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Simultaneous DNA amplification and detection using a pH-sensing semiconductor system


We developed an integrated chip for real-time amplification and detection of nucleic acid using pH-sensing complementary metal-oxide semiconductor (CMOS) technology. Here we show an amplification-coupled detection method for directly measuring released hydrogen ions during nucleotide incorporation rather than relying on indirect measurements such as fluorescent dyes. This is a label-free, non-optical, real-time method for detecting and quantifying target sequences by monitoring pH signatures of native amplification chemistries. The chip has ion-sensitive field effect transistor (ISFET) sensors, temperature sensors, resistive heating, signal processing and control circuitry all integrated to create a full system-on-chip platform. We evaluated the platform using two amplification strategies: PCR and isothermal amplification. Using this platform, we genotyped and discriminated unique single-nucleotide polymorphism (SNP) variants of the cytochrome P450 family from crude human saliva. We anticipate this semiconductor technology will enable the creation of devices for cost-effective, portable and scalable real-time nucleic acid analysis.

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Figure 1: Correlation between pH signal and amplification.
Figure 2: Schematic representation of pH-sensing integrated circuit platform.
Figure 3: On-chip amplification and detection using pH-PCR and pH-LAMP.
Figure 4: Evaluation of integrated circuit sensitivity.
Figure 5: SNP typing of CYP2C19*2 and CYP2C19*17.


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We thank T.S.K.T. Lim for his support and vision in semiconductor-based DNA analysis, T. Cass for his guidance and expert opinion, and the entire DNA Electronics team for their contributions to our wider work.

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Authors and Affiliations



C.T. invented the technology and supervised the project with S.C.R. and L.M.S.; D.M.G., H.B., B.C., P.G. and J.C.J. designed the chips and electronics; A.P., P.A. and D.C.-A. designed the integrated test card, fluidics and electrochemistry; C.-P.O., C.-J.A.W., M.L.M., L.Z., A.P. and G.I.C. designed the molecular biological methods and assays; G.I.C., K.A.-D., K.S.J., R.E.T., D.C.-A., D.M., S.S., S.T. and I.M.Q.B. performed the research; G.I.C., L.M.S., S.C.R., C.-P.O., C.-J.A.W. and P.G. wrote the manuscript.

Corresponding authors

Correspondence to Christofer Toumazou or Leila M Shepherd.

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Competing interests

C.T., L.M.S., S.C.R., G.I.C., A.P., D.M.G., C.-P.O., K.A.-D., M.L.M., H.B., L.Z., K.S.J., P.A., D.C.-A., B.C., R.E.T. and D.M. are employees of DNA Electronics Ltd. and have stock or stock options in the company.

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Toumazou, C., Shepherd, L., Reed, S. et al. Simultaneous DNA amplification and detection using a pH-sensing semiconductor system. Nat Methods 10, 641–646 (2013).

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