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In situ facile synthesis and the characterization of nanohydroxyapatite/chitosan (nHAP/CS) biocomposites were investigated for examining their potential applications in orthopedic implant technology. Firstly, the bare nHAP, europium-doped hydroxyapatite (Eu-nHAP), yttrium-doped hydroxyapatite (Y-nHAP), and Eu- and Y-codoped hydroxyapatite (Eu,Y-nHAP) nanoparticles were synthesized by the wet precipitation technique using biowaste-eggshell-derived calcium oxide powders. Then, through ultrasonication using the nanohydroxyapatite/chitosan mixtures (molar ratio = 1:2), the nHAP/CS, Eu-nHAP/CS, Y-nHAP/CS, and Eu,Y-nHAP/CS biocomposites were fabricated. Among them, Eu,Y-nHAP/CS showed higher cell viability (94.9%), higher solubility (pH = 7.6 after 21 days), and greater antibacterial activity than those of the other composites. In addition, Eu,Y-nHAP/CS exhibited improved mechanical properties compared with the other composites. For example, the nanoindentation test displayed the Eu,Y-nHAP/CS-coated 316L stainless steel implant to possess a higher Young's modulus value (9.24 GPa) and greater hardness value (300.71 MPa) than those of the others. The results indicate that the biomass-eggshell-derived Eu,Y-doped nHAP is of good use for orthopedic implant applications. [ABSTRACT FROM AUTHOR]

This study aimed to develop injectable chitosan oligosaccharide (COS) and bovine hydroxyapatite (BHA) hybrid biocomposites, and characterise their physiochemical properties for use as a dental pulp-capping material. The COS powder was prepared from chitosan through hydrolytic reactions and then dissolved in 0.2% acetic acid to create a solution. BHA was obtained from waste bovine bone and milled to form a powder. The BHA powder was incorporated with the COS solution at different proportions to create the COS–BHA hybrid biocomposite. Zirconium oxide (ZrO2) powder was included in the blend as a radiopacifier. The composite was characterised to evaluate its physiochemical properties, radiopacity, setting time, solubility, and pH. Fourier-transform infrared spectroscopic analysis of the COS–BHA biocomposite shows the characteristic peaks of COS and hydroxyapatite. Compositional analysis via ICP-MS and SEM-EDX shows the predominant elements present to be the constituents of COS, BHA, and ZrO2. The hybrid biocomposite demonstrated an average setting time of 1 h and 10 min and a pH value of 10. The biocomposite demonstrated solubility when placed in a physiological solution. Radiographically, the set hybrid biocomposite appears to be more radiopaque than the commercial mineral trioxide aggregate (MTA). The developed COS-BHA hybrid biocomposite demonstrated good potential as a pulp-capping agent exhibiting high pH, with a greater radiopacity and reduced setting time compared to MTA. Solubility of the biocomposite may be addressed in future studies with the incorporation of a cross-linking agent. However, further in vitro and in vivo studies are necessary to evaluate its clinical feasibility. [ABSTRACT FROM AUTHOR]

A collagen-based copolymer, ASC-g-Poly(methyl methacrylate-co-Ethyl Acrylate), was synthesized in the presence of Graphene Oxide (GO) via an in-situ polymerization. The presence of GO that increased the accessible surface area for initiated collagen chains allowed for an accelerated polymerization with highly improved grafting performance and efficiency. This was conducted from two polymerization systems with varied comonomer feed ratios, in which two distinguished GO loadings were used. The processability of the achieved nanocomposite was then evaluated through casting and electrospinning processing methods. Fourier Transform Infrared Spectroscopy (FT-IR), UV-Vis spectroscopy, Differential Scanning Calorimeter (DSC), Thermogravimetric analysis (TGA), Scanning Electron Microscope (SEM), Transmission electron microscopy (TEM), and tensile analysis were conducted to characterize the GO-ASC-g-P(MMA-co-EA). The nanocomposite films showed a unique morphology, multilayer nanostructure of the grafted GO monolayers that deposited simultaneously one on top of another. The morphology of the electrospun fibers was affected by the addition of GO loadings in which the increase in fiber diameter was observed while the surface of the nanofibers was decorated by the GO nanolayers. To modify the collagen, this research highlights the importance of introducing functional groups of GO and the substitution of GO loadings as an active nanostructure filler to highly monomer feed ratios improving the physiochemical properties of collagen. This easy-to-apply approach is suggested for applications intending the mechanical properties and deterred degradation of Collagen-based materials. [ABSTRACT FROM AUTHOR]

Cellulose nanocrystals (CNC) are well-suited to the preparation of biocomposite films and packaging material due to its abundance, renewability, biodegradability, and favorable film-forming capacity. In this study, different CNC and corn zein (CZ) composite films were prepared by adding CZ to the CNC suspension prior to drying, in order to change internal structure of resulting films. Films were developed to examine their performance as an alternative water vapor and oxygen-barrier for flexible packaging industry. Water vapor permeability (WVP) and oxygen transmission rate (OTR) of the biocomposite films decreased significantly in a specific ratio between CNC and CZ combined with 1,2,3,4-butane tetracarboxylic acid (BTCA), a nontoxic cross linker. In addition to the improved barrier properties, the incorporation of CZ benefitted the flexibility and thermal stability of the CNC/CZ composite films. The toughness increased by 358%, and Young's modulus decreased by 32% compared with the pristine CNC film. The maximum degradation temperature increased by 26 °C, compared with that of CNC film. These results can be attributed to the incorporation of a hydrophobic protein into the matrix creating hydrophobic interactions among the biocomposite components. SEM and AFM analysis indicated that CZ could significantly affect the CNC arrangement, and the film surface topography, due to the mechanical bundling and physical adsorption effect of CZ to CNC. The presented results indicate that CNC/CZ biocomposite films may find applications in packaging, and in multi-functionalization materials. [ABSTRACT FROM AUTHOR]

This research investigated the development of bio-based composites comprising bacterial cellulose (BC), as obtained by static culture, and acrylated epoxidized soybean oil (AESO) as an alternative to leather. AESO was first emulsified; polyethylene glycol (PEG), polydimethylsiloxane (PDMS) and perfluorocarbon-based polymers were also added to the AESO emulsion, with the mixtures being diffused into the BC 3D nanofibrillar matrix by an exhaustion process. Scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy analysis demonstrated that the tested polymers penetrated well and uniformly into the bulk of the BC matrix. The obtained composites were hydrophobic and thermally stable up to 200 °C. Regarding their mechanical properties, the addition of different polymers lead to a decrease in the tensile strength and an increase in the elongation at break, overall presenting satisfactory performance as a potential alternative to leather. [ABSTRACT FROM AUTHOR]

The distinctive ability to remember their original form after partial or complete deformation makes shape memory polymers remarkable materials for several engineering and biomedical applications. In the present work, the development of a polycaprolactone based toughened shape memory polyurethane biocomposite promoted by in situ incorporation of chitosan flakes has been demonstrated. The chitosan flakes were homogeneously present in the polymer matrix in the form of nanoflakes, as confirmed by the electron microscopic analysis and probably developed a crosslinked node that promoted toughness (a > 500% elongation at break) and led to a ~130% increment in ultimate tensile strength, as analyzed using a universal testing machine. During a tensile pull, X-ray analysis revealed the development of crystallites, which resulted from a stress induced crystallization process that may retain the shape and melting of the crystallites stimulating shape recovery (with a ~100% shape recovery ratio), even after permanent deformation. The biodegradable polyurethane biocomposite also demonstrates relatively high thermal stability (Tmax at ~360 °C). The prepared material possesses a unique shape memory behavior, even after permanent deformation up to a > 500% strain, which may have great potential in several biomedical applications. [ABSTRACT FROM AUTHOR]

Global industry is showing a great interest in the field of sustainability owing to the increased attention for ecological safety and utilization of renewable materials. For the scientific community, the challenge lies in the identification of greener synthetic approaches for reducing the environmental impact. In this context, we propose the preparation of novel biocomposites consisting of natural rubber latex (NRL) and sepiolite (Sep) fibers through the latex compounding technique (LCT), an ecofriendly approach where the filler is directly mixed with a stable elastomer colloid. This strategy favors a homogeneous dispersion of hydrophilic Sep fibers in the rubber matrix, allowing the production of high-loaded sepiolite/natural rubber (Sep/NR) without the use of surfactants. The main physicochemical parameters which control Sep aggregation processes in the aqueous medium were comprehensively investigated and a flocculation mechanism was proposed. The uniform Sep distribution in the rubber matrix, characteristic of the proposed LCT, and the percolative filler network improved the mechanical performances of Sep/NR biocomposites in comparison to those of analogous materials prepared by conventional melt-mixing. These outcomes indicate the suitability of the adopted sustainable procedure for the production of high-loaded clay–rubber nanocomposites with remarkable mechanical features. [ABSTRACT FROM AUTHOR]