Development of Amoxicillin-Loaded Electrospun Polyurethane/Chitosan/ $\beta$ -Tricalcium Phosphate Scaffold for Bone Tissue Regeneration

Current application and future perspectives of antimicrobial degradable bone substitutes for chronic osteomyelitis

Chronic osteomyelitis remains a persistent challenge for the surgeons due to its refractory nature. Generally, treatment involves extensive debridement of necrotic bone, filling of dead space, adequate antimicrobial therapy, bone reconstruction, and rehabilitation. However, the optimal choice of bone substitute to manage the bone defect remains debatable. This paper reviewed the clinical evidence for antimicrobial biodegradable bone substitutes in the treatment of osteomyelitis in recent years. Indeed, this combination was proved to eradicate infection and facilitate bone reconstruction, which might reduce the cost and hospital stay. Handling was associated with increased risk of unwanted side effect to affect bone healing. The study provides some valuable insights into the clinical evaluation of treatment outcomes in the aspects of infection eradication, bone reconstruction, and complications caused by materials. However, achieving complete infection eradication and subsequently perfect bone reconstruction remains challenging in compromised conditions, hence advanced innovative bone substitutes are imperative. In this review, we mainly focus on the desired functional effects of advanced bone substitutes on infection eradication and bone reconstruction from the future perspective. Handling property was optimized to simplify surgery process. It is expected that this review will provide an important opportunity to enhance the understanding of the design and application of innovative biomaterials to synergistically eradicate infection and restore integrity and function of bone.

Silk fibroin nanoparticles and β-tricalcium phosphate loaded tissue engineered gelatin bone scaffolds: A Nature-based, low-cost solution

Tissue engineering has recently attracted attention as an alternative to traditional treatment methods for tissue and organ damage. Since bone is one of the most important vital parts of the body, the treatment of bone damage is important. Silk fibroin is a natural polymer with properties such as biocompatibility and biodegradability, which attracts attention with its controlled release, especially in drug delivery systems. In this study, gelatin-based scaffolds loaded with silk fibroin nanoparticles and β -tricalcium phosphate (β -TCP) were developed to be used as a potential drug delivery system in bone tissue engineering. The chosen nanoparticle formulation has a 294 nm average diameter with a 0.380 polidispersity index (PDI). In vitro characterization of scaffolds was performed by mechanical, morphological characterization, swelling capacity, Differential Scanning Calorimetry (DSC), Fourier-Transform Infrared Spectroscopy (FT-IR) measurements, and biocompatibility was evaluated by cell culture studies. Swelling index, tensile strength, elongation at break, and Young modulus of the β -TCP and silk nanoparticles loaded scaffold were found as 456%, 1.476 MPa, 6.75%, and 24 MPa, respectively. In vitro cell culture studies have shown that scaffolds prepared in the present study can accelerate osteoblast differentiation and increase the healing rate of bone tissues. In addition, they have the potential to be used as a drug delivery system in bone tissue engineering that needs to be evaluated with further studies.

Recent Advancements in Electrospun Chitin and Chitosan Nanofibers for Bone Tissue Engineering Applications

Treatment of large segmental bone loss caused by fractures, osteomyelitis, and non-union results in expenses of around USD 300,000 per case. Moreover, the worst-case scenario results in amputation in 10% to 14.5% of cases. Biomaterials, cells, and regulatory elements are employed in bone tissue engineering (BTE) to create biosynthetic bone grafts with effective functionalization that can aid in the restoration of such fractured bones, preventing amputation and alleviating expenses. Chitin (CT) and chitosan (CS) are two of the most prevalent natural biopolymers utilized in the fields of biomaterials and BTE. To offer the structural and biochemical cues for augmenting bone formation, CT and CS can be employed alone or in combination with other biomaterials in the form of nanofibers (NFs). When compared with several fabrication methods available to produce scaffolds, electrospinning is regarded as superior since it enables the development of nanostructured scaffolds utilizing biopolymers. Electrospun nanofibers (ENFs) offer unique characteristics, including morphological resemblance to the extracellular matrix, high surface-area-to-volume ratio, permeability, porosity, and stability. This review elaborates on the recent strategies employed utilizing CT and CS ENFs and their biocomposites in BTE. We also summarize their implementation in supporting and delivering an osteogenic response to treat critical bone defects and their perspectives on rejuvenation. The CT- and CS-based ENF composite biomaterials show promise as potential constructions for bone tissue creation.

Progress of Polysaccharide-Contained Polyurethanes for Biomedical Applications

Polyurethane (PU) has been widely examined and used for biomedical applications, such as catheters, blood oxygenators, stents, cardiac valves, drug delivery carriers, dialysis devices, wound dressings, adhesives, pacemaker, tissue engineering, and coatings for breast implants due to its mechanical flexibility, high tear strength, biocompatibility, and tailorable foams although bio-acceptability, biodegradability and controlled drug delivery to achieve the desired properties should be considered. Especially, during the last decade, the development of bio-based PUs has raised public awareness because of the concern with global plastic waste for creating more environmentally friended materials. Therefore, it is desirable to discuss polysaccharide (PS)-contained PU for the wound dressing and bone tissue engineering among bio-based PUs because PS has several advantages, such as biocompatibility, reproducibility from the natural resources, degradability, ease of incorporation of bioactive agents, ease of availability and cost-effectiveness, and structural feature of chemical modification to meet the desired needs to overcome the disadvantages of PU itself by containing the PS into the PU.

Chitosan-Based Biomaterial Scaffolds for the Repair of Infected Bone Defects

The treatment of infected bone defects includes infection control and repair of the bone defect. The development of biomaterials with anti-infection and osteogenic ability provides a promising strategy for the repair of infected bone defects. Owing to its antibacterial properties, chitosan (an emerging natural polymer) has been widely studied in bone tissue engineering. Moreover, it has been shown that chitosan promotes the adhesion and proliferation of osteoblast-related cells, and can serve as an ideal carrier for bone-promoting substances. In this review, the specific molecular mechanisms underlying the antibacterial effects of chitosan and its ability to promote bone repair are discussed. Furthermore, the properties of several kinds of functionalized chitosan are analyzed and compared with those of pure chitosan. The latest research on the combination of chitosan with different types of functionalized materials and biomolecules for the treatment of infected bone defects is also summarized. Finally, the current shortcomings of chitosan-based biomaterials for the treatment of infected bone defects and future research directions are discussed. This review provides a theoretical basis and advanced design strategies for the use of chitosan-based biomaterials in the treatment of infected bone defects.

Biocompatibility and Angiogenic Effect of Chitosan/Graphene Oxide Hydrogel Scaffolds on EPCs

Angiogenesis in the field of tissue engineering has attracted significant attention. Graphene oxide has become a promising nanomaterial in tissue engineering for its unique biochemical properties. Therefore, herein, a series of chitosan (CS)/graphene oxide (GO) hydrogel scaffolds were synthesized by crosslinking CS and GO at different concentrations (0.1, 0.5, and 1.0 wt.%) using genipin. Compared with the CS hydrogel scaffolds, the CS/GO hydrogel scaffolds have a better network structure and mechanical strength. Then, we used endothelial progenitor cells (EPCs) extracted from human umbilical cord blood and cocultured these EPCs with the as-prepared scaffolds. The scaffolds with 0.1 and 0.5 wt.%GO showed no considerable cytotoxicity, could promote the proliferation of EPCs and tube formation, and upregulated the expressions of CD34, VEGF, MMP9, and SDF-1 in EPCs compared to the case of the scaffold with 1.0 wt.%GO. This study shows that the addition of graphene oxide improves the structure of chitosan hydrogel and enhances the proliferation activity and angiogenic capacity of EPCs.

Biomimetic Aspects of Oral and Dentofacial Regeneration

Biomimetic materials for hard and soft tissues have advanced in the fields of tissue engineering and regenerative medicine in dentistry. To examine these recent advances, we searched Medline (OVID) with the key terms “biomimetics”, “biomaterials”, and “biomimicry” combined with MeSH terms for “dentistry” and limited the date of publication between 2010–2020. Over 500 articles were obtained under clinical trials, randomized clinical trials, metanalysis, and systematic reviews developed in the past 10 years in three major areas of dentistry: restorative, orofacial surgery, and periodontics. Clinical studies and systematic reviews along with hand-searched preclinical studies as potential therapies have been included. They support the proof-of-concept that novel treatments are in the pipeline towards ground-breaking clinical therapies for orofacial bone regeneration, tooth regeneration, repair of the oral mucosa, periodontal tissue engineering, and dental implants. Biomimicry enhances the clinical outcomes and calls for an interdisciplinary approach integrating medicine, bioengineering, biotechnology, and computational sciences to advance the current research to clinics. We conclude that dentistry has come a long way apropos of regenerative medicine; still, there are vast avenues to endeavour, seeking inspiration from other facets in biomedical research.

The Effect of Chitosan on the Chemical Structure, Morphology, and Selected Properties of Polyurethane/Chitosan Composites

Materials science is an interdisciplinary area of studies. This science focuses on the influence of the physico-chemical properties of materials on their application in human everyday lives. The materials’ synthesis should be developed in accordance with sustainable development. Polyurethanes (PUR) represent a significant consumption of plastic in the world. Modification of PUR, e.g., with polysaccharide of natural origin (chitosan, Chit), should have a positive effect on their functional properties and degradability in the natural environment. The basic parameters affecting the scope and direction of changes are the size and quantity of the chitosan particles. The impact assessment of chitosan on the chemical structure, morphology, thermal properties, crystallinity, mechanical properties, flammability, water sorption, adsorption properties, degradability, and biological activity of PUR/Chit composites (without other additives) is discussed in this article. To the best of our knowledge, recent literature does not contain a study discussing the direct impact of the presence of chitosan in the structure of PUR/Chit composite on its properties, regardless of the intended uses. This paper provides an overview of publications, which presents the results of a study on the effect of adding chitosan in polyurethane/chitosan composites without other additives on the properties of polyurethane.

A Critical Review on the Production of Electrospun Nanofibres for Guided Bone Regeneration in Oral Surgery

Nanofibre-based membranes or scaffolds exhibit high surface-to-volume ratio, which allows an improved cell adhesion, representing an attractive subgroup of biomaterials due to their unique properties. Among several techniques of nanofiber production, electrospinning is a cost-effective technique that has been, to date, attractive for several medical applications. Among these, guided bone regeneration is a surgical procedure in which bone regeneration, due to bone atrophy following tooth loss, is "guided" by an occlusive barrier. The membrane should protect the initial blood clot from any compression, shielding the bone matrix during maturation from infiltration of soft tissues cells. This review will focus its attention on the application of electrospinning (ELS) in oral surgery bone regeneration. Despite the abundance of published papers related to the electrospinning technique applied in the field of bone regeneration of the jaws, to the authors' knowledge, no articles report clinical application of these structures. Moreover, only a few records can be found with in vivo application. Therefore, no human studies have to date been detectable. New approaches such as multifunctional multilayering and coupling with bone promoting factors or antimicrobial agents, makes this technology very attractive. However, greater efforts should be made by researchers and companies to turn these results into clinical practice.

Applications of chitin and chitosan nanofibers in bone regenerative engineering

Promoting bone regeneration and repairing defects are urgent and critical challenges in orthopedic clinical practice. Research on bone substitute biomaterials is essential for improving the treatment strategies for bone regeneration. Chitin and its derivative, chitosan, are among the most abundant natural biomaterials and widely found in the shells of crustaceans. Chitin and chitosan are non-toxic, antibacterial, biocompatible, degradable, and have attracted significant attention in bone substitute biomaterials. Chitin/chitosan nanofibers and nanostructured scaffolds have large surface area to volume ratios and high porosities. These scaffolds can be fabricated by electrospinning, thermally induced phase separation and self-assembly, and are widely used in biomedical applications such as biological scaffolds, drug delivery, bacterial inhibition, and wound dressing. Recently, some chitin/chitosan-based nanofibrous scaffolds have been found structurally similar to bone's extracellular matrix and can assist in bone regeneration. This review outlines the biomedical applications and biological properties of chitin/chitosan-based nanofibrous scaffolds in bone tissue engineering.