Nano

Starting from simplex drug delivery system, the graphene oxide (GO) and reduced GO (rGO) materials have been developed to be “combo” nanoplatforms containing multiple therapeutic modalities, such as the targeted drug delivery, imaging, as well as photothermal therapy (PTT) due to their distinctive physical/chemical and optical properties including excellent biocompatibility, modifiable active groups, ultra-large surface area, and intense photothermal effect. The graphene-based nanoplatforms were used for the stimuli-responsive nanocarriers, showing excellent therapeutic effects activated by endogenous stimuli including low pH, overexpressed enzymes, biomolecules, elevated glutathione, and exogenous stimuli including light, magnetic/electric field, and ultrasound. More importantly, for multimodal synergistic therapy originated from the enhanced collaborative interactions among several monotherapy types, the obtained remarkable super-additive effects were not the results just through single therapy or their theoretical combination. In this review, the recent progresses of smart graphene-based nanoplatforms for integrated cancer therapy and bio-imaging are presented. Current challenges and future perspectives of graphene-based nanoplatforms in the biomedical field are also discussed.

In the face of the fact that the development of traditional silicon-based electronic devices is increasingly limited, single molecule electronic device, which has been attracting more and more attention, is considered as one of the most hopeful candidates to realize the miniaturization of conventional electronic devices. In this paper, an overview of single molecule electronic devices is provided, including molecular electronic devices and electrode types. First, several molecular electronic devices are presented, including molecular diodes, molecular memories, molecular wires, molecular field effect transistors (FET) and molecular switches. Then the influence of different electrode types of the transport characteristics is introduced, showing that graphene is a promising electrode material for single molecule electronic devices. Moreover, other excellent characteristics of molecular devices are briefly introduced, such as potential thermoelectric effects, new thermally induced spin transport phenomena and negative differential resistance (NDR) behavior. Finally, the future challenges to the development of electronic devices based on single molecules are described.

Organic pollutants in water have been threatening public and environmental health. Developing efficient and sustainable photocatalysts working for degradation of organic pollutants under visible light becomes a big challenge. In this paper, high-efficiency visible light driven catalyst ordered mesoporous graphite nitride carbon (mpg-C₃N₄) was prepared by using SBA-15 as template and dicyandiamide (C₂H₄N₄) as precursor. The specific surface area of mpg-C₃N₄ can be increased remarkably as compared to that of the bulk graphite nitrite carbon (g-C₃N₄) by adjusting the ratio of SBA-15 to dicyandiamide. Photocatalytic performance of mpg-C₃N₄ were evaluated systematically by degradation of Rhodamine B (RhB), malachite green (MG) and tetracycline hydrochloride (TC) under visible light irradiation. The results showed that the mpg-C₃N₄ (1:0.5) has the highest photocatalytic activity and stability and the degradation rate is for RhB, MG and TC are all more than seven times that of bulk g-C₃N₄. After five recycling runs, the mpg-C₃N₄ (1:0.5) remains high photocatalytic activities for the degradation of MG (94%) and TC (81%), respectively. Additionally, radical trapping experiments certified that the main active species are $•{\mathrm{\text{O}}}_2^{-}$ and h${}^{+}$, while the role of $•$OH is irrelevant in the reaction processes. This work provides a promising pathway to prepare metal-free photocatalyst for degradation of organic pollutants under visible light irradiation.

By adding surfactant polyvinyl alcohol (PVA) and controlling the preparation process, we successfully synthesized Co–Mo catalysts. For further improving the dispersion, reduced graphene oxide sheets as catalyst carrier were introduced to synthesize Co–Mo@rGO composite catalyst as highly efficient catalysts for hydrolytic dehydrogenation of ammonia borane. The introduction of Mo for preparing Co–Mo@rGO catalyst helped to form alloy catalyst with better structure, better dispersity and smaller particle size. When the molar ratio of Co and Mo was 0.75:0.25, the bimetallic composite catalyst exhibited superior activity with TOF value of 16.29mol${}_{\mathrm{\text{H2}}}\cdot {\mathrm{\text{min}}}^{-1}\cdot {{\mathrm{\text{mol}}}_{\mathrm{\text{Co-Mo}}}}^{-1}$. The activation energy of the reaction was calculated to be 43.72kJ$\cdot {\mathrm{\text{mol}}}^{-1}$. Furthermore, the reusability tests reveal that waxberry-like Co–Mo still show good catalytic activity with 80.3% of their initial activity in five successive runs. The enhanced catalytic activities were due to the synergistic interaction between graphene sheets and waxberry-like Co–Mo NPs, which was beneficial to improve the dispersion and stability of bimetallic NPs. Also, ligand effects on the formation of waxberry-like structure and amorphous state further promoted the catalytic activity.

Au nanoparticles anchored on core–shell $\alpha$-Fe₂O₃@SnO₂ nanospindles were successfully constructed through hydrothermal synthesis process and used for fabricating a novel nonenzymatic dopamine (DA) sensor. The structure and morphology of the Au/$\alpha$-Fe₂O₃@SnO₂ trilaminar nanohybrid film were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The electrochemical properties of the sensor were investigated by cyclic voltammetry and amperometry. The experimental results suggest that the composites have excellent catalytic property toward DA with a wide linear range from 0.5$\mu$M to 0.47mM, a low detection limit of 0.17$\mu$M (S/$\mathrm{\text{N}}=3$) and high sensitivity of 397.1$\mu$AmM${}^{-1}$cm${}^{-2}$. In addition, the sensor exhibits long-term stability, good reproducibility and anti-interference.

This study is an attempt to optimize the electrospinning process to produce minimum Nylon 6,6 nanofibers by using Taguchi statistical technique. Nylon 6,6 solutions were prepared in a mixture of formic acid (FA) and Dichloromethane (DCM). Design of experiment by using Taguchi statistical technique was applied to determine the most important processing parameters influence on average fiber diameter of Nylon 6,6 nanofiber produced by electrospinning process. The effects of solvent/nylon and FA/DCM ratio on average fiber diameter were investigated. Optimal electrospinning conditions were determined by using the signal-to-noise (S/N) ratio that was calculated from the electrospun Nylon 6,6 nanofibers diameters according to “the-smaller-the-better” approach. The optimum Nylon 6,6 concentration (NY%) and FA/DCM ratio were determined. The morphology of electrospun nanofibers is significantly altered by FA/DCM solvent ratio as well as Nylon 6,6 concentration. The smallest diameter and the narrowest diameter distribution of Nylon 6,6 nanofibers ($166\pm 33$nm) were obtained for 10 wt% Nylon 6,6 solution in 80 wt% FA and 20 wt% DCM. An increase of 118%, 280% and 26% in tensile strength, modulus of elasticity and elongation at break over as-cast was obtained, respectively. Glass transition temperature of Nylon 6,6 nanofibers were determined by using differential scanning calorimeter (DSC). Analysis of variance ANOVA shows that NY% is the most influential parameter.

Porous anodic alumina (PAA) thin films, having interconnected pores, were fabricated from Cu-doped aluminum films deposited on $p$-type silicon wafers by anodization. The anodization was done at four different anodizing voltages (60V, 70V, 80V and 90V) in phosphoric acid and two voltages (60V and 70V) in oxalic acid. The aluminum and PAA samples were characterized by SEM and XRD while the pore arrangement, pore density, pore diameter, pore circularity and pore regularity were also analyzed. XRD spectra confirmed the aluminum to be crystalline with the dominant plane being (220), the Cu-rich phase have an average particle size of $15\pm 5$nm uniformly distributed within the Al matrix of 0.4-$\mu$m grain size. The steady-state current density through the anodization increased by 117% and 49% for oxalic and phosphoric acids, respectively, for 10V increase (from 60 to 70 V) in anodization voltage. Similarly, the etching rate increased by 100% for oxalic acid and by 40% for phosphoric acid which are responsible for 47% and 29% decreases in anodization duration, respectively. The highest value of circularity obtained for anodized Al–0.5wt.% Cu formed in oxalic acid at 60V was 0.86, and it was 0.80 for the phosphoric acid at 90V. Anodization of Al–0.5wt.% Cu films allows the formation of circular pores directly on $p$-type silicon wafers which is of importance for future nanofabrication of advanced electronics. The results of anodized Al–0.5wt.% Cu thin film were compared with other anodized systems such as anodized pure Al and Al doped with Si.

Intelligent, efficient silica nanoparticles for drug delivery system in cancer therapy have a great application potential, but the biodegradability of silica nanoparticles becomes an intractable hindrance. In this work, novel reactive oxygen species (ROS)-responsive hollow mesoporous organosilica nanoparticles (HMONs) coated with polydopamine (PDA) biofilm and amino-terminated methoxy poly(ethylene glycol) (mPEG-NH${}_2)$ were synthesized and applied in the smart drug delivery system (HMONs@PDA-mPEG) for the delivery of doxorubicin (DOX). The nanostructures and morphologies of nanoparticles were characterized by Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM), N₂ adsorption/desorption, dynamic light scattering (DLS) and thermogravimetric analysis. Based on the “chemical homology” mechanism, physiologically active thioacetal-bridged silsesquioxane was molecularly incorporated into the framework of silica nanoparticles to form ROS-responsive HMONs, which was verified by the in vitro degradation experiment. The in vitro drug release profiles showed a synergistically pH-dependent and ROS-responsive drug release effect. MTT assay toward A549 cells demonstrated that drug carriers had a biocompatibility, and DOX-loaded nanoparticles (DNs) presented a concentration-dependent and time-dependent cell growth inhibition effect. In summary, the novel ROS-responsive HMONs@PDA-mPEG had a promising application as a smart drug delivery system in biomedical field.

O-doping has proved to be one of the most promising approaches to further enhance the supercapacitive performance of carbon materials. However, it is presently not clear how the type of doped-O species affects the capacitive performance. In this paper, an attempt has been made to probe into the possible correlation between the type of doped-O species and the corresponding capacitive performance. Three O species (C=O, C–O and O–C=O) have been introduced onto TiC-derived carbon (TiC–CDC) by using a facile room-temperature oxidation strategy with three typical oxidizing agents (H₂O₂, HNO₃ and (NH${}_4{)}_2$S₂O${}_8)$, respectively. The results have shown that as the content of the C=O species increases, both the specific capacitance and the capacitance retention for the oxidized TiC–CDC samples become higher, showing a positively correlative performance. This work suggests that optimizing the type of doped-O species will be great potential for obtaining the optimal electrochemical performances for the O-doped carbon materials.

Nitrogen photo fixation mediated by various photocatalysts has received extensive concerns in recent years. In this work, a general strategy is proposed to enhance nitrogen photo fixation performance with some W${}_{18}$O${}_{49}$-based photocatalysts under visible-light irradiation. A series of photocatalysts were successfully synthesized in the presence of some noble-metal-free transition metals (Fe, Co and Ni) to modify the urchin-like W${}_{18}$O${}_{49}$. The resulting photocatalysts were systematically characterized using XRD, SEM, EDS, XPS, PL, N₂ adsorption–desorption isotherms, and DRS. Structural characterization of the photocatalysts revealed that the crystal morphology features were preserved, optional harvesting properties were enhanced, BET specific surface area was extended, and migration efficiency of the photo-induced charge carriers was significantly improved in the modified-W${}_{18}$O${}_{49}$ materials. Therefore, a progressed nitrogen photo fixation performance was observed. The maximum production of NH${}_4^{+}$ was approximately reached to 2752$\mu$g$\cdot$g${}^{-1}$ catal. under the optimum reaction conditions. Furthermore, a plausible nitrogen photo fixation mechanism in the presence of the synthesized composites is also proposed.

An innovative phosphorescence probe based on Mn-doped ZnS quantum dots (Mn:ZnS QDs) was developed for selective detection of chloramphenicol (CAP) via inner-filter effect (IFE). Mn:ZnS QDs were synthesized by water method and modified with L-Cysteine for better stability, and the average diameter of the nanometer particle was 3.8nm. With the excitation wavelength at 289nm, the strong phosphorescence of Mn:ZnS QDs can be emitted at 583nm. The excitation spectrum of Mn:ZnS QDs was substantially overlapped with the absorption spectrum of the target CAP. The excited light of Mn:ZnS QDs can be absorbed partially by CAP when they coexist, the phosphorescence intensity decreased with the increasing concentration of CAP, and it has a good linear relationship. Under optimal conditions, the linear relational concentration range achieved four orders of magnitude from 25 to $1.2\times 10^5\mathrm{\text{ng}}\cdot {\mathrm{\text{mL}}}^{-1}$ ($R^2=0.999$), with a detection limit (LOD; $S∕N=3$) down to 0.81$\mathrm{\text{ng}}\cdot {\mathrm{\text{mL}}}^{-1}$. The simple, rapid and low cost IFE phosphorescent probe exhibited satisfactory recoveries ranging from 88.9% to 98.5% for CAP analysis in spiked honey, which shows a potential for routine screening of CAP in ensuring the food safety.

Amphiphilic polymer carriers (PEG–St–$R$) were prepared from cassava starch and their pH response was investigated. First, hydrophobic tapioca starch polymer (St–$R$) was prepared with octyl acyl as the hydrophobic group. The hydrophilic group polyethylene glycol (mPEG) was then introduced into the polymer by esterification to produce amphiphilic tapioca starch polymer (PEG–St–$R$). Its self-assembly behavior was characterized using fluorescent probes. The morphology of PEG–St–$R$ was investigated by transmission electron microscopy (TEM). Loading of the anti-cancer drug curcumin was used to assess the delivery and slow-release performance of the amphiphilic tapioca starch polymer. Cumulative drug release was explored at various pH conditions, with the greatest release from drug-loaded micelles being observed under acidic conditions and stable in a neutral environment. These results provide a theoretical basis for the preparation of pH-responsive nanomicelle carriers, and a platform for the preparation of novel amphiphilic starch-based polymers.

An integrated tandem photoelectrochemical (PEC) cell, composed of a three-dimensional (3D) ZnO/CdS/NiFe layered double hydroxide (LDH) core/shell/hierarchical nanowire arrays (NWAs) photoanode and a $p$-Cu₂O photocathode, was designed for unassisted overall solar water splitting in this study. The optical and photoelectrochemical characteristics of ZnO-based photoanodes and Cu₂O photocathode were investigated. The results show that ZnO/CdS/NiFe LDH nanostructures offer significantly enhanced performances with a photocurrent density reaching 5.8mA$\cdot$cm${}^{-2}$ at 0.9V and an onset potential as early as 0.1V (versus RHE). The enhancement can be attributed to the existence of CdS nanoparticles (NPs) which boosts the light absorption in visible region and enhances charge separation. Moreover, the introduction of NiFe LDH nanoplates, with unique hierarchical mesoporous architecture, promotes electrochemical reactions by providing more active sites as co-catalyst. On the above basis, the ZnO/CdS/NiFe LDH–Cu₂O two-electrode tandem cell system was established. At zero bias, the device shows a photocurrent density of 0.4mA$\cdot$cm${}^{-2}$ along with the corresponding solar-to-hydrogen (STH) conversion efficiency reaching 0.50%. Our results indicate that the tandem PEC cells consisting of metal–oxide–semiconductor photoelectrodes based on Earth-abundant and low-cost materials hold promising application potential for overall solar water splitting.

In recent years, the development of biological computers is becoming faster and faster, in order to make the logical operation algorithms of biological computers more mature and stable, a new idea for the code lock logic circuit is proposed based on DNA strand displacement by using the dual-rail method. The code lock is designed by four input signals and one conversion input signal. Only when the four input codes are correct and the conversion signal code is turned on, the password lock will be in open state, otherwise the password lock will produce an alarm signal, stopping outside invasion timely. The information of key is processed to obtain the correct password; finally, the experimental simulation results are obtained by Visual DSD software. The results analysis show that the designed code lock circuit is effective, which may provide a good technical support and a good theoretical basis in biological computers development.