Molecularly imprinted polymer on roll-to-roll printed electrodes as a single use sensor for monitoring of cortisol in sweat

Abstract

Cortisol is involved in regulating many human physiological functions, with cortisol imbalance capable of causing adverse mental and physical health conditions. Existing tools for monitoring of cortisol can assist in alerting the need for mediation strategies, but these typically require time consuming processes such as sample preparation followed by laboratory analysis. This work demonstrates a miniature flexible sensor patch incorporating electrode structures produced by high throughput roll-to-roll rotary screen-printing process, which are subsequently functionalized by electropolymerization of a polypyrrole/Prussian blue molecularly imprinted polymer for measuring cortisol by chronoamperometry. The developed single use sensor patch provides acceptable selectivity for cortisol and operates in artificial eccrine perspiration across a broad concentration range of 0.1-10000 ng/mL (R 2 = 0.916). In the application of measuring thermally induced sweat, the sensor provided results in agreement with the natural circadian rhythm of fluctuating cortisol.

Development of a Redox-Label-Doped Molecularly Imprinted Polymer on β-Cyclodextrin/Reduced Graphene Oxide for Electrochemical Detection of a Stress Biomarker

“…The overoxidation method was adopted over elution using organic solvents so that the excess swelling or phase separation of PPy film can be avoided, which may distort the imprinted sites and negatively affect performance. 48 The overoxidation for elution was performed in PBS containing 5 mM HCF. The voltammogram for both the MIP and NIP ( Figure 3 c,d) is observed to be shrinking with successive cycles.…”

“…This was achieved by overoxidation of PPy which changes the charge density of the polymer and weakens hydrogen bonding between PPy and cortisol. The overoxidation method was adopted over elution using organic solvents so that the excess swelling or phase separation of PPy film can be avoided, which may distort the imprinted sites and negatively affect performance . The overoxidation for elution was performed in PBS containing 5 mM HCF.…”

Molecularly Imprinted Polymer-Based Sensor for Electrochemical Detection of Cortisol

“…The polymerization process begins with the preparation of a solution containing monomers, molecular templates, porogenic solvents, and cross-linkers. Pyrrole was the most frequently used monomer for the MIP cortisol production process [ 70 , 71 , 72 , 73 ], followed by o-phenylenediamine [ 4 , 74 ]. Pyrrole is considered an appropriate monomer because it is conductive, can be synthesized in a liquid medium, and is chemically stable, especially at neutral pH.…”

“…There are also limitations regarding the template removal process in the electro-polymerization method, during which prolonged exposure to organic solvents is avoided, and PBS is used as a template removal agent. Research conducted by Gillan et al demonstrated that organic solvents could cause swelling and damage to the MIP cavity due to prolonged immersion [ 71 ]. Figure 4 displays procedures in MIP formation via surface imprinting by applying cyclic voltammetry.…”

“…During the polymerization process, there is an interaction between cortisol and the monomer, resulting in an extensive binding affinity. At the molecular level, hydrogen bonds are formed by the oxygen atom interaction in the carboxyl group of cortisol with the nitrogen atom of pyrrole and the oxygen atom interaction in the hydroxyl group of cortisol with the nitrogen atom of pyrrole [ 71 ].…”