Category: Micro- and Nanotechnologies
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 comprising of vertically aligned metal electrodes confining the semi-conductive MoS2 nanosheets. 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. Validation of the assay construction was accomplished through ATR Fourier transform infrared spectroscopy (FTIR) as well as zeta potential measurements. 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 within the physiologically relevant range of cortisol in perspired sweat 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, demonstrating no significant response. A continuous dosing study was 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 demonstrated with the development of a portable form factor electronic device. The device conducted impedance measurements on the cortisol biosensor demonstrating a comparable dynamic range and limit of detection when compared to a conventional benchtop potentiostat, as well as demonstrating dose discrimination during the continuous dosing study. The device demonstrated a R2 correlation value of 0.998 when comparing impedance measurements to the reported values of the benchtop potentiostat. This work stands to benefit two populations of people. The first group being the percentage of the population considered to be generally sedentary, where there is a need for dynamic and non-invasive monitoring of crucial biomolecules associated with chronic conditions such as diabetes, stress, heart disease, and cancer. The second being highly specialized populations, namely astronauts, where dynamic monitoring of specific biomarkers is essential in the diagnosis of dynamically changing conditions associated with prolonged exposures to space travel, and where a portable form factor is imperative.
David Kinnamon– Research Engineer, University of Texas At Dallas, Plano, TX
University of Texas At Dallas
David Kinnamon is a Research Engineer working in the Biomedical Microdevices and Nanotechnology Laboratory (BMNL) at the University of Texas at Dallas under Dr. Shalini Prasad. David started as an undergraduate volunteer in BMNL his junior year before entering the fast-track program, completing his BS and MS degrees in Biomedical Engineering in 5 years. His Master's thesis focused on developing a portable biosensor for sweat-based detection of EtG, a metabolite of alcohol consumption, for chronic alcohol consumption monitoring. David worked his way from a volunteer, to student worker, to research assistant, and now staff as a member of BMNL where he works on multiple research projects, while also serving as a lab manager. He is in his first year as a Research Engineer, and is focusing on generating multiple publications before returning to school to seek his doctorate in 2018.