Portable biosensor for monitoring cortisol in low-volume perspired human sweat

Sci Rep. 2017 Oct 17;7(1):13312. doi: 10.1038/s41598-017-13684-7.

Abstract

A non-faradaic label-free cortisol biosensor was demonstrated using MoS2 nanosheets integrated into a nanoporous flexible electrode system. Low volume (1-5 μL) sensing was achieved through use of a novel sensor stack design comprised of vertically aligned metal electrodes confining semi-conductive MoS2 nanosheets. The MoS2 nanosheets were surface functionalized with cortisol antibodies towards developing an affinity biosensor specific to the physiological relevant range of cortisol (8.16 to 141.7 ng/mL) in perspired human sweat. Sensing was achieved by measuring impedance changes associated with cortisol binding along the MoS2 nanosheet interface using electrochemical impedance spectroscopy. The sensor demonstrated a dynamic range from 1-500 ng/mL with a limit of detection of 1 ng/mL. A specificity study was conducted using a metabolite expressed in human sweat, Ethyl Glucuronide. Continuous dosing studies were performed during which the sensor was able to discriminate between four cortisol concentration ranges (0.5, 5, 50, 500 ng/mL) for a 3+ hour duration. Translatability of the sensor was shown with a portable form factor device, demonstrating a comparable dynamic range and limit of detection for the sensor. The device demonstrated a R2 correlation value of 0.998 when comparing measurements to the reported impedance values of the benchtop instrumentation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Biosensing Techniques / instrumentation*
  • Biosensing Techniques / methods
  • Disulfides / chemistry
  • Electrochemical Techniques / instrumentation
  • Electrochemical Techniques / methods
  • Humans
  • Hydrocortisone / analysis*
  • Molybdenum / chemistry
  • Nanostructures / chemistry
  • Sweat / chemistry*

Substances

  • Disulfides
  • Molybdenum
  • Hydrocortisone
  • molybdenum disulfide