Interfacial Tuning for Detection of Cortisol in Sweat Using ZnO Thin Films on Flexible Substrates

We have demonstrated the detection of stress hormone cortisol from sweat using a flexible biosensing platform. Sweat-based detection faces many challenges such as stability of electrodes, sensitivity, and specificity. The surface states of zinc oxide (ZnO) can be leveraged for immobilizing various linker molecules for ultraspecific detection of biomolecules. In this study, we have used thiol-based linker molecule for binding to zinc terminations. We tested DSP from 5 to 100 mmol concentration in order to understand the effect of varying molarity on the electron transport properties of ZnO thin films. We performed electrochemical impedance spectroscopy measurements and Mott–Schottky analysis after incubation of the dispensed DSP linker on ZnO thin films. The optimized concentration of DSP was further incorporated in the immunoassay for detection of cortisol from 1 to 200 ng/mL spiked in sweat.

[1]  W. Marsden.  I and J , 2012 .

[2]  David P. Norton,et al.  Functionalizing Zn- and O-terminated ZnO with thiols , 2007 .

[3]  Jagdeep Singh,et al.  Thiol adsorption on metal oxides: an approach for selective deposition on zinc oxide nanoparticles , 2011, OPTO.

[4]  K. Uosaki,et al.  Effects of the Helmholtz Layer Capacitance on the Potential Distribution at Semiconductor/Electrolyte Interface and the Linearity of the Mott‐Schottky Plot , 1983 .

[5]  Shekhar Bhansali,et al.  Ultrasensitive detection of cortisol with enzyme fragment complementation technology using functionalized nanowire. , 2007, Biosensors & bioelectronics.

[6]  Aaas News,et al.  Book Reviews , 1893, Buffalo Medical and Surgical Journal.

[7]  S. Bhansali,et al.  Recent advances in ZnO nanostructures and thin films for biosensor applications: review. , 2012, Analytica chimica acta.

[8]  Ping Wang,et al.  The application of complex multiple forklike ZnO nanostructures to rapid and ultrahigh sensitive hydrogen peroxide biosensors. , 2010, Biomaterials.

[9]  Yicheng Lu,et al.  ZnO thin film transistor immunosensor with high sensitivity and selectivity , 2011 .

[10]  Jason Heikenfeld,et al.  Bioanalytical devices: Technological leap for sweat sensing , 2016, Nature.

[11]  Shekhar Bhansali,et al.  Electrochemical cortisol immunosensors based on sonochemically synthesized zinc oxide 1D nanorods and 2D nanoflakes. , 2015, Biosensors & bioelectronics.

[12]  Shekhar Bhansali,et al.  Electrochemical Immunosensing of Saliva Cortisol , 2014 .

[13]  S. Migot,et al.  Near-room temperature single-domain epitaxy of reactively sputtered ZnO films , 2013 .

[14]  Shibu Saha,et al.  Influence of surface defects in ZnO thin films on its biosensing response characteristic , 2011 .

[15]  G. Ceder,et al.  First-principles study of native point defects in ZnO , 2000 .

[16]  M. Rahman,et al.  Highly-sensitive cholesterol biosensor based on well-crystallized flower-shaped ZnO nanostructures. , 2009, Talanta.

[17]  Magnus Willander,et al.  A fast and sensitive potentiometric glucose microsensor based on glucose oxidase coated ZnO nanowires grown on a thin silver wire , 2010 .

[18]  E. Tamechika,et al.  Graphene-modified Interdigitated Array Electrode: Fabrication, Characterization, and Electrochemical Immunoassay Application , 2013, Analytical Sciences.

[19]  N. Pourmand,et al.  Label-Free Impedance Biosensors: Opportunities and Challenges. , 2007, Electroanalysis.

[20]  Ali Al-Hajry,et al.  Effect of nanostructure on the urea sensing properties of sol-gel synthesized ZnO , 2009 .

[21]  Magnus Willander,et al.  The pH Response and Sensing Mechanism of n-Type ZnO/Electrolyte Interfaces , 2009, Sensors.

[22]  Anderson Janotti,et al.  Fundamentals of zinc oxide as a semiconductor , 2009 .

[23]  J. Narang,et al.  Construction of a triglyceride amperometric biosensor based on chitosan-ZnO nanocomposite film. , 2011, International journal of biological macromolecules.

[24]  Susana Campuzano,et al.  Disposable immunosensor for cortisol using functionalized magnetic particles. , 2010, The Analyst.