title: A novel fluorescent aptasensor based on hairpin structure of complementary strand of aptamer and nanoparticles as a signal amplification approach for ultrasensitive detection of cocaine.
abstract: Cocaine is one of the most commonly misused stimulant which could influence the central nervous system. In this study, a fluorescent aptamer-based sensor (aptasensor) was designed for sensitive and selective detection of cocaine, based on hairpin structure of complementary strand of aptamer (CS), target-induced release of aptamer (Apt) from CS and two kinds of nanoparticles, including silica nanoparticles (SNPs) coated with streptavidin and gold nanoparticles (AuNPs). The designed aptasensor acquires characteristics of AuNPs such as unique optical properties and large surface area, SNPs as amplifiers of fluorescence intensity, higher affinity of Apt toward its target relative to its CS, and finally the hairpin structure of CS that brings the fluorophore (FAM) to close proximity to the surface of SNPs. In the absence of cocaine, FAM is in close proximity to the surface of AuNPs, resulting in a weak fluorescence emission. In the presence of target, FAM comes to close proximity to the surface of SNPs because of the formation of hairpin structure of CS, leading to a very strong fluorescence emission. The fabricated fluorescent aptasensor exhibited a good selectivity toward cocaine with a limit of detection (LOD) as low as 209 pM. Moreover, the designed aptasensor was successfully utilized to detect cocaine in serum with a LOD as low as 293 pM.
authors.affiliation: Cardiovascular Research Center, Ghaem hospital, Mashhad University of Medical Sciences, Mashhad, Iran.
authors.forename: Ahmad Sarreshtehdar
authors.initials: AS
authors.lastname: Emrani
authors.affiliation: Nanotechnology Research Center, School of Pharmacy, Mashhad University of Medical Sciences, Mashhad, Iran; Research Institute of Sciences and New Technology, Mashhad, Iran.
authors.forename: Noor Mohammad
authors.initials: NM
authors.lastname: Danesh
authors.affiliation: Nanotechnology Research Center, School of Pharmacy, Mashhad University of Medical Sciences, Mashhad, Iran.
authors.forename: Mohammad
authors.initials: M
authors.lastname: Ramezani
authors.affiliation: Targeted Drug Delivery Research Center, School of Pharmacy, Mashhad University of Medical Sciences, Mashhad, Iran. Electronic address: taghdisihm@mums.ac.ir.
authors.forename: Seyed Mohammad
authors.initials: SM
authors.lastname: Taghdisi
authors.affiliation: Pharmaceutical Research Center, School of Pharmacy, Mashhad University of Medical Sciences, Mashhad, Iran. Electronic address: abnouskh@mums.ac.ir.
authors.forename: Khalil
authors.initials: K
authors.lastname: Abnous
mesh_terms: D052157:Aptamers, Nucleotide / Q000737:chemistry; D015374:Biosensing Techniques / Q000379:methods*; D003042:Cocaine / Q000097:blood*; D055664:Electrochemical Techniques / Q000379:methods*; D005453:Fluorescence; D006046:Gold / Q000737:chemistry; D006801:Humans; D053768:Metal Nanoparticles / Q000737:chemistry
chemical_list: D052157:Aptamers, Nucleotide; D006046:Gold; D003042:Cocaine
keywords: Cocaine; Fluorescent aptasensor; Gold nanoparticles; Hairpin structure; Silica nanoparticles