title: Integrated biochip for label-free and real-time detection of DNA amplification by contactless impedance measurements based on interdigitated electrodes.
abstract: Here, we introduce an integrated biochip which offers accurate thermal control and sensitive electrochemical detection of DNA amplification in real-time. The biochip includes a 10-μl microchamber, a temperature sensor, a heater, and a contactless impedance biosensor. A pair of interdigitated electrodes is employed as the impedance biosensor and the products of the amplification are determined directly through tracing the impedance change, without using any labels, redox indicators, or probes. Real-time monitoring of strand-displacement amplification and rolling circle amplification was successfully performed on the biochip and a detection limit of 1 nM was achieved. Amplification starting at an initial concentration of 10 nM could be discriminated from that starting at 1 nM started concentration as well as from the negative control. Since an insulation layer covers the electrodes, the electrodes are spared from erosion, hydrolysis and bubble formation on the surface, thus, ensuring a long lifetime and a high reusability of the sensor. In comparison to bench-top apparatus, our chip shows good efficiency, sensitivity, accuracy, and versatility. Our system requires only simple equipments and simple skills, and can easily be miniaturized into a micro-scale system. The system will then be suitable for a handheld portable device, which can be applied in remote areas. It covers merits such as low cost, low-power consumption, rapid response, real-time monitoring, label-free detection, and high-throughput detection.
authors.affiliation: State Key Laboratory of Transducer Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Science, Shanghai, China.
authors.forename: Xinxin
authors.initials: X
authors.lastname: Fang
authors.forename: Qinghui
authors.initials: Q
authors.lastname: Jin
authors.forename: Fengxiang
authors.initials: F
authors.lastname: Jing
authors.forename: Huanqian
authors.initials: H
authors.lastname: Zhang
authors.forename: Feng
authors.initials: F
authors.lastname: Zhang
authors.forename: Hongju
authors.initials: H
authors.lastname: Mao
authors.forename: Baojian
authors.initials: B
authors.lastname: Xu
authors.forename: Jianlong
authors.initials: J
authors.lastname: Zhao
mesh_terms: D015374:Biosensing Techniques / Q000191:economics / Q000295:instrumentation; D004247:DNA / Q000032:analysis*; D017097:Electric Impedance; D055664:Electrochemical Techniques / Q000191:economics / Q000295:instrumentation*; D004566:Electrodes; D004867:Equipment Design; D021141:Nucleic Acid Amplification Techniques / Q000191:economics / Q000295:instrumentation*; D020411:Oligonucleotide Array Sequence Analysis / Q000295:instrumentation*; D012680:Sensitivity and Specificity
chemical_list: D004247:DNA