A simple and rapid fluorescent aptasensor for ultrasensitive detection of arsenic based on target-induced conformational change of complementary strand of aptamer and silica nanoparticles

Abstract

Simple and reliable sensors for detection of arsenic (As), a toxic heavy metal, in drinking water and blood serum are highly desirable. Herein, we reported the fabrication and characterization of a fluorescent aptasensor for the detection of As (III) using target-induced conformational change of the Biotin and FAM-labeled complementary strand of aptamer (CS1), silica nanoparticles coated with streptavidin (SNPs-Streptavidin) and a label-free aptamer (Apt). The sensor described here had several attractive features, such as simplicity, rapid response and use of label-free Apt. Upon addition of As (III), Apt released its CSs and CS1 formed a hairpin structure on the surface of SNPs-Streptavidin, leading to a strong fluorescence signal. Without introduction of As (III), Apt was hybridized with its CSs and a weak fluorescence signal was obtained. The sensor exhibited a wide linear range between 2 and 500nM and a very low detection limit of 0.45nM. In addition, the applicability of the developed method was tested using spiked tap water and serum samples with satisfactory results.