Atrazine-Based Self-Assembled Monolayers and Their Interaction with Anti-Atrazine Antibody: Building of an Immunosensor

Abstract

As a part of our objective to build an immunosensor for the detection of the pesticide atrazine (ATZ) in environmental samples, we studied the self-assembling process of the disulfide derivative of the pesticide atrazine on a gold substrate. Atrazine-based self-assembled monolayers were characterized by ellipsometry, scanning tunneling microscopy, polarization-modulation infrared reflection-absorption spectroscopy (PM IRRAS), X-ray photoelectron spectroscopy and quartz crystal microbalance (QCM) measurements. Two different time constants for the adsorption process were observed, depending on the experimental method used. The QCM data reflect adsorption kinetics of the original disulfide compound, whereas ellipsometry and ex situ PM IRRAS refer to the formation of thiolate (ATZS) monolayers. In situ QCM data demonstrated the suitability of such monolayers for the detection of atrazine in aqueous samples. Exposure of the ATZS sensing surface to an anti-atrazine antibody (anti-ATZ IgG) resulted in complete coverage of the surface by antibody, whereas approximately half of the antibody molecules were displaced from the QCM sensor surface by further addition of atrazine into the solution.

Physisorption and Chemisorption of a Self-Assembled Monolayer by the Quartz Crystal Microbalance

“…However, in the simulation, the detection was assumed to be in the liquid environment. This is to mimic the work of Kelvin et al 15 In their study, the data for adsorption were determined in the liquid phase. Their kinetics of adsorption were calculated using Langmuir equation.…”

“…QCM has been used to study the layer-formation process. , Shimazu et al studied layers formed from stirred ferrocenylundecanethiol in hexane at room temperature, and the total frequency shift suggested monolayer formation. Karpovich et al studied the adsorption of two alkanethiols, i.e., octadecanethiol and octanethiol in stirred hexane and cyclohexane solutions at room temperature over a broad range of composition (10 –3 to 10 –1 mM).…”

Removal of Thiol-SAM on a Gold Surface for Re-Use of an Interdigitated Chain-Shaped Electrode

“…The quartz crystal microbalance (QCM) is a traditionally technique to determine the adsorption of SAMs onto a gold surface. A model QCM device was used to detect the resonance frequency of the QCM chip in three stages: the bare chip, the chip immobilized with SAMs, and the chip after removing SAMs [ 21 , 22 , 23 ]. Recent QCM studies have reported: the formation of SAMs from stirred ferrocenylundecanethiol in hexane at room temperature, and the total frequency shift suggested SAMs formation [ 24 ]; the adsorption of two SAMs, i.e., octadecanethiol and octanethiol, in stirred hexane and cyclohexane solutions at room temperature over a broad range of concentrations, from 10 −3 to 10 −1 mM [ 25 ]; and the constitution of biotin-terminated thiol-SAMs on QCM for the construction of immunosensors [ 26 ].…”

Selective QCM sensor based on atrazine imprinted polymer: Its application to wastewater sample

“…A rapid and sensitive method to detect ATR is important to ensure human and environmental safety. In recent years, various sensors have been reported for selective, sensitive and rapid determination of toxic compounds, biomolecules and drugs [23][24][25][26][27][28][29][30][31]. Molecular imprinted quartz crystal microbalance (QCM) sensors using the molecules complexed with functional monomers have attracted great interests in recent years because of its simplicity and high sensitivity [32].…”