No abstract

MXenes with metallic conductivity, high pseudo-capacitance and 2D structure, are promising flexible electrode materials for supercapacitors, but suffer from the restacking issue, which hinders ion accessibility and causes sluggish ion kinetics. Herein, a simple in situ ice template strategy is proposed to fabricate free-standing, flexible 3D porous Ti 3 C 2 T x /carbon nanotubes (CNTs) film (3D-PMCF) by freeze-drying Ti 3 C 2 T x-based hydro-films without any postprocessing. During the freeze-drying process, small ice grains are in situ transformed from the residual water molecules in the Ti 3 C 2 T x interlayer and then act as a self-sacrifice template to construct a 3D porous network. CNTs introduced in the hydro-film increase the amount of interlayer water and the resultant porosity. The 3D structure of Ti 3 C 2 T x significantly increases the exposed surface active sites and accelerates the ion transport, meanwhile maintaining good flexibility. Consequently, the flexible 3D-PMCF film delivers a capacitance of 375 F g −1 at 5 mV s −1 and retains 251.2 F g −1 at 1000 mV s −1 with excellent cycling stability, much superior to the conventional densely stacked Ti 3 C 2 T x film. Being assembled into a symmetric supercapacitor, an energy density of 9.2 Wh kg −1 is realized. This work demonstrates a simple and efficient route for constructing high-performance and flexible 3D MXene film electrodes for supercapacitors.

Nitrogen-rich carbon with interconnected mesoporous structure has been simply prepared via a nano-CaCO3 template method, using polyaniline as carbon and nitrogen precursors. The preparation process includes in situ polymerization of aniline in a nano-CaCO3 aqueous solution, carbonization of the composites and removal of the template with diluted hydrochloric acid. Nitrogen sorption shows the carbon-enriched mesopores with a specific surface area of 113 m(2) g(-1). The X-ray photoelectron spectroscopy (XPS) analysis indicates that the carbon has a high nitrogen content of 7.78 at. %, in the forms of pyridinic and pyrrolic, as well as graphitic nitrogen. The nitrogen-rich mesoporous carbon shows a high reversible capacity of 338 mAh g(-1) at a current density of 30 mA g(-1), and good rate performance as well as ultralong cycling durability (110.7 mAh g(-1) at a current density of 500 mA g(-1) over 800 cycles). The excellent sodium storage performance of the nitrogen-rich mesoporous carbon is attributed to its disordered structure with large interlayer distance, interconnected porosity, and the enriched nitrogen heteroatoms.

Effects of three polymers, polyethylene glycol (PEG), polyvinylpyrrolidone (PVP), and copolymer of vinyl pyrrolidone/vinyl acetate (PVP-VA), on the dissolution behaviour of the cocrystals of flufenamic acid with theophylline (FFA-TP CO) and nicotinamide (FFA-NIC CO) were investigated at multiple length scales. At the molecular level, the interactions of crystal surfaces with a polymer were analysed by observing etching pattern changes using atomic force microscopy. At the macroscopic scale, dissolution rates of particular faces of a single crystal were determined by measurement of the physical retreat velocities of the faces using optical light microscopy. In the bulk experiments, the FFA concentration in a dissolution medium in the absence or presence of a polymer was measured under both sink and non-sink conditions. It has been found that the dissolution mechanisms of FFA-TP CO are controlled by the defect sites of the crystal surface and by precipitation of the parent drug FFA as individual crystals in the bulk fluid. In contrast, the dissolution mechanisms of FFA-NIC CO are controlled by surface layer removal and by a surface precipitation mechanism, where the parent drug FFA precipitates directly onto the surface of the dissolving cocrystals. Through controlling the dissolution environment by pre-dissolving a polymer, PVP or PVP-VA, which can interact with the crystal surface to alter its dissolution properties, improved solubility and dissolution rates of FFA-TP CO and FFA-NIC CO have been demonstrated.

No abstract

Nitrogen-doped, hierarchical porous carbons with a high surface area were simply prepared from gelatin using nano-ZnO as both the template and activating agent.

The influence of the surfactants of sodium lauryl sulfate (SLS) and Tween 80 on carbamazepine–nicotinamide (CBZ–NIC) cocrystal solubility and dissolution behaviour has been studied in this work. The solubility of the CBZ–NIC cocrystal was determined by measuring the eutectic concentrations of the drug and the coformer. Evolution of the intrinsic dissolution rate (IDR) of the CBZ–NIC cocrystal was monitored by the UV imaging dissolution system during dissolution. Experimental results indicated that SLS and Tween 80 had little influence upon the solubility of the CBZ–NIC cocrystal but they had totally opposite effects on the IDR of the CBZ–NIC cocrystal during dissolution. SLS significantly increased the IDR of the CBZ–NIC cocrystal while Tween 80 decreased its IDR.

We studied methoxy poly(ethylene glycol)-b-poly(ε-caprolactone)-b-poly(2-dimethylaminoethyl methacrylate) (mPEG-b-PCL-b-PDMAEMA) nanoparticles as the codelivery vector of hydrophobic drug and pDNA by employing dynamic light scattering (DLS), ζ potential, transmission electron microscopy (TEM), gel retardation assay, and confocal microscopy, and subsequently its in vitro cytotoxicity and transfection efficiency were tested. mPEG-b-PCL-b-PDMAEMA nanoparticles (NPs) with or without paclitaxel are both able to complex with pDNA completely when N/P ratio is equal to or above 3, and the combinatorial deliveries of paclitaxel and pDNA have equivalent transfection efficiency compared to blank NPs/pDNA complexes when N/P ratio is equal to or above 15, which indicates that the payload of hydrophobic drug does not influence pDNA condensation and transfection efficiency. Importantly, the in vitro cell experiment results confirm that the introduction of hydrophobic segment between mPEG and PDMAEMA segments can largely improve the gene transfection efficiency, which is about 15 times that of mPEG-b-PDMAEMA. NPs/pDNA complexes can be efficiently internalized into 293T cells after transfection for 2 h. The drug release rate of paclitaxel-loaded NPs in pH 5.0 release medium is higher than that in pH 7.2 release medium. These results suggest that mPEG-b-PCL-b-PDMAEMA NPs may be a promising vector to deliver anticancer drugs and pDNA simultaneously for achieving the synergistic/combined effect on cancer therapies.