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

[Display omitted] •Arsenic (As) is one of the most toxic heavy metals which can be found in natural waters, soils and atmosphere.•In this study, a fluorescent aptasensor was designed for the detection of As (III).•The sensor described here had several attractive features, such as simplicity, rapid response and use of label-free aptamer.•The sensor exhibited a wide linear range between 2 and 500nM and a very low detection limit of 0.45nM.•The applicability of the developed method was tested using tap water and serum samples with satisfactory results. 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.