Biomimetic PLGA sensor: proof of principle and application

Abstract  

Spoilage of products can mainly be attributed to microorganisms which “live on the product”, i.e. which are able to utilize and/or metabolize components and/or molecules of the product. The objective of this work was to develop and optimize sensor prototypes indicating the quality of a product “in real time”, i.e. at the time the consumer is looking at the product. The design of the presented sensors relates to optical phenomena, for example anomalous absorption and remission of light. The crucial point of the sensor prototypes is a layer sensitive to the analyte, a polymer degradable by enzymes produced by the respective microorganisms. After incubation of the sensor setup with contaminated products, the lytic enzymes released from decaying cell material change the thickness of the polymer layer and generate a colour change visible by the naked eye. Production of the sensor prototypes is very simple and inexpensive and they might be successfully integrated into product packaging.     

Chemical sensor materials based on clathrates

The solid host compound 2,2-bis (9-hydroxy-9-fluorenyl)biphenyl 1 enclathrates organic solvent vapours such as acetone, methanol and 1-butanol to give stoichiometric inclusion complexes. Using differential scanning calorimetry (DSC), desorption enthalpies were estimated to 10–20 kJ/mol, indicating weak host-guest interactions. Clathrate formations with acetone and methanol are reversible and reproducible, and show a dependence of the mass increase on the solvent concentration in a gas flow. The application of host compound 1 as receptor layer can be important for the future development of mass sensors for the determination of organic solvent vapours.Part 3. For Part 2 of this series see [13]     

Biodegradable polymeric nanoparticles based on amphiphilic principle: construction and application in drug delivery

The use of nanotechnology in drug-delivery systems (DDS) is attractive for advanced diagnosis and treatment of cancer diseases. Biodegradable polymeric nanoparticles, for example, have promising applications as advanced drug carriers in cancer treatment. In this review, we discuss the development of drug-delivery systems based on an amphiphilic principle mainly conducted by our group for anti-cancer drug delivery. We first briefly address the synthetic chemistry for amphiphilic biodegradable polymers. In the second part, we summarize progress in the application of self-assembled polymer micelles using amphiphilic biodegradable copolymers as anti-tumor drug carriers.     

水胺硫磷分子印迹传感器的制备与应用

在磷酸盐缓冲溶液(PBS)中,以邻苯二胺(o-PD)和没食子酸(GA)为功能单体,水胺硫磷(ICP)为模板分子,采用电位循环扫描法在玻碳电极(GCE)表面进行电聚合,形成绝缘性的分子印迹膜,通过电化学阻抗谱(EIS)和循环伏安法(CV)对分子印迹膜进行表征.在最佳实验条件下,以铁氰化钾[ K3Fe(CN)6]为探针,用差分脉冲伏安法( DPV)对ICP进行定量分析.该传感器在2.00×10 -7～2.00×10-4 mol/L范围内,传感器的响应信号与ICP的浓度呈良好的线性关系,检测限为6.06×10-s mol/L( S/N=3).将其用于蔬果等实际样品中ICP的测定,回收率为95.6％～104.0％.     

Recent developments on application of nanometal-oxide based gas sensor arrays

It is shown that the sensor arrays can acquire more information on a given sample than an individual sensor. The main classes of gas-sensing materials include metal-oxide semiconductors. Gas sensors based on chemiresistive semiconducting metal-oxides have many potential benefits including, their very low cost, fast response, recovery time, simple electronic interface, ease of use, and ability to detect a large analytes. Recent advances in gas sensor arrays have shown the capability to incorporate nanomaterial based cross-reactive array. In this way it is possible to increase the surface/volume ratio of the sensing layer. Therefore the surface scattering is better influenced by adsorbed species and change in sensor conductivity is higher. Also the sensitivity of semiconductor oxide materials can be improved by using of nanoparticles. Gas sensor arrays based on nanotechnology can rapidly, sensitively, and selectively detect target molecules.     

Concanavalin A electrochemical sensor based on the surface blocking principle at an ion-selective polymeric membrane

Microchimica Acta - We report on a new electrochemical sensor for Concanavalin A. It is based on blocking the surface of plasticized PVC membranes that were covalently modified with D-mannose using...     

Non-enzymatic glucose sensor based on molecularly imprinted polymer: a theoretical,strategy fabrication and application

Journal of Solid State Electrochemistry - A comprehensive theoretical screening of functional monomers, structural optimization, interaction energies (ΔE), and Gibbs free energy changes...     

Development and application of a nano-alumina based nitric oxide sensor

Microchimica Acta - A novel sensor is described for the sensitive determination of nitric oxide (NO) based on a nano-alumina (nano-Al2O3) modified glassy carbon electrode. Cyclic voltammetry,...     

Chemical sensor based on a long-period fibre grating modified by a functionalized polydimethylsiloxane coating

A chemical sensor based on a coated long-period grating has been prepared and characterized. Designer coatings based on polydimethylsiloxane were prepared by the incorporation of diphenylsiloxane and titanium cross-linker in order to provide enhanced sensitivity for a variety of key environmental pollutants and optimal refractive index of the coating. Upon microextraction of the analyte into the polymer matrix, an increase in the refractive index of the coating resulted in a change in the attenuation spectrum of the long-period grating. The grating was interrogated using ring-down detection as a means to amplify the optical loss and to gain stability against misalignment and power fluctuations. Chemical differentiation of cyclohexane and xylene was achieved and a detection limit of 300 ppm of xylene vapour was realized.     

Self-assembled sensor based on boron-doped diamond and its application in voltammetric analysis of picloram

A self-assembled sensor based on a boron-doped diamond was investigated as a sensitive tool for voltammetric analysis of a member of a pyridine herbicide family - picloram. A cyclic voltammetry and a differential pulse voltammetry were applied for investigation of the voltammetric behaviour and quantification of this herbicide. Picloram yielded one well-developed irreversible oxidation signal at a very positive potential about +1.5 V vs. Ag/AgCl/3 mol L^?1 KCl electrode in an acidic medium and 1 mol L^?1 H₂SO₄ was chosen as a suitable supporting electrolyte. Operating parameters of differential pulse voltammetry were optimized and the proposed voltammetric method provided a high repeatability (a relative standard deviation of 20 repeated measurements at a concentration level of picloram of 50 µmol L^?1 equaled to 2.58%), a linear concentration range from 2.5 to 90.9 µmol L^?1 and a low limit of detection (LD = 1.64 µmol L^?1). Practical usefulness of the ‘environmentally-green’ electrochemical sensor was verified by an analysis of spiked water samples with satisfactory recoveries.     

Preparation and application of a new glucose sensor based on iodide ion selective electrode

An electrode for glucose has been prepared by using an iodide selective electrode with the glucose oxidase enzyme. The iodide selective electrode used was prepared from 10% TDMAI and PVC according our previous study. The enzyme was immobilized on the iodide electrode by holding it at pH 7 phosphate buffer for 10 min at room temperature. The H₂O₂ formed from the reaction of glucose was determined from the decrease of iodide concentration that was present in the reaction cell. The iodide concentration was followed from the change of potential of iodide selective electrode. The potential change was linear in the 4×10⁻⁴ to 4×10⁻³ M glucose concentration (75-650 mg glucose/100ml blood) range. The slope of the linear portion was about 79 mV per decade change in glucose concentration. Glucose contents of some blood samples were determined with the new electrode and consistency was obtained with a colorimetric method. The effects of pH, iodide concentration, the amount of enzyme immobilized and the operating temperature were studied. No interference of ascorbic acid, uric acid, iron(III) and Cu(II) was observed. Since the iodide electrode used was not an AgI-Ag₂S electrode, there was no interference of common ions such as chloride present in biological fluids. The slope of the electrode did not change for about 65 days when used 3 times a day.     

Construction and application of an electrochemical sensor based on graphene-MXene nanocomposites for baicalin detectionEI北大核心CSCD

Redox graphene-MXene(rGO-MXene) nanocomposites were prepared by ion polymerization and used to construct a highly sensitive electrochemical sensor for baicalin(BA) detection. The synergistic effect of rGO and MXene increased the specific surface area and electron transport capacity of the electrode, and significantly enhanced the electrochemical response of BA. The cyclic voltammetry and differential pulse voltammetry were used to investigate the electrochemical behavior of BA on the sensor. Under the optimal conditions, the peak current exhibited a good linear relationship with BA concentration in the range of 0. 05-10 μmol / L, and the limit of detection was as low as 28 nmol / L. The method was applied to analyze traditional Chinese medicine preparations containing baicalin, such as Qingkailing Capsule and Sanhuang Tablets with good accuracy and spiked recovery. The results were highly consistent with those of high performance liquid chromatography, providing a technical means for the rapid and sensitive detection of traditional Chinese medicine preparations. © 2022, Youke Publishing Co.,Ltd. All rights reserved.     

Extraction based on the flow-injection principle: Part 4. Determination of Extraction Constants

A new approach to the determination of extraction constants is described. The aqueous and organic phases, the former containing the counter ion, are pumped continuously as small segments through an extraction coil. The sample ion is introduced into the aqueous phase before it enters the coil, where the ion-pair extraction takes place (during 20 s). After leaving the extraction coil, a certain fraction of the organic phase is pumped through the flow-cell of the spectrophotometer. The extraction constants are calculated by slope analysis from the experimental data (absorbance and counter ion concentration). The constants usually agreed within ±0.1 (log units) with values obtained from batch experiments.     

基于羟基化酞菁锌-石墨烯纳米材料的和厚朴酚电化学传感器的构建及其应用

通过非共价作用制备了可溶性四羟基酞菁锌-石墨烯纳米复合材料,并将其应用于构建新型高灵敏度和厚朴酚电化学传感器.由于水溶性四羟基酞菁锌和石墨烯的协同作用,显著提高了纳米复合材料的比表面积和导电性,增强了和厚朴酚的电化学响应.在最优实验条件下测定,和厚朴酚在0.01～1.0μmol/L和1.0～100 μmol/L范围内呈...     

Extraction based on the flow-injection principle : Part I. Description of the Extraction System

An extraction system has been developed, essentially consisting of a pump, a rotary valve and a spectrophotometer. The sample, 12–25 μl, is introduced via the rotary valve into an aqueous stream (flow injection). The aqueous stream, containing the sample plug, is divided into small segments by an organic phase and led into a Teflon coil so that a regular pattern of the two phases is obtained. No air bubbles should be present. Separation of the two phases is achieved in a specially constructed fitting and the absorbance of the organic phase is measured. The construction and performance of the system are illustrated by analysis of caffeine samples. Up to 100 samples/h can be analysed with a relative precision of better than 1%.     

基于氧化锌/碳纳米纤维材料的氧氟沙星电化学传感器的构建及应用

通过静电纺丝技术合成碳纳米纤维,以循环伏安法在此碳纤维上电聚合乙酸锌制备复合纳米材料作为一种新型的电化学增敏剂,用于修饰玻碳电极,开发了一种基于碳纤维和氧化锌复合材料的新型电化学传感器(ZnO/CNF/GCE)。使用循环伏安法、差分脉冲伏安法等进行电化学催化性能的研究,并优化实验条件。结果表明,与裸电极相比,在pH 5.5磷酸盐缓冲溶液中,ZnO/CNF/GCE修饰电极能使氧氟沙星的峰电流明显提升,线性范围1~200μmol/L,检测限为0.33μmol/L。该ZnO/CNF/GCE修饰电极已用于氧氟沙星滴耳液中氧氟沙星的含量测定。     

Wavepacket dynamics on dynamically adapting grids: application of the equidistribution principle

A moving grid approach to wavepacket dynamics is described that enables grid points to be used efficiently in regions where high resolution of the wavepacket is required. The grid movement is based on the principle of equidistribution and by using a grid smoothing technique the grid points trace a path that continuously adapt to reflect the dynamics of the wavepacket. The technique is robust and allows accurate computations to be obtained for long wavepacket propagation times. Results are presented for two systems: tunnelling dynamics in a double well potential and scattering of a wavepacket from a repulsive Eckart barrier.