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Solar-thermal technology based on phase change materials (PCMs) has received a lot of attention as a cost-effective and practical way to overcome solar energy intermittency. However, weak photothermal conversion ability and complex preparation processes have hindered the practical application of PCMs. In this work, a new approach for facile, uniform, and firm assembly of graphene nanoplatelet (GNP) through the reaction of graphene oxide (GO) with the silanized melamine foam (MF) is introduced. Here, the deposited amino siloxane layer not only promotes the adhesion and integrity of embedded GNP/GO nanosheets but also facilitates the synthetic route compared to the previous studies. Following the reduction of GO with oleylamine (OA), the hybrid GNP/rGO foams with an integrated network were obtained. The composite PCMs were prepared through the incorporation of paraffin wax (PW) into the hybrid structure. The high hydrophobicity and porosity of the GNP/rGO foams resulted in a high loading of paraffin wax (nearly 97 wt%) and thus large transition enthalpy of 182 J g-1. The GNP/rGO framework provided excellent solar-thermal storage efficiency of up to 92.2%. The PCM composite containing the highest content of GNP (6 wt%) revealed an enhanced thermal conductivity by 87% compared to the unmodified MF/PW composite.

Today's consumer electronics are made from nonrenewable and toxic components. They are also rigid, bulky, and manufactured in an energy-inefficient manner via CO2-generating routes. Though petroleum-based polymers such as polyethylene terephthalate and polyethylene naphthalate can address the rigidity issue, they have a large carbon footprint and generate harmful waste. Scalable routes for manufacturing electronics that are both flexible and ecofriendly (Fleco) could address the challenges in the field. Ideally, such substrates must incorporate into electronics without compromising device performance. In this work, we demonstrate that a new type of wood-based [nanocellulose (NC)] material made via nanosilicate (NS) reinforcement can yield flexible electronics that can bend and roll without loss of electrical function. Specifically, the NSs interact electrostatically with NC to reinforce thermal and mechanical properties. For instance, films containing 34 wt % of NS displayed an increased young's modulus (1.5 times), thermal stability (290 → 310 °C), and a low coefficient of thermal expansion (40 ppm/K). These films can also easily be separated and renewed into new devices through simple and low-energy processes. Moreover, we used very cheap and environmentally friendly NC from American Value Added Pulping (AVAP) technology, American Process, and therefore, the manufacturing cost of our NS-reinforced NC paper is much cheaper ($0.016 per dm-2) than that of conventional NC-based substrates. Looking forward, the methodology highlighted herein is highly attractive as it can unlock the secrets of Fleco electronics and transform otherwise bulky, rigid, and "difficult-to-process" rigid circuits into more aesthetic and flexible ones while simultaneously bringing relief to an already-overburdened ecosystem.

MXenes (viz., transition metal carbides, carbonitrides, and nitrides) have emerged as a new subclass of 2D materials. Due to their outstanding physicochemical and biological properties, MXenes have gained much attention in the biomedical field in recent years, including drug delivery systems, regenerative medicine, and biosensing. Additionally, the incorporation of MXenes into hydrogels has garnered significant interest in biomedical engineering as an electroactive and mechanical nanoreinforcer capable of converting nonconductive scaffolds into excellent conductors of electricity with an impressive effect on mechanical properties for the engineering of electroactive organs and tissues such as cardiac, skeletal muscle, and nerve. However, many questions and problems remain unresolved that need to be answered to usher these 2D materials toward their true destiny. Thus, this review paper aims to provide an overview of the design and applications of MXene-integrated composites for biomedical applications, including cardiac tissue engineering, wound healing, infection therapy, cancer therapy, and biosensors. Moreover, the current challenges and limitations of utilizing MXenes in vivo are highlighted and discussed, followed by its prospects as a guideline toward possible various futuristic biomedical applications. This review article will inspire researchers, who search for properties, opportunities, and challenges of using this 2D nanomaterial in biomedical applications.

This study investigates the role of halloysite nanotube as a mineral-based thixotropic admixture to 3D printable geopolymer mortar. The first part of this paper focuses on the fundamental characterization of the thermal evolution of halloysite at 30–1000 °C. In the second part, we show how the calcination and concentration of halloysite influence the fresh and hardened properties of 3D-printable geopolymer mortar. It was found that regardless of thermal treatment, using only 1–2 wt.% halloysite can significantly increase the rheological properties and buildability of the mortars without compromising their mechanical strength. However, the setting time of geopolymer only accelerated when highly reactive dehydroxylated halloysite was used. Compared with mold-cast specimens, the mechanical properties of 3D-printed specimens were lower at early ages due to their higher surface dehydration; however, the gap became closer over time.

Gellan-chitosan (GC) incorporated with CS: 0% (GC-0 CS), 10% (GC-10 CS), 20% (GC-20 CS) or 40% (GC-40 CS) w/w was prepared using freeze-drying method to investigate its physicochemical, biocompatible, and osteoinductive properties in human bone-marrow mesenchymal stromal cells (hBMSCs). The composition of different groups was reflected in physicochemical analyses performed using BET, FTIR, and XRD. The SEM micrographs revealed excellent hBMSCs attachment in GC-40 CS. The Alamar Blue assay indicated an increased proliferation and viability of seeded hBMSCs in all groups on day 21 as compared with day 0. The hBMSCs seeded in GC-40 CS indicated osteogenic differentiation based on an amplified alkaline-phosphatase release on day 7 and 14 as compared with day 0. These cells supported bone mineralization on GC-40 CS based on Alizarin-Red assay on day 21 as compared with day 7 and increased their osteogenic gene expression (RUNX2, ALP, BGLAP, BMP, and Osteonectin) on day 21. The GC-40 CS–seeded hBMSCs initiated their osteogenic differentiation on day 7 as compared with counterparts based on an increased expression of type-1 collagen and BMP2 in immunocytochemistry analysis. In conclusion, the incorporation of 40% (w/w) calcium silicate in gellan-chitosan showed osteoinduction potential in hBMSCs, making it a potential biomaterial to treat critical bone defects.

Soft and electrically active materials are currently being utilized for intelligent systems, including electronic skin, cybernetics, soft robotics, and wearable devices. However, fabricating materials that fulfill the complex requirements of such advanced applications remains a challenge. These attributes include electronic, adhesive, self-healing, flexible, moldable, printable, and strong mechanical properties. Inspired by the recent interest in transforming monofunctional materials into multifunctional ones through nanoreinforcement and mussel-inspired chemistry, we have designed a simple two-step methodology based on halloysite nanotube (HNT) and polydopamine (PDA) to address the grand challenges in the field. In brief, HNTs were coated with PDA and embedded within a poly(vinyl alcohol) (PVA)-based polymeric matrix in combination with ferric ions (Fe

This study demonstrates a two-step approach that enables quantification of concrete printability through dynamics mode rheological measurements; I) modeling shearing history during extrusion; II) monitoring the hardening evolution of deposited material by applying a strain smaller than the critical strain. It is shown that the shearing history of the material is removed by imposing a pre-shearing above the critical strain, and zero value yield stress is measured for all specimens. At step II, a linear extrapolation of the green strength development can quantify the static yield stress at the origin, which we used to quantify the material printability. As far as this yield stress surpasses the stress level that exists in the printed structure, the material retains its shape stability. We show the performance of the model on a series of geopolymer mortars with a wide range of rheological properties as a function of material composition, aging, and pre-shearing consequences.

Alginate methacrylate (ALMA) hydrogels have been prevalently used in various biomedical applications, mainly due to their photocrosslinking ability. Not only this feature allows the formation of cell-laden hydrogels, but it also facilitates the fine-tuning of hydrogels' physical attributes such as mechanical properties, pore size distribution, and degradation rate. In the past decade, various modifications were applied to ALMA hydrogels to amend their physiochemical and biological properties to enhance their performance in tissue engineering applications. Moreover, the advent of microfabrication technologies further expanded the horizon of ALMA hydrogels by facilitating the fabrication of microstructures with controlled architecture. Remarkably, these improvements opened up new avenues in biomedical research to study cell-cell interactions and cell morphogenesis in response to microstructural cues. Aside from that, ALMA hydrogels were successfully used for the regeneration of multiple tissues, including bone, cartilage, and muscle, among others. Given the current state of research on ALMA hydrogels, it is timely to map the evolution of these hydrogels and review the collective work on this topic. Herein, we have provided an extensive review of ALMA-based hydrogels covering a broad spectrum of issues on this topic, including synthesis methods, tuning of physical properties, organic/inorganic composites, microfabrication, and tissue engineering applications. Lastly, future directions regarding the application of ALMA-based hydrogels in developing advanced materials and technologies are discussed. (c) 2021 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY license ( http://creativecommons.org/licenses/by/4.0/ )

Heat transfer characteristics of copper sintered heat pipe explored using a modified graphene nanoplatelets (GNP)-containing nanofluid with great dispersion stability as a novel working fluid. Firstly, a water dispersible GNP with specific desire was synthesized by the reaction of GNP sheets with the diazonium salt (DS) of sodium 4-aminoazobenzene-4-sulfonate. An X-ray photoelectron spectroscopy (XPS) test shown successful covalent functionalization of GNP using DS which provided special water dispersibility characteristics. The results indicate that the thermal conductivity enhancement was up to 17% by adding modified GNP sheets in the base fluid. It also, exhibited a maximum sedimentation of 16% after 840 hrs. Further research works were carried on thermal performance of heat pipe by varying nanofluid concentrations, filling ratio, input heating powers and inclination angles of heat pipes. The results proof that the maximum enhancements of the effective thermal conductivity and reduction in thermal resistance for purposed nanofluid at φ = 5% were 105% and 26.4%, respectively. Moreover, these good features of the GNP/DS nanofluid make it a very promising working fluid to enhance the thermal performance and efficiency of the current heat pipe systems.

Fluorination of graphene nanomaterials has multitude merits owing to the peculiar temperament of the carbon-fluorine (C-F) bond. However, the current synthesis modalities of fluorinated graphene (FG) are based on the usage of toxic materials at high temperatures, which are problematic to be used. The methods to overcome these problems are challenging for chemists. Ionic liquids (ILs) have been used in several chemical processes as auxiliaries and eco-friendly alternatives instead of volatile organic solvents because of their properties. Consequently, herein we exploited a highly effective and green process for the synthesis of FG at mild temperature (80 °C) by using ammonium fluoride salt as fluorine agent and a synthesized acidic IL ([TEA]+[TFA]–) as a solvent. Our goal was to synthesize enriched FG with a high degree of fluorination (66.4 wt.% of F) and F/C ratio (2.2), which measured and confirmed by XPS analysis. Subsequently, the obtained FG was used as a nanocarrier for delivery of curcumin to cancerous cells. The in-vitro results showed that these nanosheets possessed a higher Cur-loading efficiency (78.43%) than commercial FG (52.12%) due to the sheet-like structure with folded edges. This, in turn, translated into an excellent in-vitro anti-cancer effect when tested against cancerous cells.

Contains fulltext : 218172.pdf (Publisher’s version ) (Closed access) Hydrogel structures with microscale morphological features have extensive application in tissue engineering owing to their capacity to induce desired cellular behavior. Herein, we describe a novel biofabrication method for fabrication of grooved solid and hollow hydrogel fibers with control over their cross-sectional shape, surface morphology, porosity, and material composition. These fibers were further configured into three-dimensional structures using textile technologies such as weaving, braiding, and embroidering methods. Additionally, the capacity of these fibers to integrate various biochemical and biophysical cues was shown via incorporating drug-loaded microspheres, conductive materials, and magnetic particles, extending their application to smart drug delivery, wearable or implantable medical devices, and soft robotics. The efficacy of the grooved fibers to induce cellular alignment was evaluated on various cell types including myoblasts, cardiomyocytes, cardiac fibroblasts, and glioma cells. In particular, these fibers were shown to induce controlled myogenic differentiation and morphological changes, depending on their groove size, in C2C12 myoblasts.

One of the long-standing challenges in materials science involves synthesizing biomaterials that recapitulate important features of native biological tissues. Even though, the number of available biomaterials at the moment are virtually limitless, few of them has unlocked all the secrets of the human body by mimicking the combinatorial-like material properties of our tissues and organs. Inspired by the human body, we have developed a polymeric gum, which combines stretchability, toughness, strength, flexibility, and self-healing. It also exhibits a high bioactivity that can target and eliminate bacterial infections fast and reliably. Notably, this material is moldable into almost any complex shape, and therefore suitable as a building block for wearables designed to conform directly with the curved and personalized anatomy of patients. It also exhibits excellent drug retention and release capacity, which altogether makes it suitable for applications in personalized wearable drug-delivery devices.

It has been over a decade since oxidative enzymes were first used to degrade carbon-based nanomaterials (CBNs). Although enormous progress has been achieved in this field, many questions and problems remain unresolved that need to be answered to usher these materials toward their true destiny. Nanobioscience researchers now know that ignoring the biomolecular corona (BMC) in nanobiomedical studies, either inadvertently or intentionally, is by no means justified. However, a major drawback to progress is that BMC effects on CBN biodegradation have been omitted from a large number of studies. What's more, many studies in the field have eliminated the BMC source in the relevant experiments. Thus, the most critical question that one needs to probe is whether the BMC and its characteristics affect the biodegradability of CBNs? In this conceptual perspective paper, recent progress and significant research in CBNs biodegradation are summarized. Then, the importance of the BMC and its possible impacts on the biodegradation of CBNs are thoroughly explored as a conceptual guide. Finally, remaining challenges and the direction of future research are provided, and barriers that need to be overcome to advance the field are discussed including recommendations regarding BMC considerations and study design and reporting guidelines.

This research explores the use of simultaneous heating and pressing techniques in order to enhance the mechanical properties of fly ash (FA) based geopolymer under relatively low temperature conditions to ensure minimum-porosity. Four effective parameters of pressing force, alkali activator/FA, duration of hot-pressing and sodium concentration are studied. Together with detailed experimental studies, our results reveal that the most dominant factor is the induced pressure. The main results indicated that the highest compressive strength of the geopolymer (134 MPa) could be obtained by employing the hot pressing, temperature and duration of 41.4 MPa, 350 °C and 20 min, respectively. The microstructure of the hot-pressed specimens showed more developed geopolymer matrix compared with conventional ones leading to higher compressive strength in much shortest time. The improved mechanical properties are generally attributed to the dense structure of the material and higher geopolymer gel production during the hot pressing process. However, further reaction of partially reacted particles improves the mechanical properties over time.

Tissue engineering aims to generate or facilitate regrowth or healing of damaged tissues by applying a combination of biomaterials, cells, and bioactive signaling molecules. In this regard, growth factors clearly play important roles in regulating cellular fate. However, uncontrolled release of growth factors has been demonstrated to produce severe side effects on the surrounding tissues. In this study, poly(lactic-co-glycolic acid) (PLGA) microspheres (MS) incorporated three-dimensional (3D) CORAGRAF scaffolds were engineered to achieve controlled release of platelet-derived growth factor-BB (PDGF-BB) for the differentiation of stem cells within the 3D polymer network. Fourier transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, scanning electron microscopy, and microtomography were applied to characterize the fabricated scaffolds. In vitro study revealed that the CORAGRAF-PLGA-PDGF-BB scaffold system enhanced the release of PDGF-BB for the regulation of cell behavior. Stromal cell attachment, viability, release of osteogenic differentiation markers such as osteocalcin, and upregulation of osteogenic gene expression exhibited positive response. Overall, the developed scaffold system was noted to support rapid cell expansion and differentiation of stromal cells into osteogenic cells in vitro for bone tissue engineering applications.

The effect of a permanent magnetic field on the heat transfer characteristics of hybrid graphene-magnetite nanofluids (hybrid nanofluid) under forced laminar flow was experimentally investigated. For this purpose, a reduced graphene oxide-Fe3O4 was synthesized by using two-dimensional (2D) graphene oxide, iron salts and tannic acid as the reductant and stabilizer. Graphene sheets acted as the supporting materials to enhance the stability and thermal properties of magnetite nanoparticles. The thermo-physical and magnetic properties of this hybrid nanofluid have been widely characterized and it shows that the thermal conductivity increased up to 11%. The hybrid nanofluid behaves as a Newtonian fluid with liquid like behavior with superparamagnetic properties as was evident from its magnetic saturation value at 45.9 emu/g. Moreover, the experimental heat-transfer results indicated that the heat transfer enhancement of the hybrid nanofluid compared to the control fluid (distilled water) was negligible when no magnetic field was applied. Additionally, the convective heat transfer was significantly improved under the influence of a magnetic field with a maximum enhancement of 82% in terms of the convective heat transfer properties of the hybrid nanofluid.

The heat transfer characteristics and entropy generation rate of hybrid graphene-magnetite nanofluids under forced laminar flow that subjected to the permanent magnetic fields were investigated. For this purpose, a nanoscale reduced graphene oxide-Fe3O4 hybrid was synthesized by using graphene oxide, iron salts and tannic acid as the reductant and stabilizer. The thermophysical and magnetic properties of the hybrid nanofluid have been widely characterized and thermal conductivity has shown an enhancement of 11%. The experimental results indicated that the heat transfer enhancement of hybrid magnetite nanofluid compared to the case of distilled was negligible when no magnetic field was applied. Additionally, the heat transfer characteristics have been improved significantly under magnetic field. The outcome of the analysis shows that the total entropy generation rate was reduced up to 41% compared to distilled water. It appears that these magnetic hybrid nanofluids can function as good alternative fluids in the magnetic thermal engineering systems.

It has been demonstrated that carbon (C) doped aluminium oxide (Al2O3) nanocomposite (C −0.012 wt%) had greater wear resistance and lower surface grains pull out percentage when compared with monolithic Al2O3. In the present study, we investigated the physicochemical, micro- and nanomechanical, cell attachment, in vitro biocompatibility and osteogenic differentiation properties of Al2O3 doped carbon (0.012 wt%) nanocomposite (Al2O3/C). Data were compared to values obtained for monolithic alumina (Al2O3). The calcined Al2O3/C nanocomposite was densified using cold isostatic pressing and followed by pressureless sintering. For physicochemical and microstructural characterisation, Energy dispersive X-ray (EDX), X-ray diffraction (XRD), Raman spectroscopy, and X-ray photoemission spectrometer (XPS) were used. EDX, XRD peaks and Raman spectroscopy demonstrated correlating to Al2O3/C. Surface profiling and contact angle investigations demonstrated highly contoured micro-surface topography. The micro and nano-hardness indicate an improved wear resistance of the Al2O3/C when compared with monolithic Al2O3. SEM, confocal images and alamar blue reduction assay suggested good cell attachment and proliferation of human bone marrow derived mesenchymal stromal cells (hBMSCs). Osteogenic protein and gene expression indicated Al2O3/C had a significant osteogenic potential (p

Given their durability and long-term stability, self-healable hydrogels have, in the past few years, emerged as promising replacements for the many brittle hydrogels currently being used in preclinical or clinical trials. To this end, the incompatibility between hydrogel toughness and rapid self-healing remains unaddressed, and therefore most of the self-healable hydrogels still face serious challenges within the dynamic and mechanically demanding environment of human organs/tissues. Furthermore, depending on the target tissue, the self-healing hydrogels must comply with a wide range of properties including electrical, biological, and mechanical. Notably, the incorporation of nanomaterials into double-network hydrogels is showing great promise as a feasible way to generate self-healable hydrogels with the above-mentioned attributes. Here, the recent progress in the development of multifunctional and self-healable hydrogels for various tissue engineering applications is discussed in detail. Their potential applications within the rapidly expanding areas of bioelectronic hydrogels, cyborganics, and soft robotics are further highlighted. S.T. and M.M. contributed equally to this work. A.D.P. acknowledges the Danish Council for Independent Research (Technology and Production Sciences, 5054-00142B), Gigtforeningen (R139-A3864) and the Villum Foundation (10103). This work is also part of the VIDI research program with project number R0004387, which is (partly) financed by the Netherlands Organisation for Scientific Research (NWO). The authors acknowledge funding from the Australian Research Council under the Discovery Early Career Researcher Award (J. Foroughi, DE130100517). The authors also thank Ashish for creating Figure 21.

Hydrogels are the most iconic class of soft materials, and since their first report in the literature, they have attracted the attention of uncountable researchers. Over the past two decades, hydrogels have become smart and sophisticated materials with numerous applications. This class of soft materials have been playing a significant role in biomedicine due to their tunable and often programmable properties. Hydrogels from renewable polymers have been popularized in biomedical applications as they are often biocompatible, easily accessible, and inexpensive. The challenge however has been to find an ideal plant-based hydrogel for biomedicine that can mimic critical properties of human tissues in terms of structure, function, and performance. In addition, natural polymers can readily be functionalized to engineer their chemical and physical uproperties pertinent to drug delivery and tissue engineering. Here, the most recent advances in the synthesis, fabrication, and applications of plant-based hydrogels in biomedical engineering are reviewed. We cover essential and updated information about plants as green sources of biopolymers for hydrogel synthesis, general aspects of hydrogels and plant-based hydrogels, and thorough discussion regarding the use of such hydrogels in the biomedical engineering area. Furthermore, this review details the present status of the field and answers several important questions about the potential of plant-based hydrogels in advanced biomedical applications including therapeutics, tissue engineering, wound dressing, and diagnostics. etc., 0, SCOPUS: re.j, info:eu-repo/semantics/published

Item does not contain fulltext Bone tissue engineering is an emerging medical field that has been developed in recent years to address pathologies with limited ability of bones to regenerate. Here we report the fabrication and characterization of microbial transglutaminase crosslinked gelatin-based scaffolds designed for serving as both cell substrate and growth factor release system. In particular, morphological, biomechanical and biological features have been analyzed. The enzyme ratio applied during the fabrication of the scaffolds affects the swelling capacity and the mechanical properties of the final structure. The developed systems are not cytotoxic according to the biocompatibility tests. The biological performance of selected formulations was studied using L-929 fibroblasts, D1 MSC and MG63 osteoblasts. Moreover, scaffolds allowed efficient osteogenic differentiation and signaling of MSCs. MSC cultured on the scaffolds not only presented lower proliferative and stemness profile, but also increased expression of osteoblast-related genes (Col1a1, Runx2, Osx). Furthermore, the in vitro release kinetics of vascular endothelial growth factor (VEGF) and bone morphogenetic protein -2 (BMP-2) from the scaffolds were also investigated. The release of the growth factors produced from the scaffolds followed a first order kinetics. These results highlight that the scaffolds designed and developed in this work may be suitable candidates for bone tissue regeneration purposes.

Great advantages bestowed by mesoporous silica nanoparticles (MSNs) including high surface area, tailorable pore diameter and surface chemistry, and large pore volume render them as efficient tools in biomedical applications. Herein, MSNs with different surface chemistries were synthesized and investigated in terms of biocompatibility and their impact on the morphology of bone marrow-derived mesenchymal stem cells both in 2D and 3D culture systems. Bare MSNs (BMSNs) were synthesized by template removing method using tetraethylorthosilicate (TEOS) as a precursor. The as-prepared BMSNs were then used to prepare amine-functionalized (AMSNs), carboxyl-functionalized (CMSNs) and polymeric amine-functionalized (PMSNs) samples, consecutively. These nanoparticles were characterized by scanning electron microscopy, zeta potential measurement, dynamic light scattering, BET (Brunauer, Emmett, Teller) analysis, and FTIR technique. In a 3D culture system, stem cells were encapsulated in alginate hydrogel in which MSNs of different functionalities were incorporated. The results showed good biocompatibility for both BMSNs and AMSNs in 2D and 3D culture systems. For these samples, the viability of about 80% was acquired after 2 weeks of 3D culture. When compared to the control, CMSNs caused higher cell proliferation in the 2D culture; while they showed cytotoxic effects in the 3D culture system. Interestingly, polymeric amine-functionalized silica nanoparticles (PMSNs) resulted in disrupted morphology and very low viability in the 2D cell culture and even less viability in 3D environment in comparison to BMSNs and AMSNs. This significant decrease in cell viability was attributed to the higher uptake values of highly positively charged PMSNs by cells as compared to other MSNs. This up-regulated uptake was evaluated by using an inductively coupled plasma optical emission spectroscopy instrument (ICP-OES). These results uncover different interactions between cell and nanoparticles with various surface chemistries. Building on these results, new windows are opened for employing biocompatible nanoparticles such as BMSNs and AMSNs, even at high concentrations, as potential cargos for carrying required growth and/or differentiation factors for tissue engineering applications.

Item does not contain fulltext Given their native-like biological properties, high growth factor retention capacity and porous nature, sulfated-polysaccharide-based scaffolds hold great promise for a number of tissue engineering applications. Specifically, as they mimic important properties of tissues such as bone and cartilage they are ideal for orthopaedic tissue engineering. Their biomimicry properties encompass important cell-binding motifs, native-like mechanical properties, designated sites for bone mineralisation and strong growth factor binding and signaling capacity. Even so, scientists in the field have just recently begun to utilise them as building blocks for tissue engineering scaffolds. Most of these efforts have so far been directed towards in vitro studies, and for these reasons the clinical gap is still substantial. With this review paper, we have tried to highlight some of the important chemical, physical and biological features of sulfated-polysaccharides in relation to their chondrogenic and osteogenic inducing capacity. Additionally, their usage in various in vivo model systems is discussed. The clinical studies reviewed herein paint a promising picture heralding a brave new world for orthopaedic tissue engineering. 01 september 2019

High value-added materials are usually made from low-value materials or wastes. Producing these materials as by-products along with the main products of any industry or project can multiply the financial benefits of economic processes. Many of these processes today use fossil fuels that have two major problems: non-renewability and environmental pollution. To make greener these economic processes, efforts are being made today to use sustainable raw materials. Also, the use of biomaterials in the production of high-value materials is essential to achieve a low-carbon and circular economy. In this comprehensive review, the production processes of high value-added materials are summarized in simple forms. In addition to reviewing processes, the most important raw materials for the production of these valuable materials have also been widely discussed. As two very important issues, the relationship between the food supply chain and conversion of its waste into high value-added materials as well as the conversion of carbon dioxide into high-value materials has also been investigated. Finally, the high potential of using these sustainable materials in a greener economic direction was shown. In general, it can be said that these environmentally friendly materials must also make economic progress. However, recent advances have been made to reduce the cost of producing some of these materials. To have a greener economy in the future, the number of processes and production materials that are economically viable must increase. The use of waste from the food supply chain must also be given significant consideration. The production of valuable materials from CO2 is also essential.

Herein, a new ecofriendly approach to generate a graphene-based nanofluid was established. Specifically, a novel mode of graphene oxide reduction through functionalization with polyphenol extracted from red wine was introduced. Comprehensive characterization methods were employed to confirm and understand the reduction process of graphene oxide in the red wine polyphenol solution. It was noted, that the deoxygenation level of the reduced graphene oxide is comparable with the levels obtained by conventional and non-ecofriendly methods. The physical and thermal properties of the generated nanofluid including chemical stability, viscosity, wettability, electrical conductivity and thermal conductivity were investigated in a comprehensive manner. A significant thermal conductivity enhancement amounting to 45.1% was obtained for a volume fraction of 4%. In addition, the convective heat transfer coefficient of the nanofluid in a laminar flow regime with uniform wall heat flux was investigated to estimate its cooling capabilities. These results, firmly confirm that the generated graphene-based nanofluid is a formidable transporter of heat and yet ecofriendly. Therefore, it's anticipate that the generated nanofluid will open a new avenue in the pursuit of ecofriendly thermal conductors for heat transfer applications.

Thermal performance of a grooved heat pipe using aqueous nitrogen-doped graphene (NDG) nanofluids was analysed. This study in particular focused on the effect of varying NDG nanosheets concentrations, heat pipe inclination angles and input heating powers. The results indicated that the inclination angle had a major influence on the heat transfer performance of heat pipes and the inclination angle (θ) of 90° was corresponded to the best thermal performance. The maximum thermal resistance reduction of 58.6% and 99% enhancement in the evaporator heat transfer coefficient of the heat pipe were observed for NDG nanofluid with concentration of 0.06 wt%, inclination angle of θ = 90 ° and a heating power of 120 W in comparison to DI-water under the exact same condition. Additionally, the surface temperature distribution was decreased by employing NDG nanosheets, which can in return increase the thermal performance of a grooved heat pipe. The present investigation indicated that the thermal performance of the grooved heat pipe can be improved significantly by using NDG nanofluids.

An overview of experimental results about the heat transfer capabilities of graphene nanofluids is reviewed. It shows that a number of publications are available on this issue and only few studies provide quantitative estimates on a complete set of experimental conditions so far. This research work includes experimental results about the capabilities of graphene nanofluids and summarizes the recent progress on preparation and evaluation methods, the ways to enhance the stability of graphene nanofluids and future applications in various fields of energy. Thermo-physical and optical properties of graphene nanofluids along with the heat transfer performance have also been reported in this review paper. Various challenges associated with the use of graphene nanofluids in actual applications has also been reported. It is expected that it could be a quick reference guide to have an overview of the different heat transfer phenomena in graphene nanofluids and the most essential parameters that influence the expected thermal performance of graphene nanofluids.

The fiber-matrix interface properties play an important role in determining the overall mechanical performance of the fiber reinforced brittle matrix composites. This study is to evaluate the effects of wettability, chemical characterization and nanometric roughness of two different fibers, polypropylene (PPF) and micro steel fibers (MSF), superposed by shrinkage of fly ash based geopolymer binder on fiber-matrix interaction and the consequent mechanical properties of the corresponding composites. The fiber incorporation in geopolymer matrix was performed by 0.5, 1, 2, 3 and 4% of the total volume of each type of fibers. The results show that MSF has strong contact with the geopolymer paste since it tends to behave as a hydrophilic material that resulted in significant improvement in energy absorption and flexural strength of the composite; while PPF led to fiber-matrix debonding due to hydrophobic characteristics of the fiber compounds by geopolymer shrinkage that weakened the mechanical performances of the composites.

Calcium silicate (CS)/graphene coatings have been used to improve the biological and mechanical fixation of metallic prosthesis. Among the extraordinary features of graphene is its very high mechanical strength, which makes it an attractive nanoreinforcement material for composites. Calcium silicate–reduced graphene oxide (CS–rGO) composites were synthesized, using an in situ hydrothermal method. CS nanowires were uniformly decorated on the rGO, with an appropriate interfacial bonding. The CS–rGO composites behaved like hybrid composites when deposited on a titanium substrate by cathodic electrophoretic deposition (EPD). Compared to a pure CS coating on Ti, the CS–1 wt% rGO coating has improved adhesion by 70%, hardness by 150% and the elastic modulus by 240%. The CS–rGO composite coatings exhibit good apatite-forming ability in simulated body fluid (SBF). Moreover, the effect of addition of rGO on morphology, adhesion and proliferation of human osteoblast cells (hFOB) was investigated in vitro.

A novel shape-stabilized phase change material (SSPCM) was fabricated by using a vacuum impregnation technique. The lightweight, ultra-high specific surface area and porous activated carbon was prepared from waste material (rice husk) through the combination of an activation temperature approach and a sodium hydroxide activation procedure. Palmitic acid as a phase change material was impregnated into the porous carbon by a vacuum impregnation technique. Graphene nanoplatelets (GNPs) were employed as an additive for thermal conductivity enhancement of the SSPCMs. The attained composites exhibited exceptional phase change behavior, having a desirable latent heat storage capacity of 175 kJ kg−1. When exposed to high solar radiation intensities, the composites can absorb and store the thermal energy. An FTIR analysis of the SSPCMs indicated that there was no chemical interaction between the palmitic acid and the activated carbon with GNPs. The thermal conductivity of the prepared composites improved by more than 97% for the highest loading of GNPs (6 wt%) compared with that of pure palmitic acid. Moreover, the SSPCMs exhibit high thermal stability, with a stable melting–freezing enthalpy and excellent reversibility. The prepared SSPCMs with enhanced heat transfer and phase change properties provide a beneficial option for building energy conservation and solar energy applications owing to the low cost of raw materials and the simple synthetic technique.

Despite the promise of hydrogel-based stem cell therapies in orthopedics, a significant need still exists for the development of injectable microenvironments capable of utilizing the regenerative potential of donor cells. Indeed, the quest for biomaterials that can direct stem cells into bone without the need of external factors has been the "Holy Grail" in orthopedic stem cell therapy for decades. To address this challenge, we have utilized a combinatorial approach to screen over 63 nanoengineered hydrogels made from alginate, hyaluronic acid, and two-dimensional nanoclays. Out of these combinations, we have identified a biomaterial that can promote osteogenesis in the absence of well-established differentiation factors such as bone morphogenetic protein 2 (BMP2) or dexamethasone. Notably, in our "hit" formulations we observed a 36-fold increase in alkaline phosphate (ALP) activity and a 11-fold increase in the formation of mineralized matrix, compared to the control hydrogel. This induced osteogenesis was further supported by X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, and energy-dispersive X-ray spectroscopy. Additionally, the Montmorillonite-reinforced hydrogels exhibited high osteointegration as evident from the relatively stronger adhesion to the bone explants as compared to the control. Overall, our results demonstrate the capability of combinatorial and nanoengineered biomaterials to induce bone regeneration through osteoinduction of stem cells in a natural and differentiation-factor-free environment.

Fluorinated graphene has recently gained much attention for cancer drug delivery, owing to its peculiar properties including high electronegativity difference, magnetic resonance imaging contrast agent, and the photothermal effect. However, the hydrophobic nature of fluorinated graphene greatly hinders its application as a biological material. Herein, a novel green method is reported for synthesis of a pH-sensitive charge-reversal and water-soluble fluorinated graphene oxide, modified with polyethyleneimine anchored to sericin-polypeptide (FPS). This nanocarrier was further loaded with curcumin (Cur), and characterized as a nanocarrier for anti-cancer drug delivery. The synthesized nanocarriers contain two different pH-sensitive amide linkages, which are negatively charged in blood pH (≈7.4) and can prolong circulation times. The amide linkages undergo hydrolysis once they reach the mildly acidic condition (pH≈6.5, corresponding to tumor extracellular matrix), and subsequently once reached the lower acidic condition (pH≈5.5, corresponded to endo/lysosomes microenvironment), the FPS charge can be switched to positive (≈+28 mV), which aids the nuclear release. This nanocarrier was designed to selectively enhance cell internalization and nuclear-targeted delivery of curcumin in HeLa, SkBr3 and PC-3 cancer cells. Moreover, FPS-Cur demonstrated high curcumin loading capacity, prolonged curcumin release and promotion of apoptosis in HeLa, SkBr3 and PC-3 cells. Therefore, with its pH-responsive charge-reversal properties, FPS-Cur would be a promising candidate for chemotherapy of cervical, breast and prostate cancers.

In spite of remarkable improvements in cancer treatments and survivorship, cancer still remains as one of the major causes of death worldwide. Although current standards of care provide encouraging results, they still cause severe systemic toxicity and also fail in preventing recurrence of the disease. In order to address these issues, biomaterial-based implantable drug delivery systems (DDSs) have emerged as promising therapeutic platforms, which allow local administration of drugs directly to the tumor site. Owing to the unique properties of biopolymers, they have been used in a variety of ways to institute biodegradable implantable DDSs that exert precise spatiotemporal control over the release of therapeutic drug. Here, the most recent advances in biopolymer-based DDSs for suppressing tumor growth and preventing tumor recurrence are reviewed. Novel emerging biopolymers as well as cutting-edge polymeric microdevices deployed as implantable antitumor DDSs are discussed. Finally, a review of a new therapeutic modality within the field, which is based on implantable biopolymeric DDSs, is given.

At the crossroads of chemistry, electronics, mechanical engineering, polymer science, biology, tissue engineering, computer science, and materials science, electrical devices are currently being engineered that blend directly within organs and tissues. These sophisticated devices are mediators, recorders, and stimulators of electricity with the capacity to monitor important electrophysiological events, replace disabled body parts, or even stimulate tissues to overcome their current limitations. They are therefore capable of leading humanity forward into the age of cyborgs, a time in which human biology can be hacked at will to yield beings with abilities beyond their natural capabilities. The resulting advances have been made possible by the emergence of conformal and soft electronic materials that can readily integrate with the curvilinear, dynamic, delicate, and flexible human body. This article discusses the recent rapid pace of development in the field of cybernetics with special emphasis on the important role that flexible and electrically active materials have played therein. A.D.-P. would like to acknowledge the Danish Council for Independent Research (Technology and Production Sciences, 5054-00142B), Danish Council for Independent Research (Technology and Production Sciences, 8105-00003B), Gigtforeningen (R139-A3864), and the Villum Foundation (10103) for support. The authors also thank "Haderer & Muller Biomedical Art" for creating the illustration presented in Figures 8 and 12. M.A. and B.M acknowledge the funding received from Natural Sciences and Engineering Research Council of Canada (NSERC)discovery grant and Canadian Institutes of Health Research (CIHR). G.O would like to acknowledge the projects SAF2016-76150-R from the Spanish Ministry of Economy, Industry and Competitiveness and PRGF 3.0 ELKARTEK KK-2017/00063 from the Basque Country Government and intellectual and technical assistance from the ICTS "NANBIOSIS", more specifically by the Drug Formulation Unit (U10) of the CIBER in Bioengineering, Biomaterials & Nanomedicine (CIBER-BBN) at the University of the Basque Country (UPV/EHU). We also appreciate the support from the Basque Country Government (Grupos Consolidados, No ref: IT907-16).

The main advantage of latent heat thermal energy storage systems is the capability to store a large quantity of thermal energy in an isothermal process by changing phase from solid to liquid, while the most important weakness of these systems is low thermal conductivity that leads to unsuitable charging/discharging rates. Heat pipes are used in many applications – as one of the most efficient heat exchanger devices – to amplify the charging/discharging processes rate and are used to transfer heat from a source to the storage or from the storage to a sink. This review presents and critically discusses previous investigations and analysis on the incorporation of heat pipe devices into latent heat thermal energy storage with heat pipe devices. This paper categorizes different applications and configurations such as low/high temperature solar, heat exchanger and cooling systems, analytical approaches and effective parameters on the performance of hybrid HP–LHTES systems.