Glutathione Immunosensing Platform Based on Total Internal Reflection Ellipsometry Enhanced by Functionalized Gold Nanoparticles

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• 作者：Antonio Garc铆a-Mar铆n ; Jos茅 M. Abad ; Eduardo Ruiz ; Encarnaci贸n Lorenzo ; Juan Piqueras ; Jos茅 L. Pau
• 刊名：Analytical Chemistry
• 出版年：2014
• 出版时间：May 20, 2014
• 年：2014
• 卷：86
• 期：10
• 页码：4969-4976
• 全文大小：360K
• 年卷期：v.86,no.10(May 20, 2014)
• ISSN：1520-6882

文摘

An immunosensor to detect small molecules, such as glutathione (GSH), has been developed by combination of ellipsometry and Kretschmann surface plasmon resonance (SPR). The Au thin film used for surface plasmon polariton (SPP) excitation is functionalized with anti-GSH to specifically bind GSH. At low concentrations, the small refractive index changes caused by the low molecular weight of GSH induced only negligible shifts in the plasmon resonant energy during GSH binding. To improve sensitivity, gold nanoparticles (AuNPs) are functionalized with glutathione acting as amplifiers of the antigen鈥揳ntibody interaction. Changes induced by the AuNP adsorption are monitored using 唯 and 螖 ellipsometric functions. After performing competitive assays using solutions containing different concentrations of free GSH and a constant amount of functionalized AuNPs, it was concluded that the resonant energy linearly shifts as the relative concentration of free GSH increases. A detection limit for free GSH in the nanomolar range is found, demonstrating the effectiveness of AuNPs to enhance the sensitivity to immunoreactions in total internal reflection ellipsometry.