Facile fabrication of linezolid/strontium coated hydroxyapatite/graphene oxide nanocomposite for osteoporotic bone defect

Hydroxyapatite (HAp) coatings currently have limited therapeutic applications because they lack anti-infection, osteoinductivity, and poor mechanical characteristics. On the titanium substrate, electrochemical deposition (ECD) was used to construct the strontium (Sr)-featuring hydroxyapatite (HAp)/graphene oxides (GO)/linezolid (LZ) nanomaterial coated with antibacterial and drug delivery properties. The newly fabricated nanomaterials were confirmed by X-ray diffraction analysis (XRD), Fourier-transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) analysis and morphological features were examined by scanning electron microscope (SEM) analysis. The results reveal multiple nucleation sites for SrHAp/GO/LZ composite coatings due to oxygen-comprising moieties on the 2D surface of GO. It was shown to be favorable for osteoblast proliferation and differentiation. The elastic modulus and hardness of LZ nanocomposite with SrHAp/GO/LZ coatings were increased by 67 % and 121 %, respectively. An initial 5 h burst of LZ release from the SrHAp/GO/LZ coating was followed by 14 h of gradual release, owing to LZ's physical and chemical adsorption. The SrHAp/GO/LZ coating effectively inhibited both S. epidermidis and S. aureus, and the inhibition lasted for three days, as demonstrated by the inhibition zone and colony count assays. When MG-63 cells are coated with SrHAp/GO/LZ composite coating, their adhesion, proliferation, and differentiation greatly improve when coated with pure titanium. A novel surface engineering nanomaterial for treating and preventing osteoporotic bone defects, SrHAp/GO/LZ, was shown to have high mechanical characteristics, superior antibacterial abilities, and osteoinductivity.

Effects of Adding Methods of Fluorane Microcapsules and Shellac Resin Microcapsules on the Preparation and Properties of Bifunctional Waterborne Coatings for Basswood

In this paper, urea-formaldehyde resin microcapsules with shellac resin as core material were prepared by in-situ polymerization. Morphologies of shellac resin microcapsules were characterized by optical microscope (OM) and scanning electron microscope (SEM). Both microcapsules were spherical in shape. The encapsulation property of shellac resin was proved by Fourier transform infrared (FTIR). Shellac resin microcapsules and fluorane microcapsules were added to waterborne primer or topcoat at the same time to prepare waterborne coatings with thermochromic and self-healing dual functions. The effects of microcapsules on optical properties, mechanical properties, self-healing properties, anti-aging performance, and thermoreversible discolouration mechanism of coating films were studied. These results showed that the topcoat with 10.0% fluorane microcapsules and 5.0% shellac resin microcapsules had a better comprehensive performance. At this time, the colour of coating transformed yellow into colourless at 32 °C, and it had a good colour recovery. Shellac resin microcapsules endowed the coating with self-healing performance, and the self-healing rate was 35.9%. The research results provide a reference for the progression of multifunctional wood coatings.

High-Temperature Aroma Mitigation and Fragrance Analysis of Ethyl Cellulose/Silica Hybrid Microcapsules for Scented Fabrics

Microencapsulation can improve the thermal stability of a fragrance, and composite wall materials are one way to further improve the thermal stability of microcapsules. This paper presents a facile approach for cotton fabric coatings by using cellulose/silica hybrid microcapsules. Lavender fragrance oil-loaded cellulose/silica hybrid microcapsules were one-step synthesized via emulsion solvent diffusion. The prepared microcapsules were found to be spherical in shape with a particle size distribution between 500 to 1000 nm. Due to the slow releasing of lavender fragrance oil in the capsules, the fragrance loss rate of (3-aminopropyl)triethoxysilane (APTES)-, triethoxy(3-glycidyloxypropyl)silane (GPTES)-, and (3-aercaptopropyl)trie-thoxysilane (MPTES)- modified cellulose/silica hybrid microcapsules are 25.2%, 35.1%, and 16.7% after six hours at 120 °C. E-nose and gas chromatography–mass spectrometry (GCMS) studies found that the fragranced cotton fabrics had good retention of characteristic aromas. It provides the basis for the application of the heating treatment of cotton fabrics in sterilization, bleaching, printing, and other processes.

Development of Injectable Hydroxyapatite/2-(dimethylamino)Ethyl Methacrylate/Polyvinylpyrrolidone Aqua-Hydrogel System to Repair of the Shoulder Joint Head for Hemiarthroplasty

This study aimed to develop osteogenic structure assembly for modular bone treatment presentations, effect of 2-(dimethylamino)ethyl methacrylate and polyvinyl pyrrolidone combination as cell adhesive molecule with hydroxyapatite-based composite as osteoconductive constituent was inspected on bone fracture repair. The prepared injectable composite hydrogel showed significantly improved mechanical stability. The ternary composite gel was characterized for functional group modifications and chemical interactions using Fourier-transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). Moreover, X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) analyses were performed to observe surface appearances of the hydrogel. The hydroxyapatite/2-(dimethylamino)ethyl methacrylate/poly-N-vinyl-2-pyrrolidone hydrogel played key role in supporting osteoblastic cell spread due to their bioactivity and strength abilities. The present findings revealed the significance of hydroxyapatite concentration on proliferation and osteogenic purpose of the cells. The developed performances of hydrogel have been improved cell proliferation and functions to repair bone fracture.

Organic Hollow Mesoporous Silica as a Promising Sandalwood Essential Oil Carrier

As film-forming agents, fillers and adsorbents, microplastics are often added to daily personal care products. Because of their chemical stability, they remain in the environment for thousands of years, endangering the safety of the environment and human health. Therefore, it is urgent to find an environmentally friendly substitute for microplastics. Using n-octyltrimethoxysilane (OTMS) and tetraethoxysilane (TEOS) as silicon sources, a novel, environmentally friendly, organic hollow mesoporous silica system is designed with a high loading capacity and excellent adsorption characteristics in this work. In our methodology, sandalwood essential oil (SEO) was successfully loaded into the nanoparticle cavities, and was involved in the formation of Pickering emulsion as well, with a content of up to 40% (w/w). The developed system was a stable carrier for the dispersion of SEO in water. This system can not only overcome the shortcomings of poor water solubility and volatility of sandalwood essential oil, but also act as a microplastic substitute with broad prospects in the cosmetics and personal care industry, laying a foundation for the preparation and applications of high loading capacity microcapsules in aqueous media.

4D spatiotemporal modulation of biomolecules distribution in anisotropic corrugated microwrinkles via electrically manipulated microcapsules within hierarchical hydrogel for spinal cord regeneration

Although traditional 3D scaffolds or biomimetic hydrogels have been used for tissue engineering and regenerative medicine, soft tissue microenvironment usually has a highly anisotropic structure and a dynamically controllable deformation with various biomolecule distribution. In this study, we developed a hierarchical hybrid gelatin methacrylate-microcapsule hydrogel (HGMH) with Neurotrophin-3(NT-3)-loaded PLGA microcapsules to fabricate anisotropic structure with patterned NT-3 distribution (demonstrated as striped and triangular patterns) by dielectrophoresis (DEP). The HGMH provides a dynamic biomimetic sinuate-microwrinkles change with NT-3 spatial gradient and 2-stage time-dependent distribution, which was further simulated using a 3D finite element model. As demonstrated, in comparison with striped-patterned hydrogel, the triangular-patterned HGMH with highly anisotropic array of microcapsules exhibits remarkably spatial NT-3 gradient distributions that can not only guide neural stem cells (NSCs) migration but also facilitate spinal cord injury regeneration. This approach to construct hierarchical 4D hydrogel system via an electromicrofluidic platform demonstrates the potential for building various biomimetic soft scaffolds in vitro tailed to real soft tissues.

Reactive oxygen species-responsive silk sericin microcapsules used for antioxidative stress damage

Silk sericin microcapsules loaded with horseradish peroxidase (HRP) are prepared through protein self-assembly in a green environment containing enzymes to protect liver cells from alcohol damage. Load content and release dynamics of HRP in sericin microcapsules are investigated. The role of HRP-loaded microcapsules in hydrogen peroxide (H₂ O₂ ) degradation is demonstrated using electrochemical method. Furthermore, the effect of the HRP-loaded microcapsules on cells and intracellular reactive oxygen species (ROS) level is evaluated using an alcohol damage model in vitro. Results show that HRP can be loaded effectively in the sericin microcapsules and can be released ROS-responsively from microcapsules. Cell survival rate increases after suffering from alcohol damage due to the presence of HRP-loaded microcapsule, and the active oxygen content in cells is maintained at a stable level even when it remained in an environment with high alcohol concentration. We believe that the internalized sericin microcapsules maintain HRP activity intracellularly, allow controlled HRP release within a host cell, and show excellent ability in antioxidative stress injury.

Silk-based microcarriers: current developments and future perspectives

Cell-seeded microcarriers (MCs) are currently one of the most promising topics in biotechnology. These systems are supportive structures for cell growth and expansion that allow efficient nutrient and gas transfer between the media and the attached cells. Silk proteins have been increasingly used for this purpose in the past few years due to their biocompatibility, biodegradability and non-toxicity. To date, several silk fibroin spherical MCs in combination with alginate, gelatin and calcium phosphates have been reported with very interesting outcomes. In addition, other silk-based three-dimensional structures such as microparticles with chitosan and collagen, as well as organoids, have been increasingly studied. In this study, the physicochemical and biological properties of these biomaterials, as well as the recent methodologies for their processing and for cell culture, are discussed. The potential biomedical applications are also addressed. In addition, an analysis of the future perspectives is presented, where the potential of innovative silk-based MCs processing technologies is highlighted.

Hydroxyapatite/sericin composites: A simple synthesis route under near-physiological conditions of temperature and pH and preliminary study of the effect of sericin on the biomineralization process

Synthesis of hydroxyapatite (HAp) and sericin (SS) nanocomposites was carried out by a simple precipitation method performed in batch in a stirred tank reactor (ST). The reaction was achieved by mixing a solution of calcium chloride dihydrate, in which SS was dissolved, with a solution of disodium hydrogen phosphate at 37 °C. Three experimental conditions were studied by varying the concentration of SS: HAp, HAp/SS1 (0.01 g/L of SS) and HAp/SS2 (1 g/L of SS). The chemical and physical properties of the resulting HAp/SS nanocomposites were studied using several techniques (Atomic Absorption Spectrometry, Ultraviolet-Visible Spectrophotometry, Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Selected area diffraction (SAED) and Thermogravimetric analysis (TGA)). pH profile was also monitored over time for each experimental condition. The results revealed that nano single-phased HAp was formed with both rod and plate-like shape. Additionally, the particles have low crystallinity, characteristic similar to biological HAp. Regarding the influence of SS, one observed that with increasing SS concentration there is an increase in the mean particle size and the number of plate-like particles, as well as an increase in the aggregation degree and a decrease of the crystallinity. Further, the composites obtained have an inorganic/organic composition comparable to bone. Finally, in vitro cytotoxicity showed that the synthetized nanoparticles are non-toxic and cell viability is higher for HAp and HAp/SS samples when compared to a commercially available HAp. The produced materials can thus be considered suitable candidates for bone related applications.

Biopolymers as bone substitutes: a review

Human bones have unique structures and characteristics, and replacing a natural bone in the case of bone fracture or bone diseases is a very complicated problem. The main goal of this paper was to summarize the recent research on polymer materials as bone substitutes and for bone repair. Bone treatment methods, bone substitute materials as well as their advantages and drawbacks, and manufacturing methods were reviewed. Biopolymers are the most promising materials in the field of artificial bones and using biopolymers with the shape memory effect can improve the integration of an artificial bone into the human body by better mimicking the structure and properties of natural bones, decreasing the invasiveness of surgical procedures by producing deployable implants. It has been shown that the application of the rapid prototyping technology for artificial bones allows the customization of bone substitutes for a patient and the creation of artificial bones with a complex structure.

Thermosensitive Behavior and Super-Antibacterial Properties of Cotton Fabrics Modified with a Sercin-NIPAAm-AgNPs Interpenetrating Polymer Network Hydrogel

Poly(N-isopropylacrylamide) (PNIPAAm), sericin (SS), and silver nitrate were combined to prepare an interpenetrating network (IPN) hydrogel having dual functions of temperature sensitivity and antibacterial properties. The structure and size of AgNPs in such an IPN hydrogel were characterized by the Fourier Transform Infrared spectrum (FT-IR), X-ray powder diffraction (XRD) and Transmission Electron Microscope (TEM), and the thermal properties of the IPN hydrogel were characterized by Differential Scanning Calorimetry (DSC). Based on XRD patterns, Ag⁺ was successfully reduced to Ag⁰ by SS. It was observed by TEM that the particle size of silver particles was lower than 100 nm. The glass transition temperature (Tg) of IPN hydrogel was better than that of the PNIPAAm/AgNPs hydrogels, and lower critical solution temperature (LCST) values of the IPN hydrogel were obtained by DSC i.e. 31 °C. The thermal stability of the IPN hydrogel was successfully determined by the TGA. This IPN hydrogel was then used to modify the cotton fabrics by the "impregnation" method using glutaraldehyde (GA) as the cross-linking agent. The structures and properties of IPN hydrogel modified cotton fabric were characterized by scanning electron microscopy (SEM), FT-IR, and the thermogravimetry analysis (TGA). The results show that NIPAAm was successfully polymerized into PNIPAAm, and that there were neglected new groups in the hydrogel IPN. The IPN hydrogel was then successfully grafted onto cotton fabrics. SEM observations showed that the IPN hydrogel formed a membrane structure between the fibers, and improved the compactness of the fibers. At the temperature close to LCST (≈31 °C), the entire system was easily able to absorb water molecules. However, the hydrophilicity tended to decrease when the temperature was higher or lower than the LCST. The antibacterial rates of the modified cotton fabric against S. aureus and E. coli were as high as 99%.

Preparation and application of flavor and fragrance capsules

The preparation methods and applications of flavor and fragrance capsules based on polymeric, inorganic and polymeric–inorganic wall materials are summarized.

Silk scaffolds in bone tissue engineering: An overview

Bone tissue plays multiple roles in our day-to-day functionality. The frequency of accidental bone damage and disorder is increasing worldwide. Moreover, as the world population continues to grow, the percentage of the elderly population continues to grow, which results in an increased number of bone degenerative diseases. This increased elderly population pushes the need for artificial bone implants that specifically employ biocompatible materials. A vast body of literature is available on the use of silk in bone tissue engineering. The current work presents an overview of this literature from materials and fabrication perspective. As silk is an easy-to-process biopolymer; this allows silk-based biomaterials to be molded into diverse forms and architectures, which further affects the degradability. This makes silk-based scaffolds suitable for treating a variety of bone reconstruction and regeneration objectives. Silk surfaces offer active sites that aid the mineralization and/or bonding of bioactive molecules that facilitate bone regeneration. Silk has also been blended with a variety of polymers and minerals to enhance its advantageous properties or introduce new ones. Several successful works, both in vitro and in vivo, have been reported using silk-based scaffolds to regenerate bone tissues or other parts of the skeletal system such as cartilage and ligament. A growing trend is observed toward the use of mineralized and nanofibrous scaffolds along with the development of technology that allows to control scaffold architecture, its biodegradability and the sustained releasing property of scaffolds. Further development of silk-based scaffolds for bone tissue engineering, taking them up to and beyond the stage of human trials, is hoped to be achieved in the near future through a cross-disciplinary coalition of tissue engineers, material scientists and manufacturing engineers.

STATEMENT OF SIGNIFICANCE

The state-of-art of silk biomaterials in bone tissue engineering, covering their wide applications as cell scaffolding matrices to micro-nano carriers for delivering bone growth factors and therapeutic molecules to diseased or damaged sites to facilitate bone regeneration, is emphasized here. The review rationalizes that the choice of silk protein as a biomaterial is not only because of its natural polymeric nature, mechanical robustness, flexibility and wide range of cell compatibility but also because of its ability to template the growth of hydroxyapatite, the chief inorganic component of bone mineral matrix, resulting in improved osteointegration. The discussion extends to the role of inorganic ions such as Si and Ca as matrix components in combination with silk to influence bone regrowth. The effect of ions or growth factor-loaded vehicle incorporation into regenerative matrix, nanotopography is also considered.

Biomineralization of a titanium-modified hydroxyapatite semiconductor on conductive wool fibers

Metal ions are frequently incorporated into crystalline materials to improve their electrochemical properties and to confer new physicochemical properties. Naturally-occurring phosphate apatite, which is formed geologically and in biomineralization processes, has extensive potential applications and is therefore an attractive functional material. In this study, we generate a novel building block for flexible optoelectronics using bio-inspired methods to deposit a layer of photoactive titanium-modified hydroxyapatite (TiHA) nanoparticles (NPs) on conductive polypyrrole(PPy)-coated wool yarns. The titanium concentration in the reaction solution was varied between 8-50 mol% with respect to the phosphorous, which led to titanate ions replacing phosphate in the hydroxyapatite lattice at levels up to 17 mol%. PPy was separately deposited on wool yarns by oxidative polymerization, using two dopants: (i) anthraquinone-2,6-disulfonic acid to increase the conductivity of the PPy layer and (ii) pyroglutamic acid, to reduce the resistivity of the wool yarns and to promote the heterogeneous nucleation of the TiHA NPs. A specific titanium concentration (25 mol% wrt P) was used to endow the TiHA NPs on the PPy-coated fibers with a desirable band gap value of 3.68 eV, and a specific surface area of 146 m² g^-1. This is the first time that a thin film of a wide-band gap semiconductor has been deposited on natural fibers to create a fiber-based building block that can be used to manufacture flexible electronic devices.

In situ protein-templated porous protein-hydroxylapatite nanocomposite microspheres for pH-dependent sustained anticancer drug release

Silk sericin, a water-soluble glue-like protein, is extensively used as a biomaterial due to its biocompatibility, hydrophilicity, biodegradability, and adequate resource. In addition, hydroxyapatite-based drug carriers are functionally efficient for drug or gene delivery due to their biodegradability, biocompatibility and easy metabolism in vivo. Herein, for the first time, this study used sericin, from a wild silkworm called Antheraea pernyi (A. pernyi), as a template to nucleate hydroxylapatite (HAp) nano-needles and form porous sericin-HAp nanocomposite microspheres as an anticancer drug carrier. Specifically, A. pernyi sericin (AS) was incubated in 1.5× simulated body fluid to induce the formation of porous AS/HAp microspheres in situ. Doxorubicin (DOX) loading and release assays proved that the microspheres exhibited pH-dependent controlled and sustained release of DOX. In particular, the microspheres can selectively release DOX at a higher rate at the acidic conditions typical for tumor microenvironment than at the physiological conditions typical for normal tissues, which will potentially reduce the side effect of the cancer drugs in normal tissues. Cancer cell toxicity assay, cancer cell imaging and intracellular DOX distribution assay provided further evidence to support the pH-dependent controlled and sustained release of DOX to cancer cells from the microspheres. Our work has demonstrated a biomimetic strategy for the design and synthesis of silk protein-based drug carriers that can be potentially employed in drug delivery and regenerative medicine.