Non-invasive sweat cortisol quantification via an electrochemical aptasensor built on MXene-derived bimetallic MOFs

This is the authors' abstract. We don't add key points for this paper.

Accurate and non-invasive quantification of cortisol, an essential human steroid hormone, is important for the early screening and clinical management of related diseases. Traditional electrochemical sensing platforms employing metal-organic frameworks (MOFs) frequently suffer from inadequate electrical conductivity, sluggish interfacial electron dynamics, and poor surface adhesion. To overcome existing limitations, two-dimensional Ti 3 C 2 T x MXene was utilized as a starting material in a metal-ion-mediated reaction to produce three-dimensional Ti-Cu bimetallic metal–organic frameworks (Ti-Cu BMOFs) with an increased specific surface area. An electrochemical aptamer-based sensor was then assembled by coating a screen-printed electrode (SPE) with these Ti-Cu BMOFs. Finally, gold nanoparticles (AuNPs) were electrodeposited onto the framework, facilitating the stable immobilization of cortisol-specific aptamers while further enhancing the electrical conductivity of the sensing interface. The sensor demonstrated a linear response to cortisol across a 0.1 nM to 1 μM range, with a limit of detection (LOD) of 37.6 pM. It exhibited selectivity, reproducibility (relative standard deviation (RSD) < 5%), and four-week storage stability. The quantitative results from the sweat samples of healthy volunteers were comparable to those obtained with a commercial enzyme-linked immunosorbent assay (ELISA) method, with relative errors of 2.48% or less. This work presents a new sensing-interface strategy for sensitive and non-invasive cortisol quantification in human sweat samples.