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    An experimental and theoretical approach to electrochemical sensing of environmentally hazardous dihydroxy benzene isomers at polysorbate modified carbon paste electrode
    (Nature Portfolio, 2022) Ganesh, Pattan-Siddappa; Kim, Sang-Youn; Kaya, Savas; Salim, Rajae
    It is well known that, surfactants provide a neutral, positive and/or negative charge on the electrode surface by forming a monolayer, which in turn affects the charge transfer and redox potential during the electroanalysis process. However, the molecular level understanding of these surfactant-modified electrodes is worth investigating because the interaction of the analyte with the electrode surface is still unclear. In this report, we used quantum chemical models based on computational density functional theory (DFT) to investigate the polysorbate 80 structure as well as the locations of energy levels and electron transfer sites. Later, the bare carbon paste electrode (bare/CPE) was modified with polysorbate 80 and used to resolve the overlapped oxidation signals of dihydroxy benzene isomers. The m/n values obtained at polysorbate/CPE was approximately equal to 1, signifying the transfer of same number of protons and electrons. Moreover, the analytical applicability of the modified electrode for the determination of catechol (CC) and hydroquinone (HQ) in tap water samples gave an acceptable recovery result. Overall, the application of DFT to understand the molecular level interaction of modifiers for sensing applications laid a new foundation for fabricating electrochemical sensors.
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    Electrochemical investigations and theoretical studies of biocompatible niacin-modified carbon paste electrode interface for electrochemical sensing of folic acid
    (Springer Int Publ Ag, 2021) Ganesh, Pattan-Siddappa; Kim, Sang-Youn; Choi, Dong-Soo; Kaya, Savas; Serdaroglu, Goncagul; Shimoga, Ganesh; Shin, Eun-Jae
    The modified electrode-analyte interaction is critical in establishing the sensing mechanism and in developing an electrochemical sensor. Here, the niacin-modified carbon paste electrode (NC/CPE) was fabricated for electrochemical sensing applications. The two stable structures of the niacin were optimized and confirmed by the absence of negative vibrational frequency, at B3LYP and B3LYP-GD3BJ level and 6-311 g** basis set. The physical and quantum chemical quantities were used to explain the molecular stability and electronic structure-related properties of the niacin. The natural bond orbital (NBO) analysis was performed to disclose the donor-acceptor interactions that were a critical role in explaining the modifier-analyte interaction. The fabricated NC/CPE was used for the determination of folic acid (FA) in physiological pH by cyclic voltammetry (CV) method. The limit of detection (LOD) for FA at NC/CPE was calculated to be 0.09 mu M in the linear concentration range of 5.0 mu M to 45.0 mu M (0.2 M PBS, pH 7.4) by CV technique. The analytical applicability of the NC/CPE was evaluated in real samples, such as fruit juice and pharmaceutical sample, and the obtained results were acceptable. The HOMO and LUMO densities are used to identify the nucleophilic and electrophilic regions of niacin. The use of density functional theory-based quantum chemical simulations to understand the sensory performance of the modifier has laid a new foundation for fabricating electrochemical sensing platforms.
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    Quantum Chemical Studies and Electrochemical Investigations of Polymerized Brilliant Blue-Modified Carbon Paste Electrode for In Vitro Sensing of Pharmaceutical Samples
    (Mdpi, 2021) Ganesh, Pattan-Siddappa; Kim, Sang-Youn; Kaya, Savas; Salim, Rajae; Shimoga, Ganesh; Lee, Seok-Han
    To develop an electrochemical sensor for electroactive molecules, the choice and prediction of redox reactive sites of the modifier play a critical role in establishing the sensing mediating mechanism. Therefore, to understand the mediating mechanism of the modifier, we used advanced density functional theory (DFT)-based quantum chemical modeling. A carbon paste electrode (CPE) was modified with electropolymerization of brilliant blue, later employed for the detection of paracetamol (PA) and folic acid (FA). PA is an analgesic, anti-inflammatory and antipyretic prescription commonly used in medical fields, and overdose or prolonged use may harm the liver and kidney. The deficiency of FA associated with neural tube defects (NTDs) and therefore the quantification of FA are very essential to prevent the problems associated with congenital deformities of the spinal column, skull and brain of the fetus in pregnant women. Hence, an electrochemical sensor based on a polymerized brilliant blue-modified carbon paste working electrode (BRB/CPE) was fabricated for the quantification of PA and FA in physiological pH. The real analytical applicability of the proposed sensor was judged by employing it in analysis of a pharmaceutical sample, and good recovery results were obtained. The potential excipients do not have a significant contribution to the electro-oxidation of PA at BRB/CPE, which makes it a promising electrochemical sensing platform. The real analytical applicability of the proposed method is valid for pharmaceutical analysis in the presence of possible excipients. The prediction of redox reactive sites of the modifier by advanced quantum chemical modeling-based DFT may lay a new foundation for researchers to establish the modifier-analyte interaction mechanisms.
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    Role of electron transfer between bare electrode and benzoguanamine to fabricate an electrochemical sensor for drugs: Theoretical and electrochemical approach
    (Elsevier, 2024) Ganesh, Pattan-Siddappa; Elugoke, Saheed Eluwale; Kim, Sang-Youn; Kaya, Savas; Ebenso, Eno E.
    Herein, a poly(benzoguanamine) (BNZ) modified carbon paste electrode (CPE) was applied for the electroanalysis of paracetamol (PA) in PA tablet and human urine. Theoretical evaluation of the quantum chemical parameters of benzoguanamine (BZ) via density functional theory (DFT) calculations show that it is a reactive monomer with a tendency for back bond formation with the bare carbon paste electrode (BCPE). Scanning electron microscopy (SEM) images of BCPE and BNZ modified CPE (BNZ/CPE) show that the BNZ films were deposited on the bare electrode in layers. Results of the electrochemical characterization of these electrodes in 1 mM K4[Fe(CN)6] revealed that the BNZ/CPE has a higher electrocatalytic activity towards K4[Fe(CN)6] oxidation than BCPE. The limit of detection (LOD) of PA at the BNZ/CPE was estimated as 13.2 nM over a linear dynamic range (LDR) of 0.05-0.45 mu M. Also, the proposed sensor offered PA recoveries of 99.2-100.4 % and 98.4-100.8 % in PA tablet solution and human urine sample, respectively. The BNZ/CPE showed remarkable shelf-life by retaining 97.4 % of its initial current response after 21 days of application for PA electroanalysis at 7 days interval. Notably, this study is the first attempt at the application of the BNZ/CPE for PA electroanalysis.