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Taghdisi S.M.,Mashhad University of Medical Sciences | Danesh N.M.,Research Institute of science and New Technology | Danesh N.M.,Mashhad University of Medical Sciences | Nameghi M.A.,Mashhad University of Medical Sciences | And 2 more authors.
Food Chemistry | Year: 2016

Sensitive and fast detection of antibiotic residues in animal derived foods and blood serum is of great interest. In this study a fluorescent aptasensor was designed for selective and sensitive detection of streptomycin (STR) based on Exonuclease III (Exo III), SYBR Gold and aptamer complimentary strand. In the absence of STR, the fluorescence intensity is weak. Upon addition of STR, the aptamer binds to its target, leading to release of complementary strand from aptamer and more protection against Exo III function. Following addition of SYBR Gold, a strong fluorescence intensity is obtained. This aptasensor showed a high selectivity toward STR with a limit of detection (LOD) as low as 54.5 nM. The validity of the procedure and applicability of the aptasensor were successfully assessed by detection of STR in a spiked milk and blood serum without interference from the sample matrix. © 2016 Elsevier Ltd. All rights reserved.


Taghdisi S.M.,Mashhad University of Medical Sciences | Danesh N.M.,Mashhad University of Medical Sciences | Danesh N.M.,Research Institute of science and New Technology | Lavaee P.,Academic Center for Education | And 4 more authors.
RSC Advances | Year: 2015

Lead (Pb) is a serious environmental contaminant and one of the most toxic heavy metals. In this study a colorimetric aptasensor was designed for selective, sensitive and rapid detection of Pb2+, based on a triple-helix molecular switch (THMS) and peroxidase-like activity of gold nanoparticles (AuNPs). This sensor inherits the properties of THMS, including high stability and preserving the affinity and selectivity of the original aptamer and properties of peroxidase-like activity of AuNPs, such as fast readout and improvement of the sensitivity. In the absence of Pb2+, THMS is intact, leading to complete peroxidase-like activity of AuNPs and an obvious color change to purplish-blue. In the presence of Pb2+, the aptamer binds to Pb2+, the signal transduction probe (STP) leaves the THMS and adsorbs onto the surface of AuNPs, leading to inhibition of the peroxidase-like activity of AuNPs and no color change is observed. The designed aptasensor showed high selectivity toward Pb2+ with a limit of detection as low as 602 pM for Pb2+. The presented aptasensor was successfully used to detect Pb2+ in water and serum. © The Royal Society of Chemistry 2015.


Taghdisi S.M.,Mashhad University of Medical Sciences | Danesh N.M.,Mashhad University of Medical Sciences | Danesh N.M.,Research Institute of science and New Technology | Ramezani M.,Mashhad University of Medical Sciences | Abnous K.,Mashhad University of Medical Sciences
RSC Advances | Year: 2016

Clinical application of vincristine in treatment of cancer is restricted because of its poor solubility and neuropathy. Targeted delivery of cytotoxic drugs could improve their therapeutic efficacy and reduce their severe side effects. Biocompatibility and high accumulation of human serum albumin nanoparticles (HSA) in tumors make this substance an ideal candidate for biomedical usage. Here, a Vincristine-HSA-Sgc8c aptamer (Apt) complex was designed and assessed for the treatment of Molt-4 cells (human acute lymphoblastic leukemia T-cell, target). Vincristine-HSA conjugate and Vincristine-HSA-Apt complex formations were analyzed by particle size analyzer, transmission electron microscopy (TEM) and gel retardation assay. Internalization of the Vincristine-HSA-FAM (3′-fluorescein)-labeled Apt complex into Molt-4 (target) and U266 cells (B lymphocyte human myeloma, nontarget) was monitored by confocal imaging and flow cytometry analysis. For cell viability (MTT assay), both cell lines were treated with vincristine, Vincristine-HSA conjugate, HSA-Apt conjugate and Vincristine-HSA-Apt complex. Vincristine was efficiently loaded (8.5%) into HSA. The results of confocal imaging and flow cytometry analysis indicated that the Vincristine-HSA-FAM-labeled Apt complex was effectively internalized into target cells (Molt-4) but not into nontarget cells (U266). The results of MTT assay also confirmed the internalization data. The Vincristine-HSA-Apt complex had less cytotoxicity in U266 cells compared to vincristine alone and Vincristine-HSA conjugate. In conclusion, the developed drug delivery system acquired properties of high drug loading, high cancer cell accumulation and cancer cell targeting. © 2016 The Royal Society of Chemistry.


Taghdisi S.M.,Mashhad University of Medical Sciences | Danesh N.M.,Mashhad University of Medical Sciences | Danesh N.M.,Research Institute of science and New Technology | Beheshti H.R.,Testa Quality Control | And 2 more authors.
Nanoscale | Year: 2016

Analytical approaches for the detection and quantitation of ochratoxin A (OTA) in blood serum and food products are high in demand. In this study, a fluorescent aptamer-based sensor (aptasensor) is developed for the selective and sensitive detection of OTA, based on a complementary strand of aptamer (CS) and two types of nanoparticles, gold nanoparticles (AuNPs) and silica nanoparticles (SNPs) coated with streptavidin. The fabricated aptasensor inherits the characteristics of SNPs, as enhancers of fluorescence intensity; AuNPs, such as large surface area and unique optical properties; and high affinity of the aptamer toward its target compared to its CS. In the absence of OTA, no FAM and biotin-labeled CS is in the environment of the SNPs coated with streptavidin, which leads to no fluorescence emission. In the presence of the target, an FAM and biotin-labeled CS-SNPs coated with streptavidin conjugate is formed, thus resulting in a very strong fluorescence emission. The designed fluorescent aptasensor exhibits high selectivity toward OTA with a limit of detection (LOD) as low as 0.098 nM. Furthermore, the fabricated aptasensor was successfully applied for the detection of OTA in grape juice and serum with LODs of 0.113 and 0.152 nM, respectively. © 2016 The Royal Society of Chemistry.


Ramezani M.,Mashhad University of Medical Sciences | Mohammad Danesh N.,Mashhad University of Medical Sciences | Mohammad Danesh N.,Research Institute of science and New Technology | Lavaee P.,Academic Center for Education | And 3 more authors.
Biosensors and Bioelectronics | Year: 2015

Detection methods of antibiotic residues in blood serum and animal derived foods are of great interest. In this study a colorimetric aptasensor was designed for sensitive, selective and fast detection of tetracycline based on triple-helix molecular switch (THMS) and gold nanoparticles (AuNPs). As a biosensor, THMS shows distinct advantages including high stability, sensitivity and preserving the selectivity and affinity of the original aptamer. In the absence of tetracycline, THMS is stable, leading to the aggregation of AuNPs by salt and an obvious color change from red to blue. In the presence of tetracycline, aptamer binds to its target, signal transduction probe (STP) leaves the THMS and adsorbs on the surface of AuNPs. So the well-dispersed AuNPs remain stable against salt-induced aggregation with a red color. The presented aptasensor showed high selectivity toward tetracyclines with a limit of detection as low as 266. pM for tetracycline. The designed aptasensor was successfully applied to detect tetracycline in serum and milk. © 2015 Elsevier B.V.

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