Colloidal-based localized surface plasmon resonance (LSPR) biosensor for the quantitative determination of stanozolol
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This work reports the systematic preparation of biosensors through the use of functionalized glass substrates, noble metal gold colloid, and measurement by localized surface plasmon resonance (LSPR). Glass substrate was modified through chemical silanization, and the density of gold colloid was carefully controlled by optimizing the conditions of silanization through the use of mixed silanes and selective mixing procedures. At this point, samples were exposed to bioreagents and changes in the shallow dielectric constant around the particles were observed by dark-field spectroscopy. Biological binding of high affinity systems (biotin/streptavidin and antigen/antibody) was subsequently investigated by optimizing coating layers, receptor concentration profiling, and finally quantitative determination of the analyte of interest, which in this case was a small organic molecule—the widely used, synthetic anabolic steroid called stanozolol. For this system, high specificity was achieved (>97%) through extensive nonspecific binding tests, with a sensitivity measurable to a level below the minimum required performance level (MRPL) as determined by standard chromatographic methods. Analytical best-fit parameters of Hillslope and regression coefficient are also commented on for the final LSPR biosensor. The LSPR biosensor showed good reproducibility (<5% RSD) and allowed for rapid preparation of calibration curves and determination of the analyte (measurement time of each sample ca. 2 min). As an alternative method for quantitative steroidal analysis, this approach significantly simplifies the detection setup while reducing the cost of analysis. In addition the system maintains comparable sensitivity to standard surface plasmon resonance methods and offers great potential for miniaturization and development of multiplexed devices.
KeywordsLocalized surface plasmon resonance Stanozolol Colloid Nanoparticles Biosensor
This work was supported by the Spanish Ministry of Science and Technology (TIC2003-01038 & AGL2005-07700-C06-01 & DEP2007-73224-C03-00) and by the European Commission (IST-2003-508774 & NMP2-CT-2003-505485) and the Regional Development Fund. MPK thanks the Ministerio de Educación, Cultura y Deporte for his fellowship under the National Program of Mobility for Professors and Researchers. The AMR group is a Grup de Recerca de la Generalitat de Catalunya and has support from the Departament d’Universitats, Recerca i Societat de la Informació la Generalitat de Catalunya (expedient 2005SGR 00207).
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