Publications by authors named "Masoud A Mehrgardi"

22 Publications

  • Page 1 of 1

A label-free electrochemical aptasensor for breast cancer cell detection based on a reduced graphene oxide-chitosan-gold nanoparticle composite.

Bioelectrochemistry 2021 Mar 26;140:107807. Epub 2021 Mar 26.

Department of Chemistry, University of Isfahan, Isfahan 81746-73441, Iran. Electronic address:

Regarding the cancer fatal consequences, early detection and progression monitoring are the most vital issues in patients' treatment and mortality reduction. Therefore, there is a great demand for fast, inexpensive, and selective detection methods. Herein, a graphene-based aptasensor was designed for sensitive human breast cancer cell detection. A reduced graphene oxide-chitosan-gold nanoparticles composite was used as a biocompatible substrate for the receptor stabilization. The significant function of the aptamer on this composite is due to the synergistic effects of the components in improving the properties of the composite, including increasing the electrical conductivity and effective surface area. After the aptasensor incubation in MCF-7 cancer cells, the cell membrane proteins interacted specifically with the three dimensional-structure of the AS1411 aptamer, resulting in the cell capture on the aptasensor. The aptasensor fabrication steps were investigated by cyclic voltammetry and electrochemical impedance spectroscopy. The higher cell concentrations concluded to the higher captured cells on the aptasensor which blocked the Ferro/Ferricyanide access to the sensor, causing increases in the charge transfer resistances. This aptasensor shows a linear relationship with the cell concentration logarithm, high selectivity, a wide linear range of 1 × 10-1 × 10 cells/mL, and a low detection limit of 4 cells/mL.
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http://dx.doi.org/10.1016/j.bioelechem.2021.107807DOI Listing
March 2021

Folic acid-functionalized gadolinium-loaded phase transition nanodroplets for dual-modal ultrasound/magnetic resonance imaging of hepatocellular carcinoma.

Talanta 2021 Jun 26;228:122245. Epub 2021 Feb 26.

Department of Chemistry, University of Isfahan, Isfahan, 81746-73441, Iran. Electronic address:

Dual-modal molecular imaging by combining two imaging techniques can provide complementary information for early cancer diagnosis and therapeutic monitoring. In the present manuscript, folic acid (FA)-functionalized gadolinium-loaded nanodroplets (NDs) are introduced as dual-modal ultrasound (US)/magnetic resonance (MR) imaging contrast agents. These phase-change contrast agents (PCCAs) with alginate (Alg) stabilizing shell and a liquid perfluorohexane (PFH) core were successfully synthesized via the nano-emulsion method and characterized. In this regard, mouse hepatocellular carcinoma (Hepa1-6) as target cancer cells and mouse fibroblast (L929) as control cells were used. The in vitro and in vivo cytotoxicity assessments indicated that Gd/PFH@Alg and Gd/PFH@Alg-FA nanodroplets are highly biocompatible. Gd-loaded NDs do not induce organ toxicity, and no significant hemolytic activity in human red blood cells is observed. Additionally, nanodroplets exhibited strong ultrasound signal intensities as well as T-weighted MRI signal enhancement with a high relaxivity value of 6.40 mM s, which is significantly higher than that of the clinical Gadovist contrast agent (r = 4.01 mM s). Cellular uptake of Gd-NDs-FA by Hepa1-6 cancer cells was approximately 2.5-fold higher than that of Gd-NDs after 12 h incubation. Furthermore, in vivo results confirmed that the Gd-NDs-FA bound selectively to cancer cells and were accumulated in the tumor region. In conclusion, Gd/PFH@Alg-FA nanodroplets have great potential as US/MR dual-modal imaging nanoprobes for the early diagnosis of cancer.
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http://dx.doi.org/10.1016/j.talanta.2021.122245DOI Listing
June 2021

Trastuzumab and folic acid functionalized gold nanoclusters as a dual-targeted radiosensitizer for megavoltage radiation therapy of human breast cancer.

Eur J Pharm Sci 2020 Oct 21;153:105487. Epub 2020 Jul 21.

Department of Chemistry, University of Isfahan, Isfahan 81746-73441, Iran. Electronic address:

In the present study, the effect of functionalized gold nanoclusters (AuNCs) with trastuzumab (Herceptin®) and/or folic acid (FA) as a single and dual-targeted radiosensitizers for the enhancement of megavoltage radiation therapy efficacy was investigated. SK-BR3 breast cancer cells as human epidermal growth factor 2 (HER2) and folate overexpressing cell line and the murine fibroblast (L929) as a control cell line were selected. The cellular uptake was followed using inductively coupled plasma optical emission spectrometry (ICP-OES) that showed AuNCs-FA-HER uptake by SK-BR3 cells was 3 times more than the non-targeted AuNCs after 12 h incubation. MTT and clonogenic assays revealed that the viability and surviving fraction of cancer cells were significantly inhibited by treating with all AuNCs under radiation compared to treating with radiation alone. However, these effects in the dual-targeted AuNCs group (AuNCs-FA-HER) was significantly greater than non-targeted and single-targeted AuNCs groups. Also, apoptosis was evaluated using an Annexin V-FITC/propidium iodide (PI) kit in flow cytometry. All AuNCs, in combination with 4 Gy of photon beam, induced more apoptosis. By fitting the survival fraction data on the linear-quadratic model, the sensitization enhancement factor (SER) of AuNCs, AuNCs-FA, AuNCs-HER, and AuNCs-FA-HER, were obtained 1.17, 1.32, 1.48 and 1.77, respectively. SER for AuNCs-FA-HER was significantly higher than that non-targeted and single-targeted AuNCs (p-value < 0.05) that can be attributed to more internalization in the cancer cells. It was concluded that functionalized AuNCs with both folic acid and Herceptin could represent a promising strategy for increased cellular internalization that improved radiation therapy efficiency in SK-BR3 breast cancer cells.
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http://dx.doi.org/10.1016/j.ejps.2020.105487DOI Listing
October 2020

AS1411-conjugated gold nanoparticles affect cell proliferation through a mechanism that seems independent of nucleolin.

Nanomedicine 2019 10 20;21:102060. Epub 2019 Jul 20.

Université de Lyon, Centre de Recherche en Cancérologie de Lyon, Cancer Cell Plasticity Department, UMR INSERM 1052 CNRS 5286, Centre, Léon Bérard, Lyon, France; Université de Lyon, Ecole Normale Supérieure de Lyon, Lyon, France. Electronic address:

G-rich oligonucleotide, AS1411, has been shown to interact with nucleolin and to inhibit cancer cell proliferation and tumor growth. This antiproliferative action is increased when AS1411 is conjugated to different types of nanoparticles. However, the molecular mechanisms are not known. In this work, we show in several cell lines that optimized AS1411-conjugated gold nanoparticles (GNS-AS1411) inhibit nucleolin expression at the RNA and protein levels. We observed an alteration of the nucleolar structure with a decrease of ribosomal RNA accumulation comparable to what is observed upon nucleolin knock down. However, the expression of genes involved in cell cycle and the cell cycle blockage by GNS-AS1411 are not regulated in the same way as that in cells where nucleolin has been knocked down. These data suggest that the anti-proliferative activity of GNS-AS1411 is not the only consequence of nucleolin targeting and down-regulation.
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http://dx.doi.org/10.1016/j.nano.2019.102060DOI Listing
October 2019

Enhanced Visual Wireless Electrochemiluminescence Immunosensing of Prostate-Specific Antigen Based on the Luminol Loaded into MIL-53(Fe)-NH Accelerator and Hydrogen Evolution Reaction Mediation.

Anal Chem 2019 05 23;91(9):6383-6390. Epub 2019 Apr 23.

Chemical Injuries Research Center, Systems Biology and Poisonings Institute , Baqiyatallah University of Medical Sciences , 14359-16471 Tehran , Iran.

A sensitive prostate-specific antigen (PSA) detection method using a visual-readout closed bipolar electrode (BPE) system has been introduced by integration of hydrogen evolution reaction (HER) in cathodic pole and electrochemiluminescence (ECL) of luminol loaded within the MIL-53(Fe)-NH (L@MIL-53(Fe)-NH) in the anodic pole. The cathode of the BPE was electrochemically synthesized by 3D porous copper foam, followed by decorating with nitrogen-doped graphene nanosheet and ruthenium nanoparticles. As an alternative, we employed carboxylate-modified magnetic nanoparticles (MNPs) for immobilization of the primary antibody (Ab1) and utilized the L@MIL-53(Fe)-NH conjugated to secondary antibody (Ab2) as a signaling probe and coreaction accelerator. After sandwiching the target PSA between Ab1 and Ab2, the MNP/Ab1-PSA-Ab2/L@MIL-53(Fe) were introduced to a gold anodic BPE. Finally, the resulting ECL of luminol and HO at the anodic poles was monitored using a photomultiplier tube (PMT) or digital camera. The PMT and visual (camera)-based detections showed linear responses from 1 pg mL to 300 ng mL (limit of detection 0.2 pg mL) and 5 pg mL to 200 ng mL (limit of detection 0.1 pg mL), respectively. This strategy provides an effective method for high-performance bioanalysis and opens a new door toward the development of the highly sensitive and user-friendly device.
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http://dx.doi.org/10.1021/acs.analchem.9b01506DOI Listing
May 2019

Investigation of different targeting decorations effect on the radiosensitizing efficacy of albumin-stabilized gold nanoparticles for breast cancer radiation therapy.

Eur J Pharm Sci 2019 Mar 31;130:225-233. Epub 2019 Jan 31.

Department of Chemistry, University of Isfahan, Isfahan 81746-73441, Iran. Electronic address:

Gold nanoparticles (GNPs) radiosensitizing effect strongly depends on the tumor targeting efficacy. The aim of this study is to identify the most ideal targeting decoration for BSA-GNPs according to tumor targeting and biodistribution. Therefore, three well-known targeting agents (folic acid, glucose, and glutamine) were utilized for BSA-GNPs decoration. Glucose-BSA-GNPs, glutamine-BSA-GNPs, and folic acid-BSA-GNPs were synthesized and then, characterized by Fourier-transform infrared spectroscopy and UV-Spectrometry. Then, the GNPs were intravenously injected 10 mg/kg to 4T1 breast tumor-bearing mice to evaluate biodistribution and radiosensitizing effects. Folic acid and glutamine decorations could significantly increase tumor targeting efficacy of BSA-GNPs as 2.1 and 2.4 times increase of gold accumulation was detected in comparison with BSA-GNPs. They exhibited the highest radiosensitizing efficacy and caused about 33% decrease in tumors volume in comparison with BSA-GNPs after 6 Gy radiation therapy. All the GNPs were completely biocompatible. Although, glutamine-BSA-GNPs and folic acid-BSA-GNPs could significantly enhance the tumor targeting and radiosensitizing efficacy of BSA-GNPs, did not exhibit any significant advantage over each other. Therefore, glutamine and folic acid decoration of BSA-GNPs can significantly increase the tumor targeting and therapeutic efficacy as radiosensitizer.
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http://dx.doi.org/10.1016/j.ejps.2019.01.037DOI Listing
March 2019

AS1411 aptamer-targeted gold nanoclusters effect on the enhancement of radiation therapy efficacy in breast tumor-bearing mice.

Nanomedicine (Lond) 2018 10 18;13(20):2563-2578. Epub 2018 Oct 18.

Department of Physiology, Applied Physiology Research Center, Cardiovascular Research Institute, Isfahan 81746-73461, Iran.

Aim: Herein, the AS1411 aptamer-targeted ultrasmall gold nanoclusters (GNCs) were assessed at different aspects as a radiosensitizer.

Materials & Methods: AS1411 aptamer-conjugated gold nanoclusters (Apt-GNCs) efficacy was evaluated at cancer cells targeting, radiosensitizing effect, tumor targeting, and biocompatibility in breast tumor-bearing mice.

Results: Flow cytometry and fluorescence microscopy exhibited more cellular uptake for Apt-GNCs in comparison with GNCs. In addition, inductively coupled plasma optical emission spectrometry results demonstrated its effective tumor targeting as the tumors' gold content for GNCs and Apt-GNCs were 8.53 and 15.33 μg/g, respectively. Apt-GNCs significantly enhanced radiotherapy efficacy as mean tumors' volume decreased about 39% and 9 days increase in the mice survival was observed. Both GNCs and Apt-GNCs were biocompatible.

Conclusion: The Apt-GNCs is a novel and efficient  radiosensitizer.
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http://dx.doi.org/10.2217/nnm-2018-0180DOI Listing
October 2018

Alive attenuated Salmonella as a cargo shuttle for smart carrying of gold nanoparticles to tumour hypoxic regions.

J Drug Target 2019 03 3;27(3):315-324. Epub 2018 Oct 3.

d Department of Chemistry , University of Isfahan , Isfahan , Iran.

In the present study, alive attenuated Salmonella typhi Ty21a was introduced as a vehicle for smart delivery of gold nanoparticles to the tumours' hypoxic regions. At the first step, the uptakes of gold nanoparticles with seven different decorations by S. typhi Ty21a was investigated using flow cytometry and inductively coupled plasma optical emission spectroscopy. The analyses demonstrated that folic acid functionalised gold nanoparticles (FA-GNPs) are the best candidates for producing the Golden Bacteria (GB). Subsequently, the GB and FA-GNPs efficacies for tumour targeting were investigated after intravenous injection to CT-26 tumour-bearing mice. The GB exhibited more GNPs delivery to the tumour in comparison with FA-GNPs. Moreover, GB injection causes more delivery of GNPs to the tumours' central regions in comparison with tumours' periphery. This trend is completely in reverse for FA-GNPs injected group. The ratios of peripheral to central regions' gold concentration of the tumours were 1.95 ± 0.13 and 0.61 ± 0.10 for FA-GNPs and GB groups, respectively. This observation demonstrates higher accumulation of gold nanoparticles in the centre of the tumour due to their active delivery by the S. typhi Ty21a to the deeps of tumours.
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http://dx.doi.org/10.1080/1061186X.2018.1523417DOI Listing
March 2019

Aptamer functionalized magnetic nanoparticles for effective extraction of ultratrace amounts of aflatoxin M1 prior its determination by HPLC.

J Chromatogr A 2018 Aug 9;1564:85-93. Epub 2018 Jun 9.

Department of Chemistry, University of Isfahan, Isfahan, 81746/73441, Iran.

Aptamers, due to the inherently high selectivity towards target analytes, are promising candidate for surface modification of the nanoparticles. Therefore, aptamer-functionalized magnetic nanoparticles (AMNPs) was prepared and used to develop a magnetic solid-phase extraction procedure for clean-up of milk and dairy products samples before measuring the aflatoxin M1 (AFM1) contents by the high-performance liquid chromatography. The prepared sorbent was characterized by different instrumental methods such as FT-IR, FESEM, TEM, EDX and AGFM. The AMNPs was used in extraction and pre-concentration of ultratrace amounts AFM1 from local milk samples. The amount of sorbent, elution volume, extraction time, and salt addition were optimized. Based on the results, calibration plot is linear over the 0.3 to 1 ng·L and 5 to 50 ng·L AFM1 concentration ranges. The limits of detection of the developed method were obtained 0.2 ng·L which is the smallest value that has been reported up to now. The results show that this new superior sorbent has a large potential to simplify the complex matrix of the samples and can used for detection, preconcentration and accurate determination of ultratrace amounts of the AFM1 from milk and dairy products.
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http://dx.doi.org/10.1016/j.chroma.2018.06.022DOI Listing
August 2018

Visual electrochemiluminescence biosensing of aflatoxin M1 based on luminol-functionalized, silver nanoparticle-decorated graphene oxide.

Biosens Bioelectron 2018 Feb 21;100:382-388. Epub 2017 Sep 21.

Department of Chemistry, University of Isfahan, Isfahan 81746-73441, Iran.

A sensitive electrochemiluminescence (ECL) aptasensor for aflatoxin M1 (AFM1) detection by a closed bipolar electrode (BPE) array has been introduced. The thiolated AFM1 aptamer was immobilized on gold nanoparticle-coated magnetic FeO nanoparticles (Apt-GMNPs). Luminol-functionalized silver nanoparticle-decorated graphene oxide (GO-L-AgNPs) participates in π-π interactions with the unpaired bases of the immobilized aptamer (Apt-GMNPs-GO-L-AgNPs). After the Apt-GMNPs-GO-L-AgNPs were introduced to a gold anodic BPE array, the individual electrodes were subjected to different concentrations of AFM1. Upon the interaction of AFM1 with the aptamers, the GO-L-AgNPs detach from the aptamer; the resulting ECL of luminol and HO at the anodic poles is monitored using a photomultiplier tube (PMT) or smartphone, and the images are analyzed using ImageJ software. This process triggers thionine reduction at the cathodic poles. Under the optimal conditions obtained by a face-centered central composite design (FCCD), the PMT-based detection of the BPE-ECL aptasensor exhibit a linear response over a wide dynamic range from 5 to 150ngmL, with a detection limit of 0.01ngmL. Additionally, smartphone-based detection shows a linear relationship between the ECL image gray value and the logarithmic concentration of the AFM1 target over a range of 10-200ngmL, with a detection limit of 0.05ngmL. Furthermore, the BPE-ECL aptasensor was successfully used to detect AFM1 in milk complex media without any serious interferences with reliable reproducibility (average relative standard deviation (RSD = 2.3%)). This smartphone-based detection opens a new horizon for bioanalysis that does not require a trained technician to operate and is a promising technology for point-of-care testing.
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http://dx.doi.org/10.1016/j.bios.2017.09.035DOI Listing
February 2018

Amplified detection of hepatitis B virus using an electrochemical DNA biosensor on a nanoporous gold platform.

Bioelectrochemistry 2017 Oct 15;117:83-88. Epub 2017 Jun 15.

Department of Chemistry, University of Isfahan, Isfahan 81746-73441, Iran. Electronic address:

In the present study, a nanoporous gold platform was applied for the amplified detection of Hepatitis B virus (HBV) by an electrochemical DNA biosensor. Ferrocene as a redox reporter was covalently attached to the DNA probe and its electrochemical signal was recorded as the biosensor response. For real samples, DNA was firstly extracted from blood of patients and then amplified by polymerase chain reaction (PCR) for 5cycles. Sensitivity of this biosensor was enhanced by using nanoporous gold electrode, therefore this sensor can discriminate the genome of HBV in real sample with low PCR cycles. By this strategy and signal amplification using nanoporous platform and covalently attached electroactive label, the biosensor can distinguish between healthy and HBV patients with limited PCR cycles. Moreover, the errors of PCR with large cycles can be disregarded. A linear dynamic range of 0.4 to 10nmol of mutant DNA was achieved, with reliable reproducibility (RSD) 8.9%.
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http://dx.doi.org/10.1016/j.bioelechem.2017.06.006DOI Listing
October 2017

Aptamer-conjugated Magnetic Nanoparticles as Targeted Magnetic Resonance Imaging Contrast Agent for Breast Cancer.

J Med Signals Sens 2016 Oct-Dec;6(4):243-247

Department of Clinical Biochemistry, School of Pharmacy and Isfahan Pharmaceutical Sciences Research Center, Isfahan University of Medical Sciences, Isfahan, Iran.

Early detection of breast cancer is the most effective way to improve the survival rate in women. Magnetic resonance imaging (MRI) offers high spatial resolution and good anatomic details, and its lower sensitivity can be improved by using targeted molecular imaging. In this study, AS1411 aptamer was conjugated to FeO@Au nanoparticles for specific targeting of mouse mammary carcinoma (4T1) cells that overexpress nucleolin. cytotoxicity of aptamer-conjugated nanoparticles was assessed on 4T1 and HFFF-PI6 (control) cells. The ability of the synthesized nanoprobe to target specifically the nucleolin overexpressed cells was assessed with the MRI technique. Results show that the synthesized nanoprobe produced strongly darkened T-weighted magnetic resonance (MR) images with 4T1 cells, whereas the MR images of HFFF-PI6 cells incubated with the nanoprobe are brighter, showing small changes compared to water. The results demonstrate that in a Fe concentration of 45 μg/mL, the nanoprobe reduced by 90% MR image intensity in 4T1 cells compared with the 27% reduction in HFFF-PI6 cells. Analysis of MR signal intensity showed statistically significant signal intensity difference between 4T1 and HFFF-PI6 cells treated with the nanoprobe. MRI experiments demonstrate the high potential of the synthesized nanoprobe as a specific MRI contrast agent for detection of nucleolin-expressing breast cancer cells.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5157001PMC
December 2016

Amplified detection of leukemia cancer cells using an aptamer-conjugated gold-coated magnetic nanoparticles on a nitrogen-doped graphene modified electrode.

Bioelectrochemistry 2017 Apr 12;114:24-32. Epub 2016 Dec 12.

Department of chemistry, University of Isfahan, Isfahan 81746-73441, Iran. Electronic address:

The increasing demands for early, accurate and ultrasensitive diagnosis of cancers demonstrate the importance of the development of new amplification strategies or diagnostic technologies. In the present study, an aptamer-based electrochemical biosensor for ultrasensitive and selective detection of leukemia cancer cells has been introduced. The thiolated sgc8c aptamer was immobilized on gold nanoparticles-coated magnetic FeO nanoparticles (Apt-GMNPs). Ethidium bromide (EB), intercalated into the stem of the aptamer hairpin, provides the read-out signal for the quantification of the leukemia cancer cells. After introduction of the leukemia cancer cells onto the Apt-GMNPs, the hairpin structure of the aptamer is disrupted and the intercalator molecules are released, resulting in a decrease of the electrochemical signal. The immobilization of nitrogen-doped graphene nanosheets on the electrode surface provides an excellent platform for amplifying the read-out signal. Under optimal conditions, the aptasensor exhibits a linear response over a wide dynamic range of leukemia cancer cells from 10 to 1×10cellmL. The present protocol provides a highly sensitive, selective, simple, and robust method for early stage detection of leukemia cancer. Furthermore, the fabricated aptasensor was successfully used for the detection of leukemia cancer cells in complex media such as human blood plasma, without any serious interference.
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http://dx.doi.org/10.1016/j.bioelechem.2016.12.001DOI Listing
April 2017

Wireless electrochemiluminescence bipolar electrode array for visualized genotyping of single nucleotide polymorphism.

Anal Chem 2015 Aug 29;87(16):8123-31. Epub 2015 Jul 29.

Department of Chemistry, University of Isfahan, Isfahan 81746-73441, Iran.

The development of simple, inexpensive, hand-held, user-friendly biosensor for high throughput and multiplexed genotyping of various single nucleotide polymorphisms (SNPs) in a single run experiment by a nonspecialist user is the main challenge in the analysis of DNA. Visualizing the signal and possibility to monitor SNPs by a digital camera opens a new horizon for the routine applications. In the present manuscript, a novel wireless electrochemiluminescence (ECL) DNA array is introduced for the visualized genotyping of different SNPs on the basis of ECL of luminol/hydrogen peroxide system on a bipolar electrode (BPE) array platform. After modification of anodic poles of the array with the DNA probe and its hybridization with the targets, genotyping of various SNPs is carried out by exposing the array to different monobase modified luminol-platinum nanoparticles (M-L-PtNPs). Upon the hybridization of M-L-PtNPs to mismatch sites, the ECL of luminol is followed using a photomultiplier tube (PMT) or digital camera and the images are analyzed by ImageJ software. This biosensor can detect even thermodynamically stable SNP (G-T mismatches) in the range of 2-600 pM. Also, by combining the advantages of BPE and the high visual sensitivity of ECL, it could be easily expected to achieve sensitive screening of different SNPs. The present biosensor demonstrates the capability for the discrimination between PCR products of normal, heterozygous, and homozygous beta thalassemia genetic disorders.
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http://dx.doi.org/10.1021/acs.analchem.5b02515DOI Listing
August 2015

Dual amplification of single nucleotide polymorphism detection using graphene oxide and nanoporous gold electrode platform.

Analyst 2014 Oct 13;139(20):5192-9. Epub 2014 Aug 13.

Department of Chemistry, University of Isfahan, Isfahan 81746-73441, Iran.

In the present manuscript, a strategy to prompt the sensitivity of a biosensor based on the dual amplification of signal by applying a nanoporous gold electrode (NPGE) as a support platform and soluble graphene oxide (GO) as an indicator has been developed. By increasing the surface area of the biosensing platform and because of unique GO/ss-DNA interactions, the sensitivity for the detection of SNPs is enhanced. In the presence of SNPs, because of less effective hybridization of mutant targets compared to complementary targets, further GO could adsorb on mutant targets-modified NPGE viaπ-π interactions, causing a large increase in the charge transfer resistance (Rct) of the electrode. This protocol provides a cost-effective and fast method for the discrimination of different SNPs. Furthermore, this biosensor can detect thermodynamically stable SNP (G-T mismatches) in the range of 15-1600 pM. The present strategy is a label-free and sensitive protocol and does not require sophisticated fabrication.
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http://dx.doi.org/10.1039/c4an01171fDOI Listing
October 2014

Ultrasensitive detection of human liver hepatocellular carcinoma cells using a label-free aptasensor.

Anal Chem 2014 May 8;86(10):4956-60. Epub 2014 May 8.

Biosensors and Bioelectronics Centre, Institute of Physics, Chemistry and Biology, Linköping University , Linköping S-58183, Sweden.

Liver cancer is one of the most common cancers in the world and has no effective cure, especially in later stages. The development of a tangible protocol for early diagnosis of this disease remains a major challenge. In the present manuscript, an aptamer-based, label-free electrochemical biosensor for the sensitive detection of HepG2, a hepatocellular carcinoma cell line, is described. The target cells are captured in a sandwich architecture using TLS11a aptamer covalently attached to a gold surface and a secondary TLS11a aptamer. The application of TLS11a aptamer as a recognition layer resulted in a sensor with high affinity for HepG2 cancer cells in comparison with control cancer cells of human prostate, breast, and colon tumors. The aptasensor delivered a wide linear dynamic range over 1 × 10(2) to 1 × 10(6) cells/mL, with a detection limit of 2 cells/mL. This protocol provides a precise method for sensitive detection of liver cancer with significant advantages in terms of simplicity, low cost, and stability.
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http://dx.doi.org/10.1021/ac500375pDOI Listing
May 2014

Aptamer-based electrochemical biosensor for detection of adenosine triphosphate using a nanoporous gold platform.

Bioelectrochemistry 2013 Dec 5;94:47-52. Epub 2013 Jun 5.

Department of Chemistry, University of Isfahan, Isfahan 81746-73441, Iran.

In spite of the promising applications of aptamers in the bioassays, the development of aptamer-based electrochemical biosensors with the improved limit of detection has remained a great challenge. A strategy for the amplification of signal, based on application of nanostructures as platforms for the construction of an electrochemical adenosine triphosphate (ATP) aptasensor, is introduced in the present manuscript. A sandwich assay is designed by immobilizing a fragment of aptamer on a nanoporous gold electrode (NPGE) and its association to second fragment in the presence of ATP. Consequently, 3, 4-diaminobenzoic acid (DABA), as a molecular reporter, is covalently attached to the amine-label of the second fragment, and the direct oxidation signal of DABA is followed as the analytical signal. The sensor can detect the concentrations of ATP as low as submicromolar scales. Furthermore, 3.2% decrease in signal is observed by keeping the aptasensor at 4 °C for a week in buffer solution, implying a desirable stability. Moreover, analog nucleotides, including GTP, UTP and CTP, do not show serious interferences and this sensor easily detects its target in deproteinized human blood plasma.
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http://dx.doi.org/10.1016/j.bioelechem.2013.05.005DOI Listing
December 2013

Nanoporous gold electrode as a platform for the construction of an electrochemical DNA hybridization biosensor.

Biosens Bioelectron 2012 Oct-Dec;38(1):252-7. Epub 2012 Jun 7.

Department of Chemistry, Faculty of Science, University of Isfahan, Isfahan 81746-73441, Iran.

The application of a nanoporous gold electrode (NPGE) in the fabrication of an electrochemical sensing system for the detection of single base mismatches (SBMs) using ferrocene-modified DNA probe has been investigated in the present manuscript. Ferrocene carboxylic acid is covalently attached to the amino-modified probe using EDC/NHS chemistry. By covalent attachment of the redox reporter molecules on the top of DNA, the direct oxidation of the ferrocene on the electrode surface is avoided. On the other hand, the electrochemical signals are amplified by anodizing the electrode surface and converting it to nanoporous form. By improving the sensitivity of the biosensor, the different SBMs including the thermodynamically stable G-A and G-T mismatches, can be easily distinguished. In this research, NPGE was prepared by anodization and chemical reduction of Au surface and used for signal amplification. Nanoporous electrode enhances the sensitivity of DNA biosensor and makes it capable to detect complementary target DNA in sub-nanomole scales.
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http://dx.doi.org/10.1016/j.bios.2012.05.040DOI Listing
December 2012

Aptamer-conjugated silver nanoparticles for electrochemical detection of adenosine triphosphate.

Biosens Bioelectron 2012 Aug-Sep;37(1):94-8. Epub 2012 May 8.

Department of chemistry, University of Isfahan, Isfahan 81746-73441, Iran.

The capability of silver nanoparticles (SNP) as redox tag in the construction of an electrochemical aptasensor for the detection of adenosine triphosphate (ATP) is investigated in the present manuscript. To construct the aptasensor, a well-known ATP binding aptamer (ABA) splits into two segments. The first amino-labeled segment of the aptamer was covalently immobilized on 3-mercaptopropionic acid modified gold electrode surface by the formation of carbodiimide bond. The second segment was modified by SNPs and associated with the first segment in the presence of ATP. The direct oxidation signal of SNPs is followed as the analytical signal to detect ATP. The sandwich assay shows a suitable signal gain and importantly, a good response time. The sensor can detect the concentrations of ATP as low as micromolar scales with a desirable stability under optimum conditions. Furthermore, analog nucleotides including GTP, UTP and CTP, do not show serious interferences and this sensor readily detects its target in a complex media such as human blood plasma.
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http://dx.doi.org/10.1016/j.bios.2012.04.045DOI Listing
September 2012

Design and construction of a label free aptasensor for electrochemical detection of sodium diclofenac.

Biosens Bioelectron 2012 Mar 3;33(1):184-9. Epub 2012 Jan 3.

Department of Chemistry, University of Isfahan, Isfahan, 81746-73441, Iran.

The present manuscript describes a label free electrochemical aptasensor for the detection of sodium diclofenac (DCF). In order to construct the biosensor, the amino-functionalized diclofenac binding aptamer (DBA) was covalently immobilized on the surface of the glassy carbon electrode (GCE). The conformation of the DBAs on the surface of the electrode is changed when this is exposed to different concentrations of DCF. The introduction of DCF induces an alteration in the conformation of the surface immobilized DBA and causes a decrease in the charge transfer resistance of the aptasensor. However, the charge transfer resistance is increased by incubation of GCE/DBA/DCF in the secondary DBA. The changes in the charge transfer resistance have been monitored using the voltammetric and electrochemical impedance spectroscopic (EIS) techniques. The aptasensor shows two different linear dynamic ranges over 0-5.0 μM and 10 μM to 1mM, and the sensitivity of 15.7 kΩ μM(-1) and detection limit of 2.7 × 10(-7)M were obtained. The validity of the method and applicability of the aptasensor were successfully evaluated by detection of DCF in a blood serum sample without interference from the sample matrix. Furthermore, the aptasensor has shown good stability.
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http://dx.doi.org/10.1016/j.bios.2011.12.050DOI Listing
March 2012

Silver nanoparticles as redox reporters for the amplified electrochemical detection of the single base mismatches.

Biosens Bioelectron 2011 Jul 16;26(11):4308-13. Epub 2011 Apr 16.

Department of Chemistry, Faculty of Science, University of Isfahan, Isfahan 81746-73441, Iran.

In this manuscript, a strategy for the amplification of the responses of an electrochemical DNA hybridization biosensor using silver nanoparticles (Ag-NPs) as redox reporters and its capability for the detection of a single base mismatches (SBM) including thermodynamically stable ones, is described. In this assay, Ag-NPs are immobilized on the top of recognition layer and their oxidation signals are followed. Differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS) are used to monitoring the electrode response. Only for complementary target sequence, electron can transfer between Electrode surface and nanoparticles via DNA and Ag-NPs can be oxidized. Therefore this DNA biosensor could differentiate between complementary target and one containing either SBM or thermodynamically stable G-A and G-T targets through oxidation signal of Ag-NPs. This biosensor is able to detect SBM by overcome the direct electron transfer of redox reporter with electrode surface and positioning of it before the mismatch position.
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http://dx.doi.org/10.1016/j.bios.2011.04.020DOI Listing
July 2011

Carbon nanofiber electrodes and controlled nanogaps for scanning electrochemical microscopy experiments.

Anal Chem 2006 Oct;78(19):6959-66

Department of Chemistry and Biochemistry and the Center for Nano and Molecular Science, The University of Texas at Austin, Austin, Texas 78712, USA.

The electrochemical behavior of electrodes made by sealing carbon nanofibers in glass or with electrophoretic paint has been studied by scanning electrochemical microscopy (SECM). Because of their small electroactive surface area, conical geometry with a low aspect ratio and high overpotential for proton and oxygen reduction, carbon nanofiber (CNF) electrodes are promising candidates for producing electrode nanogaps, imaging with high spatial resolution and for the electrodeposition of single metal nanoparticles (e.g., Pt, Pd) for studies as electrocatalysts. By using the feedback mode of the SECM, a CNF tip can produce a gap that is smaller than 20 nm from a platinum disk. Similarly, the SECM used in a tip-collection substrate-generation mode, which subsequently shows a feedback interaction at short distances, makes it possible to detect a single CNF by another CNF and then to form a nanometer gap between the two electrodes. This approach was used to image vertically aligned CNF arrays. This method is useful in the detection in a homogeneous solution of short-lifetime intermediates, which can be electrochemically generated at one electrode and collected at the second at distances that are equivalent to a nanosecond time scale.
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http://dx.doi.org/10.1021/ac060723mDOI Listing
October 2006