Ultrahigh sensitivity assays for human cardiac troponin I using TiO2nanotube arrays

Abstract

Rapid, highly sensitive troponin assays for the analysis of serum at the point-of-care are particularly desirable for the effective treatment of myocardial infarction (MYI). TiO₂ nanotube arrays constitute a low cost, high surface area, semiconducting architecture with great promise for biosensing applications due to their compatibility with multiple detection techniques. Using TiO₂ nanotube arrays functionalized with highly robust and ordered carboxyalkylphosphonic acid self-assembled monolayers, we have developed a simple and highly sensitive fluorescence immunoassay which can detect concentrations of human cardiac troponin I as low as 0.1 pg ml⁻¹ without the use of enzymatic amplification. Varying the morphological parameters of the nanotube arrays allows tuning the detection range over 6 orders of magnitude of the troponin concentration from 0.1 pg ml⁻¹–100 ng ml⁻¹.