The necessity of managing stress levels is becoming increasingly apparent as the world suffers from different kinds of stresses including the extent of pandemic, the corona virus disease 2019 . Cortisol, a clinically confirmed stress hormone related to depression and anxiety, affects individuals mentally and physically. However, current cortisol monitoring methods require expert personnel, large and complex machines, and long time for data analysis. Here, we present a flexible and wearable cortisol aptasensor for simple and rapid cortisol real-time monitoring. The sensing channel was produced by electrospinning conducting polyacrylonitrile (PAN) nanofibers (NFs) and subsequent vapor deposition of carboxylated poly(3,4-ethylenedioxythiophene) (PEDOT). The conjugation of the cortisol aptamer on the PEDOT-PAN NFs provided the critical sensing mechanism for the target molecule. The sensing test was performed with a liquid-ion gated field-effect transistor (FET) on a polyester (polyethylene terepthalate). The sensor performance showed a detection limit of 10 pM (<5 s) and high selectivity in the presence of interference materials at 100 times higher concentrations. The practical usage and real-time monitoring of the cortisol aptasensor with a liquid-ion gated FET system was demonstrated by successful transfer to the swab and the skin. In addition, the real-time monitoring of actual sweat by applying the cortisol aptasensor was also successful since the aptasensor was able to detect cortisol approximately 1 nM from actual sweat in a few minutes. This wearable biosensor platform supports the possibility of further application and on-site monitoring for changes of other numerous biomarkers.
Abstract:In recent years, conducting polymer (CP) nanomaterials have been used in a variety of fields, such as in energy, environmental, and biomedical applications, owing to their outstanding chemical and physical properties compared to conventional metal materials. In particular, nanobiosensors based on CP nanomaterials exhibit excellent performance sensing target molecules. The performance of CP nanobiosensors varies based on their size, shape, conductivity, and morphology, among other characteristics. Therefore, in this review, we provide an overview of the techniques commonly used to fabricate novel CP nanomaterials and their biosensor applications, including aptasensors, field-effect transistor (FET) biosensors, human sense mimicking biosensors, and immunoassays. We also discuss prospects for state-of-the-art nanobiosensors using CP nanomaterials by focusing on strategies to overcome the current limitations.
To overcome the limitation of two-dimensional cell culture not being able to mimic the in vivo microenvironment, three-dimensional (3D) bioprinting technology for 3D cell culture has emerged as an innovative culture platform. 3D bioprinting technologies can be divided into five types: inkjet-based bioprinting, extrusion-based bioprinting, stereolithography bioprinting, laser-assisted bioprinting and digital laser processing-based bioprinting technology. The 3D printing strategies achieved through a combination of these technologies can be applied to develop tissue regeneration, drug evaluation and drug delivery systems. In addition, the choice of cells and biomaterials is an important factor in fabricating tissue/organ models. Biomaterials for 3D bioprinting can be divided into natural polymers (alginate, gelatin, collagen, chitosan, agarose, and hyaluronic acid) and synthetic polymers (polylactic acid, polyvinyl alcohol, polycaprolactone, polyethylene oxide and thermoplastic polyurethane). Depending on the goals of 3D bioprinting experiments, biomaterials can be used alone or in combination with various polymers. 3D bioprinting technology has the potential to be applied for personalized medicine, precision medicine and the fabrication of artificial tissue/organs.
Adequate serotonin levels are pivotal to human well-being; thus, serotonin can be used as a biomarker because it regulates a wide range of physical and psychological functions. As an imbalance of serotonin is highly likely to initiate the pathogenesis of various disorders, monitoring serotonin levels in real time is in high demand for the early detection of disease. We fabricated a field-effect transistor (FET) biosensor based on aptamer-immobilized conducting polymer nanohybrids, which showed an instantaneous response toward serotonin in solution. The mechanism of serotonin detection was based on aptamer deformation after aptamer-ligand interaction and the consequential decrease in the charge carrier density of the FET template. Docking simulations with AutoDock/Vina and PyMOL were successfully used to investigate the binding site of serotonin in the loop structure of the aptamer. The fabricated FET template showed high sensitivity toward serotonin in the range of 10 fM to 100 nM, and the limit of detection (LOD) was exceptionally low at 10 fM. Moreover, the selectivity toward serotonin was confirmed by observing no signal after the injection of structural analogs, functional analogs and excess physiological biomolecules. The potential clinical application of this sensor was confirmed because it remained consistent when the buffer solution was exchanged for artificial serum or artificial cerebrospinal fluid (CSF). † S.G.L. and S.E.S. contributed equally to this work.
Serotonin is a stress biomarker and is one of the major neurotransmitters, and its concentration in the body is related to psychological functions such as mental illness. In particular, this biomarker is used to indicate depression caused by the increased stress of modern society. Therefore, detection and monitoring technologies are important for tracing concentration changes. In this study, we developed a serotonin antibodyconjugated graphene micropatterned field-effect transistor (SAb-GMFET)-based portable device for on-site or self-diagnosis of serotonin. The SAb-GMFET consisted of a graphene micropatterned channel, SAb for selective detection, and electrodes to supply the voltage. The SAb was immobilized by forming an amide bond with a diamine linker. SAb-GFMET showed high performance of limit of detection of 10 pM within 10 s and exhibited excellent selective detection among the interfering materials. For on-site and self-diagnosis applications, a portable device was developed with a sim chip, and the SAb-GMFET was connected to a printed circuit board using wire bonding. The portable SAb-GMFET showed a similar performance to that of the SAb-GMFET. Therefore, this portable platform can be utilized for point-of-care tests.
The transmission and pathogenesis of highly contagious fatal respiratory viruses are increasing, and the need for an on‐site diagnostic platform has arisen as an issue worldwide. Furthermore, as the spread of respiratory virus continues, different variants have become the dominant circulating strains. To prevent virus transmission, the development of highly sensitive and accurate on‐site diagnostic assays is urgently needed. Herein, we present a facile diagnostic device for multi‐detection based on the results of detailed receptor‒ligand dynamics simulations for the screening of various viral strains. Our novel bioreceptor‒treated electronics (receptonics) device consists of a multichannel graphene transistor and cell‐entry receptors conjugated to N‐heterocyclic carbene (NHC). We achieved ultrasensitive multi‐detection performance without the need for sample pretreatment, which will enable rapid diagnosis and prevent the spread of pathogens. This platform can be applied for the diagnosis of variants of concern in clinical respiratory virus samples and primate models. Our multi‐screening platform can be used to enhance surveillance and discriminate emerging virus variants before they become a severe threat to public health.This article is protected by copyright. All rights reserved
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