TY - GEN A1 - Hammami, Asma A1 - Raouafi, Noureddine A1 - Mirsky, Vladimir M. T1 - Electrically controlled Michael addition: Addressing of covalent immobilization of biological receptors T2 - Biosensors and Bioelectronics N2 - Electrically addressed covalent immobilization of biomolecules to the defined electrodes of an electrode array is described. It is based on Michael addition of the thiol group of biomolecules to α,β-unsaturated carbonyl groups of benzoquinone. This “click” reaction was tested by immobilization of a number of thiolated compounds on the simplest array consisting of two gold electrodes coated by a self-assembled monolayer of benzoquinone-terminated hexanethiol. Electrically controlled binding of hexanethiol, ferrocenylhexanethiol, human serum albumin and thiol-terminated single-stranded DNA (ssDNA) was investigated. The binding was studied using cyclic voltammetry, X-ray photoelectron spectroscopy and surface plasmon resonance. The reaction requires the oxidized state of the benzoquinone moiety; this can be reached by applying of a moderate anodic potential to the electrode. Surface plasmon resonance measurements demonstrated that the thiol-modified ssDNA immobilized by this technique binds complementary synthetic oligonucleotides or PCR-amplified DNA fragments. The developed technology of electrical addressing of covalent immobilization can be applied for fabrication of sensor arrays. KW - Self-assembled monolayer Immobilization of biomolecules Addressable immobilization Michael addition Cyclic voltammetry Surface plasmon resonance Y1 - 2018 U6 - https://doi.org/10.1016/j.bios.2018.08.044 SN - 1873-4235 SN - 0956-5663 VL - 121 SP - 72 EP - 79 ER - TY - GEN A1 - Laroussi, Arwa A1 - Kot, Małgorzata A1 - Flege, Jan Ingo A1 - Raouafi, Noureddine A1 - Mirsky, Vladimir M. T1 - Self-assembled monolayers from symmetrical di-thiols: Preparation, characterization and application for the assembly of electrochemically active films T2 - Applied Surface Science N2 - 1,3-dimercaptopropan-2-ol, a symmetrical di-thiol, has been synthesized and applied as a new type of anchor molecule to prepare a self-assembled monolayer (SAM) on the gold surface. The formed monolayers were studied by cyclic voltammetry, impedance spectroscopy, X-ray photoelectron spectroscopy, kinetic capacitance, and contact angle measurements. The SAM structure depends on the adsorption conditions. A short incubation time of the electrode at high concentration of this di-thiol leads to the predominating binding through one thiol group of the adsorbate to the gold surface, while a long incubation at low concentration leads to the predominating binding by both thiol groups. A comparative study of the desorption and replacement of SAMs indicates a strong stability increase when the SAM molecules bond gold surface by two bonds mainly. This monolayer was used to immobilize electrochemically active p-benzoquinone moiety. The surface concentration of p-benzoquinone obtained from cyclic voltammetry is 2.5 ± 0.2 × 10−10 mol·cm−2 which corresponds to the functionalization of 65 ± 5% of SAM molecules. The obtained highly stable SAM with redox-active terminal group can be applied for different tasks of chemical sensing and biosensing. As an example, an application of this system for electrocatalytical oxidation of dihydronicotinamide adenosine dinucleotide (NADH) was tested. KW - self-assembled monolayer (SAM) KW - cyclic voltammetry KW - impedance spectroscopy KW - X-ray photoelectron spectroscopy (XPS) KW - kinetic capacitance KW - contact angle Y1 - 2020 U6 - https://doi.org/10.1016/j.apsusc.2020.145827 SN - 0169-4332 SN - 1873-5584 VL - 513 ER - TY - GEN A1 - Laroussi, Arwa A1 - Raouafi, Noureddine A1 - Mirsky, Vladimir M. T1 - Electrocatalytic Sensor for Hydrogen Peroxide Based on Immobilized Benzoquinone T2 - Electroanalysis N2 - An amperometric chemosensor for the detection of hydrogen peroxide is reported. The sensor is based on 1,4-benzoquinone immobilized on the gold electrode using self-assembled monolayer of short chain symmetrical dithiol as an anchor layer. Sensor analysis was performed by cyclic voltammetry at the potential range from −0.6 V till +0.9 V as well as in the anodic or cathodic potential ranges only. The results indicate oxidative electrochemical decomposition of hydrogen peroxide at the potential of ∼+0.4 V leading to the formation of oxygen while at cathodic potentials a reduction of the formed oxygen as well as of the hydrogen peroxide occur. A decrease in the oxidation potential of hydrogen peroxide on the gold electrode coated by self-assembled monolayer with 1,4-benzoquinone in comparison with that measured on the electrodes coated by the same self-assembled monolayer without 1,4-benzoquinone, indicates electrocatalytic effect of this moiety on oxidative decomposition of hydrogen peroxide. Analytical evaluation of the sensor performance was done in the voltammetric as well as in the chronoamperometric mode. The sensor exhibited linear response over the concentration range till 2.5 mM with a limit of detection ∼4 μM. KW - Hydrogen peroxide KW - Chemical sensor KW - Electrocatalysis KW - Benzoquinone KW - Self-assembled monolaye Y1 - 2021 U6 - https://doi.org/10.1002/elan.202100113 SN - 1521-4109 VL - 33 IS - 9 SP - 2062 EP - 2070 ER - TY - GEN A1 - Laroussi, Arwa A1 - Raouafi, Noureddine A1 - Mirsky, Vladimir M. T1 - Electrocatalytical Chemical Sensor for Hydrogen Peroxide T2 - Engineering Proceedings N2 - The fast and selective determination of hydrogen peroxide (H2O2) is of importance not only because of strong interest in this widely applied analyte, but also because of the development of enzymatic biosensors for glucose or other metabolites where the sensor for H2O2 can be used as the transducer. Here, we report on an electrocatalytical amperometric sensor for the detection of H2O2. It is a sensor that consists of a gold electrode covered by a self-assembled monolayer (SAM) with immobilized p-benzoquinone. To provide highly stable immobilization of p-benzoquinone at the distance of effective electron tunneling, a new anchor compound—1,3-dimercaptopropan-2-ol—was synthesized and used for preparation of the SAM. Due to two thiol groups binding gold surface, this compound provides high stability of the SAM. The surface concentration of p-benzoquinone obtained from cyclic voltammetry is 2.5 ± 0.2 × 10−10 mol·cm−2. Cyclic voltammetry and chronoamperometry experiments proved that the immobilized benzoquinone exhibited high electrocatalytic activity towards the decomposition of H2O2. Depending on the used potential range, different sensing modes can be realized. For example, one can measure electrochemical response due to the oxidation of H2O2 at anodic potentials, or due to the reduction of oxygen formed during oxidative decomposition of H2O2. Also, amperometric response at fixed potential of +0.4 V vs. Ag/AgCl corresponding to the oxidation of benzoquinone to hydroquinone was studied. The sensor exhibited a linear response over a concentration range of 0.1–2 mM with a low detection limit of 4.24 µM. The reproducibility of three different electrodes prepared was examined at the H2O2 concentration range from 0.1 till 3 mM, which resulted in a relative standard deviation below 4.2%. KW - self-assembled monolayer KW - p-benzoquinone KW - electron transfer KW - cyclic voltanmetry KW - chronoamperometry KW - hydrogen peroxide KW - electrocatalysis KW - chemical sensor Y1 - 2021 U6 - https://doi.org/10.3390/I3S2021Dresden-10168 SN - 2673-4591 N1 - Presented at the 8th International Symposium on Sensor Science, 17–28 May 2021 VL - 6 IS - 1 ER - TY - GEN A1 - Laroussi, Arwa A1 - Kot, Małgorzata A1 - Flege, Jan Ingo A1 - Raouafi, Noureddine A1 - Mirsky, Vladimir M. T1 - Self-Assembled Monolayers from Symmetrical Di-Thiols: Preparation, Characterization and Application for the Assembly of Electrochemically Active Films T2 - Engineering Proceedings N2 - 1,3-dimercaptopropan-2-ol, a symmetrical di-thiol, has been synthesized and applied as a new type of anchor molecule to prepare a self-assembled monolayer (SAM) on a gold surface. The formed monolayers were studied by cyclic voltammetry, impedance spectroscopy, X-ray photoelectron spectroscopy, kinetic capacitance, and contact angle measurements. The SAM structure depends on the adsorption conditions. A short incubation time of the electrode at high concentration of this di-thiol leads to the predominating binding through one thiol group of the adsorbate to the gold surface, while a long incubation at low concentration leads to the predominating binding by both thiol groups. A comparative study of the desorption and replacement of SAMs indicates a strong stability increase when the SAM molecules bond gold surfaces by two bonds mainly. This monolayer was used to immobilize electrochemically active p-benzoquinone moiety. The surface concentration of p-benzoquinone obtained from cyclic voltammetry is 2.5 ± 0.2 × 10−10 mol cm−2, which corresponds to the functionalization of 65 ± 5% of SAM molecules. The obtained highly stable SAM with redox-active terminal group can be applied for different tasks of chemical sensing and biosensing. As an example, an application of this system for electrocatalytical oxidation of dihydronicotinamide adenosine dinucleotide (NADH) was tested. KW - self-assembled monolayer KW - immobilization fashion KW - X-ray photoelectron spectroscopy KW - p-benzoquinone KW - electron transfer KW - cyclic voltammetry KW - NADH sensor Y1 - 2021 U6 - https://doi.org/10.3390/I3S2021Dresden-10112 SN - 2673-4591 N1 - Presented at the 8th International Symposium on Sensor Science, 17–28 May 2021 VL - 6 IS - 1 ER -