Immobilization of atrazine on gold, a first step towards the elaboration of an indirect immunosensor: characterization by XPS and PM-IRRAS

Abstract

As part of our long-term goal to design a novel type of immunosensor based on IR transduction, we devised two strategies to immobilize derivatives of the herbicide atrazine on the surface of planar gold substrates. Both strategies take advantage of the well-known formation of self-assembled monolayers of thiolates via spontaneous chemisorption of thiols or disulphides on noble metal surfaces. The first strategy involved the direct chemisorption of a disulphide derivative of atrazine, while the second strategy was based on the covalent attachment of a polymer tethered with atrazine derivatives to a previously adsorbed thiolate carrying a carboxylic acid head group. The resulting organic thin films on gold were characterized by polarization modulation infrared reflection-absorption spectroscopy (PM-IRRAS) and XPS. The binding of a polyclonal anti-atrazine antibody to both sensing layers was also tested and compared. It appeared that specific molecular recognition occurred only on the atrazine disulphide sensing layer.

Reactive amine surfaces for biosensor applications, prepared by plasma-enhanced chemical vapour modification of polyolefin materials

“…In the second region (Figure 1), the presence of carboxylic group vibrational peaks (at 1754 cm -1 and 1734 cm -1 associated to n(C=O) ester and n(C=O) carboxylic acid) was observed (Dreesen 2007, Finke 2009, Salmain 2006. The peak intensity/area varied following the trend:…”

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

“…Data in Figure also indicate that the deposition time of 2 h is sufficient to obtain maximum adsorbate coverage on the gold substrate. The peaks at 1739, 1662, 1620, and 1581 cm –1 have been assigned previously to ν(CO) of the ester moiety, to amide I band, two triazine ring stretching bands and to amide II band …”

“…Atrazine (ATZ) was purchased as a pesticide reference material from Dr. Ehrenstorfer, GmbH (Augsburg, Germany). Atrazine disulfide (ATZSSATZ) having chemical formula C 32 H 50 O 6 N 12 Cl 2 S 2 (Chart ) was synthesized according to a previously published procedure . The antiatrazine polyclonal antibody (anti-ATZ IgG) was obtained by immunization of rabbits and the IgG fraction was purified according to a published procedure .…”

“…Atrazine disulfide (ATZSSATZ) having chemical formula C 32 H 50 O 6 N 12 Cl 2 S 2 (Chart 1) was synthesized according to a previously published procedure. 25 The antiatrazine polyclonal antibody (anti-ATZ IgG) was obtained by immunization of rabbits and the IgG fraction was purified according to a published procedure. 18 Rabbit IgG and donkey serum were purchased from Sigma.…”

Preparation and Characterization of Carbon Nanotubes/Hydroxyethyl Cellulose Hybrid Material

“…Both show two components and the same one at 400.2 eV. After functionalization, the characteristic emission at 399.1 eV from N=C in triazine rings of the MWNT-triazine shifted to a higher binding energy of 399.4 eV [12]. It may relate to the substitution of chlorine atoms in the the triazine rings by oxygen atoms, and formation of a new structure of N=C-O(N).…”