Three-dimensional (3D) printing by material extrusion is being widely explored to prepare patient-specific scaffolds from biodegradable polyesters such as poly(lactic acid) (PLA). Although they ...provide the desired mechanical support, PLA scaffolds lack bioactivity to promote bone regeneration. The aim of this work was to develop a surface engineering approach for enhancing the osteogenic activity of 3D printed PLA scaffolds. Macro-porous PLA scaffolds were prepared by material extrusion with 70.2% porosity. Polyethyleneimine was chemically conjugated to the alkali-treated PLA scaffolds followed by conjugation of citric acid. These polymer-grafted scaffolds were immersed in the simulated body fluid to yield scaffolds coated with calcium-deficient hydroxyapatite (PLA-HaP). Surface roughness and water wettability were enhanced after surface modification. PLA-HaP scaffolds exhibited a steady release of calcium ions in an aqueous medium for 10 days. The adhesion and proliferation of human mesenchymal stem cells (hMSCs) on PLA-HaP was ~50% higher than on PLA. Mineral deposition resulting from hMSC osteogenesis on PLA-HaP scaffolds was nearly twice that on PLA scaffolds. This was corroborated by the increase in alkaline phosphatase activity and expression of several osteogenic genes. Thus, this work presents a surface modification strategy to enhance the bioactivity of 3D printed scaffolds for bone tissue regeneration.
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•3D printed scaffolds of poly(lactic acid) with 70% porosity were prepared by materials extrusion.•Scaffold surface was modified by grafting polyethyleneimine and citric acid followed by deposition of calcium phosphate.•Scaffolds released calcium ions and exhibited enhanced roughness and water wettability after surface modification.•Adhesion and proliferation of mesenchymal stem cells increased by 50% after surface modification.•Enhanced stem cell osteogenesis on the surface modified scaffolds resulted in doubling of the mineralization.
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Various oils discharged from daily life and industrial production, as well as frequent oil spillages, have led to severe water pollution and ecological problems. Mussel-inspired ...polydopamine has been widely applied for fabrication of superhydrophobic materials for oil/water separation. However, the need of additional nanoparticles via tedious steps to construct nanostructures, and the high cost of dopamine itself limit its practical applications. Moreover, the application modes of superhydrophobic materials for oil/water separation are monotonous, which will limit the applied range of the superhydrophobic materials. For example, superhydrophobic sponge was usually used for adsorbing oil droplets or oil spills from water, while superhydrophobic fabric or mesh was usually used for separating bulk layered oil/water mixture. Therefore, developing simple and low-cost mussel-inspired surface modification strategy toward superhydrophobic materials, as well as diverse application modes for oil/water separation, is still highly desired. In this study, superhydrophobic sponge and fabric with nanostructures, which exhibits excellent performance for diverse oil/water separation, have been fabricated through a novel one-step and cost-effective mussel-inspired approach. The resultant superhydrophobic sponge exhibits outstanding oil absorption capability (weight gains up to 8860%), while the superhydrophobic fabric can effectively separate oil/water mixture. Moreover, diverse modes for oil/water separation have been developed for the first time. For example, water-in-oil emulsion can be highly-efficient separated by a compressed superhydrophobic sponge (~1800L m-2h−1 bar−1 for water-in-oil emulsion, and above 99% rejection rate for water droplets), while crude oil spills can be efficiently collected by a superhydrophobic boat (above 98%).
Surface adsorption behavior and electron transfer determine the catalytic activity in hydrogen evolution reaction (HER). However, the inevitable surface oxidation of NbC hinders electron transfer and ...hydrogen conversion. The surface adsorption behavior and electron transfer of NbC are optimized by doping Cu+ as well as modifying the orbital hybridizations. Benefiting from the introduced electron interaction of Cu+, the lower p-d hybridization between Nb and O reduces the Nb-O bond and affords the Cu-NbC thinner surface oxidation layer. The reduced surface oxidation degree favors electron transfer. Further, the electron orbital hybridization modulates the electron states and optimizes the hydrogen adsorption behavior of Cu-NbC for efficient hydrogen conversion. As the electrochemical results, the obtained Cu-NbC demands 271 mV to drive 10 mA cm−2, which is 50 times higher than that of NbC (only 0.2 mA cm−2 at the same overpotential). Hence, we believe the orbital hybridization manipulation strategy renders a valuable solution for designing efficient HER catalysts.
A orbital hybridization engineering for boosting the HER kinetics by doping Cu+ in NbC is first proposed. The orbital hybridization engineering optimizes the electron structure of Cu-NbC, reducing the surface oxidation layer and optimizing the hydrogen adsorption strength. Then thus, the boosting electron transfer and intermediates conversion promote the HER kinetic. This work paves a new way for rationally designing efficient catalysts for alkaline HER. Display omitted
•Cu+ is doped into NbC by a one-pot molten salt method.•Introduced electron interaction of Cu+ modify p-d hybridization between Nb and O.•The reducing surface oxidation degree favors the electron transfer.•Orbital hybridization engineering optimizes the electron state at Fermi Level.•Efficient electron transfer and optimized adsorption behavior boost the reaction kinetics.
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•Design of a biofunctionalization approach for the fabrication of 3D-printed immunosensors.•Development of the 3D-printed COVID-19 immunosensor with electronic readout.•Determination ...of the COVID-19 recombinant protein via competitive immunoassay.•Feasibility of 3D-printed electronic devices to aid with the COVID-19 pandemic.
3D printing technology has brought light in the fight against the COVID-19 global pandemic event through the decentralized and on-demand manufacture of different personal protective equipment and medical devices. Nonetheless, since this technology is still in an early stage, the use of 3D-printed electronic devices for antigen test developments is almost an unexplored field. Herein, a robust and general bottom-up biofunctionalization approach via surface engineering is reported aiming at providing the bases for the fabrication of the first 3D-printed COVID-19 immunosensor prototype with electronic readout. The 3D-printed COVID-19 immunosensor was constructed by covalently anchoring the COVID-19 recombinant protein on a 3D-printed graphene-based nanocomposite electrode surface. The electrical readout relies on impedimetrically monitoring changes at the electrode/electrolyte interface after interacting with the monoclonal COVID-19 antibody via competitive assay, fact that hinders the redox conversion of a benchmark redox marker. Overall, the developed 3D-printed system exhibits promising electroanalytical capabilities in both buffered and human serum samples, displaying an excellent linear response with a detection limit at trace levels (0.5 ± 0.1 μg·mL−1). Such achievements demonstrate advantage of light-of-speed distribution of 3D printing datafiles with localized point-of-care low-cost printing and bioelectronic devices to help contain the spread of emerging infectious diseases such as COVID-19. This technology is applicable to any post-COVID-19 SARS diseases.
Laser-textured surfaces enabling reversible wettability switching and improved optical properties are gaining importance in cutting-edge applications, including self-cleaning interfaces, tunable ...optical lenses, microfluidics, and lab-on-chip systems. Fabrication of such surfaces by combining nanosecond-laser texturing and low-temperature annealing of titanium Ti-6Al-4V alloy was demonstrated by Lian et al. in ACS Appl. Mater. Inter. 2020, 12 (5), 6573–6580. However, it is difficult to agree with (i) their contradictory explanation of the wettability transition due to low-temperature annealing and (ii) their theoretical description of the optical behavior of the laser-textured titanium surface. This comment provides an alternative viewsupported by both experimental results and theoretical investigationon how the results by Lian et al. could be interpreted more correctly. The annealing experiments clarify that controlled contamination is crucial in obtaining consistent surface wettability alterations after low-temperature annealing. Annealing of laser-textured titanium at 100 °C in contaminated and contaminant-free furnaces leads to completely different wettability transitions. Analysis of the surface chemistry by XPS and ToF-SIMS reveals that (usually overlooked) contamination with hydrophobic polydimethylsiloxane (PDMS) may arise from the silicone components of the furnace. In this case, a homogeneous thin PDMS film over the entire surface results in water repellency (contact angle of 161° and roll-off angle of 15°). In contrast, annealing under the same conditions but in a contaminant-free furnace preserves the initial superhydrophilicity, whereas the annealing at 350 °C turns the hydrophobicity “off”. The theoretical calculations of optical properties demonstrate that the laser-induced oxide layer formed during the laser texturing significantly influences the surface optical behavior. Consequently, the interference of light reflected by the air–oxide and the oxide–metal interfaces should not be neglected and enables several advanced approaches to exploit such optical properties.
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•Ultrathin sulfated NiFe-LDH nanosheets were synthesized.•High-valence Ni and Fe sites were present on the surface of sulfated NiFe-LDH nanosheets.•High-valence Fe promoted an O-O ...coupling on Ni sites at low overpotential.•Sulfated NiFe-LDH nanosheets exhibited excellent OER activity and high stability.
High-valence Ni and Fe metal sites have demonstrated a crucial role in enhancing the catalytic performances of NiFe-LDH electrocatalysts in oxygen evolution reaction (OER). Although considerable OER catalytic performances achieved under high overpotential, the catalytic talent of NiFe-LDH electrocatalysts at low overpotential is rarely realized due to the absence of high-valence Ni and Fe sites. We herein report a surface engineering route to fabricate sulfated NiFe-LDH nanosheets via ion exchange strategy in sulfate-rich media. XPS results reveal a modified surface electronic structure with high-valence Ni and Fe after ion exchange reaction. Computational PDOS results suggest that computed d-band centers (εd) of Fe and Ni for sulfated NiFe-LDH show a significant downward shift resulting an increased valence of metal cation with orbital volume shrinkage. The high-valence Fe can facilitate a optimized multi-electron process of Ni center from NiII-OH−/NiIII-OH− to NiIV-OOH rather than NiII/NiIII to NiIV at low overpotential. The high-valence Ni can serve as the highly active center for O-O coupling during OER process. Combined with the synergetic action of high-valence Fe and Ni, the sulfated NiFe-LDH nanosheets exhibit much larger reaction kinetics and outstanding electrocatalytic activity on glassy carbon electrode (η10 = 219 mV, η50 = 288 mV) with a remarkable long-term stability.
Wind turbine performance can be significantly reduced when the surface integrity of the turbine blades is compromised. Many frontier high-energy regions that are sought for wind farm development ...including Nordic, warm-humid, and desert-like environments often provide conditions detrimental to the surface of the turbine blade. In Nordic climates ice can form on the blades and the turbine structure itself through a variety of mechanisms. Initial ice adhesion may slightly modify the original aerodynamic profile of the blade; continued ice accretion can drastically affect the structural loading of the entire rotor leading to potentially dangerous situations. In warmer climates, a humid wind is desirable for its increased density; however, it can come at a price when the region supports large populations of insects. Insect collisions with the blades can foul blade surfaces leading to a marked increase in skin drag, reducing power production by as much as 50%. Finally, in more arid regions where there is no threat from ice or insects, high winds can carry soil particles eroded from the ground (abrasive particles). Particulate-laden winds effectively sand-blast the blade surfaces, and disrupt the original skin profile of the blade, again reducing its aerodynamic efficiency. While these problems are challenging, some mitigative measures presently exist and are discussed in the paper. Though, many of the current solutions to ice or insect fouling actually siphon power from the turbine itself to operate, or require that the turbine be stopped, in either case, profitability is diminished. Our survey of this topic in the course of our research suggests that a desirable solution may be a single surface engineered coating that reduces the incidence of ice adhesion, insect fouling, and protects the blade surface from erosive deterioration. Research directions that may lead to such a development are discussed herein.
All-inorganic perovskites nanostructures, such as CsPbCl3 nanocrystals (NCs), are promising in many applications including light-emitting diodes, photovoltaics, and photodetectors. Despite the ...impressive performance that was demonstrated, a critical issue remains due to the instability of the perovskites in ambient. Herein, we report a method of passivating crystalline CsPbCl3 NC surfaces with 3-mercaptopropionic acid (MPA), and superior ambient stability is achieved. The printing of these colloidal NCs on the channel of graphene field-effect transistors (GFETs) on solid Si/SiO2 and flexible polyethylene terephthalate substrates was carried out to obtain CsPbCl3 NCs/GFET heterojunction photodetectors for flexible and visible-blind ultraviolet detection at wavelength below 400 nm. Besides ambient stability, the additional benefits of passivating surface charge trapping by the defects on CsPbCl3 NCs and facilitating high-efficiency charge transfer between the CsPbCl3 NCs and graphene were provided by MPA. Extraordinary optoelectronic performance was obtained on the CsPbCl3 NCs/graphene devices including a high ultraviolet responsivity exceeding 106 A/W, a high detectivity of 2 × 1013 Jones, a fast photoresponse time of 0.3 s, and ambient stability with less than 10% degradation of photoresponse after 2400 h. This result demonstrates the crucial importance of the perovskite NC surface passivation not only to the performance but also to the stability of the perovskite optoelectronic devices.
Securing an affordable and environmentally friendly fuel source is a pressing global need. Hydrogen gas, renowned for being carbon-free and derived from water, stands as an abundant and low-cost ...energy resource. Efficient water electrolysis hinges upon selecting economical yet effective electrocatalysts. In this context, copper-based chalcogenides have garnered attention for driving water electrolysis. This report presents a newly developed electrocatalyst: copper sulfide (CuS) supported silver indium selenide-nickel foam (AgInSe2–NF) composites, characterized by a diverse array of morphologies. The optimized CuS@15%AgInS2 electrocatalyst showcased superior performance when related to electrocatalysts based on noble metals and metal sulfides which were reported previously. CuS@15%AgInSe2–NF nanocomposite exhibits significant potential in water oxidation, revealing a marked reduction in overpotential: 289 mV at a benchmark current density of 10 mA cm−2 for OER and 85 mV for HER. This heightened efficiency is accredited to various exceptional elements associated with design of nanocomposite, which offers abundant reactive sites and ion transfer pathways within its structure. Furthermore, this design fortifies structural integrity and conductivity of CuS@15%AgInSe2 heterostructure. Additionally, synergistic interplay between AgInSe2 and CuS enhances electron transport and augments electrocatalytic properties. Notably, electrocatalyst exhibits exceptional stability, consistently producing hydrogen gas for over 25 h. These findings not only highlight potential of CuS@15%AgInSe2 for a multitude of OER and HER applications but also underscore effectiveness of material hybridization as a straightforward yet potent method to enhance the electrochemical performance of an electrode.
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