A DNA sequence-specific electrochemical biosensor based on alginic acid-coated cobalt magnetic beads for the detection of E. coli

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• 作者：Ping Geng^a ; Xinai Zhang^a ; Yingqiao Teng^a ; Ying Fu^a ; Lili Xu^a ; Min Xu^b ; ; Litong Jin^a ; Wen Zhang^a ; ^{wzhang@chem.ecnu.edu.cn}
• 关键词：DNA electrochemical biosensor ; Magnetic beads ; Hybridization detection ; E. coli
• 刊名：Biosensors and Bioelectronics
• 出版年：2011
• 出版时间：15 March 2011
• 年：2011
• 卷：26
• 期：7
• 页码：3325-3330
• 全文大小：810 K

文摘

A new type of DNA sequence-specific electrochemical biosensor based on magnetic beads for the detection of Escherichia coli is reported in the present work. Alginic acid-coated cobalt magnetic beads, capped with 5′-(NH₂) oligonucleotide and employed not only for magnetic separation but also as the solid adsorbent, were used as DNA probes to hybridize with the target E. coli DNA sequence. This assay was specific for E. coli detection depending on the uid A gene, which encodes for the enzyme β-d-glucuronidase produced by E. coli strains. When daunomycin (DNR) was used as DNA hybridization indicator, the target sequences of E. coli hybridized with the probes resulted in the decrease of DNR reduction peak current, which was proportional to the E. coli concentration. The optimization of the hybridization detection was carried out and the specificity of the probes was also demonstrated. This DNA biosensor can be employed to detect a complementary target sequence for 3.0 × 10⁻¹⁰ mol/L and denatured PCR products for 0.5 ng/μL. The linear range of the developed biosensor for the detection of E. coli cells was from 1.0 × 10² to 2.0 × 10³ cells/mL with a detection limit of 50 cells/mL. After a brief enrichment process, a concentration of 10 cells/mL E. coli in real water samples was detected by the electrochemical biosensor.