MohammadEbrahim Minaee; Mojtaba Saadati; Mostafa Najafi; Hossein Hinari
Volume 22, Issue 5 , November and December 2015, , Pages 797-804
Abstract
Background & Objectives: Nanobiosensors could be used instead of traditional detection methods of Escherichia coli O157:H7. In this paper, a nanobiosensor for detection of rfbE gene of the Escherichia coli O157:H7 has been studied by immobilization and hybridization single strand DNA (ssDNA) sequences ...
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Background & Objectives: Nanobiosensors could be used instead of traditional detection methods of Escherichia coli O157:H7. In this paper, a nanobiosensor for detection of rfbE gene of the Escherichia coli O157:H7 has been studied by immobilization and hybridization single strand DNA (ssDNA) sequences on the electrode surface modified with gold nanoparticles.
Materials & Methods: Electrochemical impedance spectroscopy technique was used to study the properties of the sensing modified electrode. The working electrode surface was modified by electrochemical method with gold nanoparticles. The single-stranded DNA sequence using self-assembled monolayer was immobilized on the gold electrode for two hours. A mixed monolayer comprising both mercaptohexanol (MCH) and mercaptopropionic acid (MPA) were used as blocking layer. The hybridization DNA/DNA was performed by immersion of the modified gold electrode into ssDNA at a concentration of 1 μM target DNA.
Results: The results showed that the electrode modified with gold nanoparticles after immobilizing ssDNA effectively detected rfbE gene of Escherichia coli O157:H7 by DNA hybridization . The nanobiosiosensor showed suitable selectivity for the detection of target DNA complementary sequence compared with the mismatched oligonucleotides sequence and the noncomplementary oligonucleotides sequence.
Conclusion: According to the results obtained and similar studies, the electrochemical nanobiosensor based on DNA hybridization has advantages such as low cost, simplicity, and miniaturization and can provide a basis for the development of genomic detection tools.
Babak barati; Shahram Nazarian; Mehdi Shirazi; Nasibeh Ghorbani; Mojtaba Saadati; Mohammadbagher Salehi; Hadi Shirzad
Volume 16, Issue 4 , January and February 2010, , Pages 221-227
Abstract
Background and Purpose: Typhoid fever, a disease caused by Salmonella typhi, is still one of the most important infectious diseases across the world. Different methods such as biochemical and Elisa methods are used for detection of this bacterium, which produce false responses in addition to being time-consuming ...
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Background and Purpose: Typhoid fever, a disease caused by Salmonella typhi, is still one of the most important infectious diseases across the world. Different methods such as biochemical and Elisa methods are used for detection of this bacterium, which produce false responses in addition to being time-consuming and expensive. Therefore, the present research was conducted to detect Salmonella typhi by PCR method which is rapid, inexpensive and specific. Materials and methods: In this descriptive study which was conducted via diagnostic method, polymerase chain reaction (PCR) assay was developed for detection of Salmonella typhi. This strain had formerly been confirmed by biochemical methods. For detection by PCR, one primer pair was designed, being specific to ViaB gene. The PCR product was digested by restricted enzyme. For specificity of assay, 6 different strains were used as control negative and for sensitivity of PCR reaction, serial dilution of bacteria was used. Results: The PCR product of Salmonella typhi was 530 bp which were then confirmed by digestion enzymes. In testing the specificity of the assay, Salmonella typhimorium, Shigella flexneri, E. coli, Clostridium botulinum, Staphylococcus aureus and Bacillus subtilis were used as negative control, and did not yield a PCR product. The sensitivity of this method was estimated to be about 50 CFU/ml. Conclusion: The results of this study suggest that detection of ViaB gene with PCR method can be used for diagnossis of Salmonella typhi in clinical samples as a rapid, inexpensive, specific and highly sensitive method.
B BARATI; M SHIRAZI; M SAADATI; MJ SOLTANPOUR
Volume 14, Issue 2 , July and August 2007, , Pages 117-127
Abstract
Background and purpose: Staphylococcus aureus is a pathogen which can cause food poisoning, under certain conditions though growth in nutrients and producing enterotoxin. Only some strains are capable of producing enterotoxin and causing food poisoning and their presence can be detected by DNA amplification ...
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Background and purpose: Staphylococcus aureus is a pathogen which can cause food poisoning, under certain conditions though growth in nutrients and producing enterotoxin. Only some strains are capable of producing enterotoxin and causing food poisoning and their presence can be detected by DNA amplification and gene sequence specification. Therefore, this research was conducted to detect type e enterotoxin producing staphylococcus aureus.
Methods and Materials: 95 staphylococcus aureus strains were isolated from 150 nasal carriers using sterilized swabs and were confirmed by biochemical tests. Then primers were designed and the PCR was used to amplify amplify the staphylococcal enterotoxin e gene (sec) in order to detect type C enterotoxogenic strains.
Results: DNA amplification fragments of 397 bp for staphylococcal nuclease and those of 271 bp for type e gene were confirmed by enzymatic digestion. Only 9.5% of the isolated strains contained sec gene. Specificity and sensitivity were also evaluated and its sensitivity was found to be 125 cells.
Conclusion: this technique is a rapid, sensitive, specific, inexpensive and different alternative to conventional biochemical and serologic assays and it can be used to detect the agent producing type C staphylococcal enterotoxin.