| 1. |
- Changsan, Titiwan, et al.
(författare)
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Magnetic microsphere sorbent on CaCO3 templates: Simple synthesis and efficient extraction of trace carbamate pesticides in fresh produce
- 2021
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Ingår i: Food Chemistry. - : Elsevier Applied Science Publishers. - 0308-8146 .- 1873-7072. ; 342
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Tidskriftsartikel (refereegranskat)abstract
- Polypyrrole magnetic microspheres were synthesized and used to extract carbaryl, carbofuran, and methomyl before analysis by a high-performance liquid chromatography with diode array detection. Under optimal conditions, four times the preconcentration was achieved with the use of only 1.2 mL of sample. Good linearity with ranges of 3.0–7.5 × 103, 6.0–4.5 × 103, and 15–3.0 × 103 ng kg−1 and limits of detection of 1.37 ± 0.10, 4.7 ± 1.2, and 10.1 ± 5.7 ng kg−1 were obtained, respectively. Good reproducibility (RSDs < 5%) was achieved over 24 cycles of extraction and regeneration. Good accuracy (recoveries 81.6 ± 1.5%–108.3 ± 2.2%) and good precision (RSDs 0.11%–4.5%) were obtained. Carbaryl was detected in apple (2.75 ± 0.23 ng kg−1), carbofuran in tomato (11.34 ± 0.61 ng kg−1), and methomyl in watermelon (34.7 ± 1.7 ng kg−1). The relative expanded uncertainty of the measurement method was less than 14% for all three pesticides.
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| 2. |
- Ivanov, Alexander, et al.
(författare)
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Thin semitransparent gels containing phenylboronic acid: porosity, optical response and permeability for sugars.
- 2008
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Ingår i: Journal of Molecular Recognition. - : Wiley. - 1099-1352 .- 0952-3499. ; 21:2, s. 89-95
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Tidskriftsartikel (refereegranskat)abstract
- Radical copolymerization of acrylamide (Am) (90 mol%) with N-acryloyl-m-aminophenylboronic acid (NAAPBA) (10 mol%) carried out on the surface of glass slides in aqueous solution and in the absence of chemical cross-linkers, resulted in the formation of thin semitransparent gels. The phenylboronic acid (PBA) ligand density was ca. 160 micromol/ml gel. The gels exhibited a macroporous structure and displayed optical response to sucrose, lactose, glucose and fructose in 50 mM sodium phosphate buffer, in the pH range from 6.5 to 7.5. The response was fairly reversible and linearly depended on glucose concentration in the wide concentration range from 1 to 60 mM at pH 7.3. The character of response was explained by the balance of two competing equilibrium processes: binding of glucose to phenylboronate anions and binary hydrophobic interactions of neutral PBA groups. The apparent diffusion coefficient of glucose in the gels was ca. 2.5 x 10(-7) cm(2)/s. A freshly prepared gel can be used daily for at least 1 month without changes in sensitivity. Autoclaving (121 degrees C, 1.2 bar, 10 min) allows for the gels sterilization, which is important for their use as glucose sensors in fermentation processes. Copyright (c) 2008 John Wiley & Sons, Ltd.
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| 3. |
- Jantra, Jongjit, et al.
(författare)
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Real-time label-free affinity biosensors for enumeration of total bacteria based on immobilized concanavalin A
- 2011
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Ingår i: Journal of Environmental Science and Health. Part A: Toxic/Hazardous Substances and Environmental Engineering. - : Informa UK Limited. - 1093-4529. ; 46:13, s. 1450-1460
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Tidskriftsartikel (refereegranskat)abstract
- This work presents the results of the use of flow injection surface plasmon resonance and impedimetric affinity biosensors for detecting and enumerating total bacteria based on the binding between E. coli and Con A, immobilized on amodified gold electrode. The single analysis time for both techniques was less than 20 min. Dissociation between the immobilized Con A and the E. coli using 200 mM of glucose in HClt at pH of 2.00 enabling the sensor to be reused for between 29-35 times. Impedimetric detection provided a much lower limit of detection (12 CFU mL(-1)) than the surface plasmon resonance method (6.1 x 10(7) CFU mL(-1)). Using the impedimetric system, real sample analysis was performed and the results were compared to the plate count agar method. Cell concentrations obtained by the biosensor were only slightly different from the result obtained from the plate count agar. The proposed system offers a rapid and useful tool for screening detection and enumeration of total bacteria.
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| 4. |
- Kangkamano, Tawatchai, et al.
(författare)
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Product-to-intermediate relay achieving complete oxygen reduction reaction (cORR) with Prussian blue integrated nanoporous polymer cathode in fuel cells
- 2020
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Ingår i: Nano Energy. - : ELSEVIER. - 2211-2855 .- 2211-3282. ; 78
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Tidskriftsartikel (refereegranskat)abstract
- The oxygen reduction reaction (ORR) is an essential process in electrocatalysis limiting the commercialization of sustainable energy conversion technologies, such as fuel cells. The use of conducting polymers as molecular porous and conducting catalysts obtained from the high abundance elements enables the route towards low cost and high-throughput fabrication of disposable plastic electrodes of fuel cells. Poly(3,4-ethylenedioxythiophene) (PEDOT) is a 2-electron ORR electrocatalyst yielding specifically hydrogen peroxide that limits the full utilization of chemical energy of oxygen. Here, we demonstrated an innovative product-to-intermediate relay approach achieving complete oxygen reduction reaction (cORR) with Prussian blue (PB) integrated microporous PEDOT cathode in fuel cells. The microporous structured PEDOT electrode prepared via a simple cryosynthesis allows the bulk integration and stabilization of the poor conducting PB co-catalyst into the PEDOT ion-electron conductor, while the microporous PEDOT allows effective oxygen diffusion into the matrix. We evaluated systematically the effect of sequential PEDOT 2-electron ORR followed by PB co-catalysis launching hydrogen peroxide reduction reaction (HPRR) into H2O. This resulted in the establishment of electronic and ionic transport between PEDOT and PB catalyst enabling the combination of enhanced ORR electrocatalysis by means of the ORR course extension from 2to 4-electron reduction to achieve cORR. The cORR performance delivered by the product-to-intermediate relay between microporous PEDOT and PB co-catalysis led to a four times increase in power density of model proton-exchange membrane fuel cell (PEMFC) assembled from the polymer-based air breathing cathode.
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| 5. |
- Kongkaew, Supatinee, et al.
(författare)
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Craft-and-Stick Xurographic Manufacturing of Integrated Microfluidic Electrochemical Sensing Platform
- 2023
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Ingår i: Biosensors. - : MDPI. - 2079-6374. ; 13:4
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Tidskriftsartikel (refereegranskat)abstract
- An innovative modular approach for facile design and construction of flexible microfluidic biosensor platforms based on a dry manufacturing "craft-and-stick" approach is developed. The design and fabrication of the flexible graphene paper electrode (GPE) unit and polyethylene tetraphthalate sheet (PET)6/adhesive fluidic unit are completed by an economic and generic xurographic craft approach. The GPE widths and the microfluidic channels can be constructed down to 300 mu m and 200 mu m, respectively. Both units were assembled by simple double-sided adhesive tapes into a microfluidic integrated GPE (MF-iGPE) that are flexible, thin (<0.5 mm), and lightweight (0.4 g). We further functionalized the iGPE with Prussian blue and glucose oxidase for the fabrication of MF-iGPE glucose biosensors. With a closed-channel PET fluidic pattern, the MF-iGPE glucose biosensors were packaged and sealed to protect the integrated device from moisture for storage and could easily open with scissors for sample loading. Our glucose biosensors showed 2 linear dynamic regions of 0.05-1.0 and 1.0-5.5 mmol L-1 glucose. The MF-iGPE showed good reproducibility for glucose detection (RSD < 6.1%, n = 6) and required only 10 mu L of the analyte. This modular craft-and-stick manufacturing approach could potentially further develop along the concept of paper-crafted model assembly kits suitable for low-resource laboratories or classroom settings.
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| 6. |
- Kongkaew, Supatinee, et al.
(författare)
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Evaluation on the Intrinsic Physicoelectrochemical Attributes and Engineering of Micro-, Nano-, and 2D-Structured Allotropic Carbon-Based Papers for Flexible Electronics
- 2021
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 37:49, s. 14302-14313
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Tidskriftsartikel (refereegranskat)abstract
- Flexible electronics have gained more attention for emerging electronic devices such as sensors, biosensors, and batteries with advantageous properties including being thin, lightweight, flexible, and low-cost. The development of various forms of allotropic carbon papers provided a new dry-manufacturing route for the fabrication of flexible and wearable electronics, while the electrochemical performance and the bending stability are largely influenced by the bulk morphology and the micro-/nanostructured domains of the carbon papers. Here, we evaluate systematically the intrinsic physicoelectrochemical properties of allotropic carbon-based conducting papers as flexible electrodes including carbon-nanotubes-paper (CNTs-paper), graphene-paper (GR-paper), and carbon-fiber-paper (CF-paper), followed by functionalization of the allotropic carbon papers for the fabrication of flexible electrodes. The morphology, chemical structure, and defects originating from the allotropic nanostructured carbon materials were characterized by scanning electron microscopy (SEM) and Raman spectroscopy, followed by evaluating the electrochemical performance of the corresponding flexible electrodes by cyclic voltammetry and electrochemical impedance spectroscopy. The electron-transfer rate constants of the CNTs-paper and GR-paper electrodes were similar to 14 times higher compared with the CF-paper electrode. The CNTs-paper and GR-paper electrodes composed of nanostructured carbon showed significantly higher bending stabilities of 5.61 and 4.96 times compared with the CF-paper. The carbon-paper flexible electrodes were further functionalized with an inorganic catalyst, Prussian blue (PB), forming the PB-carbon-paper catalytic electrode and an organic conducting polymer, poly(3,4-ethylenedioxythiophene) (PEDOT), forming the PEDOT-carbon-paper capacitive electrode. The intrinsic attribute of different allotropic carbon electrodes affects the deposition of PB and PEDOT, leading to different electrocatalytic and capacitive performances. These findings are insightful for the future development and fabrication of advanced flexible electronics with allotropic carbon papers.
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| 7. |
- Kueseng, Pamornrat, et al.
(författare)
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Molecularly imprinted polymer for analysis of trace atrazine herbicide in water
- 2009
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Ingår i: Journal of Environmental Science and Health. Part B - Pesticides, Food Contaminants, and Agricultural Wastes. - : Informa UK Limited. - 1532-4109. ; 44:8, s. 772-780
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Tidskriftsartikel (refereegranskat)abstract
- A molecularly imprinted polymer (MIP) for atrazine was synthesized by non-covalent method. The binding capacity of MIP was 1.00 mg g(-1) polymer. The selectivity and recovery were investigated with various pesticides which are mostly, found in the environment, for both similar and different chemical structure of atrazine. The competitive recognition between atrazine and structurally similar compounds was evaluated and it was found that the system provided highest recovery and selectivity for atrazine while low recovery and selectivity were obtained for the other compounds. The highest recovery was obtained from MIP compared with non-imprinted polymer (NIP), a commercial C-18 and a granular activated carbon (GAC) sorbent. The method provided high recoveries ranged from 94 to 99% at two spiked levels with relative standard deviations less than 2%. The lower detection limit of the method was 80 ng L-1. This method was successfully applied for analysis of environmental water samples.
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| 8. |
- Kumlanghan, Ampai, et al.
(författare)
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Microbial BOD sensor for monitoring treatment of wastewater from a rubber latex industry
- 2008
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Ingår i: Enzyme and Microbial Technology. - : Elsevier BV. - 0141-0229. ; 42:6, s. 483-491
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Tidskriftsartikel (refereegranskat)abstract
- A cell-based biosensor system was designed for monitoring an anaerobic process for treatment of high biochemical oxygen demand (BOD) levels in wastewater samples from a factory processing concentrated rubber latex. The BOD biosensor used immobilized mixed culture of microorganisms as the biological sensing element and an oxygen electrode as the transducer. The assay principle is based on the determination of the oxygen consumption rate caused by microbial respiration. Synthetic wastewater according to the OECD specifications was used as standard solution for calibration of the BOD biosensor. Response time of the sensor was 10-15 min. The BOD of the influent and the effluent from an anaerobic reactor was measured using both the cell-based biosensor system and a standard method (BOD5). Good agreement was achieved between the results from the two assay methods with a percentage difference of less than 10%. However, when exposing the mixed culture to wastewaters from other industrial plants the agreement between the results of the two assays was poor. The anaerobic treatment of the wastewater from the concentrated latex process resulted in a COD removal efficiency of 97% at a hydraulic retention time (HRT) of 50 days. The BOD biosensor was successfully applied to off-line and on-line monitoring of the anaerobic reactor treatment process.
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| 9. |
- Kumlanghan, Ampai, et al.
(författare)
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Microbial fuel cell-based biosensor for fast analysis of biodegradable organic matter
- 2007
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Ingår i: Biosensors & Bioelectronics. - : Elsevier BV. - 1873-4235 .- 0956-5663. ; 22:12, s. 2939-2944
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Tidskriftsartikel (refereegranskat)abstract
- The current study was made to develop a biosensor based on a single-chamber microbial fuel cell in which anaerobes were retained in the anode compartment separated from the cathode compartment by a proton exchange membrane. In the sensor a replaceable anaerobic consortium was used for analyzing biodegradable organic matter. The anaerobes acted as biocatalysts in oxidizing organic matter and transferring electrons to the anode. The biocatalysts were renewed for each sample analysis by replacing the old anaerobic consortium with an equal amount of fresh one. A glucose standard solution was used as the target substrate. To obtain the maximum sensor output, the MFC-based sensor system was optimized using an 800 0 resistor as the load to the external electric circuit and 25 mM phosphate buffer with 50 mM NaCl as catholyte in the aerobic compartment. The temperature of anaerobic compartment was maintained at optimal 37 degrees C. The cell potential across the electrodes increased with increasing loading of glucose. The sensor response was linear against concentration of glucose up to 25 gl(-1). The detection limit was found as 0.025 gl(-1). The microbial fuel cell with replaceable anaerobic consortium could be used as a biosensor for on-line monitoring of organic matter. (c) 2006 Elsevier B.V. All rights reserved.
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| 10. |
- Kuzimenkova, Marina, et al.
(författare)
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Optical responses, permeability and diol-specific reactivity of thin polyacrylamide gels containing immobilized phenylboronic acid
- 2008
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Ingår i: Polymer. - : Elsevier BV. - 0032-3861. ; 49:6, s. 1444-1454
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Tidskriftsartikel (refereegranskat)abstract
- Thin semitransparent gels were prepared by radical copolymerization of N-acryloyl-m-aminophenylboronic acid (NAAPBA) and acrylamide (AAm) taken in molar ratios from 8:92 to 16:84, respectively, in water. The gels were characterized by the content of immobilized NAAPBA and monomer conversion. Scanning electron microscopy revealed the micrometer size pores in the dried gels. The wet gels displayed a linear optical response to sugars with sensitivity decreasing in the series: D-fructose, D-galactose, D-glucose, D-mannose, N-acetyl-D-glucosamine in the sugar concentration range from 1 to 40-60 mM at pH 7.3. Cross-linking of the gels with N,N-methylene-bis-acrylamide decreased the strength of optical response. Specific binding capacity of a diol-containing dye Alizarin Red S in the gels at pH 7.0 coincided with the content of immobilized NAAPBA indicating the 1: 1 stoichiometry of the reaction and, therefore, good accessibility of the boronic acid ligands for water-soluble diols. Permeability of the gels was studied with a non-interacting dye Ethyl Orange exhibiting the pore diffusion coefficient of 1.4 x 10(-7) cm(2)/s. The rate of optical response of the gels to glucose was found to be determined by diffusion of sugar into the relatively thick gels (1 = 0.35-1 mm) with effective diffusion coefficients of 2 x 10(-7) cm(2)/S. In the thinner gels (l = 0.1 mm) the input of other kinetic processes, such as affinity binding or structural rearrangements of the gel, was noticeable. (c) 2008 Elsevier Ltd. All rights reserved.
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