Turn-off Fluorescent Determination of Adenosine Deaminase Using Oxidized Single-Walled Carbon Nanohorns

Abstract

We present a simple and low-cost approach for adenosine deaminase (ADA) determination by assembling a purpose-designed carboxyfluorescein (FAM)-labeled aptamer with oxidized single-walled carbon nanohorns (oxSWCNHs). A carboxyfluorescein (FAM) labeled aptamer that had a strong affinity for adenosine was synthesized. The mixing of FAM-labeled aptamer with oxSWCNHs formed by a self-assembly of two components via their electrostatic interactions. As a result, the fluorescence of the FAM-labeled aptamer was quenched by the efficient electron transfer for the determination of adenosine deaminase. In the presence of adenosine, the FAM-labeled aptamer in the self-assembly was released from the oxSWCNHs surface, thereby inducing the fluorescence recovery. Upon reaction with ADA, the fluorescence of the complex was quenched as a consequence of the removal of adenosine converted into inosine which has no affinity for this aptamer. Thus, a simple and rapid strategy for assaying ADA is reported with a detection limit of 0.10 U/mL and linear range from 0.25 to 3.125 U/mL. The method was employed ADA in human and mouse serum.