Characterization of Ligand-Functionalized Microcantilevers for Metal Ion Sensing

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• 作者：Pampa Dutta ; Peter J. Chapman ; Panos G. Datskos ; and Michael J. Sepaniak
• 刊名：Analytical Chemistry
• 出版年：2005
• 出版时间：October 15, 2005
• 年：2005
• 卷：77
• 期：20
• 页码：6601 - 6608
• 全文大小：186K
• 年卷期：v.77,no.20(October 15, 2005)
• ISSN：1520-6882

文摘

A sensor for metal cations is demonstrated using singleand binary mixtures of different thiolated ligands as self-assembled monolayers (SAMs) functionalized on siliconmicrocantilevers (MCs) with gold nanostructured surfaces. Binding of charged metal ions to the active surfaceof a cantilever induces an apparent surface stress, therebycausing static bending of the MC that is detected in thiswork by a beam-bending technique. A MC responsemechanism based on changes in surface charge is discussed. The monodentated ligands arranged as SAMs onthe MC surface are not expected to fully satisfy thecoordination sphere of the detected metals. This leads tolower binding constants than would be expected forchelating ligands, but reversible responses. The modestbinding constants are compensated in terms of themagnitudes of responses by the inherent higher sensitivityof the nanostructured approach as opposed to moretraditional smooth surface MCs. Response characteristicsare optimized in terms of SAM formation time, concentration of ligand solution, and pH of working buffer solution.Limits of detection for the tested mono-, di-, and trivalentmetal ions are in low to submicromolar range. The resultsindicated that shapes and magnitudes of response profilesare characteristics of the metal ions and type of SAM. Theresponse factors for a given SAM with the tested metalions, or for a given metal with the tested SAMs, varied byroughly 1 order of magnitude. While the observed selectivity is not large, it is anticipated that sufficient ionicrecognition contrast is available for selective metal ionidentification when differentially functionalized arrays ofMCs (different ligands on different cantilevers in the array)are used in conjunction with pattern recognition techniques.