Chitosan, an amino polysaccharide mostly derived from crustaceans, has been recently highlighted for its biological activities that depend on its molecular weight (MW), degree of deacetylation (DD), and acetylation pattern (AP). More importantly, for some advanced biomaterials, the homogeneity of the chitosan structure is an important factor in determining its biological activity. Here we review emerging enzymes and cell factories, respectively, for in vitro and in vivo preparation of chitosan oligosaccharides (COSs), focusing on advances in the analysis of the AP and structural modification of chitosan to tune its functions. By 'mapping' current knowledge on chitosan's in vitro and in vivo activity with its MW and AP, this work could pave the way for future studies in the field.
Global increase in demand for food supply has resulted in surplus generation of wastes. What was once considered wastes, has now become a resource. Studies were carried out on the conversion of biowastes into wealth using methods such as extraction, incineration and microbial intervention. Agro-industry biowastes are promising sources of carbon for microbial fermentation to be transformed into value-added products. In the era of circular economy, the goal is to establish an economic system which aims to eliminate waste and ensure continual use of resources in a close-loop cycle. Biowaste collection is technically and economically practicable, hence it serves as a renewable carbon feedstock. Biowastes are commonly biotransformed into value-added materials such as bioethanol, bioplastics, biofuels, biohydrogen, biobutanol and biogas. This review reveals the recent developments on microbial transformation of biowastes into biotechnologically important products. This approach addresses measures taken globally to valorize waste to achieve low carbon economy. The sustainable use of these renewable resources is a positive approach towards waste management and promoting circular economy.
Broad interest in developing new hemostatic technologies arises from unmet needs in mitigating uncontrolled hemorrhage in emergency, surgical, and battlefield settings. Although a variety of hemostats, sealants, and adhesives are available, development of ideal hemostatic compositions that offer a range of remarkable properties including capability to effectively and immediately manage bleeding, excellent mechanical properties, biocompatibility, biodegradability, antibacterial effect, and strong tissue adhesion properties, under wet and dynamic conditions, still remains a challenge. Benefiting from tunable mechanical properties, high porosity, biocompatibility, injectability and ease of handling, polymeric hydrogels with outstanding hemostatic properties have been receiving increasing attention over the past several years. In this review, after shedding light on hemostasis and wound healing processes, the most recent progresses in hydrogel systems engineered from natural and synthetic polymers for hemostatic applications are discussed based on a comprehensive literature review. Most studies described used in vivo models with accessible and compressible wounds to assess the hemostatic performance of hydrogels. The challenges that need to be tackled to accelerate the translation of these novel hemostatic hydrogel systems to clinical practice are emphasized and future directions for research in the field are presented.
As one of the potential bionanomaterials, nanocellulose has appeared as a favorable candidate for photoremediation of the environment because of its abundance in nature, inexpensive, eco-friendly, decomposable, high surface area, and outstanding mechanical properties. The current review carefully summarized the diverse type of nanocellulose, their preparation approaches, and several previous works on the use of nanocellulose for photoremediation. These include the role of nanocellulose for the increased surface active site of the hybrid photocatalysts by providing a large surface area for enhanced adsorption of photons and pollutant molecules, as a dispersing agent to increase distribution of metal/non-metal dopants photocatalysts, as well as for controlled size and morphology of the dopants photocatalysts. Furthermore, the recommendations for upcoming research provided in this review are anticipated to ignite an idea for the development of other nanocellulose-based photocatalysts. Other than delivering beneficial information on the present growth of the nanocellulose biomaterials photocatalysts, this review is expected will attract more interest to the utilization of nanocellulose photocatalyst and distribute additional knowledge in this exciting area of environmental photoremediation. This could be attained by considering that a review on nanocellulose biomaterials for environmental health photoremediation has not been described elsewhere, notwithstanding intensive research works have been dedicated to this topic.
Chitin, as the main component of the exoskeleton of Arthropoda, is a highly available natural polymer that can be processed into various value-added products. Its most important derivative, i.e., chitosan, comprising β-1,4-linked 2-amino-2-deoxy-β-d-glucose (deacetylated d-glucosamine) and N-acetyl-d-glucosamine units, can be prepared via alkaline deacetylation process. Chitosan has been used as a biodegradable, biocompatible, non-antigenic, and nontoxic polymer in some in-vitro applications, but the recently found potentials of chitosan for in-vivo applications based on its biological activities, especially antimicrobial, antioxidant, and anticancer activities, have upgraded the chitosan roles in biomaterials. Chitosan approval, generally recognized as a safe compound by the United States Food and Drug Administration, has attracted much attention toward its possible applications in diverse fields, especially biomedicine and agriculture. Despite some favorable characteristics, the chitosan's structure should be customized for advanced applications, especially due to its drawbacks, such as low drug-load capacity, low solubility, high viscosity, lack of elastic properties, and pH sensitivity. In this context, derivatization with relatively inexpensive and highly available mono- and di-saccharides to soluble branched chitosan has been considered a "game changer". This review critically scrutinizes the emerging technologies based on the synthesis and application of lactose- and galactose-modified chitosan as two important chitosan derivatives. Some characteristics of chitosan derivatives and biological activities have been detailed first to understand the value of these natural polymers. Second, the saccharide modification of chitosan has been discussed briefly. Finally, the applications of lactose- and galactose-modified chitosan have been scrutinized and compared to native chitosan to provide an insight into the current state-of-the research for stimulating new ideas with the potential of filling research gaps.
Maintenance of oral health is a major challenge in dentistry. Different materials have been used to treat various dental diseases, although treatment success is limited by features of the biomaterials used. To overcome these limitations, materials incorporated with nanoparticles (NPs) can be used in dental applications including endodontics, periodontics, tissue engineering, oral surgery, and imaging. The unique properties of NPs, including their surface:volume ratio, antibacterial action, physical, mechanical, and biological characteristics, and unique particle size have rendered them effective vehicles for dental applications. In this review, we provide insights into the various applications of NPs in dentistry, including their benefits, limitations, properties, actions and future potential.
Human hair is a potential biomaterial for biomedical applications. Improper disposal of human hair may pose various adverse effects on the environment and human health. Therefore, proper management of human hair waste is pivotal. Human hair fiber and its derivatives offer various advantages as biomaterials such as biocompatibility, biodegradability, low toxicity, radical scavenging, electroconductivity, and intrinsic biological activity. Therefore, the favorable characteristics of human hair have rendered its usage in tissue engineering (TE) applications including skin, cardiac, nerve, bone, ocular, and periodontal. Moreover, the strategies by utilizing human hair as a biomaterial for TE applications may reduce the accumulation of human hair. Thus, it also improves human hair waste management while promoting natural, environmental-friendly, and nontoxic materials. Furthermore, promoting sustainable materials production will benefit human health and well-being. Hence, this article reviews and discusses human hair characteristics as sustainable biomaterials and their recent application in TE applications. Impact Statement This review article highlights the sustainability aspects of human hair as raw biomaterials and various elements of human hair that could potentially be used in tissue engineering (TE) applications. Furthermore, this article discusses numerous benefits of human hair, highlighting its value as biomaterials in bioscaffold development for TE applications. Moreover, this article reviews the role and effect of human hair in various TE applications, including skin, cardiac, nerve, bone, ocular, and periodontal.
Hydrogel is the most emblematic soft material which possesses significantly tunable and programmable characteristics. Polymer hydrogels possess significant advantages including, biocompatible, simple, reliable and low cost. Therefore, research on the development of hydrogel for biomedical applications has been grown intensely. However, hydrogel development is challenging and required significant effort before the application at an industrial scale. Therefore, the current work focused on evaluating recent trends and issues with hydrogel development for biomedical applications. In addition, the hydrogel's development methodology, physicochemical properties, and biomedical applications are evaluated and benchmarked against the reported literature. Later, biomedical applications of the nano-cellulose-based hydrogel are considered and critically discussed. Based on a detailed review, it has been found that the surface energy, intermolecular interactions, and interactions of hydrogel adhesion forces are major challenges that contribute to the development of hydrogel. In addition, compared to other hydrogels, nanocellulose hydrogels demonstrated higher potential for drug delivery, 3D cell culture, diagnostics, tissue engineering, tissue therapies and gene therapies. Overall, nanocellulose hydrogel has the potential for commercialization for different biomedical applications.
The recurrent environmental and economic issues associated with the diminution of fossil fuels are the main impetus towards the conversion of agriculture, aquaculture and shellfish biomass and the wastes into alternative commodities in a sustainable approach. In this review, the recent progress on recovering and processing these biomass and waste feedstocks to produce a variety of value-added products via various valorisation technologies, including hydrolysis, extraction, pyrolysis, and chemical modifications are presented, analysed, and discussed. These technologies have gained widespread attention among researchers, industrialists and decision makers alike to provide markets with bio-based chemicals and materials at viable prices, leading to less emissions of CO2 and sustainable management of these resources. In order to echo the thriving research, development and innovation, bioresources and biomass from various origins were reviewed including agro-industrial, herbaceous, aquaculture, shellfish bioresources and microorganisms that possess a high content of starch, cellulose, lignin, lipid and chitin. Additionally, a variety of technologies and processes enabling the conversion of such highly available bioresources is thoroughly analysed, with a special focus on recent studies on designing, optimising and even innovating new processes to produce biochemicals and biomaterials. Despite all these efforts, there is still a need to determine the more cost-effective and efficient technologies to produce bio-based commodities.
Three-dimensional (3D) bioprinting is a unique combination of technological advances in 3D printing and tissue engineering. It has emerged as a promising approach to address the dilemma in current dental treatments faced by clinicians in order to repair or replace injured and diseased tissues. The exploration of 3D bioprinting technology provides high reproducibility and precise control of the bioink containing the desired cells and biomaterial over the architectural and dimensional features of the scaffolds in fabricating functional tissue constructs that are specific to the patient treatment need. In recent years, the dental applications of different 3D bioprinting techniques, types of novel bioinks, and the types of cells used have been extensively explored. Most of the findings noted significant challenges compared to the non-biological 3D printing approach in constructing the bioscaffolds that mimic native tissues. Hence, this review focuses solely on the implementation of 3D bioprinting techniques and strategies based on cell-laden bioinks. It discusses the in vitro applications of 3D-bioprinted scaffolds on cell viabilities, cell functionalities, differentiation ability, and expression of the markers as well as the in vivo evaluations of the implanted bioscaffolds on the animal models for bone, periodontal, dentin, and pulp tissue regeneration. Finally, it outlines some perspectives for future developments in dental applications.
Functionally graded material (FGM) is a heterogeneous composite material including a number of constituents that exhibit a compositional gradient from one surface of the material to the other subsequently, resulting in a material with continuously varying properties in the thickness direction. FGMs are gaining attention for biomedical applications, especially for implants, owing to their reported superior composition. Dental implants can be functionally graded to create an optimized mechanical behavior and achieve the intended biocompatibility and osseointegration improvement. This review presents a comprehensive summary of biomaterials and manufacturing techniques researchers employ throughout the world. Generally, FGM and FGM porous biomaterials are more difficult to fabricate than uniform or homogenous biomaterials. Therefore, our discussion is intended to give the readers about successful and obstacles fabrication of FGM and porous FGM in dental implants that will bring state-of-the-art technology to the bedside and develop quality of life and present standards of care.
Calcium silicate (CaSiO3, CS) ceramic composites reinforced with graphene nanoplatelets (GNP) were prepared using hot isostatic pressing (HIP) at 1150°C. Quantitative microstructural analysis suggests that GNP play a role in grain size and is responsible for the improved densification. Raman spectroscopy and scanning electron microscopy showed that GNP survived the harsh processing conditions of the selected HIP processing parameters. The uniform distribution of 1 wt.% GNP in the CS matrix, high densification and fine CS grain size help to improve the fracture toughness by ∼130%, hardness by ∼30% and brittleness index by ∼40% as compared to the CS matrix without GNP. The toughening mechanisms, such as crack bridging, pull-out, branching and deflection induced by GNP are observed and discussed. The GNP/CS composites exhibit good apatite-forming ability in the simulated body fluid (SBF). Our results indicate that the addition of GNP decreased pH value in SBF. Effect of addition of GNP on early adhesion and proliferation of human osteoblast cells (hFOB) was measured in vitro. The GNP/CS composites showed good biocompatibility and promoted cell viability and cell proliferation. The results indicated that the cell viability and proliferation are affected by time and concentration of GNP in the CS matrix.
Biodegradable elastomers have clinical applicability due to their biocompatibility, tunable degradation and elasticity. The addition of bioactive glasses to these elastomers can impart mechanical properties sufficient for hard tissue replacement. Hence, a composite with a biodegradable polymer matrix and a bioglass filler can offer a method of augmenting existing tissue. This article reviews the applications of such composites for skeletal augmentation.
Organ repair, regeneration, and transplantation are constantly in demand due to various acute, chronic, congenital, and infectious diseases. Apart from traditional remedies, tissue engineering (TE) is among the most effective methods for the repair of damaged tissues via merging the cells, growth factors, and scaffolds. With regards to TE scaffold fabrication technology, polyurethane (PU), a high-performance medical grade synthetic polymer and bioactive material has gained significant attention. PU possesses exclusive biocompatibility, biodegradability, and modifiable chemical, mechanical and thermal properties, owing to its unique structure-properties relationship. During the past few decades, PU TE scaffold bioactive properties have been incorporated or enhanced with biodegradable, electroactive, surface-functionalised, ayurvedic products, ceramics, glass, growth factors, metals, and natural polymers, resulting in the formation of modified polyurethanes (MPUs). This review focuses on the recent advances of PU/MPU scaffolds, especially on the biomedical applications in soft and hard tissue engineering and regenerative medicine. The scientific issues with regards to the PU/MPU scaffolds, such as biodegradation, electroactivity, surface functionalisation, and incorporation of active moieties are also highlighted along with some suggestions for future work.
Design and development of novel therapeutic strategies to regenerate lost tissue structure and function is a serious clinical hurdle for researchers. Traditionally, much of the research is dedicated in optimising properties of scaffolds. Current synthetic biomaterials remain rudimentary in comparison to their natural counterparts. The ability to incorporate biologically inspired elements into the design of synthetic materials has advanced with time. Recent reports suggest that functionally graded material mimicking the natural tissue morphology can have a more exaggerated response on the targeted tissue. The aim of this review is to deliver an overview of the functionally graded concept with respect to applications in clinical dentistry. A comprehensive understanding of spatiotemporal arrangement in fields of restorative, prosthodontics, periodontics, orthodontics and oral surgery is presented. Different processing techniques have been adapted to achieve such gradients ranging from additive manufacturing (three dimensional printing/rapid prototyping) to conventional techniques of freeze gelation, freeze drying, electrospinning and particulate leaching. The scope of employing additive manufacturing technique as a reliable and predictable tool for the design and accurate reproduction of biomimetic templates is vast by any measure. Further research in the materials used and refinement of the synthesis techniques will continue to expand the frontiers of functionally graded membrane based biomaterials application in the clinical domain.
This study developed a novel bioactive bone substitute (hydroxyapatite, HA) with improved anti-biofilm activity by functionalizing with curcumin (anti-biofilm compound) which provide sufficient flux of curcumin concentration for 14 days. The released curcumin acts to inhibit biofilm formation and control the number of viable planktonic cells simultaneously. To prepare curcumin-functionalized HA, different concentrations of curcumin (up to 3% w/v) were added simultaneously during the precipitation process of HA. The highest loading (50 mg/g HA) of curcumin onto HA was achieved with 2% w/v of curcumin. Physicochemical characterizations of curcumin-functionalized HA composites revealed that curcumin was successfully incorporated onto HA. Curcumin was sustainably released over 14 days, while higher curcumin release was observed in acidic condition (pH 4.4) compared to physiological (pH 7.4). The cytotoxicity assays revealed that no significant difference on bone cells growth on curcumin-functionalized HA and non-functionalized HA. Curcumin-functionalized HA was effective to inhibit bacterial cell attachment and subsequent biofilm maturation stages. The anti-biofilm effect was stronger against Staphylococcus aureus compared to Pseudomonas aeruginosa. The curcumin-functionalized HA composite significantly delayed the maturation of S. aureus compared to non-functionalized HA in which microcolonies of cells only begin to appear at 96 h. Up to 3.0 log reduction in colony forming unit (CFU)/mL of planktonic cells was noted at 24 h of incubation for both microorganisms. Thus, in this study we have suggested that curcumin loaded HA could be an alternative antimicrobial agent to control the risk of infections in post-surgical implants.
Corrosion prevention in biomaterials has become crucial particularly to overcome inflammation and allergic reactions caused by the biomaterials' implants towards the human body. When these metal implants contacted with fluidic environments such as bloodstream and tissue of the body, most of them became mutually highly antagonistic and subsequently promotes corrosion. Biocompatible implants are typically made up of metallic, ceramic, composite and polymers. The present paper specifically focuses on biocompatible metals which favorably used as implants such as 316L stainless steel, cobalt-chromium-molybdenum, pure titanium and titanium-based alloys. This article also takes a close look at the effect of corrosion towards the implant and human body and the mechanism to improve it. Due to this corrosion delinquent, several surface modification techniques have been used to improve the corrosion behavior of biocompatible metals such as deposition of the coating, development of passivation oxide layer and ion beam surface modification. Apart from that, surface texturing methods such as plasma spraying, chemical etching, blasting, electropolishing, and laser treatment which used to improve corrosion behavior are also discussed in detail. Introduction of surface modifications to biocompatible metals is considered as a "best solution" so far to enhanced corrosion resistance performance; besides achieving superior biocompatibility and promoting osseointegration of biocompatible metals and alloys.
Biocomposites are materials that are easy to manufacture and environmentally friendly. Sugar palm fibre (SPF) is considered to be an emerging reinforcement candidate that could provide improved mechanical stiffness and strength to the biocomposites. Numerous studies have been recently conducted on sugar palm biocomposites to evaluate their physical, mechanical and thermal properties in various conditions. Sugar palm biocomposites are currently limited to the applications of traditional household products despite their good thermal stability as a prospective substitute candidate for synthetic fibres. Thus, thermal analysis methods such as TGA and DTG are functioned to determine the thermal properties of single fibre sugar palm composites (SPCs) in thermoset and thermoplastic matrix as well as hybrid SPCs. The biocomposites showed a remarkable change considering thermal stability by varying the individual fibre compositions and surface treatments and adding fillers and coupling agents. However, literature that summarises the thermal properties of sugar palm biocomposites is unavailable. Particularly, this comprehensive review paper aims to guide all composite engineers, designers, manufacturers and users on the selection of suitable biopolymers for sugar palm biocomposites for thermal applications, such as heat shields and engine components.