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This review is intended to provide an overview of the design and fabrication of ionic liquid-based ionic electroactive polymer (IL-iEAP) transducers for advanced applications in biological and electronic fields. The iEAP is a class of smart materials that can perform sensing or actuating functions by controlling the movement of cations and anions in the active layer. This type of material can deform under low voltage stimulation and generate electrical signals when undergoing mechanical deformation because of ion redistribution. Numerous research attention has been focused on studying the deformation mechanisms and the potential for actuation, sensing, and energy harvesting applications. Compared to the traditional water-based iEAP, the non-volatile IL-iEAP delivers a wider electrochemical window and a more stable actuation performance. In this paper, the classification of iEAP with different actuation mechanisms is first outlined, followed by introducing various preparation methods including nanotechnology for IL-iEAPs, and discussing the key factors governing their actuation performance. In addition, the advanced functions of IL-iEAP in actuating and sensing, especially self-sensing in bionics and electromechanical equipment applications, are reviewed. Finally, novel nanotechnologies used for fabricating IL-iEAPs and the prospects of their microelectromechanical system (MEMS) applications are discussed.

UV protection and coatings for plastics are important in many applications. The cladding of low microwave (MW) absorption composite coatings on high MW transparent plastic substrates is a challenge due to their disparate dielectric properties. Moreover, an uneven heat energy conversion within the composite creates an additional hurdle in producing a coating with good surface integrity. In this study, a protocol was developed to overcome these difficulties based on a hybrid approach. The adverse effect of temperature mismatch between the coating and substrate was reduced through a two-way susceptor-aided heating mechanism. Low MW absorbing sol–gel derived composite coatings consisting of silicon dioxide (SiO2) and titanium dioxide (TiO2) were successfully cladded on the surface of MW and visual light transparent polycarbonate to produce a clear protective coating with UV-resistance. Nanoindentation tests were conducted to assess the effectiveness of the proposed protocol. Significant enhancement in the surface elastic modulus and hardness were achieved.

Nowadays, energy and the environment have become critical issues for determining the sustainability of the Earth. Freshwater crises, as an increasingly serious global problem, pose a great threat to our economies, the environment and us. Solar-driven evaporation has emerged as a promising and sustainable approach to convert solar energy into clean water. In fact, the production of freshwater is not only governed by heat generation at the interface, but the process also relies on the coordination and cooperation of functional modules in the solar-driven evaporation system. This review begins with system designs of solar evaporators, considering thermal manipulation structures, water transportation pathways, and vapour condensation modules, which focus on improving the overall energy utilization, long-term usability, and freshwater yield. This is followed by a summary and discussions of cutting-edge solar evaporation applications and their underlying mechanisms. Finally, existing challenges and potential solutions for future applications are discussed and provided. This review aims to provide useful guidelines and references to scientists and researchers for the future development of clean water generation systems.

Diamondoids are cage-like hydrocarbon materials with unique characteristics such as low dielectric constants, negative electron affinity, large steric bulk, and electron-donating ability. They are widely used for advanced functional materials in nanocomposite science. Surface modification of diamondoids also produces functional derivatives that broaden its applications. This article provides a concise review of the fundamentals of diamondoids, including their origin and functionalization, electronic structure, optical properties, and vibrational characteristics. The recent advances of diamondoids and their derivatives in applications, such as nanocomposites and thin film coatings, are presented. The fabrication of diamondoid-based nanostructured devices, including electron emitters, catalyst sensors, and light-emitting diodes, are also reviewed. Finally, the future developments of this unique class of hydrocarbon materials in producing a novel nanostructure system using advanced nanotechnologies are discussed. This review is intended to provide a basic understanding of diamondoid properties, discuss the recent progress of its modifications and functionalization, and highlight its novel applications and future prospects.

Electroactive hydrogels have received increasing attention due to the possibility of being used in biomimetics, such as for soft robotics and artificial muscles. However, the applications are hindered by the poor mechanical properties and slow response time. To address these issues, in this study, supramolecular ionic polymer–carbon nanotube (SIPC) composite hydrogels were fabricated via in situ free radical polymerization. The polymer matrix consisted of carbon nanotubes (CNTs), styrene sulfonic sodium (SSNa), β-cyclodextrin (β-CD)-grafted acrylamide, and ferrocene (Fc)-grafted acrylamide, with the incorporation of SSNa serving as the ionic source. On applying an external voltage, the ions accumulate on one side of the matrix, leading to localized swelling and bending of the structure. Therefore, a controllable and reversible actuation can be achieved by changing the applied voltage. The tensile strength of the SIPC was improved by over 300%, from 12 to 49 kPa, due to the reinforcement effect of the CNTs and the supramolecular host–guest interactions between the β-CD and Fc moieties. The inclusion of CNTs not only improved the tensile properties but also enhanced the ion mobility, which lead to a faster electromechanical response. The presented electro-responsive composite hydrogel shows a high potential for the development of robotic devices and soft smart components for sensing and actuating applications.

Four-dimensional (4D) printable light-powered materials have emerged as a new generation of materials for the development of functional devices. The design of these types of materials is mostly based on the trans-cis transformation of azobenzene moieties in a liquid crystalline elastomer (LCE) matrix, in which the motion is triggered by ultraviolet (UV) irradiation. In this paper, we first report on a direct laser printable photoresist for producing light-powered 4D structures with enhanced mechanical properties and near-infrared (NIR) responsive mechanical deformation. The reported nanocomposite design is based on the photothermal effects of gold nanorods (AuNRs), which can induce the nematic-to-isotropic transition of LCE upon exposure to NIR irradiation. The miscibility between AuNRs and LCE is enhanced by thiol functionalization. Appropriate printing parameters are determined, and nanocomposites containing 0-3 wt % of AuNR loading are fabricated via femtosecond two-photon direct laser writing. The effects of the AuNR loading fraction and laser power on the light-powered actuating performance are evaluated. It is found that the nanocomposite with AuNR loading of 3 wt % demonstrates the maximum percentage (20%) of elongation under an NIR laser power of 2 W. An increase in laser power can lead to faster deformation but slower restoration. The nanocomposites demonstrate relatively good stability. Even after 300 actuation cycles, 80% of the elongation magnitude can be retained. In addition, an improvement of 80% in the complex modulus of the nanocomposites, due to the inclusion of AuNRs, is observed.

A thermal and photo dual-responsive drug delivery system is newly designed for controlled anticancer drug delivery. The concept of this design is to encapsulate upconversion nanoparticles in a phot...

Consumer grade supercapacitors as power supply resources require outstanding electrode materials with large conductivity, high durability and retention rates, as well as large capacity. Graphene is a promising functional material as an electrical double layer capacitance electrode due to its large surface area, high chemical stability and moderate conductivity. However, the existing graphene synthesis methods, including CVD and chemical exfoliation, are limited to lab scale production. Although laser induced graphene has demonstrated outstanding performance as an electrode material for microsupercapacitors, its difficulty to attach to the metallic current collector limits its application as a large capacity electrode material. Herein, laser induced forward transfer of graphene is developed for additively depositing laser induced graphene onto nickel foam as a composite electrode. The laser annealing enhanced the lattice matching between the extended Basal plane of graphene and Ni (111) resulting in its high electrical conductivity (359 712 S m−1), high retention rate (over 98% capacitance retention after 10 000 cycles), and large areal specific capacitance (995 mF cm−2) and power density (9.39 mW cm−2). The assembled supercapacitors with these additively printed electrodes can work as a USB charger with a stable 5 V output voltage, for charging smart phones and other smart devices.

Poly[2-( tert-butylaminoethyl) methacrylate] (PTA), an important class of antimicrobial polymers, has demonstrated its great biocidal efficiency, favorable nontoxicity, and versatile applicability. To further enhance its antimicrobial efficiency, an optimization of the chemical structure of PTA polymers is performed via atom transfer radical polymerization (ATRP) in terms of the antimicrobial ability against Escherichia coli ( E. coli) and Staphylococcus aureus ( S. aureus). After the optimization, the resulting PTA is blended into a polylactide (PLA) matrix to form PTA/PLA composite thin films. It is first found, that the antimicrobial efficiency of PTA/PLA composites was significantly enhanced by controlling the PLA crystallinity and the PLA spherulite size. A possible mechanistic route regarding this new finding has been rationally discussed. Lastly, the cytotoxicity and mechanical properties of a PTA/PLA composite thin film exhibiting the best biocidal effect are evaluated for assessing its potential as a new material for creating antimicrobial biomedical devices.

Wearable sensing technologies are vital for realizing personalized health monitoring. Noninvasive human sweat sampling is essential for monitoring an individual's physical state using rich physiological data. However, existing wearable sensing technologies lack the controlled capture of body sweat and in performing on-device measurement without inflammatory contact. Herein, we report the development of a wearable sweat-capture device using patterned graphene arrays with controlled superwettability and electrical conductivity for simultaneously capturing and electrochemically measuring sweat droplets. The sweat droplets exhibited strong attachment on the superhydrophilic graphene patterns, even during moderate exercising. The captured sweat droplets present strong electrochemical signals using graphene films as the working electrode and metal pins as the counter electrode arrays assembled on 3D printed holders, at the detection limit of 6 μM for H2O2 sensing. This research enables full-body spatiotemporal mapping of sweat, which is beneficial for a broad range of personalized monitoring applications, such as drug abuse detection, athletics performance optimization, and physiological wellness tracking.

Powder metallurgy and rapid microwave (MW) sintering techniques were successfully applied to engineer a hybrid cell structure into magnesium alloy AZ61 syntactic foams. The hybrid cell structure, comprising open- and closed-cells, originated from leached carbamide granules and hollow microspheres of fly ash (HS), respectively. External MW susceptors accelerated the sintering process and greatly mitigated the formation of undesirable interfacial reactions. The cell hybridisation technique facilitated control over the density and strength of the syntactic foams. Accordingly, floatable syntactic foams with a density of about 0.79 g/cm3 and compressive strength of 16 MPa were synthesised without recourse to any surface modification or chemically-induced superhydrophobicity. The processing techniques were capable of mitigating damage to the HS microspheres as confirmed by microstructural examinations. Furthermore, potential applications of the floatable syntactic foam sample, as a microboat and chemical release agent, were demonstrated by using ethanol as a propellant. AZ61 syntactic foams synthesised in this study exhibited low density and adequate strength, suggesting their applicability as alternative materials to polymer composite foams. Keywords: Magnesium alloy, Powder metallurgy, Microwave sintering, Mechanical properties, Syntactic foam, Hybrid cells

Near infrared to ultraviolet (NIR-to-UV) up-conversion nanocomposites, composed of an upconversion nanoparticle (UCNP) core and a transformable polyspiropyran shell, were prepared by distillation precipitation polymerization and the template method. The polyspiropyran shell can undergo reversible hydrophoblic-hydrophilic transformations through the switching of UV and visible light and by variation of pH. About 10 wt% of the anticancer drug, doxorubicin (DOX), can be loaded into the drug carrying layer under pH 7.4 by electrostatic force. The NIR and pH responsive features of the polyspiropyran shell were shown by the dynamic light scattering (DLS) results, in which the size of nanocomposites (UCNPs@SP-MA/MAA) became larger under NIR irradiation and pH 4.5. The hydrophobic to hydrophilic surface transformation alters the permittivity of the polyspiropyran shell and the release behavior. The cumulative release rate of the DOX-loaded UCNPs@SP-MA/MAA reached 53.8% under pH 4.5 and NIR irradiation. The cytotoxicity of the bare UCNPs@SP-MA/MAA and the DOX-loaded UCNPs@SP-MA/MAA were evaluated against breast cancer cells and the results confirmed that the toxicity of UCNPs@SP-MA/MAA nanocomposites was minimal, even at high dosage (100 μg/mL), while the toxicity of DOX can be triggered by NIR light.

With the ever-growing demand in fresh water supply, great efforts have been devoted to developing sustainable systems which could generate fresh water continuously. Solar vapor generation is one of the promising strategies which comprise an unlimited energy source and efficient solar-to-heat generators for overcoming fresh water scarcity. However, current solar vapor generation systems suffer either from inefficient utilization of solar energy or an expensive fabrication process. In this paper, we introduced a nano-plasmonic approach, i.e., a floatable nanocompoiste where copper sulfide nanorods (Cu2-xS NRs) are embedded in a polyvinyl alcohol (PVA) matrix, for solar-to-vapor generation. A high solar vapor generation efficiency of ~87% and water evaporation rate of 1.270 kg m&minus, 2 h&minus, 1 were achieved under simulated solar irradiation of 1 sun. With the illumination of natural daylight, seawater was purified using Cu2-xS NRs-PVA gel, with high purity, as distilled drinking water. The plasmonic nanocomposites demonstrated here are easy to fabricate and highly efficient for solar vapor generation, illustrating a potential solution for future seawater desalination.

The present study proposes an efficient processing scheme for fabricating carbon nanotubes (CNTs)-reinforced magnesium (Mg) alloy AZ61 composite foams with enhanced compressive and energy absorption properties. The scheme combines powder metallurgy, rapid microwave (MW) sintering, and pore wall reinforcement to overcome the low strength, non-uniform pore structure, prolonged sintering process, and high production cost associated with conventional unreinforced Mg-based foams. In the proposed scheme, a dual-stage mixing method is used to homogeneously disperse and incorporate CNTs into the matrix for strength enhancement, and susceptor role, and carbamide granules are used to control the pore size and porosity fractions. In addition, MW sintering is used to rapidly consolidate the samples in 20 min through the synergy between an external and an internal susceptor (i.e. CNTs), which facilitates uniform and volumetric heating of the entire samples. Thus, sample oxidation and the formation of deleterious secondary phases are minimised, while up to 69% energy is saved. Experimental results show that the dispersion and incorporation of CNTs into the matrix, via the present processing scheme, clearly enhance the compressive and energy absorption properties of the composite foams, as compared with the unreinforced foams. The proposed processing scheme is a rapid and energy-saving efficient technique, which can be used to fabricate high quality Mg alloy composite foams with improved compression and energy absorption properties.

In this study, dual-responsive polymeric nanocapsules, in which the state (swelling or collapse) can be repeatedly controlled by external stimuli (i.e., temperature and light), have been designed and prepared through distillation–precipitation polymerization. Temperature sensitive monomers of N-isopropylacrylamide are cross-linked by photoresponsive bis(methacryloylamino) onto a silica nanospherical template to form a core–shell (SiO2–PNIPAM/Azo) structure. The silica core is then removed by hydrofluoric acid to produce PNIPAM/Azo nanocapsules (P/ANCs) of diameter ∼238 nm at ∼25 °C. The size of the nanocapsule is temperature responsive and, as such, its diameter could be reduced to ∼182 nm on increasing the temperature to 40 °C. In addition, the permeability of nanocapsules can be adjusted by UV irradiation. The cis–trans transformation of modified azobenzene allowed us to perform both the encapsulation and controlled release of molecules. Rhodamine B (RhB) was successfully encapsulated using the photomec...

Seawater dehydrates humans when it is drunk untreated, due to its high concentrations of salts. Currently, it can only be purified into large amounts of freshwater using reverse osmosis, with large electricity consumption, carbon emissions and environmental damage. Although seawater directly evaporates under natural sunlight, the efficiencies and scales are too small for practical collection. Herein, we report a floating graphene membrane for evaporating seawater into freshwater exclusively using solar energy, with high efficiency and large scalability. Polyimide films can be fully converted to graphene membranes using one-step laser scribing, without involving chemicals or generating wastes. These green desalination graphene membranes evaporate water at a rate up to 1.37 kg m−2 h−1 under one sun illumination, which possesses even higher purity than domestic water. These graphene membranes can float firmly at the air–water interface with a self-righting ability, such that the process is feasible for practical water desalination on ocean surfaces.

Microwave heating is an efficient alternative approach for synthetic chemistry with many distinctive advantages of high heating rate, selective and homogeneous heating. In this study, a new laser-microwave hybridization method, which comprises laser micropatterning, microwave heating and in situ synthesis has been developed to produce titania/hydroxyapatite/tricalcium phosphate (TiO 2 /HA/TCP) composite coating on titanium alloy (Ti6Al4V) substrate. The composite coating with a fine porous network microarchitecture was selectively produced on the Ti6Al4V surface by laser ablation and alkaline treatment. Using TiO 2 sol-gel and mixed powders of calcium carbonate (CaCO 3 ) and dicalcium phosphate dihydrate (CaHPO 4 ·2H 2 O), the composite coating synthesized at a temperature of 800 °C in a short time of 20 min exhibited homogeneous microstructure, strong hydrophilicity and good adhesion strength of 34 MPa. The in vitro apatite-forming capability of the coating was examined by immersing the coated Ti6Al4V specimen into a simulated body fluid (SBF) for up to 7 days. Biodissolution was observed in the early stage of incubation, followed by apatite precipitation. The quantity and size of the apatite globules increased over time. After 7 days of immersion, the coating surface was nearly covered by a layer of bone-like apatite, showing a significant improvement of its osteoconductive property over the uncoated sample. The laser-microwave hybridization provides an efficient route to synthesize HA/TCP based coatings for bioactivity enhancement, and serves as an effective sterilization tool for implant materials.

A near infrared (NIR) and pH dual-responsive nanocomposite, composed of a lanthanide-doped upconversion nanoparticle (UCNP) core and a transformable poly-o-nitrobenzyl shell, was prepared by the distillation precipitation polymerization and template method. The poly-o-nitrobenzyl shell can undergo hydrophobic-hydrophilic transformation upon an irradiation of 980 nm, rendering the capability of NIR-activated drug release. The anticancer drug, doxorubicin (DOX), can be loaded into these nanocomposites with a loading efficiency of 7.23 wt%. Furthermore, pH responsiveness caused by the hydrogen bond and charge interactions between DOX and nanocapsules can trigger the release of drugs at low pH. Under visible light irradiation and neutral (pH 7.4) conditions, the cumulative release of DOX was only 8.35% after 300 min, while it reached 59.5% under the synergistic effect of NIR irradiation and acidic conditions. The Baker-Lonsdale model was used to describe the drug release kinetics of this system, and the diffusion coefficient (3DCs/r02C0) and R2 under different conditions were determined to be 4.15 × 10−6 and 0.98 (pH 7.4 and visible light), 2.64 × 10−5 and 0.99 (NIR light), 3.26 × 10−5 and 0.97 (pH 4.5 and visible light), 2.59 × 10−4 and 0.99 (pH 4.5 and NIR light), respectively. This controlled release feature makes the nanocomposite a promising therapeutic agent for treating diseases.

Pickering emulsion, in which the oil–water emulsion interface is stabilised by colloids, has emerged as a promising approach for the preparation of drug delivery systems in the biomedical field. In this study, Pickering emulsion and solvent evaporation were incorporated with high-intensity ultrasonication to successfully fabricate biodegradable poly(lactic-co-glycolic acid) (PLGA)–chitosan core-shell nanocomposites (PLGA-CS) with a narrow size distribution. Our strategy was based on using aqueous-phase chitosan colloids to stabilise the hydrophobic PLGA core without the addition of molecular surfactants or chemical cross-linkers. The use of high-intensity ultrasonication was found to facilitate the efficient dispersion of emulsion droplets so that the particle size of PLGA-CS (255.1–824.8 nm) could be controlled with the application of different amplitudes. A low amplitude (20% of total power) enables the formation of drug-loaded PLGA-CS with a small diameter (255.1 nm) and a high level of monodispersity (polydispersity index, 0.078). The PLGA core allows hydrophobic drugs to be loaded and is encapsulated in a chitosan shell that offers two functions: (i) dispersion of PLGA in an aqueous solution and (ii) modulation of in vitro drug release. Our results reveal that the modified strategy shows promise for the design and preparation of monodisperse polymer-based drug carriers.

In this paper, a miniature fluidic synthesis platform utilizing millimeter dimension channels for the synthesis of cadmium sulfide (CdS) quantum dots and nanocrystals is demonstrated. Traditional nanoparticle synthesis techniques involve macroscopic flasks where reaction conditions may vary at different positions inside the vessel. Therefore challenges in terms of batch reproducibility for large scale production are of great concern. Here, we show that it is possible to replicate reaction conditions so as to produce nanoparticles with similar optical characteristics across different batches using the same reaction parameters. Particle size control was established by varying the flow rate of the precursors, yielding gradually increasing nanocrystal sizes from 2.4 nm to 3.7 nm with increasing residence time. The as-synthesized CdS nanoparticles exhibited tunable photoluminescence by adjusting the molar ratio of the cadmium and sulfur precursors, giving rise to greenish-blue and orange-red emissions under ultraviolet light illumination. The particles were then studied and characterized using transmission electron microscopy (TEM), ultraviolet-visible (UV-Vis) absorbance, photoluminescence, X-ray diffraction (XRD) and selected area electron diffraction (SAED) techniques. Lastly, bioimaging of RAW264.7 mice macrophage cells using ligand exchanged CdS nanoparticles is presented.

Nickel-titanium (NiTi) shape memory alloy is one of the popular implant materials in orthopaedic applications due to its special mechanical properties. However, the presence of Ni has raised safety concerns and hence limited its applications. In the present study, this issue was addressed through laser diffusion nitriding on NiTi to form TiN coating on the surface. Optimum laser parameters to produce desirable surface without changing the surface topography of NiTi substrate were determined. This paper detailed the nitriding of NiTi by fiber laser for enhancing the hydrophilicity and biological performance. The laser treated surfaces were characterized by scanning-electron microscopy (SEM) and X-ray diffraction (XRD). The wettability and cell viability performance were studied using contact angle measurement and MTT assay. The results demonstrated that an optimized laser treated surface could lead to improvements in biocompatibility of NiTi.

In this study, the effect of the inclusion of nano-hydroxyapatite (nano-HAp) and the porous structure on the shape memory behavior of poly- d - l -lactide (PDLLA) composites was investigated. Porous, thermal-responsive shape memory composites, PDLLA/nano-HAp, were prepared by a newly developed polymer coagulation, particulate leaching, and cold compression moulding technique. The inclusion of nano-HAp to PDLLA led to a higher shape memory transition temperature, improved mechanical strength and larger recovery force as compared with the neat PDLLA. The nanocomposite with 10 wt% of nano-HAp exhibited the best shape fixity and recoverability with the shortest recovery time. Further increase in the filler content of nano-HAp would reduce the recovery force and prolong the recovery time due to restriction in the movement of the amorphous PDLLA chain segments. The morphologies, thermal properties and shape memory behavior were measured by scanning electron microscopy, thermal gravimetric analyzer, differential scanning calorimeter, dynamic mechanical analysis, physical bending test and cyclic thermo-mechanical test. These results provide important information for designing biomedical devices using this novel type of bioabsorbable shape memory polymer composite.

Geopolymers have emerged as a promising alternative to ordinary cement due to their attractive physical and thermal properties. The typical compressive strength of geopolymers and their composites is usually limited to around 80 MPa, therefore they should be further strengthened for wider applications, such as ultrahigh strength concrete and bone replacement. This paper presents a facile method for enhancing the compressive strength by incorporating silicon carbide particles (SiCp) and silicon carbide whiskers (SiCw) into a geopolymer matrix via the geopolymerization of metakaolin (MK). The effects of the reinforcement of SiCp and SiCw on the microstructure, thermal properties and compressive properties of the composites were investigated. The SEM images showed that both SiCp and SiCw were well dispersed in the geopolymer matrix. Due to the bridging effect among the SiCw particles, the silicon carbide whisker/geopolymer (SiCw/GP) composites possessed higher porosity and lower density, and thus lower thermal stability and thermal conductivity as compared with the silicon carbide particle/geopolymer (SiCp/GP). The mechanical tests showed that the compressive strength of SiCp/GP composites increased with the increase of SiCp concentration. With an optimum concentration of 10 wt % of SiCp, the compressive strength of the composite was enhanced to 155 MPa, corresponding to a 100% increase as compared with the unfilled geopolymer.

In the past, plasmonics were always referred to as the collective oscillation of free electrons on metal surfaces such as gold (Au) and silver (Ag). This changed when plasmonic behaviour was experimentally demonstrated in semiconductors, i.e. self-doped copper sulfur, nanocrystals (Cu2−xS NCs) in 2009. In fact, Cu2−xS NC possesses different plasmonic behaviour than Au and Ag, in which the resonant condition is governed by another regime (free holes as the carriers) and its sensing capability has not yet been fully explored. In this contribution, the as-prepared (organic phase) Cu2−xS NCs were transferred in water and were tested with glycerin-water mixtures and anions. The results showed that Cu2−xS NC is very sensitive to the variation of refractive index in the surrounding environment. Furthermore, it was found that the plasmonic properties of these NCs are also very sensitive to the presence of anions. By taking the advantages of this “additional” effect, Cu2−xS NC can be used as a potential su...

Remarkable progress has been made on the use of polymer electrolyte membranes (PEMs) for renewable-energy-related research. In particular, carbon nanotubes (CNTs) have emerged as versatile nanomaterials to modify PEMs. However, the inert ionic conduction ability and possible short-circuiting risk are the two major obstacles to their further development. In this work, CNTs are firstly functionalized with an inorganic proton conductor, boron phosphate (BPO 4 ), using a facile polydopamine-assisted sol-gel method to yield BPO 4 @CNTs. This new additive is then used to modify sulfonated poly(ether ether ketone) (SPEEK). Polydopamine coating layer can act as an extraordinary glue to homogeneously adhere BPO 4 nanoparticles on CNTs, thereby not only reducing the risk of short-circuiting, but also fabricating new proton-conducting pathways in the composite membranes. A comprehensive characterization reveals that the thermal stability, tensile properties, and dimensional stability of PEMs are significantly improved. Compared with pure SPEEK, the proton conductivity of SPEEK/BPO 4 @CNTs-2 is improved by 45% and 150% at 20 °C and at 80 °C, respectively. Furthermore, the H 2 /O 2 cell performance of SPEEK/BPO 4 @CNTs-2 membrane exhibits a peak power density of 340.7 mW cm −2 at 70 °C, which is significantly better than that of pure SPEEK (254.2 mW cm −2 ), demonstrating the great potential of proton conductors-functionalized CNTs in PEMs.

Finite element modelling of a magnesium alloy matrix filled with a 2% volume fraction of carbon nanotubes (CNT) under 2.45 GHz microwave (MW) irradiation is reported. The effective dielectric and permeability data of the simulated compact are evaluated using the effective medium approximation. Subsequently, these values are used to solve Maxwell’s electromagnetic equations followed by the heat conduction equation, thus both the field distribution in the oven cavity and the predicted heating of the model compact are obtained. At an applied power of 1 kW and a 9-minute simulation time, the results show poor coupling between the monolithic metal compact and the MW, resulting in a maximum temperature of ~163 °C. It is in good agreement with earlier studies and theory in which metals did not couple very well with MWs at room temperatures. The model also predicts the temperature in the 2% CNT-filled alloy compact to be 13 °C higher than in the monolithic compact after a similar simulated microwave irradiation duration. Furthermore, the effect of susceptor-assisted microwave heating is investigated by introducing a susceptor kiln into the model. Simulation results predict the temperature of the compact to rise to about 600 °C after 9 minutes, highlighting the importance of susceptor-assisted sintering. The model developed is significant in providing important details for predicting the response of metal compacts and their composites to MW heating as well as further improving the development of MW technology for the production of materials with enhanced properties.

In this study, a powder metallurgy processing technique combined with rapid microwave sintering was used to synthesise carbon nanotubes (CNTs) filled AZ61 magnesium alloy composites under ambient conditions, without recourse to any secondary process. In order to determine the appropriate amount of CNTs for taking full advantage of the AZ61/CNTs composite, a powder mixture of the CNTs, in varying volume fractions of 1–3%, and the AZ61 alloy was prepared through a mechanical milling process. The optimized milling intensity allowed for reducing the powder size for effective microwave absorption, and thus improved the dispersion of the CNTs in the Mg alloy matrix without reducing the structural integrity of CNTs. In addition to the incorporation of the CNTs with the dual role of mechanical reinforcement and microwave susceptor, microwave sintering was achieved in only 8 min by using a synergetic combination of graphite and silicon carbide as microwave susceptors in a microwave furnace. The sintered samples, whose porosity ranged between 4 and 6%, were characterised for microstructural, hardness, compressive and fracture properties. The results of hardness and compression tests indicated that these properties of all the composites were significantly improved compared to the monolithic samples. The highest microhardness value (∼105% increment) was recorded for the composite with 3.0% volume fraction of CNTs, while the composite sample with 1.0% volume fraction of CNTs had the highest ultimate compressive yield strength and 0.2% offset yield strength with approximate increments of 59% and 127%, respectively. The failure mechanisms of the composites as compared with the monolithic samples were discussed.

Heterogeneous nucleation is a frequently encountered phenomenon in the crystallization of inorganic nanoparticle/polymer systems, and has a great influence on the morphology and properties (such as optical, mechanical and degradable properties) of the nanocomposites. In this study, a solution casting method was adopted to fabricate CdSe–ZnS quantum dots (QDs)/poly(lactic acid) (PLA) nanocomposites films of various QDs concentrations by using chloroform as the solvent. Fourier transform infrared (FT-IR) spectroscopy, polarized optical microscopy (POM), differential scanning calorimetry (DSC), and X-ray diffractometry (XRD) were used to characterize the crystallization behavior of the nanocomposites films that had been thermally treated differently from the as-cast state. The FT-IR and POM results showed that the nucleation density and the crystallization ability of PLA are greatly enhanced with addition of the QDs in the processes of isothermal crystallization at 403 K. The results of DSC revealed that the glass transition temperature of PLA has no obvious change with the addition of QDs. For the QDs/PLA samples which were isothermally annealed at 403 K for 30 min, the degree of (melt) crystallinity increased with increase of QD concentrations in the PLA matrix. All the results obtained from FT-IR spectroscopy, POM, DSC, and XRD were consistent, suggesting that the CdSe–ZnS QDs can serve as an efficient heterogeneous nucleating agent for the acceleration and enhancement of the melt crystallization of PLA at the optimized condition.

Optical imaging techniques are becoming increasingly urgent for the early detection and monitoring the progression of tumor development. However, tumor vasculature imaging has so far been largely unexplored because of the lack of suitable optical probes. In this study, we demonstrated the preparation of near-infrared (NIR) florescent RGD peptide probes for noninvasive imaging of tumor vasculature during tumor angiogenesis. The peptide optical probes combined the advantages of NIR emission and RGD peptide, which possesses minimal biological absorption and specially targets the integrin, which highly expressed on activated tumor endothelial cells. In vivo optical imaging of nude mice bearing pancreatic tumor showed that systemically delivered NIR probes enabled us to visualize the tumors at 24 hours post-injection. In addition, we have performed in vivo toxicity study on the prepared fluorescent RGD peptide probes formulation. The blood test results and histological analysis demonstrated that no obvious toxicity was found for the mice treated with RGD peptide probes for two weeks. These studies suggest that the NIR fluorescent peptide probes can be further designed and employed for ultrasensitive fluorescence imaging of angiogenic tumor vasculature, as well as imaging of other pathophysiological processes accompanied by activation of endothelial cells. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 910–916, 2016.

First-line therapy of chronic myelogenous leukemia (CML) has always involved the use of BCR-ABL tyrosine-kinase inhibitors which is associated with an abnormal chromosome called Philadelphia chromosome. Although the overall survival rate has been improved by the current therapeutic regime, the presence of resistance has resulted in limited efficacy. In this study, an RNA interference (RNAi)-based therapeutic regime is proposed with the aim to knockdown the BCR-ABL hybrid oncogene using small interfering RNA (siRNA). The siRNA transfection rates have usually been limited due to the declining contact probability among polyplexes and the non-adherent nature of leukemic cells. Our work aims at addressing this limitation by using a biodegradable charged polyester-based vector (BCPV) as a nanocarrier for the delivery of BCR-ABL-specific siRNA to the suspension culture of a K562 CML cell line. BCR-ABL siRNAs were encapsulated in the BCPVs by electrostatic force. Cell internalization was facilitated by the BCPV and assessed by confocal microscopy and flow cytometry. The regulation of the BCR-ABL level in K562 cells as a result of RNAi was analyzed by real-time polymerase chain reaction (RT-PCR). We observed that BCPV was able to form stable nanoplexes with siRNA molecules, even in the presence of fetal bovine serum (FBS), and successfully assisted in vitro siRNA transfection in the non-adherent K562 cells. As a consequence of downregulation of BCR-ABL, BCPV-siRNA nanoplexes inhibited cell proliferation and promoted cell apoptosis. All results were compared with a commercial transfection reagent, Lipofectamine2000™, which served as a positive control. More importantly, this class of non-viral vector exhibits biodegradable features and negligible cytotoxicity, thus providing a versatile platform to deliver siRNA to non-adherent leukemia cells with high transfection efficiency by effectively overcoming extra- and intra-cellular barriers. Due to the excellent in vitro transfection results from BCPV-siRNA, a newly developed biodegradable transfection agent, BCPV, is being probed for transfection performance in an animal model.

Stretchable conductive hydrogels have received significant attention due to their possibility of being utilized in wearable electronics and healthcare devices. In this work, a semi-interpenetrating polymer network (SIPN) strategy was employed to fabricate a set of flexible, stretchable and conductive composite hydrogels composed of polyvinyl alcohol (PVA) in the presence of glutaraldehyde as the crosslinker, HCl as the catalyst and poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS) as the conductive medium. The results from FTIR, Raman, SEM and TGA indicate that a chemical crosslinking network and interactions of PVA and PEDOT:PSS exist in the SIPN hydrogels. The swelling ratio of hydrogels decreased with increasing content of PEDOT:PSS. Due to the chemical crosslinking network and interactions of PVA and PEDOT:PSS, PVA networks semi-interpenetrated with PEDOT:PSS exhibited excellent tensile and compression properties. The tensile strength and elongation at breakage of the composite hydrogels with 0.14 wt% PEDOT:PSS were 70 KPa and 239%, respectively. The compression stress of the composite hydrogels with 0.14 wt% PEDOT:PSS at a strain of 50% was about 216 KPa. The electrical conductivity of the hydrogels increased with increasing PEDOT:PSS content. The flexible, stretchable and conductive properties endow the composite hydrogel sensor with a superior gauge factor of up to 4.4 (strain: 100%). Coupling the strain sensing capability to the flexibility, good mechanical properties and high electrical conductivity, we consider that the designed PVA/PEDOT:PSS composite hydrogels have promising applications in wearable devices, such as flexible electronic skin and sensitive strain sensors.

Poly-D-L-lactide/nano-hydroxyapatite (PDLLA/nano-HA) can be used as the biological scaffold material in bone tissue engineering as it can be readily made into a porous composite material with excellent performance. However, constitutive modeling for the mechanical response of porous PDLLA/nano-HA under various stress conditions has been very limited so far. In this work, four types of fundamental compressible hyper-elastic constitutive models were introduced for constitutive modeling and investigation of mechanical behaviors of porous PDLLA/nano-HA. Moreover, the unitary expressions of Cauchy stress tensor have been derived for the PDLLA/nano-HA under uniaxial compression (or stretch), biaxial compression (or stretch), pure shear and simple shear load by using the theory of continuum mechanics. The theoretical results determined from the approach based on the Ogden compressible hyper-elastic constitutive model were in good agreement with the experimental data from the uniaxial compression tests. Furthermore, this approach can also be used to predict the mechanical behaviors of the porous PDLLA/nano-HA material under the biaxial compression (or stretch), pure shear and simple shear.

In this paper, a new method for synthesizing non-aqueous copper sulfide nanocrystals with different shapes and sizes using a homemade continuous-flow millifluidic chip is presented. Conventionally, the shape control of nanocrystals was accomplished using a surfactant-controlled approach, where directional growth is facilitated by selective passivation of a particular facet of the nanocrystals using surfactants. We demonstrate a "surfactant-free" approach where different sizes and shapes (i.e. spherical, triangular prism and rod) of plasmonic copper sulfide (Cu(2-x)S) nanocrystals can be fabricated by adjusting the flow rate and precursor concentrations. As continuous-flow synthesis enables uniform heating and easy variation of precursors' stoichiometries, it serves as an excellent incubation platform for nanoparticles due to its simplicity and high reproducibility. Transmission electron microscopy (TEM), fast Fourier transform (FFT) and X-ray diffraction (XRD) techniques were used to characterize the as-synthesized nanocrystals and revealed structures ranging from copper-deficient covellite (CuS), spionkopite (Cu1.39S), roxbyite (Cu1.75S), to copper-rich djurleite (Cu1.94S). The localized surface plasmon resonance (LSPR) peak of the nanocrystals can be tuned from 1115 to 1644 nm by simply varying the copper to sulfur molar ratio and flow rate. Furthermore, photothermal effects of Cu(2-x)S nanocrystals were also demonstrated to annihilate the RAW264.7 cells upon near infra-red laser irradiation.

Theranostic platform integrating diagnostic imaging and therapeutic function into a single system has become a new direction of nanoparticle research. In the process of treatment, therapeutic efficacy is monitored. The use of theranostic nanoparticle can add an additional "layer" to keep track on the therapeutic agent such as the pharmacokinetics and biodistribution. In this report, we have developed quantum rod (QR) based formulations for the delivery of small interfering RNAs (siRNAs) to human neuronal cells. PEGlyated QRs with different surface functional groups (amine and maleimide) were designed for selectively down-regulating the dopaminergic signaling pathway which is associated with the drug abuse behavior. We have demonstrated that the DARPP-32 siRNAs were successfully delivered to dopaminergic neuronal (DAN) cells which led to drastic knockdown of specific gene expression by both the electrostatic and covalent bond conjugation regimes. The PEGlyated surface offered high biocompatibilities and negligible cytotoxicities to the QR formulations that may facilitate the in vivo applications of these nanoparticles. Published Version

In this work, a surfactant-free emulsion polymerization method was utilized to synthesize poly(styrene-ran-methyl acrylate) (PSMA) at a styrene/(methyl acrylate) mole ratio of 75/25 with the aim to compatibilize high impact polystyrene (HIPS)/poly(lactic acid) (PLA) interface. HIPS/PLA blends with different PSMA contents were prepared. Their phase morphologies, mechanical properties, and rheological and crystallization behaviors were investigated using scanning electron microscopy, tensile tests, rotational rheometry, and differential scanning calorimetry. The rheological results showed that the complex viscosity, storage moduli, and loss moduli of PLA/HIPS blends were enhanced with increasing PSMA content. A decrease in the degree of crystallinity of PLA in PLA/HIPS blends with the addition of PSMA was observed in the differential scanning calorimetry results. It was also revealed that the addition of a small amount of PSMA can effectively improve the compatibility and thus the interfacial adhesion of the PLA/HIPS blends, thereby reducing the size of the HIPS dispersion phase. When 1 wt % of PSMA was used, compared with the PLA/HIPS blends without PSMA, the tensile strength and notched Charpy impact strength of PLA/HIPS blends were improved by 95.3% and 104.8%, respectively. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 135, 45799.

Well-defined chitosan nanocapsules (CSNCs) with tunable sizes were synthesized through the interfacial cross-linking of N-maleoyl-functionalized chitosan (MCS) in miniemulsions, and their application in the delivery of doxorubicin (Dox) was investigated. MCS was prepared by the amidation reaction of CS with maleic anhydride in water/DMSO at 65 °C for 20 h. Subsequently, thiol-ene cross-linking was conducted in oil-in-water miniemulsions at room temperature under UV irradiation for 1 h, using MCS as both a surfactant and precursor polymer, 1,4-butanediol bis(3-mercapto-propionate) as a cross-linker, and D-α-tocopheryl poly(ethylene glycol) 1000 succinate as a cosurfactant. With the increase in cosurfactant concentration in the reaction systems, the sizes of the resulting CSNCs decreased steadily. Dox-loaded CSNCs were readily prepared by in situ encapsulation of Dox during miniemulsion cross-linking. With acid-labile β-thiopropionate cross-linkages, the Dox-loaded CSNCs demonstrated a faster release rate under acidic conditions. Relative to free Dox, Dox-loaded CSNCs exhibited enhanced cytotoxicity toward MCF-7 breast cancer cells without any noticeable cytotoxicity from empty CSNCs. The effective delivery of Dox to MCF-7 breast cancer cells via Dox-loaded CSNCs was also observed.

Nanoprobes with multiple imaging modality have attracted a great deal of attention due to the capability of offering complementary information from each individual component. This work presents a hybrid approach to synthesize manganese doped near infrared (NIR) emitting quantum dots. The Mn-doping process was accomplished in aqueous phase followed by a phase transfer to organic phase for ZnS coating. This bimodal nanoprobe displayed high NIR luminescence quantum yield (~14%) and capability of magnetic resonance imaging (MRI) (1.44 mMsup-1/supssup-1/sup). The RGD-targeted nanoprobes have been exploited for in vitro cell labelling, in vivo tumor targeting and lymph node mapping. In addition, no adverse toxic effects were observed, demonstrating the high biocompatibility of this nanoprobe.