Optical sensor for the quantification of monoclonal antibodies

B. Riquelmeª ^{, b}, O. Rubioª, and J. Valverdeª ^{, b}

ª Facultad de Cs. Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Argentina e–mail: riquelme@ifir.ifir.edu.ar

^b Óptica Aplicada a la Biología, Instituto de Física Rosario (CONICET–UNR), Rosario, Argentina e–mail: orubio@fbioyf.unr.edu.ar , nitavalverde@yahoo.com.ar

Recibido el 27 de octubre de 2004
Aceptado el 25 de mayo de 2005

Abstract

An optical sensor for the quantification of a monoclonal antibody (MoAb) in solution by the reflectometry technique is shown in this work. A silicon wafer was chosen as a reflecting surface. An amount of AB blood group antibody (anti–AB) is added to the sample when the pseudo–Brewster angle of incidence has been fixed. The reflected laser intensity is registered in real time as the protein is being adsorbed onto the wafer. The mathematical analysis of the results verifies that the antibody adsorption follows Langmuir's kinetics. From the curve analysis, the parameters related to the anti–AB concentration are extracted and the calibration curve is constructed. This curve allows us to obtain the desired commercial antiserum quantification.

Keywords: Laser reflectometry; immunosensor; Langmuir adsorption.

Resumen

Se presenta un sensor óptico basado en la técnica de reflectometría láser, para la cuantificación de anticuerpos monoclonales (MoAb) anti–AB en solución. Se eligió como superficie reflectante una oblea de silicio. Fijado el ángulo de pseudo Brewster, se agrega una cantidad de anti–AB. Se registra la intensidad láser reflejada en función del tiempo a medida que la proteína es adsorbida. El análisis matemático de los resultados verifica que la adsorción de anticuerpos sigue la cinética de Langmuir. Se calculan parámetros relacionados con la concentración de anti–AB con los que se construye una curva de calibración que permite cuantificar anticuerpos monoclonales en solución.

Descriptores: Reflectometría láser; inmunosenor; adsorción de Langmuir.

PACS: 42.81.Pa; 71.45.Gm; 87.64.–t; 78.40.–q ; 78.40.–q; 87.15.Rn

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Acknowledgments

In memory of Dr. Rodolfo José Rasia, who guided us in these investigations and whose important contributions to this work have been essential.

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