Automated real-time SPR immunosensor for specific detection of low-molecular-mass analytes in natural water samples

COCCO MAURO; AUGUIE BAPTISTE; TOGNALLI NICOLAS; DAZA MILONE MARIA A.; CHAIN YAMIL; VELA MARIA ELENA; SALVAREZZA ROBERTO; RUMBO MARTIN; DOCENA GUILLERMO H.; MONTOYA JORGELINA; FAINSTEIN ALEJANDRO

Santiago d Chile

Congreso; LAPRW 2015: 5° Congreso latinoamericano de residuos de plaguicidas; 2015

Though the toxicity of pesticide and herbicide compounds in many cases has still to be determined, their extended use has raised public awareness for the potential consequences upon the environment and human health. In Argentina this is particularly the case with the widespread use of transgenic glyphosate-resistant soybean, a concern that has motivated the development of cost-effective real-time monitoring techniques applicable to glyphosate in phreatic waters. We describe a fully self-contained and automated portable surface plasmon resonance (SPR) immunosensor designed for real-time analysis of low-molecular-mass analytes in natural water samples. An alkanethiol self-assembled monolayer allows the automated regeneration and repeated use of the same sensor surface. The system integrates pumps and valves for sample injection and substrate regeneration, and the automation of the optical alignment neccesary for its operation. The device is tested with the model system dinitrophenol(DNP)-anti-dinitrophenol in an inhibition scheme, and the sensitivity is assessed.Purified monoclonal antibodies specific to 2,4-Dinitrophenol (DNP) were used. The surface modification of the SPR gold substrate (Fig. 1) starts with the ex-situ formation of a self-assembled monolayer (SAM) of mercaptoundecanoic acid (MUA) during 24 hs. A mixed solution of the coupling agents EDC and NHS are then put in contact during 15 min with the MUA functionalized sensor chip to activate the carboxylate groups, followed by the covalent attachment of a BSA-DNP conjugate. Finally, ethanolamine is used as blocking agent for the non-bonded carboxylate functional MUA groups. A NaOH solution was used for substrate regeneration. The sensor chip was introduced in the fluid cell and the experiments were carried out using serial dilutions of a 0.54 mg/ml anti-DNP solution (Fig. 1). These experiments have shown a limit of detection (LOD) of 540ppb of anti-DNP, which corresponds approximately to a DNP LOD of approximately 4ppb.