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    Enhancement of Electrochemical Detection of Gluten with Surface Modification Based on Molecularly Imprinted Polymers Combined with Superparamagnetic Iron Oxide Nanoparticles
    (2022-01-01)
    Limthin, Dalawan
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    Leepheng, Piyawan
    ;
    Klamchuen, Annop
    ;
    Novel molecularly imprinted polymers (MIPs) represent a selectively recognized technique for electrochemical detection design. This rapid and simple method prepared via chemical synthesis consists of a monomer crosslinked with an initiator, whereas low sensitivity remains a drawback. Nanomaterials can improve charge transfer for MIP surface modification in order to overcome this problem. SPIONs have semiconductor and superparamagnetic properties that can enhance carrier mobility, causing high sensitivity of electrochemical detection. In this work, surface modification was achieved with a combination of MIP and SPIONs for gluten detection. The SPIONs were synthesized via the chemical co-precipitation method and mixed with MIPs by polymerizing gluten and methyl methacrylate (MMA), presented as a template and a monomer. Magnetic MIP (MMIP) was modified on a carbon-plate electrode. The morphology of modified electrode surfaces was determined by scanning electron microscopy–energy-dispersive X-ray spectrometry. The performance of the MMIP electrode was confirmed by cyclic voltammetry, amperometry, and electrochemical impedance spectroscopy. The MMIP electrode for gluten detection shows a dynamic linear range of 5–50 ppm, with a correlation coefficient of 0.994 and a low detection limit of 1.50 ppm, which is less than the U.S. Food and Drug Administration requirements (20 ppm); moreover, it exhibits excellent selectivity, sensitivity, stability, and reproducibility.
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    Enhancing the sensitivity and selectivity of salbutamol detection using reduced graphene oxide combined with molecularly imprinted polymers (RGO/MIP)
    (2022-06-01)
    Limthin, Dalawan
    ;
    Leepheng, Piyawan
    ;
    ; ;
    Klamchuen, Annop
    In this study, to enhance the selectivity and sensitivity of salbutamol detection performed by a carbon plate electrode, the electrode was modified using a novel molecularly imprinted polymer (MIP) combined with reduced graphene oxide (RGO). The RGO/MIP combination was prepared by the polymerization of methacrylic acid as a monomer using salbutamol as a template. The surface morphologies of the modified electrodes were studied using field-emission scanning electron microscopy (FE-SEM), and their performance was tested by an electrochemical technique that investigated both the cyclic voltammetry (CV) and amperometry (AMP) modes. The performance of the modified RGO/MIP electrode was compared with that of an MIP electrode, in which the RGO/MIP electrode was demonstrated to have 4.16 nA/ppm of sensitivity, more than the 0.91 nA/ppm of the MIP electrode. The limit of detection (LOD) of the RGO/MIP electrode, which was 0.83 ppm, was lower than that of the MIP electrode. Moreover, the RGO/MIP electrode’s dynamic range extended from 1 to 1000 ppm, and it exhibited consistency, repeatability, a fast response, and high selectivity for salbutamol detection.
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    Preparation of surface-modified electrode of copper(ii) oxide mixed with the molecularly imprinted polymer for enhancement of melamine detection with photoelectrochemical technique
    (2023-05-15)
    Limthin, Dalawan
    ;
    Leepheng, Piyawan
    ;
    ; ;
    Klamchuen, Annop
    Melamine contamination in food and beverages affects short- and long-term health. In this work, enhanced sensitivity and selectivity in photoelectrochemical determination for melamine detection was achieved using copper(ii) oxide (CuO) combined with a molecularly imprinted polymer (MIP). A CuO nanomaterial was used to achieve MIP surface modification via co-precipitation synthesis. An MIP film was deposited by polymerizing the methacrylic acid monomer and a melamine template. The properties of the CuO nanomaterials, such as the surface morphology, chemical oxidation state, and crystalline structure, were characterized using field emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction patterns (XRD), respectively. The diffuse reflection spectroscopy technique was applied to evaluate the optical properties of the CuO nanoparticles. The results indicated that the synthesized CuO nanomaterials had a monoclinic structure with an optical bandgap of 1.49 eV, which corresponds to absorbance in the visible light region. CPE electrodes with surface-modified CuO/MIP were measured using the photoelectrochemical techniques of cyclic voltammetry, differential pulse voltammetry (DPV), and amperometry. The modified CuO/MIP electrode for melamine detection in 7.4 pH PBS buffer solution exhibited a high sensitivity of 0.332 nA nM<sup>−1</sup>, with a linear range of 5.0-75.0 nM and a limit of detection of 2.45 nM. Moreover, real samples of various kinds of milk were applied to evaluate the sensing response of the prepared CuO/MIP electrode. The modified CuO/MIP electrodes could be reused seven times with good reproducibility and high selectivity for melamine detection.
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    Item type:Publication,
    Surface modification of superparamagnetic iron oxide nanoparticles and methyl methacrylate molecularly imprinted polymer for gluten detection
    (2019-11-18)
    Limthin, Dalawan
    ;
    Klamchuen, Annop
    ;
    Gluten is a protein found in cereal grain such as wheat, barley, and rye. A small amount of gluten causes an autoimmune disease that leads to damage in the digestive system as well as a skin body system. The detection of gluten in food attracts tremendous attention. Surface modification by molecularly imprinted polymers electrode has been studied for specific detection of gluten using electrochemical superparamagnetic iron oxide nanoparticles trapped into a polymer matrix to improve gluten sensitivity with a magnetic property. A gold screen-printed electrode was modified by the magnetic molecularly imprinted polymers using surface polymerization of methyl methacrylate as monomer and gluten as a template. The magnetic iron oxide with a particle size less than 100 nm was modified and characterized using VSM, DLS and TEM techniques. SEM techniques confirmed the surface morphology of gold screen-printed electrodes modified with the MMIP. Finally, MMIP electrodes were used to detect gluten by an electrochemical method.
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    Item type:Publication,
    GROWTH TIME DEPENDENCE ON PHOTOELECTROCHEMICAL PROPERTY of ZINC OXIDE NANORODS PREPARED by HYDROTHERMAL SYNTHESIS
    (2018-12-01)
    Rattanawarinchai, Prapakorn
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    Jessadaluk, Sukittaya
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    Chananonnawathorn, Chanunthorn
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    Horprathum, Mati
    Here, the dependence of growth time on the growth behavior, morphology and photoelectrochemical (PEC) properties of ZnOnanorods (ZnO-NRs) as a photoanode are demonstrated. Vertical-aligned ZnO-NRs with c-axis perpendicular to substrate were accomplished via seed-assisted hydrothermal technique at the growth time varying between 0.5 and 24h. Growth behaviors of ZnO-NRs can be described into three regimes, which consist of the nucleation stage, ZnO-NRs growth and saturation growth, respectively. ZnO nanoparticles (NPs) corresponding to the nucleation site occur at the growth time below 1h. Afterward, the growth regime of ZnO-NRs, which originated from the competition between the vertical and the lateral growth, is clearly observed, and leads to increase in length and diameter. The whole growth of ZnO-NRs is terminated after 16h, attributed to low amount of Zn <sup>2+</sup> and OH <sup>-</sup> supplied from growth solution. PEC measurement reveals the fast solar response and high photostability of ZnO-NRs. Additionally, the photoconversion efficiency (η) improves with the growth time of 4h and degrades for longer time due to the change of total surface area. The maximum η of 0.13% at 0.63V <inf>RHE</inf> is obtained for the growth time of 4h. Our results highlight that the growth time plays a crucial role in controlling growth behavior and the total surface area directly related with the PEC properties of ZnO-NRs.
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    Gold nanoparticles decorated zinc oxide nanorods as electrodes for a highly sensitive non-enzymatic electrochemical glucose detection
    (2019-01-01)
    Rattanawarinchai, Prapakorn
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    Soyeux, Nathan
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    Jessadaluk, Sukittaya
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    Klamchuen, Annop
    The controlling and monitoring of blood glucose are very important for diabetes patients. We present highly sensitive non-enzymatic electrodes for glucose electrochemical detection based on gold nanoparticles (Au-NPs) decorated zinc oxide nanorods (ZnO-NRs). We prepared ZnO seed layer on ITO/glass substrate and synthesis ZnO-NRs structure by hydrothermal growth technique. A label-free electrode for glucose detection was successfully accomplished by functionalizing Au-NPs on ZnO-NRs. By controlling the Au-NPs density along the ZnO-NRs, the electrode exhibit high sensitivity (157.34 μA cm<sup>-2</sup> mM<sup>-1</sup>) with wide range (0.5-10 mM), low limit of detection (0.055 mM), with excellent stability and repeatability. Moreover, the interference effect of the other molecules such as ascorbic acid (AA) and uric acid (UA) was investigated. Our results illustrate that the present electrode is suitable for glucose detection in human blood samples.
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    Item type:Publication,
    Enhancement in Sensitivity and Selectivity of Electrochemical Technique with CuO/g-C3N4 Nanocomposite Combined with Molecularly Imprinted Polymer for Melamine Detection
    (2024-07-01)
    Limthin, Dalawan
    ;
    Leepheng, Piyawan
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    ;
    Klamchuen, Annop
    ;
    Suramitr, Songwut
    This study focused on enhancing the sensitivity and selectivity to detect melamine by utilizing a photoelectrochemical method. This was achieved by combining a melamine-imprinted polymer with a CuO/g-C<inf>3</inf>N<inf>4</inf> nanocomposite, which was synthesized through chemical precipitation and calcination. The resulting nanocomposite exhibits improved carrier mobility and photoelectrochemical properties. A molecularly imprinted receptor for selective detection was created through bulk polymerization with methacrylic acid and a melamine template. The characterization of the nanocomposite was performed using X-ray photoelectron spectroscopy for the chemical oxidation state, X-ray diffraction patterns for the crystalline structure, and ultraviolet/visible/near-infrared spectroscopy for optical properties. The CuO/g-C<inf>3</inf>N<inf>4</inf> nanocomposite exhibits photoactivity under visible light. The modified electrode, incorporating the CuO/g-C<inf>3</inf>N<inf>4</inf> nanocomposite and melamine-imprinted polymer, demonstrates a linear detection range of 2.5 to 50 nM, a sensitivity of 4.172 nA/nM for melamine, and a low detection limit of 0.42 nM. It shows good reproducibility and high selectivity to melamine, proving effective against interferences and real samples, showcasing the benefits of the molecularly imprinted polymer.
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    Item type:Publication,
    Methyl methacrylate magnetic molecularly imprinted polymer for gluten determination
    (2019-01-01)
    Limthin, Dalawan
    ;
    Chattrairat, Kunanon
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    Leepheng, Pitawan
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    Wisutthipat, Sawita
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    Gansa, Poompun
    The gluten protein is found in some rice and flour. The allergy of gluten, a little bit of gluten in diet cause long-term damage and dangerous to the body. Even tiny amounts of gluten in diet may bring enormous symptoms. The rapid and simple method for gluten detection is molecularly imprinted polymers (MIP) combined with electrochemical analysis. In addition, magnetic molecularly imprinted polymers (MMIP) as known as Fe3O4 magnetic nanoparticles have used in combination with electrochemical measurement as well to improve the sensitivity of detection. In this work, the MMIP was combined with electrochemical technique. The Fe3O4 magnetic nanoparticles were synthesized by chemical reaction and then encapsulated with methyl methacrylate (MMA) as a functional group for gluten detection. Dynamic light scattering measurement clearly illustrates the average size of as-synthesized Fe3O4 nanoparticles as low as 150 nm. Chemical bonding, morphology, crystal structure and magnetic properties were characterized by fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), X-ray diffractometer (XRD), and vibrating sample magnetometer (VSM), respectively.