A multifaceted coating for hard tissue implants, with favorable osteogenesis, angiogenesis, and osteoimmunomodulation abilities, would be of great value since it could improve osseointegration and ...alleviate prosthesis loosening. However, to date there are few coatings that fully satisfy these criteria. Herein we describe a microporous TiO2 coating decorated with hydroxyapatite (HA) nanoparticles that is generated by micro-arc oxidation of pure titanium (Ti) and followed annealing. By altering the annealing temperature, it is possible to simultaneously tune the coating's physical (morphology and wettability) and chemical (composites and crystallinity) properties. A coating produced with micro-arc oxidization (MAO) with an annealing temperature of 650 °C (MAO-650) exhibits numerous favorable physicochemical properties, such as hybrid micro-nano morphology, superhydrophilicity, and highly crystalline HA nanoparticles. In vitro experiments reveal that the MAO-650 coating not only supports proliferation and differentiation of both osteoblasts and endothelial cells, but also inhibits the inflammatory response of macrophages and enables a favorable osteoimmunomodulation to facilitate osteo/angio-genesis. In vivo evaluation mirrors these results, and shows that the MAO-650 coating results in ameliorative osseointegration when compared with the pristine MAO coating. These data highlight the profound effect of surface physicochemical properties on the regulation of osteo/angio-genesis and osteoimmunomodulation in the enhancement of osseointegration.
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Polyether-ether-ketone (PEEK) is clinically used as a bio-implant for the healing of skeletal defects. However, the osseointegration of clinical-sized bone grafts remains limited. In this study, ...surface-porous PEEK was created by using a sulfonation method and a metal-polysaccharide complex MgCS was introduced on the surface of sulfonated PEEK to form MgCS@SPEEK. The as-prepared MgCS@SPEEK was found to have a porous surface with good hydrophilicity and bioactivity. This was followed by an investigation into whether MgCS loaded onto sulfonated PEEK surfaces could promote osseointegration and angiogenesis. The in vitro results showed that MgCS@SPEEK had a positive effect on reducing the expression levels of inflammatory genes and promoting osteogenesis and angiogenesis-related genes expression levels. Furthermore, porous MgCS@SPEEK was implanted in critical-sized rat tibial defects for in vivo evaluation of osseointegration. The micro-computed tomography evaluation results revealed substantial bone formation at 4 and 8 weeks. Collectively, these findings indicate that MgCS@SPEEK could provide improved osseointegration and an attractive strategy for orthopaedic applications.
Hydrogen is considered as one of the most important clean and renewable energy sources for a sustainable energy future. However, its efficient and cost-effective purification still remains ...challenging. In this work, we report the development of novel zeolite@metal–organic framework (MOF) composites comprised of MOF-74 and zeolite-5A with core–shell structure for efficient purification of H2. The composites were synthesized hydrothermally through the addition of zeolite particles with and without carboxyl functional groups to the MOF synthesis solution. The zeolite/MOF weight ratio was varied systematically to find the optimum composition based on the adsorption performance. The formation of zeolite@MOF composites was confirmed by various characterization techniques. Single-component adsorption isotherms of CO2, CO, CH4, N2, and H2 over composites were measured at 25 °C to determine their equilibrium adsorption capacity. It was found that the zeolite-5A@MOF-74 with weight ratio of 5:95 exhibited a similar morphology to that of pristine MOF-74, but with higher surface area and total pore volume. Moreover, this composite showed 20–30% increase in CO2, CO, CH4, and N2 uptake than the bare MOF, which could be attributed to the formation of new mesopores at the MOF–zeolite interface. The estimated selectivity values for CO2/H2, CO/H2, CH4/H2, and N2/H2 were higher than those of the zeolite and/or MOF. Our results also indicated that surface modification of zeolite prior to composite formation does not enhance the adsorption capacities of the composites. Overall, the findings of this study suggest that the zeolite-5A@MOF-74 composites with core–shell structure are promising candidates for industrial H2 purification processes.
Nanoparticle-based therapies are found to be effective due to the unique mechanisms-of-action to engineered nanoparticles. These nanoparticles are programmed to be target specific and they can hold ...drugs along with imaging agents for simultaneous diagnostic and therapeutic purposes. They are making their way into the clinical realm. In this work we propose to develop Cadmium sulphide (CdS) nanoparticles with reduced toxicity that could function as a theranostic nanoparticle for bio- imaging applications. The work focuses on the toxicological investigation of surface modified cadmium sulphide nanoparticles. Uncoated and Chitosan coated CdS nanoparticles were synthesized by wet chemical method. The physico-chemical properties of the nanoparticles were characterized by X-ray diffraction, UV–Vis absorption, Fourier transform infrared, photoluminescence, X-ray photoelectron spectroscopy, dynamic light scattering, zeta potential and transmission electron microscopy. MTT assay was performed for toxicity profiling of the synthesized CdS nanoparticles in Human Jurkat cell and erythrocytes cell lines. The results showed a significant reduction in toxicity when the CdS nanoparticles surface was modified with Chitosan. Flow cytometer studies were performed to assess the incorporation of the synthesized nanoparticles into the cells. Photoluminescence studies showed that the surface modified CdS nanoparticles retained their fluorescence intensity regardless of their surface modification with Chitosan. Chitosan modified surface of the nanoparticles served as an effective barricade against the degradation of cadmium core. Surface modification with Chitosan, reduced the toxicity of cadmium sulphide nanoparticles retaining their fluorescent property in the cells. Thus by intentionally attaching bio-conjugates can be efficiently used for drug delivery to target specific cells as well as enable the imaging for cells.
•Chitosan coating preserves the integrity and stability of the CdS NPs.•Surface modification with chitosan showed a significant reduction in the toxicity of CdS NPs.•Chitosan modified surface served as an effective safeguard against the degradation of cadmium ions.•Chitosan coated CdS NPs can serve as an effective theranostics probe for bio-imaging.
Photocatalytic water splitting is a promising strategy to convert solar energy into chemical energy. Herein, a series of g-C3N4/polydopamine (g-C3N4/PDA) composites were successfully fabricated by in ...situ polymerization of dopamine on the g-C3N4 surface. Among all the as-prepared composites, the best photocatalytic hydrogen evolution rate of the as-prepared composites was up to 69 μmol h–1 under the irradiation of visible light (λ > 420 nm), which was about 4.5 times than that of pristine g-C3N4 (16 μmol h–1). The enhancement of photocatalytic H2 evolution is reasonably attributed to the markedly enhanced light harvesting, broadened spectral response range and low onset potential of H2 production, as well as effective separation and rapid transportation of photogenerated charge carriers. More importantly, the surface modification of g-C3N4 by a small amount of PDA can effectively inhibit the overgrowth of Pt nanoparticles (NPs) during the photocatalytic reactions, which promotes the photoelectron injection and better photocatalytic activity. This work should provide a new insight into preparing metal-free polymer–polymer composites with effective solar energy conversion.
Presented are the synthesis, characterizations, and reactive surface modification (RSM) of a novel nine atomic layered V4C3T
x MXene. With the advantages of the multilayered V4C3T
x MXene that can ...simultaneously support the RSM reaction and keep the inner skeleton stable, a series of amorphous Ni/Fe/V‐ternary oxide hydroxides thin layer can be successfully modified on the surface of the V4C3T
x MXene (denoted as MOOH @V4C3T
x, M = Ni, Fe, and V) without disrupting its original structure. Attributed to the in situ reconstruction of highly active oxide hydroxide layer, the nanohybrids exhibited an enhanced oxygen evolution reaction (OER) activity and excellent long‐time stability over 70 hours. In particular, a current density of 10 mA cm−2 can be reached by the nanohybrid with the optimized Ni/Fe ratio at an overpotential (η) as low as 275.2 mV, which is comparable to most of the state‐of‐the‐art OER catalysts and better than other MXene‐based derivatives. Demonstrated by the tunable physicochemical properties and excellent structural stability of these nanohybrids, we may envision the promising role of the M4X3‐based MXenes as substrates for a wide range of energy conversion and storage materials.
Presented are the novel nine atomic layered V4C3T
x MXene and its ternary metal oxide hydroxides modified derivatives (denoted as MOOH@V4C3T
x, M = Ni, Fe, and V). The nanohybrids present good OER activity and excellent long‐time stability, which demonstrates the promising future of multilayered M4X3 MXenes as substrates for the reactive synthesis of advanced energy conversion and storage materials.
Cellulose is a linear biopolymer which is composed of nanofibrils, thus having a large surface area. This low-cost, low-density, high-specific-surface-area, easily processable polymer is found in ...nature in the form of plants, bacteria and tunicates. Cellulose has outstanding characteristics including low cytotoxicity, biocompatibility, good mechanical properties, high chemical stability, and cost effectiveness which make them suitable candidates for biomedical applications. The manipulation of cellulose at nanoscale resulted in nanocellulose having exceptional physicochemical properties. Therefore, cellulose nanocomposite is a fascinating area of research which has applications in biomedical fields like wound healing, bone tissue engineering, three dimensional printing, drug carriers, medical implants etc. This review is mainly focused on the developments in the generation of cellulose nanocomposites and their potential applications in the biomedical field.
Surface nanocrystallization together with compressive residual stresses can significantly improve the mechanical properties of metallic materials. An innovative surface process called ...magnetic-assisted ultrasonic nanocrystal surface modification (MA-UNSM) is reported here. By coupling integrates magnetoplasticity and shocking-induced plasticity, the MA-UNSM can enhance the plastic deformation capability of materials without significantly increasing the USNM processing temperature, thus realizing more effective grain refinement, deeper plastic-affected depth and higher-magnitude residual stresses, as evidenced by microscopic characterization and mechanical measurements. Our results demonstrated that the magnetic field improves the plasticity of the material by reducing the resistance between dislocations and pinning obstacles and thus enhances the effectiveness of ultrasonic peening treatment. Magnetic field with two intensities (0.25 T and 0.6 T) were used to assist UNSM, and the results showed that 0.6 T was the better condition.
•MA-UNSM demonstrates superior processing efficiency over UNSM.•Magnetic field improved Ti64 alloy plasticity, revealed by hardness tests.•Magnetic field improves plasticity by reducing dislocation depinning resistance.
The dispersibility of silica sol particles modified by γ-methacryloxy propyl trimethoxyl silane (γ-MPS) in an ethanol–water mixed solvent was investigated. In the modification process, the ...hydrolysate of γ-MPS condensed to form oligomers, which further formed hydrogen bonds with the hydroxyl groups on the surface of the silica sol particles to cause agglomeration. Increasing the ethanol concentration inhibited the hydrolysis of γ-MPS and the formation of oligomers, thus inhibiting the agglomeration of silica sol particles. When the ethanol concentration was above 74 wt%, the γ-MPS-modified silica sol slurry was transparent and with a TEM image in a single-particle dispersed state. The dispersibility of the silica sol particles was determined by a double electric layer repulsion mechanism before modification and a steric hindrance mechanism by organic molecules grafted on the surface of the particles after modification. The grafting density of γ-MPS on the surface of silica sol particles affected the hydrophobicity of the modified particles, which can be effectively controlled.
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•High ethanol concentration facilitates high dispersibility of particles.•High ethanol concentration inhibits γ-MPS hydrolysis and particle agglomeration.•Modified particles are single-particle dispersed by steric-hindrance.•Particle hydrophobicity has a positive correlation with γ-MPS grafting density.
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