Ultrasensitive Stress Biomarker Detection Using Polypyrrole Nanotube Coupled to a Field-Effect Transistor

Abstract

Stress biomarkers such as hormones and neurotransmitters in bodily fluids can indicate an individual’s physical and mental state, as well as influence their quality of life and health. Thus, sensitive and rapid detection of stress biomarkers (e.g., cortisol) is important for management of various diseases with harmful symptoms, including post-traumatic stress disorder and depression. Here, we describe rapid and sensitive cortisol detection based on a conducting polymer (CP) nanotube (NT) field-effect transistor (FET) platform. The synthesized polypyrrole (PPy) NT was functionalized with the cortisol antibody immunoglobulin G (IgG) for the sensitive and specific detection of cortisol hormone. The anti-cortisol IgG was covalently attached to a basal plane of PPy NT through an amide bond between the carboxyl group of PPy NT and the amino group of anti-cortisol IgG. The resulting field-effect transistor-type biosensor was utilized to evaluate various cortisol concentrations. Cortisol was sensitively measured to a detection limit of 2.7 × 10−10 M (100 pg/mL), with a dynamic range of 2.7 × 10−10 to 10−7 M; it exhibited rapid responses (<5 s). We believe that our approach can serve as an alternative to time-consuming and labor-intensive health questionnaires; it can also be used for diagnosis of underlying stress-related disorders.

Open‐Bandgap Graphene‐Based Field‐Effect Transistor Using Oligo(phenylene‐ethynylene) Interfacial Chemistry

“…The curves appeared linear and were slightly decreased from 1.38 to 1.2 upon conjugation of magainin I with the amine group of the OPE terminus. Although the conductivity (Δ I /Δ V ) was decreased by functionalization, the curves followed Ohm's law and maintained ohmic behavior [20, 40, 41] . Figure 4c illustrates the 3D structures and the amino acid sequence of magainin I for the specific detection of Gram‐negative bacteria.…”

A Portable Graphene Micropatterned Field-Effect Transistor Device for Rapid Real-Time Monitoring of Serotonin

“…where 𝑁 is the normalized sensitivity, 𝐶 is the concentration of serotonin, and the obtained 𝐾 value for serotonin was 1.63 × 10 −10 M −1 [31]. To demonstrate selective detection, real-time monitoring was carried out by using the interfering materials cortisol, epinephrine, oxytocin, and dopamine as neurotransmitters, and tryptamine as a precursor [Fig.…”

Biosensors Based on Mechanical and Electrical Detection Techniques

“…Furthermore, FET surfaces can be functionalised effectively through the formation of nanowires for the channel between source and drain. This has been proven to decrease the limit of detection down to incredibly small concentrations by Kim et al with the use of polypyrole nanotubes [ 233 ]. The nanotubes were deposited across interdigitated source and drain electrodes and functionalised with immunoglobulin G. When the cortisol analyte was added, it bound to the immunoglobulin G and increased the current between source and drain, as illustrated in Figure 19 .…”

“…( b ) S and D represent source and drain electrodes, while the gate electrode was immersed in the buffer as a liquid-ion gate. Reprinted from [ 233 ] under CC BY 4.0 ( ).…”