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A portable acetylcholinesterase (AChE)-based electrochemical sensor based on a screen-printed carbon electrode (SPCE) and a miniature potentiostat was constructed for the rapid field detection of organophosphorus pesticides (OPs).

A gold nanocluster Au17Cd2(PNP)2(SR)12 (PNP = 2,6-bis(diphenylphosphinomethyl)pyridine, SR = 4-MeOPhS) consisting of an icosahedral Au13 kernel, two Au2CdS6 staple motifs, and two PNP pincer ligands has been designed, synthesized and well characterized. This cadmium and PNP pincer ligand co-modified gold nanocluster showed high catalytic efficiency in the KA2 reaction, featuring high TON, mild reaction conditions, broad substrate scope as well as catalyst recyclability. Comparison of the catalytic performance between Au17Cd2(PNP)2(SR)12 and the structurally similar single cadmium (or PNP) modified gold nanoclusters demonstrates that the co-existence of the cadmium and PNP on the surface is crucial for the high catalytic activity of the gold nanocluster. This work would be enlightening for developing efficient catalysts for cascade reactions and discovering the catalytic potential of metal nanoclusters in organic transformations.

The potential threat that has originated from chemical warfare agents (CWAs) has promoted the development of advanced materials to enhance the protection of civilian and military personnel. Zr-based metal–organic frameworks (Zr-MOFs) have recently been demonstrated as excellent catalysts for decomposing CWAs, but challenges of integrating the microcrystalline powders of Zr-MOFs into monoliths still remain. Herein, we report hierarchically porous monolithic UiO-66-X xerogels for the destruction of CWAs. We found that the UiO-66-NH2 xerogel with a larger pore size and a higher surface area than the UiO-66-NH2 powder possessed better degradability of 2-chloroethyl ethyl sulfide (2-CEES), which is a sulfur mustard simulant. These UiO-66-X xerogels exhibit outstanding performance for decomposing CWAs. The half-lives of vesicant agent sulfur mustard (HD) and nerve agent O-ethyl S-[2-(diisopropylamino)ethyl] methylphosphonothioate (VX) are as short as 14.4 min and 1.5 min, respectively. This work is, to the best of our knowledge, the first report on macroscopic monolithic UiO-66-X xerogels for ultrafast decomposition of CWAs.

Fabrication of graphene-based conductive circuits via inkjet printing processes would be very significant, but preparation of graphene inks which can be used in ordinary household inkjet printer is still a challenge. Graphene oxide (GO) is an important graphene derivative with good dispersion properties in water, because it has a lot of oxygen-containing functional groups. In this paper, the relationship between the concentration of GO and the viscosity and surface tension of its dispersion were studied first, GO were prepared by modified Hummers' method. Moreover, the influence of two surfactants-sodium dodecyl sulfate (SDS) and Triton-X100 (TX-100) on viscosity and surface tension of inks were also investigated. It was found that the concentration of GO was 3.9 mg/mL, and the amount of the addition of SDS and TX-100 were 1 mg/mL and 2.5 mg/mL respectively, which can form stable GO-based inks. Finally, the resultant GO-based inks can be printed by home inkjet printer HP-1010 on normal printing paper, flexible polyimide film and thin aluminum foil. It is expected that the development of inkjet printable GO-based inks will decrease the cost of the preparation of graphene electrode/circuits and open up new ways for the application of GO-based thin film and patterns.

This paper systematically studies the influence of temperature during KOH activation of graphene on quantities and types of oxygen-containing groups, pore structure, specific surface area, and performance of supercapacitor. The changes of the amount and types of oxygen-containing functional groups were observed with the aid of Fourier transform infrared spectroscopy, Raman and X-ray photoelectron spectroscopy. The pore structure and specific surface area were characterized by means of X-ray powder diffraction, N2 adsorption-desorption and transmission electron microscopy. Electrochemical properties were assessed by cyclic voltammetry, electrochemical impedance and galvanostatic charge-discharge. As the temperature increased, the oxygen content of activated graphene decreased, while its specific surface area increased. The specific capacitance of the activated graphene first increased and then decreased with a maximum (326 F/g) at 400 °C. When the temperature was 800 °C, the surface area of the material peaked (3269 m2/g), and the specific capacitance was 204 F/g.

A flexible metal–organic framework (MOF)-based one-dimensional photonic crystal (1DPC) was fabricated by a spin-coating method. The flexible MOF, NH2-MIL-88B (MIL = Materials from Institute Lavoisier), was selected and implanted as the intrinsic functional layer of 1DPCs because of its selective breathing behavior upon exposure to various guests. TiO2 nanoparticles were used as another component to ensure a high refractive index contrast. The optical properties of the 1DPCs were tailored by varying the number of bilayers, incident angles, and physical thickness of the individual slabs. The fabricated 1DPCs showed a selective response toward various organic vapors as a result of the selective breathing behavior of the NH2-MIL-88B layer. Selective quantitative measurements of the ethanol concentration were achieved when the 1DPC was exposed to the vapors of an ethanol and water mixture. The fabricated 1DPCs exhibited high long-term, thermal, and mechanical stability, which are beneficial for practical applications.

Chemically functionalized graphene (CFG) is proposed as a novel nanoscale optical heater by uniformly dispersing it in poly(dimethylsiloxane) (PDMS) matrix. And subsequently, a simple, fast, and localized heating method on microfluidic chips is demonstrated. CFG is prepared through simultaneous modification and reduction of graphene oxide with dodecylamine by a solvothermal route. It is well dispersed in PDMS suspension to form uniform CFG/PDMS composite due to the presence of the long-dodecyl chain. The obtained CFG/PDMS composites are readily made into microfluidic chips by standard soft lithography. The localized optical heating on the chip is realized by employing a conventional semiconductor laser as light source. The prepared chips with low to 0.05 wt% CFG contents can exhibit temperature increase (

A new graphene-based electrochemical biosensor was constructed and applied for the simple, rapid and highly selective determination of glucose. The modified glassy carbon electrode (GCE) was prepared using dopamine (DA) as a reducing agent for graphene oxide (GO) and as a capping agent to stabilize and coat the resulting reduced graphene oxide (RGO) surface as it can polymerize to form polydopamine (PDA). PDA-RGO composites were dropped onto a glassy carbon electrode surface, and glucose oxidase (GOx) was immobilized on the surface of the composites by Michael addition. Finally, Pt nanoparticles (PtNPs) were electrodeposited on the modified electrode. Such modified electrodes (denoted as GCE/PDA-RGO/GOx/PtNPs) were characterized by UV-visible spectroscopy, atomic force microscopy, X-ray power diffractometry, Fourier-transform infrared spectroscopy, and scanning electron microscopy. Electrochemical behaviors were investigated by cyclic voltammetry and electrochemical impedance spectroscopy. The fabricated biosensor exhibited a high sensitivity of 33 μA mM−1 cm−2 over a wide linear range of 0.2 mM to 1 mM, good stability, excellent repeatability, and a detection limit of 0.10 mM.

Tuning MOFs: When a metal-organic framework (MOF) with an ordered three-dimensional macroporous structure is integrated into a film, the resulting materials have an additional optical element, which can be used as a general and effective signal transducer. This, in combination with the hierarchical pore structure, makes these films interesting dynamic photonic materials with potential applications in sensors.

Based on stepwise deposition of MOF films on a colloid crystal substrate, a strategy for fabricating photonic MOF films was developed. We found that the integration of a photonic structure endows MOF materials with unique optical properties, which can be used as a general and effective transduction scheme for a convenient study of the host–guest chemistry of MOFs.

A rapid and facile method was found to access one-molecule-thick free-standing organic nanosheets in a high yield with controllable size and shape by self-assembly of cucurbit[8]uril and small organic molecules.

Metal–organic frameworks (MOFs) as thin films have gained considerable attention in recent years because of their potential applications in different fields. However, preparation of integrated photonic MOF films still remains a major challenge. This study reports an approach for the fabrication of NH2-MIL-88B photonic films with potential for general application to other MOF films based on the simple spin-coating technique. A systematic study on the effect of MOF suspension concentration, rotation speed, and rotation cycles on the thickness and optical quality of coated films is presented. Moreover, the sensing performance of the NH2-MIL-88B photonic film deposited on a silicon wafer is evaluated using ultraviolet-visible reflection analysis and an optical digital camera, revealing the selective response to various organic vapors. More importantly, such selective sensing behavior can be easily and rapidly visualized by the naked eye.

Based on the confinement effect of the CB[8] cavity, a new strategy for explosives detection was developed by using a naphthalene embedded CB[8] complex as receptor. It was found that, dependent on the electronic structures and size of the tested explosives, the trapping of such analytes can significantly influence the photophysical properties of the naphthalene in the CB[8] nanocavity, leading to the direct detection and discrimination of distinctively different groups of trace explosives in the vapor phase, especially including the challenging aliphatic nitro-organics. Control experiments were performed to show the different sensing behaviors between the common organic vapors and nitrate-based explosives, which made it easy to realize the discrimination between target analytes and interferents. Due to the surface attached sensing elements, very fast response and high sensitivity were found in this system. The performed experiments suggested that the naphthalene embedded CB[8]-based sensing protocol opened a new way to develop a new kind of explosive sensor to enable a richer identification of threats.

A novel graphene oxide (GO)-based hydrogel with drug molecules as crosslinking agents was fabricated. Metformin hydrochloride (MFH), which has no aromatic groups, but only has N-containing functionalities, was chosen as a model drug. When a very small amount of MFH was introduced into a GO solution, a supramolecular assembled hydrogel was rapidly formed without any polymers or chemical additives. The gelation process can be influenced by the weight ratio of MFH to GO. The driving forces were hydrogen bonding and electrostatic attraction. Both air-dried and freeze-dried samples of GO–MFH hydrogels were utilized for controlled drug release in water (pH = 7) and hydrochloric acid (pH = 1, 3 and 5). The release mechanism of capsulated MFH was Fickian diffusion according to the fitted results. Both the freeze-dried and air-dried samples released around 74% of the MFH in a strongly acidic medium after 70 h, but only 50% in a neutral solution. This pH-sensitivity makes it a potential candidate for the controlled release of drugs in the acidic environment of the stomach.

A convenient and cost-effective chemical approach was developed to fabricate Au aggregates with uniform 1 nm nanogaps through the assembly of cucurbit[n]urils with Au colloids. Cucurbit[n]urils located in the nanogap region can be used as a useful SERS hot-spot nanocontainer to realize the SERS enhancement of an "inert" molecule up to 10(9).

The combination of poly (ionic liquid) and photonic structure affords a new class of self-reporting humidity sensory materials with excellent reversibility, which are able to rapidly, sensitively and visually indicate environmental humidity with colour change from blue to green, orange, and red, covering the whole visible range.

Here we report the design and preparation of a novel self-reporting sensor for cholic acid, an important biological compound produced in hepatocytes. Traditional detection methods of cholic acid are mostly dependent on analytical equipment, and are either time-consuming or require a derivatization process. In this work, a new approach based on molecularly imprinted photonic hydrogels (IPHs) is described, by which direct, sensitive and label-free detection of cholic acid can be achieved without any derivatization treatment and expensive instruments. The unique 3D ordered porous hydrogels that reveal optical changes in responsive to cholic acid concentration were prepared by combining colloidal crystal templating with the molecular imprinting technique. Due to their special hierarchical porous structure, which consists of 3D-ordered interconnected macroporous arrays with nanocavities derived from molecular imprinting, the formed photonic hydrogels allow rapid and ultrasensitive detection of the target analyte. The interconnected macropores are favorable for the rapid transport of the analyte in the hydrogel, while the inherent high affinity of nanocavities distributed in thin hydrogel walls allows IPHs to recognize the analyte with high specificity.

A general protocol based on spontaneous adsorption of cucurbit[n]uril (CB[n]) molecules through a strong multivalence interaction between CB[n] and gold is described, by which the formation of self-assembled CB[n] monolayers on gold surfaces can be efficiently achieved.