Label-Free Sensitive Detection of Steroid Hormone Cortisol Based on Target-Induced Fluorescence Quenching of Quantum Dots

Abstract

We discovered that several types of steroid hormones quench the fluorescence of quantum dots (QDs) at close proximity. Inspired by the finding, we developed a new type of biosensor for the sensitive detection of cortisol via direct fluorescence quenching of functionalized QD probes directly induced by the capture of target cortisol without additional reporter reagents. The detection selectivity was provided by cortisol-selective aptamers or anticortisol antibodies conjugated on the QD surfaces. With the magnetic nanoparticle labeling, the new sensing method enabled rapid cortisol sensing at physiologically relevant concentrations and yielded the detection limit of ∼1 nM for aptamer-based sensors and ∼100 pM for antibody-based sensors. We also evaluated the new detection method using saliva samples with an optimized sample preparation process under the assistance of magnetic manipulation. The result showed a satisfying recovery rate for spiked saliva tests. The facile sensing technology offers an appealing approach for the detection of steroid hormones in point-of-care settings.

A Disposable Printed Liquid Gate Graphene Field Effect Transistor for a Salivary Cortisol Test

“…The other chemicals are TCPP, 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC·HCl), N -hydroxysuccinimide (NHS), cortisone, and corticosterone, which were purchased from Shanghai Yuanye Biological Technology Co., Ltd., China. The cortisol nucleic acid aptamer probe is a 3′-amino-modified oligonucleotide with a sequence of 5′-GGAAT GGATC CACAT CCATG GATGG GCAAT GCGGG GTGGA GAATG GTTGC CGCAC TTCGG CTTCA CTGCA GACTT GACGA AGCTT-3′ in a purified HPLC degree, , purchased from Shanghai Sangon Biotech, China.…”

“…Therefore, the TCPP decoration may not only make Lg-GFETs sensitive to cortisol but also cover the oxygen-containing groups and inhibit the response for pH variations in saliva samples. Recently developed cortisol aptamers made a good contribution to cortisol sensing, , so in this work, it was covalently anchored on the TCPP-modified Lg-GFET to capture the cortisol molecules. The biofunctionalization protocol is seriously evaluated in different background solutions, i.e., phosphate buffer solution (PBS), artificial saliva, and real saliva.…”

New Trends in Fluorescent Nanomaterials-Based Bio/Chemical Sensors for Neurohormones Detection─A Review

“…High variations of cortisol levels occur during stressed status; hence, it is considered the major stress hormone. 46 , 138 , 187 Anomalous increments in cortisol concentration can inhibit inflammation, depress the immune system, and increase fatty and amino acid levels in blood. Extremely high levels can cause Cushing’s disease, while decreased cortisol levels lead to Addison’s disease.…”

Molecularly imprinted electrochemical aptasensor based on functionalized graphene and nitrogen-doped carbon quantum dots for trace cortisol assay

“…3 Cortisol levels are associated with post-traumatic stress disorder, depression disorder and Cushing's syndrome. 4–6 Therefore, maintaining a proper cortisol balance is essential to human health. In recent years, salivary sampling has attracted considerable attention in the analysis and detection of cortisol concentration.…”