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In recent years, the incidence of bone defects has been increasing year by year. Bone transplantation has become the most needed surgery after a blood transfusion and shows a rising trend. Three-dimensional-printed implants can be arbitrarily shaped according to the defects of tissues and organs to achieve perfect morphological repair, opening a new way for non-traumatic repair and functional reconstruction. In this paper, strontium-doped mineralized collagen was first prepared by an in vitro biomimetic mineralization method and then polylactic acid was homogeneously blended with the mineralized collagen to produce a comprehensive bone repair scaffold by a gas extrusion 3D printing method. Characterization through scanning electron microscopy, X-ray diffraction, and mechanical testing revealed that the strontium-functionalized composite scaffold exhibits an inorganic composition and nanostructure akin to those of human bone tissue. The scaffold possesses uniformly distributed and interconnected pores, with a compressive strength reaching 21.04 MPa. The strontium doping in the mineralized collagen improved the biocompatibility of the scaffold and inhibited the differentiation of osteoclasts to promote bone regeneration. This innovative composite scaffold holds significant promise in the field of bone tissue engineering, providing a forward-thinking solution for prospective bone injury repair. [ABSTRACT FROM AUTHOR]

The use of AgNO3-polyvinyl alcohol (PVA) ink and oxygen plasma to form conductive coatings on plastic substrates was studied. It was found that oxygen plasma can decompose silver complexes to form metallic silver without high-temperature heating. The AgNO3-PVA ratio and plasma parameters (time, power) were optimized to obtain uniform conductive coatings. The morphology and electrical characteristics of the coatings were evaluated. Composite coatings with high reflectivity and good adhesion were prepared with a resistivity of 1.66 × 10−6 Ω·m using MOD inks with a silver ion mass fraction of 5%, after 300 W plasma treatment of the PET substrate for 2 min (the chamber temperature was 37.3 °C). These results demonstrate the potential feasibility of silver MOD inks and oxygen plasma treatment for the production of silver connectors, electromagnetic shielding films, and antimicrobial coatings on low-cost plastic substrates. [ABSTRACT FROM AUTHOR]

A simple and novel method for the deposition of polypyrrole (PPy) and cellulose nanocrystal (CNC) composites on different fiber substrates by reactive ink-jet printing was proposed. PPy/CNCs composites were successfully prepared, and the surface resistance of conductive layer deposited on different fiber substrates is the least when the monomer concentration is 0.6 M. PPy/CNCs were deposited on polyethylene terephthalate (PET) to form a conductive layer by adding polyvinyl alcohol (PVA), and the optimum sintering temperature is 100 °C (monomer/PVA ratio 4.0, conductivity 0.769 S cm−1). The PPy/CNCs conductive layer deposited on the paper has the lowest surface resistance and the best adhesion, and the surface resistance of PPy/CNCs conductive layer decreases first and then increases with the increase of sulfonate concentration. Moreover, the volume of anion in sulfonate will affect the arrangement and aggregation of PPy molecular chain in composite materials. Appropriate sulfonate doping can improve the conductivity and stability of conductive paper, and the maximum conductivity is 0.813 S cm−1. Three devices based on PPy/CNCs conductive paper were proposed and fabricated. Therefore, this ink-jet printing provides a new method for the preparation of conductive materials, sensors, energy storage and electromagnetic shielding, etc. [ABSTRACT FROM AUTHOR]

A polymer network with a memory effect based on a polymer-stabilized narrow-bandwidth cholesteric liquid crystal (CLC) was prepared using the washing-out/refill method. The effects of different polymerization conditions on the reflection properties of CLC films were investigated. Meanwhile, the selective reflection property and narrow-bandwidth reflection memory effect of the polymer network were proved, and the response mechanism was provided. Furthermore, different materials from liquid crystals, with an anisotropic refractive index, to toluene, with an isotropic refractive index, were refilled to polymer scaffolds with helical structures, which originated from the periodic arrangement of CLCs. It was confirmed that the reflection bandwidth of these films can be dramatically narrowed by the reduced birefringence (Δn) of the refilled materials. The narrowest bandwidth of 22.5 nm refilling toluene with an isotropic refractive index (Δn = 0) was obtained. These results may provide a novel idea for flexible reflective displays, color filters, printing, and colored cladding of a variety of objects. [ABSTRACT FROM AUTHOR]

Flexible sensors play an important role in collecting stimuli information and sending them to a central processing unit or cloud for analysis and decision‐making. As much information is needed to be collected, the fabrication of multiparameter flexible sensors is becoming increasingly urgent. To this end, conducting polymer‐based composites have been proven as promising materials for developing pressure‐temperature dual‐parameter sensors. However, fabrication of ideal dual‐parameter sensors with fully decoupled pressure‐temperature readings, good sensitivity, and a simple preparation process remain challenges. Here, a strategy of fabricating a pressure‐temperature dual‐parameter sensor based on conformal printing of conducting polymer poly(3,4‐ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) on the surface of microstructured polydimethylsiloxane (PDMS) substrate is demonstrated. It is found that secondary doped PEDOT:PSS provides temperature‐independent conductivity. Combined with the sea‐island microstructured PDMS substrate, a screen‐printed flexible sensor demonstrates fully decoupled pressure‐temperature reading ability, competitive sensitivity, and good stability. The excellent sensing properties of the devices, with a maximum pressure sensitivity of 134.25 kPa−1 and linear response region over 300 kPa as well as highly sensitive temperature sensing for finger touch, together with their unique advantages of low‐cost and large‐area fabrication, make the printed flexible dual‐parameter sensors promising applications in electric‐skin (e‐skin), human‐machine interaction, and robotics. [ABSTRACT FROM AUTHOR]

Herein, a simple approach for the fabrication of luminous self-assembled fibers based on halogen-bonded azopyridine complexes and oleic acid-modified quantum dots (QDs) is reported. The QDs uniformly align on the edge of the self-assembled fibers through the formation of van der Waals force between the alkyl chain of oleic acid on the QD surface and the alkyl chain of the halogen-bonded complexes, 15Br or 15I. Furthermore, the intermolecular interaction mechanism was elucidated by using Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, and density functional theory (DFT) calculations. This approach results in retention of the fluorescence properties of the QDs in the fibers. In addition, the bromine-bonded fibers can be assembled into tailored directional fibers upon evaporation of the solvent (tetrahydrofuran) when using capillaries via the capillary force. Interestingly, the mesogenic properties of the halogen-bonded complexes are preserved in the easily prepared halogen-bonded fluorescent fibers; this provides new insight into the design of functional self-assembly materials. [ABSTRACT FROM AUTHOR]

On this basis, a novel recombinant human‐like collagen (RHLC)/silk fibroin scaffold material with high porosity and controllable aperture was prepared. The compatibility of osteoblasts (OB) with the blends was tested in vitro. The morphology, adhesion and growth of scaffold cells were observed by scanning electron microscope and laser confocal microscope. Extensive measurements, including 3‐[4, 5‐dimethylthiazole‐2‐acyl]‐2, 5‐diphenyl tetrabrominate assays, intracellular total protein content, and alkaline phosphatase activity assays were performed after 7 days of culture. Survival and protein content increased in RHLC/fibroin stents. LSCM and SEM results confirmed that the cells grew better in the mixed scaffolds than in the pure silk scaffolds, and showed that the cells were easy to adhere and diffuse in the RHLC/silk scaffolds. RHLC/silk fibroin scaffolds are promising biomaterials for bone tissue engineering. [ABSTRACT FROM AUTHOR]

Surface‐modified thermally expandable microcapsules (TEMs) hold potential for applications in various fields. In this work, we discussed the possible surface coating mechanism and reported the properties of TEMs coated with polyaniline (PANI) and polydisperse graphene oxide sheets (ionic liquid‐graphene oxide hybrid nanomaterial (ILs‐GO)). The surface coating of PANI/ ILs‐GO increased the corresponding particle size and its distribution range. The morphologies analyzed by scanning electron microscopy indicated that no interfacial gap was observed between the microspheres ink and substrate layer during the substrate application. The thermal properties were determined by thermogravimetric and differential thermal analyses. The addition of ILs‐GO to the polyaniline coating significantly improved the thermal expansion and thermal conductivity of the microcapsules. The evaporation of hexane present in the core of TEMs was not prevented by the coating of PANI/ ILs‐GO. The printing application of TEMs showed excellent adaptability to various flexible substrates with great 3D appearance. By incorporating a flame retardant agent into TEMs coated by PANI/ILs‐GO, finally, these TEMs also demonstrated a great flame retardant ability. We expect that these TEM‐coated PANI/ ILs‐GO are likely to have the potential to improve the functional properties for various applications. [ABSTRACT FROM AUTHOR]

The specific roles of solvents in the synthesis of meso‐tetraphenylporphyrin (TPP) using a classical mixed‐solvent of acetic acid, propionic acid, and nitrobenzene are unclear to date. In this work, we explored the acid‐activation process between benzaldehyde and pyrrole using DFT calculations. The catalytic role of carboxylic acids was proven by the formation of a carbocation intermediate. Moreover, the oxidation behavior of nitrobenzene or its analogs was studied by UV/Vis spectroscopy. In particular, the formation of the corresponding amides derived from the reduction of nitrobenzene and its analogs directly confirmed their oxidation behaviors. Specifically, yields of up to 38% of TPP can be obtained from nominally pure to quite pure using the mixed‐solvent method with meta‐nitrotoluene as the oxidant. Hand in hand: The acid activation of carboxylic acids and oxidation behavior of nitrobenzene or its analogs in tetraphenylporphyrin (TPP) synthesis using a mixed‐solvent method were confirmed by computational calculations and experimental characterizations, respectively. [ABSTRACT FROM AUTHOR]

Halogen bonding interactions in the formation of liquid crystalline phases have been recognised in recent years. Here, we report a novel series of iodine-bonded liquid crystals using 1,2-diiodotetrafluorobenzene (1,2-DITFB) and azopyridine derivatives (AnAzPy), showing a smectic A phase and concurrent photoresponsive behaviour. These were characterised by using a polarising optical microscope, differential scanning calorimetry and UV-vis absorption spectroscopy. The formation of iodine bonding in the complexes was confirmed by X-ray photoelectron spectroscopy and Raman spectroscopy. Importantly, these iodine-bonded complexes demonstrated a low liquid crystal temperature range (30-50°C) among those reported for photoresponsive halogen-bonded liquid crystals. The molar ratio of the iodine-bonded donor and acceptor was 1:1 upon the self-assembly of the supramolecular complex molecule, as indicated by 1D-WAXD experiments of mixed samples of 1,2-DITFB and AnAzPy with different molar ratios. This study offers a new family of photoresponsive halogen-bonded liquid crystals and broadens the potential applications in their associated systems. [ABSTRACT FROM AUTHOR]

Abstract: Three‐arm star azopyridinium salts self‐organize into various morphologies in water/organic mixed solvents. Interesting AIE and self‐assembling features are observed due to the strong interaction of the azopyridinium moieties with the highly polar H2O molecules causing the salts to aggregate, which restricts the molecular motion and induces the fluorescence. [ABSTRACT FROM AUTHOR]

A novel recombinant human-like collagen/fibroin scaffold has been prepared previously, which has high porosity, controllable pore size, and much better mechanical properties than the reported fibroin-based scaffold. In this research, the cell responses of vascular smooth muscle cells to this blend scaffold were examined in vitro. Cell morphology, adherence, and growth in scaffolds were observed by scanning electron microscopy, laser scanning confocal microscopy after staining of the cells with propidium iodide at 1, 3, 5, and 7 days, respectively. A wide range of measurements, including 3-[4,5–dimethylthiazol-2-yl]-2, 5-diphenyl tetrasodium bromide assay, and total intracellular protein content at the end of 7 days culture, were conducted. An increase of viability and protein content of vascular smooth muscle cells cultured in recombinant human-like collagen/fibroin scaffold was found. The laser scanning confocal microscopy and scanning electron microscopy results confirm that the cells readily adhered and proliferation in the blend than in fibroin scaffold, and indicate a better adhesion process. The positive effects were especially significant for vascular smooth muscle cells. The recombinant human-like collagen/fibroin scaffold could be a promising biomaterial for vascular tissue engineering. [ABSTRACT FROM AUTHOR]

A thorough research of the optical properties of ZnO/Ag structures sputtered by RF on PS colloidal crystal molds with different diameters is reported. The influences of the period of the substrates on the performance of ZnO thin films were studied. The results of scanning electron microscopic, X-ray diffraction patterns and UV–vis absorption spectroscopy indicated that the ZnO/Ag thin films were well-covering on PS colloidal crystal molds. The diameter of the polystyrene particles significantly influenced the PL spectrum intensity of ZnO/Ag by affecting the interferences of light. After adding PS colloidal crystal molds with different diameters, all the samples show two luminescent regions, namely a strong, narrow UV emission peak and a wide, weak visible emission band. However, the signal of UV emission increases more significantly. In particular, the maximum enhancement occurs when the diameter is 300 nm. This work proposes an effective way to improve ZnO light emission based on a simple, rapid and cost effective method to fabricate ordered periodic substrates by preparing single layer polystyrene microspheres masks. [ABSTRACT FROM PUBLISHER]

The temperature dependency and reversibility of the sheet resistance of silver nanoparticles covered by 3-mercaptopropionic acid (Ag-MPA) molecules, used in the printed temperature sensor, has been investigated. The microstructural evaluation, the FTIR spectra and thermal property analyses of the Ag-MPA films suggest co-existence of both weakly adsorbed as well as firmly adsorbed MPA molecules on the surface of Ag nanoparticles. The weakly adsorbed MPA molecules was to a great extent be desorbed and removed from the surfaces of silver nanoparticles when heated up to 180 °C for the first time. While the firmly adsorbed MPA molecules remain on the surfaces of silver nanoparticles even at higher temperature. Yet the firmly adsorbed MPA molecules are likely having gone through a transformation circle from/to the gauche and trans conformations in correspondence to a heating and cooling cycle, which results in temperature dependent and reversible sheet resistance. The MPA molecules in the gauche conformation are more densely packed on the surface of silver nanoparticles and can hinder the electron's movability within the Ag-MPA film. While in the trans conformation with lower 'surface space' coverage by the MPA molecules, electrons move more freely within the film. Based on the temperature dependent nature, the fully printed temperature sensor using the Ag-MPA nanoparticles as the functional layer was made, of which the highest sensitivity is 5.12% °C at 200 °C. [ABSTRACT FROM AUTHOR]

The reversible photoisomerization of azobenzenes has been extensively studied to construct systems with optical responsiveness; however, this process limits the luminescence of these compounds. Recently, there have been many efforts to design and synthesize fluorescent azobenzene compounds, such as inhibition of electron transfer, inducing aggregation, and metal-enhancement, which make the materials ideal for application in fluorescence probes, light-emitting devices, molecular detection, etc. Herein, we review the recently reported progress in the development of various fluorescent azobenzenes and summarize the possible mechanism of their fluorescence emission. The potential applications of these materials are also discussed. Finally, in order to guide research in this field, the existing problems and future development prospects are discussed. [ABSTRACT FROM AUTHOR]

Metalloporphyrins have attracted great attention in the potential application of biomimetic catalysis. Especially, they were widely investigated as green catalysts in the chemical oxidation of various hydrocarbons through the catalytic activation of molecular oxygen. The structural properties of active central metal ions were reported to play a decisive role in catalytic activity. However, those delicate structural changes are difficult to be experimentally captured or elucidated in detail. Herein, we explored the electronic structural properties of metalloporphyrins (metal porphyrin (PMII, PMIIICl)) and their corresponding catalytically active intermediates (metal(III)-peroxo(PMIII-O2), metal(III)-hydroperoxo(PMIII-OH), and metal(IV)-oxo(PMIV=O), (M=Fe, Mn, and Co)) through the density functional theory method. The ground states of these intermediates were determined based on the assessment of relative energy and the corresponding geometric structures of ground states also further confirmed the stability of energy. Furthermore, our analyses of Mulliken charges and frontier molecular orbitals revealed the potential catalytic behavior of reactive metalloporphyrin intermediates. [ABSTRACT FROM AUTHOR]

Flexible pressure sensors have attracted tremendous attention from researchers for their widely applications in tactile artificial intelligence, electric skin, disease diagnosis, and healthcare monitoring. Obtaining flexible pressure sensors with high sensitivity in a low cost and convenient way remains a huge challenge. In this paper, the composite dielectric layer based on the mixture of carbon nanotubes (CNTs) with different aspect ratios and polydimethylsiloxane (PDMS) was employed in flexible capacitive pressure sensor to increase its sensitivity. In addition, the screen printing instead of traditional etching based methods was used to prepare the electrodes array of the sensor. The results showed that the aspect ratio and weight fraction of the CNTs play an important role in improving the sensitivity of the printed capacitive pressure sensor. The prepared capacitive sensor with the CNTs/PDMS composite dielectric layer demonstrated a maximum sensitivity of 2.9 kPa−1 in the pressure range of 0–450 Pa, by using the CNTs with an aspect ratio of 1250–3750 and the weight fraction of 3.75%. The mechanism study revealed that the increase of the sensitivity of the pressure sensor should be attributed to the relative permittivity increase of the composite dielectric layer under pressure. Meanwhile, the printed 3 × 3 and 10 × 10 sensor arrays showed excellent spatial resolution and uniformity when they were applied to measure the pressure distribution. For further applications, the flexible pressure sensor was integrated on an adhesive bandage to detect the finger bending, as well as used to create Morse code by knocking the sensor to change their capacitance curves. The printed and flexible pressure sensor in this study might be a good candidate for the development of tactile artificial intelligence, intelligent medical diagnosis systems and wearable electronics. [ABSTRACT FROM AUTHOR]

Silicon oxynitride (SiNxOy) is a highly promising functional material for its luminescence performance and tunable refractive index, which has wide applications in optical devices, non-volatile memory, barrier layer, and scratch-resistant coatings. This review presents recent developments, and discusses the preparation methods, performance, and applications of SiNxOy film. In particular, the preparation of SiNxOy film by chemical vapor deposition, physical vapor deposition, and oxynitridation is elaborated in details. [ABSTRACT FROM AUTHOR]

Patterning technology on the paper based on wettability difference for paper‐based devices has attracted significant attention for its low cost, easy degradability, and high flexibility. Here, conductive lines are rapidly prepared by patterned wettability‐assisted bar‐coating for low cost paper‐based circuits. It is found that 7 s plasma treatment time for acquiring wettability difference is optimal, which resulted in not only effective splitting of the liquid film but also highly consistent line width with mask. Moreover, low retention force of hydrophobic surface is imperative for self‐confinement of the ink into hydrophilic areas, especially for ink with high solid content. The sheet resistance of patterns can reach 5 Ω ◻−1 after 980 nm laser sintering when using 50 wt% solid content ink with 110 cP viscosity. The geometries of line patterns, i.e., line width and spacing, can be readily tuned by varying the designed size of mask patterns. As‐prepared conductive patterns show good conductivity even after 500 bending cycles at 2 mm bending radius. It is believed that this study will provide deeper understanding of wettability difference‐assisted patterning process and represents a general strategy for selective wetting, especially for high viscosity ink. [ABSTRACT FROM AUTHOR]

Flexible transparent conductive electrodes (TCEs) are widely applied in flexible electronic devices. Among these electrodes, silver (Ag) nanowires (NWs) have gained considerable interests due to their excellent electrical and optical performances. Ag NWs with a one-dimensional nanostructure have unique characteristics from those of bulk Ag. In past 10 years, researchers have proposed various synthesis methods of Ag NWs, such as ultraviolet irradiation, template method, polyol method, etc. These methods are discussed and summarized in this review, and we conclude that the advantages of the polyol method are the most obvious. This review also provides a more comprehensive description of the polyol method for the synthesis of Ag NWs, and the synthetic factors including AgNO3 concentration, addition of other metal salts and polyvinyl pyrrolidone are thoroughly elaborated. Furthermore, several problems in the fabrication of Ag NWs-based TCEs and related devices are reviewed. The prospects for applications of Ag NWs-based TCE in solar cells, electroluminescence, electrochromic devices, flexible energy storage equipment, thin-film heaters and stretchable devices are discussed and summarized in detail. [ABSTRACT FROM AUTHOR]