A Label-Free Porous Alumina Interferometric Immunosensor

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• 作者：Sara D. Alvarez ; Chang-Peng Li ; Casey E. Chiang ; Ivan K. Schuller ; Michael J. Sailor
• 刊名：ACS Nano
• 出版年：2009
• 出版时间：October 27, 2009
• 年：2009
• 卷：3
• 期：10
• 页码：3301-3307
• 全文大小：307K
• 年卷期：0
• ISSN：1936-086X

文摘

Anodization of Al is used to produce optically smooth porous alumina (Al₂O₃) films with pores ∼60 nm in diameter and ∼6 μm deep. The capture protein, protein A, is adsorbed to the pore walls by noncovalent, electrostatic interactions, and thin film interference spectroscopy is used to detect binding of immunoglobulin (IgG). The porous alumina films are stable against corrosion and dissolution in aqueous media at pH 7, allowing quantitative monitoring of steady-state and time-resolved biomolecular binding. The bare porous Al₂O₃ surface displays a significantly greater affinity for protein A than for IgG. The known species specificity of protein A binding to IgG is confirmed; the protein-A-modified sensor responds to IgG derived from rabbit, but not chicken (IgG/IgY). A “cascaded”, or multiprobe sensing approach, is demonstrated, in which a specific target, sheep IgG, is administered to a sample modified with a protein A/rabbit anti-sheep IgG assembly. Binding measurements are confirmed by fluorescence microscopy using fluorescein-labeled IgG.