A highly selective and sensitive electrochemical CS–MWCNTs/Au-NPs composite DNA biosensor for Staphylococcus aureus gene sequence detection

• Published in: Talanta (Oxford) 2015-08, Vol.141, p.300-306
• Main Authors: Sun, Yange, He, Xingxing, Ji, Jian, Jia, Min, Wang, Zhouping, Sun, Xiulan
• Format: Article
• Language: English
• Subjects: Animals; Bacterial Proteins - genetics; Biosensing Techniques - instrumentation; Biosensing Techniques - methods; Calibration; DNA biosensor; Electrochemical Techniques - instrumentation; Electrochemical Techniques - methods; Electrodes; Equipment Design; Gold - chemistry; Gold nanoparticles; Immobilized Nucleic Acids; Methylene blue (MB); Methylene Blue - chemistry; Micrococcal Nuclease - genetics; Milk - microbiology; MWCNTs; Nanoparticles - chemistry; Nanotubes, Carbon; Polymerase Chain Reaction; Sensitivity and Specificity; Staphylococcus aureus; Staphylococcus aureus - genetics; Water Microbiology
• ISSN: 0039-9140; 1873-3573
• DOI: 10.1016/j.talanta.2015.03.052

This paper presents a new electrochemical DNA biosensor constructed using a substrate electrode composed of a novel nanocomposite material prepared using gold nanoparticles (Au-NPs) and multiwalled carbon nanotubes (MWCNTs) and further modified with an Au electrode (AuE), which was used as the substrate electrode. A single-stranded DNA (ssDNA) probe was immobilized on the Au-NPs/CS–MWCNTs/AuE electrode by means of facile gold–thiol affinity, which resulted in hybridization with the target ssDNA sequence. Hybridization reactions were assessed by using the reduction peak current of methylene blue (MB) as an electrochemical indicator. The advantages of the nanomaterials were found to include high surface area, favorable electronic properties, and strong electrocatalytic activity. The amount of ssDNA adsorbed on the electrode surface was increased and the electrochemical response of MB accelerated. The differential pulse voltammetric responses of MB were in line with the specific target ssDNA sequence within the concentration range 1.0×10−15–1.0×10−8M with the detection limit 3.3×10−16M (3σ). In the colony forming unit (CFU) we were able to detect 10CFUmL−1of Staphylococcus aureus in the tap water, achieving good discrimination ability between one- and three-base mismatched ssDNA sequences. The polymerase chain reaction (PCR) amplification products of S. aureus nuc gene sequence were also detected with satisfactory results. [Display omitted] •Methylene blue (MB) is utilized as the electrochemical hybridization indicator.•The proposed strategy could detect the target DNA down to the level of 3.3×10−16M.•We applied this sensor for the analysis of real samples (water) with 10CFUmL−1.