Preparation, Structural Characterization, and Biomedical Applications of Gypsum-Based Nanocomposite Bone Cements

Hard tissues are natural nanocomposites comprising collagen nanofibers that are interlocked with hydroxyapatite (HAp) nanocrystallites. This mechanical interlocking at the nanoscale provides the unique properties of hard tissues (bone and teeth). Upon fracture, cements are usually used for treatment of simple fractures or as an adhesive for the treatment of complicated fractures that require the use of metallic implants. Most of the commercially available bone cements are polymer-based, and lack the required bioactivity for a successful cementation. Besides calcium phosphate cements, gypsum is one of the early recognized and used biomaterials as a basi for a self-setting cementation. It is based on the controlled hydration of plaster of Paris at room temperature and its subsequent conversion to a self-setting solid gypsum product. In our work, we have taken this process further towards the development of a set of nanocomposites that have enhanced bioactivity and mechanical properties. This chapter will outline the formation, characterization, and properties of gypsum-based nanocomposites for bone cement applications. These modified cements can be formulated at room temperature and have been shown to possess a high degree of bioactivity, and are considered potential candidates for bone fracture and defect treatment

Fabrication and characterization of cellulose acetate-based nanofibers and nanofilms for H2S gas sensing application

Electrospun nanofibers and solution-casting nanofilms were produced from an environmentally friendly cellulose acetate (CA) blended with glycerol (as an ionic liquid (IL)), mixed with polypyrrole (PPy, a conducting polymer) and doped with tungsten oxide (WO3) nanoparticles. The sensing membranes fabricated were used to detect H2S gas at room temperature and shown to exhibit high performance. The results revealed that the lowest operating temperature of both nanofiber and nanofilm sensors was 20oC, with a minimum gas detection limit of 1 ppm. Moreover, the sensor exhibits a reasonably fast response, with a minimum average response time of 22.8 and 31.7 s for the proposed nanofiber and nanofilm based sensors, respectively. Furthermore, the results obtained indicated an excellent reproducibility, long-term stability, and low humidity dependence. Such distinctive properties coupled with an easy fabrication technique provide a promising potential to achieve a precise monitoring of harmful H2S gas in both indoor and outdoor atmospheres

Enhancing the Stability of Cu‐BTC Metal‐Organic Framework via the Formation of Cu‐BTC@Cu3(PO4)2 MOF Core‐Shell Nanoflower Hierarchical Hybrid Composites

Abstract Hybrid organic‐inorganic nanoflowers (NFs) have recently emerged as a critical tool in enhancing the stability and activity of biomolecules due to their expansive surface area and porosity. The delicate petal‐like features of NFs offer innumerable sites for biomolecule adsorption, including but not limited to proteins, amino acids, and enzymes. Cu‐BTC, a copper‐based Metal‐Organic Framework (MOF) has been hindered in its potential for diverse applications by its instability in humid and aqueous conditions. To overcome this limitation, this study explores the stabilization of Cu‐BTC via the mineralization of its surface with the formation of copper phosphate nanoflowers (NFs). To initiate the mineralization process and provide a template for the growth of the NFs, a physiologically rich amino acid medium is employed. The inclusion of amino acids in the RPMI medium played a crucial role in the preservation of the Cu‐BTC hierarchical structure by facilitating the self‐assembly of copper phosphate nanoflowers on its surface, thereby producing a Cu‐BTC@Cu3(PO4)2 core‐shell structure. The innovative mechanism behind the formation of copper phosphate nanoflowers in this study and its consequential stabilization of the Cu‐BTC MOF structure underscore its novel nature

Preparation and Characterization of Blank and Nerolidol-Loaded Chitosan–Alginate Nanoparticles

Recently, there has been a growing interest in using natural products as treatment alternatives in several diseases. Nerolidol is a natural product which has been shown to have protective effects in several conditions. The low water solubility of nerolidol and many other natural products limits their delivery to the body. In this research, a drug delivery system composed of alginate and chitosan was fabricated and loaded with nerolidol to enhance its water solubility. The chitosan–alginate nanoparticles were fabricated using a new method including the tween 80 pre-gelation, followed by poly-ionic crosslinking between chitosan negative and alginate positive groups. Several characterization techniques were used to validate the fabricated nanoparticles. The molecular interactions between the chitosan, alginate, and nerolidol molecules were confirmed using the Fourier transform infrared spectroscopy. The ultraviolet spectroscopy showed an absorbance peak of the blank nanoparticles at 200 nm and for the pure nerolidol at 280 nm. Using both scanning and transmission electron microscopy, the nanoparticles were found to be spherical in shape with an average size of 12 nm and 35 nm for the blank chitosan–alginate nanoparticles and the nerolidol-loaded chitosan–alginate nanoparticles, respectively. The nanoparticles were also shown to have a loading capacity of 51.7% and an encapsulation efficiency of 87%. A controlled release profile of the loaded drug for up to 28 h using an in vitro model was also observed, which is more efficient than the free form of nerolidol. In conclusion, chitosan–alginate nanoparticles and nerolidol loaded chitosan–alginate nanoparticles were successfully fabricated and characterized to show potential encapsulation and delivery using an in vitro model

Tunable Hydroxyapatite/Magnetite Nanohybrids with Preserved Magnetic Properties

Magnetic nanoparticles (MNPs) have been extensively investigated in a wide range of biomedical applications. Controlled coating of the MNPs is commonly utilized to protect and maintain their magnetic properties and to improve their biocompatibility, hydrophilicity, colloidal stability and overall biodistribution. Hydroxyapatite (HAp), a highly biocompatible material, is considered for the functionalization of MNPs. In this study, two simple chemical approaches are used to prepare nanohybrid MNPs-on-HAp and HAp-on-MNPs composites. The effect of heat treatment on the phase com-position, morphology, and magnetic properties of both types of magnetic composites is extensively evaluated. In the presence of HAp, MNPs are segregated onto their surfaces and their transformation to hematite upon heat treatment is delayed. On the other hand, needle-shaped HAp nano-crystallites preferentially grow onto the hydroxylated MNPs surfaces, leading to a synergistic enhancement in the magnetic properties of the produced nanocomposites, with preserved magnetic properties. Compared with a saturation magnetization (Ms) value of 80 emu g−1 of pure MNPs, a MNPs-on HAp nanohybrid shows a maximum of 14 emu g−1, while nanohybrids based on HAp-on-MNPs show Ms values in the range of 43–78 emu g−1. These findings demonstrate the ability to fine-tune the magnetic properties of the HAp/MNPs nano hybrids via optimizing their processing conditions.This work was financially supported by United Arab Emirates University (Grant Code: UPAR-G00002150 and fund code 31S246) and by the Faculty of Engineering at McMaster University. Electron microscopy and related characterization were performed at the Canadian Centre for Electron Microscopy at McMaster University. Zeta potential measurements were also carried out by Matthew Campea (Dr. Todd Hoare's laboratory), McMaster University

Developing transgenic wheat to encounter rusts and powdery mildew by overexpressing barley chi26 gene for fungal resistance

Abstract Background The main aim of this study was to improve fungal resistance in bread wheat via transgenesis. Transgenic wheat plants harboring barley chitinase (chi26) gene, driven by maize ubi promoter, were obtained using biolistic bombardment, whereas the herbicide resistance gene, bar, driven by the CaMV 35S promoter was used as a selectable marker. Results Molecular analysis confirmed the integration, copy number, and the level of expression of the chi26 gene in four independent transgenic events. Chitinase enzyme activity was detected using a standard enzymatic assay. The expression levels of chi26 gene in the different transgenic lines, compared to their respective controls, were determined using qRT-PCR. The transgene was silenced in some transgenic families across generations. Gene silencing in the present study seemed to be random and irreversible. The homozygous transgenic plants of T4, T5, T6, T8, and T9 generations were tested in the field for five growing seasons to evaluate their resistance against rusts and powdery mildew. The results indicated high chitinase activity at T0 and high transgene expression levels in few transgenic families. This resulted in high resistance against wheat rusts and powdery mildew under field conditions. It was indicated by proximate and chemical analyses that one of the transgenic families and the non-transgenic line were substantially equivalent. Conclusion Transgenic wheat with barley chi26 was found to be resistant even after five generations under artificial fungal infection conditions. One transgenic line was proved to be substantially equivalent as compared to the non-transgenic control