A Rapid Colorimetric Sensor for Soluble Interleukin-2 Receptor alpha, Based on Aptamer-Adsorbed AuNP

Abstract

The soluble interleukin-2 receptor alpha (sIL-2R alpha) is a broad indicator of clinical disease activity in various inflammatory diseases. Here we have developed, for the first time, a rapid, washing-free colorimetric aptasensor based on a sIL-2R alpha aptamer (K-d=1.33 nm). The aptasensor was fabricated with Au nanoparticles (AuNPs) adsorbing sIL-2R alpha aptamers. On addition of sIL-2R alpha, the aptamers become desorbed from the AuNPs, and this in turn weakens the absorption corresponding to AuNP-catalyzed oxidation of ortho-phenylenediamine (oPD) with H2O2. The aptasensor was characterized by TEM imaging, zeta potential measurements, dynamic light scattering (DLS) analysis, and UV/Vis spectrometry, followed by further optimization. The fabricated sensor exhibited great analytical performance, with a linear range of 1 to 100 nm and a detection limit of 1 nm both in buffer and in spiked human serum within 25 min. Other proteins, such as bovine serum albumin (BSA), IL-17R alpha, IL-5R alpha, IL-13R alpha(2), and CD166, showed negligible effects on the aptasensor. Thanks to the great advantages of the aptamers and AuNPs, this aptasensor provides a rapid, simple, and inexpensive process that might offer insights into various diagnostic applications of sIL-2R alpha.