pH值对水热法制备的Bi4Ti3O12晶体光催化活性的影响

采用无助剂、非模板的水热法可控制备Bi4Ti3O12（BIT）晶体．通过调节反应物的pH值可以选择性地获得BIT纳米球、纳米带和纳米片．通过对不同pH值制备的样品的结构分析研究了这些不同形貌的形成机制．pH值为1制备的IT样品在可见光下光催化活性最高．基于不同pH值制备的BIT样品的形状、尺寸和局部结构振动分析了光催化活性不同的原因。     

Facile Solvothermal Synthesis of Mesostructured Fe3O4/Chitosan Nanoparticles as Delivery Vehicles for pH‐Responsive Drug Delivery and Magnetic Resonance Imaging Contrast Agents

We report a facile fabrication of a host–metal–guest coordination‐bonding system in a mesostructured Fe₃O₄/chitosan nanoparticle that can act as a pH‐responsive drug‐delivery system. The mesostructured Fe₃O₄/chitosan was synthesized by a solvothermal approach with iron(III) chloride hexahydrate as a precursor, ethylene glycol as a reducing agent, ammonium acetate as a porogen, and chitosan as a surface‐modification agent. Subsequently, doxorubicin (DOX), acting as a model drug (guest), was loaded onto the mesostructured Fe₃O₄/chitosan nanoparticles, with chitosan acting as a host molecule to form the NH₂? Zn^II? DOX coordination architecture. The release of DOX can be achieved through the cleavage of coordination bonds that are sensitive to variations in external pH under weakly acidic conditions. The pH‐responsive nature of the nanoparticles was confirmed by in vitro releases and cell assay tests. Furthermore, the relaxation efficiency of the nanoparticles as high‐performance magnetic resonance imaging contrast agents was also investigated. Experimental results confirm that the synthesized mesostructured Fe₃O₄/chitosan is a smart nanovehicle for drug delivery owing to both its pH‐responsive nature and relaxation efficiency.     

Multiple approaches for enhancing all-organic electronics photoluminescent sensors: Simultaneous oxygen and pH monitoring

Key issues in using organic light emitting diodes (OLEDs) as excitation sources in structurally integrated photoluminescence (PL)-based sensors are the low forward light outcoupling, the OLEDs’ broad electroluminescence (EL) bands, and the long-lived remnant EL that follows an EL pulse. The outcoupling issue limits the detection sensitivity (S) as only ~20% of the light generated within standard OLEDs can be forward outcoupled and used for sensor probe excitation. The EL broad band interferes with the analyte-sensitive PL, leading to a background that reduces S and dynamic range. In particular, these issues hinder designing compact sensors, potentially miniaturizable, that are devoid of optical filters and couplers. We address these shortcomings by introducing easy-to-employ multiple approaches for outcoupling improvement, PL enhancement, and background EL reduction leading to novel, compact all-organic device architectures demonstrated for simultaneous monitoring of oxygen and pH. The sensor comprises simply-fabricated, directionally-emitting, narrower-band, multicolor microcavity OLED excitation and small molecule- and polymer-based organic photodetectors (OPDs) with a more selective spectral response. Additionally, S and PL intensity for oxygen are enhanced by using polystyrene (PS):polyethylene glycol (PEG) blends as the sensing film matrix. By utilizing higher molecular weight PS, the ratio τ₀/τ₁₀₀ (PL decay time τ at 0% O₂/τ at 100% O₂) that is often used to express S increases ×1.9 to 20.7 relative to the lower molecular weight PS, where this ratio is 11.0. This increase reduces to ×1.7 when the PEG is added (τ₀/τ₁₀₀ = 18.2), but the latter results in an increase ×2.7 in the PL intensity. The sensor's response time is <10 s in all cases. The microporous structure of these blended films, with PEG decorating PS pores, serves a dual purpose. It results in light scattering that reduces the EL that is waveguided in the substrate of the OLEDs and consequently enhances light outcoupling from the OLEDs by ~60%, and it increases the PL directed toward the OPD. The multiple functional structures of multicolor microcavity OLED pixels/microporous scattering films/OPDs enable generation of enhanced individually addressable sensor arrays, devoid of interfering issues, for O₂ and pH as well as for other analytes and biochemical parameters.     

BODIPY-based fluorometric sensor array for the highly sensitive identification of heavy-metal ions

A BODIPY(4,4-difluoro-4-bora-3a,4a-diaza-s-indacene)-based fluorometric sensor array has been developed for the highly sensitive detection of eight heavy-metal ions at micromolar concentration. The di-2-picolyamine (DPA) derivatives combine high affinities for a variety of heavy-metal ions with the capacity to perturb the fluorescence properties of BODIPY, making them perfectly suitable for the design of fluorometric sensor arrays for heavy-metal ions. 12 cross-reactive BODIPY fluorescent indicators provide facile identification of the heavy-metal ions using a standard chemometric approach (hierarchical clustering analysis); no misclassifications were found over 45 trials. Clear differentiation among heavy-metal ions as a function of concentration was also achieved, even down to 10⁻⁷ M. A semi-quantitative interpolation of the heavy-metal concentration is obtained by comparing the total Euclidean distance of the measurement with a set of known concentrations in the library.     

Development of a colorimetric microfluidic pH sensor for autonomous seawater measurements

High quality carbonate chemistry measurements are required in order to fully understand the dynamics of the oceanic carbonate system. Seawater pH data with good spatial and temporal coverage are particularly critical to apprehend ocean acidification phenomena and their consequences. There is a growing need for autonomous in situ instruments that measure pH on remote platforms. Our aim is to develop an accurate and precise autonomous in situ pH sensor for long term deployment on remote platforms. The widely used spectrophotometric pH technique is capable of the required high-quality measurements. We report a key step towards the miniaturization of a colorimetric pH sensor with the successful implementation of a simple microfluidic design with low reagent consumption. The system is particularly adapted to shipboard deployment: high quality data was obtained over a period of more than a month during a shipboard deployment in northwest European shelf waters, and less than 30 mL of indicator was consumed. The system featured a short term precision of 0.001 pH (n = 20) and an accuracy within the range of a certified Tris buffer (0.004 pH). The quality of the pH system measurements have been checked using various approaches: measurements of certified Tris buffer, measurement of certified seawater for DIC and TA, comparison of measured pH against calculated pH from pCO₂, DIC and TA during the cruise in northwest European shelf waters. All showed that our measurements were of high quality. The measurements were made close to in situ temperature (+0.2 ?C) in a sampling chamber which had a continuous flow of the ship’s underway seawater supply. The optical set up was robust and relatively small due to the use of an USB mini-spectrometer, a custom made polymeric flow cell and an LED light source. The use of a three wavelength LED with detection that integrated power across the whole of each LED output spectrum indicated that low wavelength resolution detectors can be used instead of the current USB mini spectrophotometer. Artefacts due to the polychromatic light source and inhomogeneity in the absorption cell are shown to have a negligible impact on the data quality. The next step in the miniaturization of the sensor will be the incorporation of a photodiode as detector to replace the spectrophotometer.     

Development of Voltammetric Sensor for Determination of Tryptophan Using MWCNTs‐modified Sol‐gel Electrode

In the present work, an electrochemical sensor was developed for simple and sensitive determination of tryptophan (Trp) using multi‐walled carbon nanotubes modified sol‐gel electrode (MWCNTs/SGE). The electrocatalytic oxidation of tryptophan was investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). It was found that the oxidation peak current of Trp at the MWCNTs/SGE was greatly improved compared with that of the bare SGE. Furthermore, at the MWCNTs/SGE, the anodic peak potential of Trp is shifted about 220 mV to more negative value indicated that modified electrode has better electrocatalytic activity for electro‐oxidation of Trp. The anodic peak currents increased linearly with the concentration of tryptophan in the range of 0.2 × 10^?6 to 15 × 10^?6 M with a detection limit of 0.139 × 10^?6 M (at an S/N = 3).     

Amantadine antiparkinsonian drug adsorption on the AlN and BN nanoclusters: A computational study

To find a sensor for Amantadine (AM) antiparkinsonian drug, we studied its interaction with Al₁₂N₁₂ and B₁₂N₁₂ nanoclusters by density functional theory calculations. The AM molecule attaches via its –NH₂ group to the Al or B atoms of Al₁₂N₁₂ or B₁₂N₁₂ with Gibbs free energy change about −31.5 or −26.1 kcal/mol. Increasing the AM concentration, the interaction becomes weaker due to steric effects. The AM adsorbs on the Al₁₂N₁₂ and B₁₂N₁₂ with two different mechanisms, including electrostatic and charge transfer, respectively. The AM significantly reduces the Al₁₂N₁₂ work function from 4.50 to 3.66 eV, increasing the electron field emission. Thus, the AlN cluster may be a work function type sensor. Upon the AM adsorption on the BN cage, the HOMO level is largely destabilized, reducing the E_g from 6.84 to 5.01 eV which largely increases the electrical conductivity. This indicates that the BN cluster may be a potential electronic sensor.     

pH对外源性稀土元素镧在水-底泥中分配影响的研究

通过模拟试验，研究了在不同pH条件下外源性稀土元素镧(La)在水-底泥中的分配情况．结果表明，La易在底泥中沉积，低浓度(9．9mg／L)处理组要比高浓度(47．6mg／L)处理组沉积速度快；水溶液中La的消长符合一级动力学方程Ct＝C0e^-kt，其速率常数k分别为0．2969(9．9mg／L处理组)和0．1926(47．6mg／L处理组)；在酸性条件下，La可从底泥中再溶出，溶出量依次为酸性＞碱性＞偏酸性．     

pH对背角无齿蚌(Anodonta woodiana)5种免疫因子的影响

在pH值为6.0、6.5、6.8、7.5、8.0、8.5条件下,对背角无齿蚌(Anodonta woodiana)血清超氧化物歧化酶(SOD),肝过氧化氢酶(CAT),血清碱性磷酸酶(AKP),血清酸性磷酸酶(ACP)活性及肝丙二醛(MDA)含量的变化进行了测定。结果发现蚌体内SOD、CAT、ACP和AKP活性在pH8.5时均低于对照组;     

Single tungsten nanowires as pH sensitive electrodes

The electrochemical potentials of tungsten nanowire samples, covered with their own oxide, were measured in dependence of the pH value. The samples were prepared by selective etching of a directionally solidified eutectic NiAl–W alloy. Directional solidification in a Bridgman-type crystal growth furnace yields nanostructured two-phase materials. Electrochemical processing allows selective etching of the phases exposing the nanoscale structures. In this work, pointed samples with a single wire 200 nm in diameter protruding from the tip were produced. Subsequently the tungsten oxide layer on these single nanowires was electrochemically modified to optimize their pH sensing capabilities. The method has a potential for further downsizing since the wire diameter and exposed length can be controlled by the process parameters during solidification and during electrochemical processing. The advantages of these nanowire pH probes along with possible applications such as the pH measurement in ultra small cavities and other small systems of interest such as corrosion pits and biological cells are discussed.