The use of ecological materials for building and industrial applications contributes to minimizing the environmental impact of new technologies. In this context, the cement and geopolymer sectors are ...considering natural fibers as sustainable reinforcement for developing composites. Natural fibers are renewable, biodegradable, and non-toxic, and they exhibit attractive mechanical properties in comparison with their synthetic fiber counterparts. However, their hydrophilic character makes them vulnerable to high volumes of moisture absorption, thus conferring poor wetting with the matrix and weakening the fiber–matrix interface. Therefore, modification and functionalization strategies for natural fibers to tailor interface properties and to improve the durability and mechanical behavior of cement and geopolymer-based composites become highly important. This paper presents a review of the physical, chemical and biological pre-treatments that have been performed on natural fibers, their results and effects on the fiber–matrix interface of cement and geopolymer composites. In addition, the degradation mechanisms of natural fibers used in such composites are discussed. This review finalizes with concluding remarks and recommendations to be addressed through further in-depth studies in the field.
Due to the relatively poor cell-material interaction of alginate hydrogel, alginate-gelatin crosslinked (ADA-GEL) hydrogel was synthesized through covalent crosslinking of alginate di-aldehyde (ADA) ...with gelatin that supported cell attachment, spreading and proliferation. This study highlights the evaluation of the physico-chemical properties of synthesized ADA-GEL hydrogels of different compositions compared to alginate in the form of films. Moreover, in vitro cell-material interaction on ADA-GEL hydrogels of different compositions compared to alginate was investigated by using normal human dermal fibroblasts. Viability, attachment, spreading and proliferation of fibroblasts were significantly increased on ADA-GEL hydrogels compared to alginate. Moreover, in vitro cytocompatibility of ADA-GEL hydrogels was found to be increased with increasing gelatin content. These findings indicate that ADA-GEL hydrogel is a promising material for the biomedical applications in tissue-engineering and regeneration.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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.
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Large bone defects resulting from fractures and disease are a medical concern, being often unable to heal spontaneously by the body’s repair mechanisms. Bone tissue engineering (BTE) ...is a promising approach for treating bone defects through providing a template to guide osseous regeneration. 3D scaffolds with microstructure mimicking host bone are necessary in common BTE strategies. Bioactive glasses (BGs) attract researchers’ attention as BTE scaffolds as they are osteoconductive and osteoinductive in certain formulations. In vivo animal models allow understanding and evaluation of materials’ performance in the complex physiological environment, being an inevitable step before clinical trials. The aim of this paper is to review for the first time published research investigating the in vivo osseous regenerative capacity of 3D BG scaffolds in bone defect animal models, to better understand and evaluate the progress and future outlook of the use of such scaffolds in BTE. The literature analysis reveals that the regenerative capacity of BG scaffolds depends on several factors; including BG composition, fabrication method, scaffold microstructure and pore characteristics, in addition to scaffold pretreatment and whether or not the scaffolds are loaded with growth factors. In addition, animal species selected, defect size and implantation time affect the scaffold in vivo behavior and outcomes. The review of the literature also makes clear the difficulty encountered to compare different types of bioactive glass scaffolds in their bone forming ability. Even considering such limitations of the current state-of-the-art, results generated from animal bone defect models provide an essential source of information to guide the design of BG scaffolds in future.
Bioactive glasses are at the centre of increasing research efforts in bone tissue engineering as the number of research groups around the world carrying out research on this type of biomaterials continues to increase. However, there are no previous reviews in literature which specifically cover investigations of the performance of bioactive glass scaffolds in bone defect animal models. This is the topic of the present review, in which we have analysed comprehensively all available literature in the field. The review thus fills a gap in the biomaterials literature providing a broad platform of information for researchers interested in bioactive glasses in general and specifically in the outcomes of in vivo models. Bioactive glass scaffolds of different compositions tested in relevant bone defect models are covered.
The incorporation of bioactive glass into bone tissue-engineered scaffolds can be widely beneficial based on emerging evidence in the literature about the angiogenic potential of this material, ...particularly 45S5 Bioglass((R)). This article reviews the literature discussing in vitro studies which have demonstrated that increases in angiogenic indicators have been achieved through both direct and indirect contact of relevant cells with 45S5 Bioglass((R)) particles or with their dissolution products. A few available in vivo studies confirming the ability of bioactive glass, incorporated into scaffolds, to stimulate neovascularization are also discussed. Suggestions for further research are given, highlighting the need for specific investigations designed to assess the effect of particular ion dissolution products from bioactive glasses and their relative concentration on angiogenesis both in vitro and in vivo.
Herbal medicine, the use of plants or plant extracts with known beneficial biological effects to treat and/or prevent diverse health disorders, has been known for thousands of years. After their ...replacement by synthetic drugs in the beginning of the 20th century, plant derived therapeutic agents have been recently attaining more attention again. Phytotherapeutics, which can be extracted from a wide range of different herbal plants, are believed to have a broad spectrum of therapeutic effects and less negative side effects than synthetic drugs. On the other hand, it is often difficult to prove the therapeutic effect of herbal drugs due to their chemical complexity. In the last decade, research has focused increasingly on the relatively new concept of the combination of herbal drugs with modern engineered biomaterials in order to achieve synergy of their therapeutic effects. Even if several studies based on this concept have been published, no systematic overview of the performed investigations and their results is available. In this context, this review focuses on the combination of phytotherapeutics with bioactive glasses (BGs), which are bioactive and biodegradable materials capable of releasing biologically active ions being suitable for several applications as bone substituting and replacing materials as well as in the regeneration of soft and hard tissue. The literature search was carried out using the WEB OF SCIENCE® and SCOPUS® databases using a combination of relevant keywords. Besides giving an overview of the research done in the last years and summarizing the results obtained in those studies, the possible synergistic effects of herbal drugs in combination with BGs are critically discussed, and potential health risks are overviewed. Of all plant-derived drugs investigated so far, the coumarin family appears to be the one that has been most widely combined with BGs showing beneficial outcomes. Overall, the analysis of the literature has revealed the great potential of this organic-inorganic multi-functional system approach as an advantageous alternative to conventional medicine in several applications, but also highlights the need for more systematic in vivo studies to evaluate the effective time and dose dependent combined effects of BGs and phytotherapeutic agents.
Cardiac tissue engineering is a promising strategy to prevent functional deterioration or even to enhance cardiac function upon myocardial infarction. Here, electrospun fiber mats containing ...different combinations of electrically conductive polyaniline, collagen, and/or hyaluronic acid are assessed regarding material properties and compatibility with cardiomyocyte attachment and function. Microstructure analysis reveals that collagen fiber mats contain a wide range of fiber diameters after crosslinking (from ≈300 nm to ≈5 µm); all other fiber mats contain fibers in the range of ≈120 to ≈300 nm. Fiber mats exhibit comparable electrical conductivity to and greater mechanical properties than the native human myocardium, which is considered beneficial. Cell–matrix interaction analysis utilizing postnatal rat cardiomyocytes reveals that the fiber mats are non‐cytotoxic and permit cell attachment and contraction. Fiber mats containing collagen (9.89%), hyaluronic acid (1.1%), and polyaniline (PANi, 1.34%) exhibit the most favorable properties with longer contraction time, higher contractile amplitude, and lower beating rates. Improved contraction is accompanied by increased connexin 43 expression. Importantly, this fiber mat is a suitable material for human‐induced pluripotent stem cell–derived cardiomyocytes regarding cytotoxicity, cell attachment, and function. Collectively, these data demonstrate that fiber mats made of collagen, hyaluronic acid, and polyaniline are promising materials for cardiac tissue engineering.
Facilitating intercellular electrical communication in tissue engineering is challenging. Here, electroconductive fibrous scaffolds with tailorable mechanical and electrical properties are presented. Cardiomyocytes show improved contractile amplitude, intercellular junctions, and higher beating rates.
Porous 45S5 Bioglass-based glass-ceramic scaffolds with high porosity (96%) and interconnected pore structure (average pore size 300 micron) were prepared by the foam replication method. To improve ...the mechanical properties and to incorporate a drug release function, the scaffolds were coated with a drug loaded solution, consisting of PHBV and vancomycin. The mechanical properties of the scaffolds were improved by the PHBV coating. The bioactivity of scaffolds upon immersion in SBF was maintained for the PHBV-coated scaffolds although the formation of hydroxyapatite was slightly retarded by the presence of the coating. The encapsulated drug in the coated scaffolds was released in a sustained manner (99.9% in 6 days) when compared with the rapid release (99.5% in 3 days) of a drug directly adsorbed on the uncoated scaffolds. The drug-loaded and bioactive composite scaffolds are promising candidates for bone tissue engineering applications.
For biomedical applications such as soft tissue engineering, plant proteins are becoming increasingly attractive. Zein, a class of prolamine proteins found in corn, offers excellent properties for ...application in the human body, but has inferior mechanical properties and lacks aqueous stability. In this study, electrospun scaffolds from neat zein and zein blended with prepolymer and mildly cross-linked poly(glycerol sebacate) (PGS) were fabricated. Less toxic solvents like acetic acid and ethanol were used. The morphological, physiochemical and degradation properties of the as-spun fiber mats were determined. Neat zein and zein-PGS fiber mats with high zein concentration (24 wt % and 27 wt %) showed defect-free microstructures. The average fiber diameter decreased with increasing PGS amount from 0.7 ± 0.2 µm to 0.09 ± 0.03 µm. The addition of PGS to zein resulted in a seven-fold increase in ultimate tensile strength and a four-fold increase in failure strain, whereas the Young's Modulus did not change significantly. Degradation tests in phosphate buffered saline revealed the morphological instability of zein containing fiber mats in contact with aqueous media. Therefore, the fibers were in situ cross-linked with
-(3-Dimethylaminopropyl)-
'-ethylcarbodiimide (EDC)/
-Hydroxysuccinimide (NHS), which led to improved morphological stability in aqueous environment. The novel fibers have suitable properties for application in soft tissue engineering.
The use of bioactive glass (BG) particles as a filler for the development of composite electrospun fibers has already been widely reported and investigated. The novelty of the present research work ...is represented by the use of benign solvents (like acetic acid and formic acid) for electrospinning of composite fibers containing BG particles, by using a blend of PCL and chitosan. In this work, different BG particle sizes were investigated, namely nanosized and micron-sized. A preliminary investigation about the possible alteration of BG particles in the electrospinning solvents was performed using SEM analysis. The obtained composite fibers were investigated in terms of morphological, chemical and mechanical properties. An in vitro mineralization assay in simulated body fluid (SBF) was performed to investigate the capability of the composite electrospun fibers to induce the formation of hydroxycarbonate apatite (HCA).
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•Use of benign solvents for electrospinning of composite PCL/chitosan fibers containing nano and micronsized BG particles.•Successfully dispersion of BG nano and micronsized particles in electrospun PCL/chitosan nanofibrous mats.•Deposition of hydroxycarbonate apatite after immersion in SBF solution confirmed for both composites fibers.
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