In this study, we developed a dental floss-based on-demand point-of-care diagnostic platform for noninvasive, real-time quantitative analysis of salivary cortisol using molecularly imprinted polymer structures embedded with redox molecules and thread-like microfluidics.
Here, we explored high-surface-area graphene-based electrode substrates for electrochemical synthesis of selective cortisol molecularly imprinted polymers and combined them with thread-like microfluidics to construct a highly sensitive cortisol sensing platform for stress monitoring.
The platform uses dental floss to collect saliva and delivers it to a flexible electrochemical sensor via capillary microfluidics, where the stress biomarker cortisol is measured. This strategy enabled us to detect cortisol as low as 0.048 pg mL –1 in real time with a detection range of 0.10–10,000 pg mL –1 ( R2 = 0.9916).
The saliva-sensing dental floss provides results within 11–12 minutes. The thread-based microfluidic design minimizes interference and ensures consistent repeatability when testing artificial and real human saliva samples, with recoveries of 98.64-102.4% and a relative standard deviation of 5.01%, demonstrating high accuracy and precision.
For human saliva samples (as part of a stress study), the platform showed high correlation (r = 0.9910) with traditional ELISA test results. Combined with wireless readout capabilities, this saliva floss provides a convenient method for daily monitoring of stress levels. It can be expanded to detect other key salivary biomarkers with high sensitivity and selectivity in complex environments.
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