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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
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Leepheng, Piyawan
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Tunhoo, Benchapol
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Klamchuen, Annop
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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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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
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Leepheng, Piyawan
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Tunhoo, Benchapol
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Onlaor, Korakot
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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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Enhancing the sensitivity and selectivity of salbutamol detection using reduced graphene oxide combined with molecularly imprinted polymers (RGO/MIP)
(2022-06-01)
Limthin, Dalawan
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Leepheng, Piyawan
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Onlaor, Korakot
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Tunhoo, Benchapol
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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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Selective electrochemical determination based on magnetic molecularly imprinted polymers for albumin detection
(2022-06-01)
Leepheng, Piyawan
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Limthin, Dalawan
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Onlaor, Korakot
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Tunhoo, Benchapol
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Thiwawong, Thutiyaporn
Egg allergy is one of the most common allergies in humans. Allergenic egg protein as ovalbumin is the most abundant protein found in egg white. A selective electrode in electrochemical analysis for albumin from egg white was developed based on magnetic molecularly imprinted polymers (albumin-MMIPs) modified on a screen-printed electrode. Surface modification was applied using methyl methacrylate polymer to create surface specificity for albumin protein. The modified surface was characterized by a field-emission scanning electron microscope (FE-SEM). The average pore size was obtained by Brunauer-Emmett-Teller (BET) analysis, and the potentiostat obtained all electrochemical analysis. The albumin-MMIP electrode was selectivity with albumin, comparison with gluten, glycine, casein, and glucose. The modified electrodes present selectivity of 1.13 × 104 μAg-1ml and a limit of detection of 0.18 mg ml-1. The electrode can be applied to albumin protein detection in solution form in food industries.
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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
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Klamchuen, Annop
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Phromyothin, Darinee
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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Modification of selective electrode based on magnetic molecularly imprinted polymer for bisphenol A determination
(2021-06-01)
Leepheng, Piyawan
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Limthin, Dalawan
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Onlaor, Korakot
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Tunhoo, Benchapol
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Phromyothin, Darinee
Selective electrodes were modified by using the magnetic molecularly imprinted polymer (MMIP) technique on a screen-printed electrode (SPE) to detect bisphenol A (BPA). Superparamagnetic iron oxide nanoparticles (SPIONs) greatly enhance electrochemical signals due to their superparamagnetic properties. The SPIONs are non-toxic, biocompatible and highly stable. The SPIONs, especially magnetite (Fe3O4), were synthesized from ferrous chloride and ferric chloride using a chemical co-precipitation method. The crystalline structure of the synthesized SPIONs was obtained by X-ray diffractometer, representing cubic inverse spinel structure like magnetite. The synthesized SPIONs had particle sizes of 9.87 α 2.67 nm, which was confirmed by transmission electron microscope. The magnetic property was measured by a vibrating sample magnetometer, which presented the saturated magnetization, magnetic remanence value and coercivity as 48.76 emu g-1, 0.497 emu g-1 and 6.265 Oe, respectively. The surfaces of modified electrodes were characterized by a scanning electron microscope, which revealed BPA template cavities on the electrode surface. The electrochemical properties were studied by cyclic voltammetry and amperometry. The bisphenol A-magnetic molecularly imprinted polymer electrode (BPA-MMIP/SPE) has a sensitivity of 2.909 with a limit of detection of 2.053 × 10-8 M. The concentration range for BPA detection is 2.5 × 10-8 to 1.00 × 10-4 M, which can be applied to detection in a real sample.
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An experimental and theoretical study of molecularly imprinted electrode based on methyl methacrylate polymer for pesticide detection
(2020-06-01)
Leepheng, Piyawan
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Limthin, Dalawan
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Homchan, Wisa
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Suramitr, Songwut
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Phromyothin, Darinee
A selective electrode based on molecularly imprinted polymer (MIP) was developed by the polymerization of methyl methacrylate polymer on a screen-printed electrode for pesticide detection. Cypermethrin is one of the pesticides in the pyrethroid group, which has high toxicity in an organism and humans and causes environmental pollution. Cypermethrin-MIP and non-imprinted polymer films on electrodes were characterized for their surface morphology. The electrochemical analysis of cypermethrin pesticide was measured by amperometry under the potential of -0.23 V versus Ag/AgCl. Decreasing the current was directly proportional to the concentration of cypermethrin in the range of 15.50 ppb-10.00 ppm, and the limit of detection value was calculated to be 15.00 ppb. The proposed modified electrode has high sensitivity of 0.094 μA ppm<sup>-1</sup> and effective selective detection of cypermethrin in samples of real vegetable juice. The computational analyses were performed with the density functional theory at M06-2x/6-31 g(d,p), which predicted interaction and study mechanism between the MIP matrix with target pesticides.
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Surface modification of superparamagnetic iron oxide nanoparticles and methyl methacrylate molecularly imprinted polymer for gluten detection
(2019-11-18)
Limthin, Dalawan
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Klamchuen, Annop
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Phromyothin, Darinee
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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Methyl methacrylate magnetic molecularly imprinted polymer for gluten determination
(2019-01-01)
Limthin, Dalawan
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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.

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