentration of zein (30% w/v) and then evaluated. The optimized dual-medicated implant (D-ZIFI 1) containing pitavastatin, tedizolid, sodium hyaluronate (3% w/v), and BGT₅ (1% w/v) was prepared and compared to IFI lacking both sodium hyaluronate and BGT₅ (D-ZIFI 2). D-ZIFI 1 and 2 sustained the release profiles of both drugs for 28 days. SEM images proved the interconnected porous structure of D-ZIFI 1 due to sodium hyaluronate. In vivo studies on surgically induced bone defects in Sprague–Dawley rats signified the proper accelerated bone healing ability of D-ZIFI 1 over D-ZIFI 2. Results presented D-ZIFI 1 as a promising, effective, non-surgical approach for bone healing.

Molecular Indicators of Biomaterials Osteoinductivity - Cell Migration, BMP Production and Signalling Turns a Key

In this work we dissected the osteoinductive properties of selected, PLGA-based scaffolds enriched with gel-derived bioactive glasses (SBGs) of either binary SiO₂-CaO or ternary SiO₂-CaO-P₂O₅ system, differing in CaO/SiO₂ ratio (i.e. high -or low-calcium SBGs). To assess the inherent ability of the scaffolds to induce osteogenesis of human bone marrow stromal cells (BMSC), the study was designed to avoid any osteogenic stimuli beyond the putative osteogenic SBG component of the studied scaffolds. The bioactivity and porosity of scaffolds were confirmed by SBF test and porosimetry. Condition media (CM) from BMSC-loaded scaffolds exhibited increased Ca and decreased P content corresponding to SBGs CaO/SiO₂ ratio, whereas Si content was relatively stable and overall lower in CM from scaffolds containing binary SBGs. CM from cell-loaded scaffolds containing high-calcium, binary SBGs promoted migration of BMSC and BMP-response in reporter osteoblast cell line. BMSC culture on these scaffolds or the ones containing ternary, low-calcium SBGs resulted in the activation of BMP-related signaling and expression of several osteogenic markers. Ectopic bone formation was induced by scaffolds containing binary SBGs, but high-calcium ones produced significantly more osteoid. Scaffolds containing ternary SBGs negatively influenced the expression of osteogenic transcription factors and Cx43, involved in cell-cell interactions. High-calcium scaffolds stimulated overall higher Cx43 expression. We believe the initial cell-cell communication may be crucial to induce and maintain osteogenesis and high BMP signaling on the studied scaffolds. The presented scaffolds’ biological properties may also constitute new helpful markers to predict osteoinductive potential of other bioactive implant materials.

Biological and bioactivity assessment of dextran nanocomposite hydrogel for bone regeneration

Insufficient biological and bioactive properties of dextran hydrogels limit their applications as promising scaffolds for tissue engineering. We developed nanocomposite dextran hydrogels comprised of bioactive glass (nBGC: 64% SiO2, 31% CaO, 5% P₂O₅) nanoparticles with an average particle size of 77 nm using a chemical crosslinking of dextran chains to form 3D hydrogel networks. In the current study; bioactivity of the obtained nanocomposite hydrogels was evaluated through the formation of apatite crystal structures after the incubation in simulated body fluid (SBF) at various submersion periods and nBGC content. The scanning electron microscopy (SEM) micrographs represented an enhanced hydroxyapatite formation on the cross section of nanocomposite comprising of nBGC content from 2 to 8 (% by wt). Biomineralization results of Dex-8 (% by wt) composite during 7, 14 and 28 days immersion indicated the apatite layer formation and the growth of apatite crystal size on the surface and cross section of the nanocomposite. Moreover, MTT assessments indicated that human osteosarcoma cells (SaOS-2) were able to adhere and spread within the dextran hydrogels reinforced with the bioactive glass nanoparticles. With regard to enhanced bioactivity and biocompatibility, the developed dextran-nBGC hydrogel could be considered as a suitable candidate for bone tissue engineering application.

Subcutaneous toxicity of a dual ionically cross-linked atelocollagen and sodium hyaluronate gel: Rat in vivo study for biological safety evaluation of the injectable hydrogel

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Hydrogel wound dressings are commonly used to stop bleeding and enhance healing.

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Hyaluronic acid and collagen are beneficial for wound healing, however, each polymer has limitations.

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A dual hydrogel combining the benefits of both biopolymers can be more effective for the treatment of various wound types.

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A composite of collagen and sodium hyaluronate did not generate significant subacute toxicity or reactivity in vivo.

Hydrogels are commonly used in wound dressing, as they retain moisture, accelerate healing, and break down necrotic tissue. This process enhances patient comfort levels while simultaneously reducing pain caused by dead tissue. The purpose of this study was to investigate the in vivo toxicity of a dual hydrogel consisting of type I atelocollagen cross-linked with sodium hyaluronate hydrogel used for wound dressing.

Porcine type I atelocollagen was cross-linked with sodium hyaluronate to form the hydrogel. For subcutaneous implantation, 0.5 ml of dual hydrogel was injected into two different sites of twenty rats per group. High density polyethylene rods were implanted subcutaneously to serve as a control material. Hematological assessment, blood biochemistry, histopathological, and histological evaluations were scored and graded after 4 weeks. A bioreactivity rating was used for evaluation of subacute toxicity.

Differences observed in blood chemical analysis and hematological analysis between control and test groups were within normal variations and considered unrelated to the test article implantation. No significant implantation-related lesions were observed in any of the major organs of all test animals. The overall histopathological index of the test article implantation sites was evaluated as 0. The bioreactivity rating was evaluated as non-irritant after 4-week subcutaneous implantation.

Overall, these results indicate that the dual hydrogel of type I atelocollagen and sodium hyaluronate is biologically and chemically safe for clinical application as a wound dressing.

Chitosan-Based Scaffold for Mineralized Tissues Regeneration

Conventional bone grafting procedures used to treat bone defects have several limitations. An important aspect of bone tissue engineering is developing novel bone substitute biomaterials for bone grafts to repair orthopedic defects. Considerable attention has been given to chitosan, a natural biopolymer primarily extracted from crustacean shells, which offers desirable characteristics, such as being biocompatible, biodegradable, and osteoconductive. This review presents an overview of the chitosan-based biomaterials for bone tissue engineering (BTE). It covers the basic knowledge of chitosan in terms of biomaterials, the traditional and novel strategies of the chitosan scaffold fabrication process, and their advantages and disadvantages. Furthermore, this paper integrates the relevant contributions in giving a brief insight into the recent research development of chitosan-based scaffolds and their limitations in BTE. The last part of the review discusses the next-generation smart chitosan-based scaffold and current applications in regenerative dentistry and future directions in the field of mineralized tissue regeneration.

Bioactive Glass Applications: A Literature Review of Human Clinical Trials

The use of bioactive glasses in dentistry, reconstructive surgery, and in the treatment of infections can be considered broadly beneficial based on the emerging literature about the potential bioactivity and biocompatibility of these materials, particularly with reference to Bioglass^® 45S5, BonAlive^® and 19-93B3 bioactive glasses. Several investigations have been performed (i) to obtain bioactive glasses in different forms, such as bulk materials, powders, composites, and porous scaffolds and (ii) to investigate their possible applications in the biomedical field. Although in vivo studies in animals provide us with an initial insight into the biological performance of these systems and represent an unavoidable phase to be performed before clinical trials, only clinical studies can demonstrate the behavior of these materials in the complex physiological human environment. This paper aims to carefully review the main published investigations dealing with clinical trials in order to better understand the performance of bioactive glasses, evaluate challenges, and provide an essential source of information for the tailoring of their design in future applications. Finally, the paper highlights the need for further research and for specific studies intended to assess the effect of some specific dissolution products from bioactive glasses, focusing on their osteogenic and angiogenic potential.