Towards the development of a sensitive and selective electrochemical aptamer-based ampicillin sensor

Zhi gang Yu, Arin L. Sutlief, Rebecca Y. Lai

Research output: Contribution to journalArticlepeer-review

55 Scopus citations


We report the design and fabrication of a “signal-on” electrochemical aptamer-based (E-AB) sensor for detection of ampicillin (AMP). The conventional E-AB sensor is fabricated on a gold disk electrode using a thiolated and methylene blue (MB)-modified DNA aptamer probe. Binding of AMP alters the probe conformation and flexibility, resulting in an increase in the MB signal. However, this target-induced change in conformation and flexibility is insufficient to generate a large signal gain. To circumvent the issue with limited signal gain, we employed a displacement-based approach to the design of this sensor. For the displacement-based E-AB sensor, the aptamer probe is first hybridized to a displacement probe (DP) of a specific length and/or Tm; binding of AMP to the aptamer probe displaces the DP from the DNA duplex. This change in probe conformation and flexibility should produce a substantial increase in the MB signal. The extent of the signal gain, however, is dependent on the length and/or Tm of the DP. Among the nine DPs used in this study, the 12-base S7 probe is ideal for the displacement-based sensor design. The S7 sensor has a lower limit of detection and a broader linear dynamic range when compared to the conventional E-AB sensor. Despite being a displacement-based sensor, the response time of the S7 sensor is short, and signal saturation can be achieved in <80 s. It is also specific and selective enough to be employed directly in 50% milk, urine, saliva, and aquifer water. With further optimization, this sensor could find applications in clinical and environmental analysis of AMP.

Original languageEnglish (US)
Pages (from-to)722-729
Number of pages8
JournalSensors and Actuators, B: Chemical
StatePublished - Apr 1 2018


  • Alternating current voltammetry
  • Ampicillin
  • Displacement probe
  • Electrochemical aptamer-based sensor
  • Melting temperature
  • Methylene blue

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Instrumentation
  • Condensed Matter Physics
  • Surfaces, Coatings and Films
  • Metals and Alloys
  • Electrical and Electronic Engineering
  • Materials Chemistry


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