Ultrafast, sensitive, and portable detection of COVID-19 IgG using flexible organic electrochemical transistors

Abstract

The outbreak of COVID-19 and its continued spread have seriously threatened public health. Antibody testing is essential for infection diagnosis, seroepidemiological analysis, and vaccine evaluation. However, convenient, fast, and accurate antibody detection remains a challenge in this protracted battle. Here, we report an ultrafast, lowcost, label-free, and portable SARS-CoV-2 immunoglobulin G (IgG) detection platform based on organic electrochemical transistors (OECTs), which can be remotely controlled by a mobile phone. To enable faster detection, voltage pulses are applied on the gate electrode of the OECT to accelerate binding between the antibody and antigen. By optimizing ion concentrations and pH values of test solutions, we realize specific detection of SARS-CoV-2 IgG in several minutes with a detectable region from 10 fM to 100 nM, which encompasses the range of serum SARS-CoV-2 IgG levels in humans. These portable sensors show promise for use in diagnosis and prognosis of COVID-19.

Micro/nano biomedical devices for point-of-care diagnosis of infectious respiratory diseases

“…Xue et al reported an intelligent wearable face mask integrated with a flexible immunosensor for highly sensitive screening of exhaled coronavirus aerosols. In addition, some other kinds of on-site detection devices, such as the electrochemical biosensors, allow detection of multiple kinds of molecules, including antigens and antibodies with high sensitivity and specificity [ 160 , 161 , 162 , 163 ]. Yakoh et al reported a paper-based electrochemical biosensor for label-free detection of SARS-CoV-2 antibodies without the specific requirements of antibodies [ 164 ].…”

Design and simulation of a millifluidic device for differential detection of SARS-CoV-2 and H1N1 based on triboelectricity

“…Markedly, Antibody and antigen surface proteins comprised of zwitterionic amino acid sequences with positively- or negatively-charged functional groups corresponding to the IEP and pH values of the electrolyte. Most of the therapeutic monoclonal antibodies (mAbs) in infected human serum, e.g., anti-SARS-CoV-2 IgG and anti-H1N1 IgG, suggest IEP values above 8.0 and thereby carry a slight net positive charge in phosphate-buffered saline (PBS) solution (pH 7.4) [25] . Moreover, each virion keeps its RBDs distribution, being consistent with specific cell receptors on the host cell’s membrane [6] .…”

“…, polarity and dielectric constant) are brought into contact with or rubbed against each other, the charge neutrality disappears, and two surfaces acquire equivalent but opposite charges. Electrostatic charges induced on the back-electrodes further generate a potential drop, driving electrons to flow between the two electrodes [25] . Taking four operation modes of TENG into account, lateral sliding and freestanding modes require an additional surface modification such as superhydrophobicity for fluid-based TENGs [44] .…”

“…Pulsed amperometric detection was applied as an electroanalytical method [24] . In a label-free SARS-CoV-2 immunoglobulin G (IgG) sensor based on an organic electrochemical transistor, sensitivity has been enhanced by increasing Debye length and protein net charge through regulation of electrolyte ion concentration and pH value, respectively [25] .…”

Vertical organic transistors with short channels for multifunctional optoelectronic devices

“…FETs of this kind, based on organic semiconductor (OSC) active materials, have been successfully employed for both fundamental studies and for a variety of applications from electronics 1–7 to biology, 8–11 artificial intelligence, and biosensors and even for Covid-19 detection. 12,13 While the traditional silicon technology relies on expensive manufacturing processes and on the typical use of rigid and brittle materials that are unsuitable for cheap and flexible electronics, organic semiconductors are promising candidates for the next-generation of smart, portable and wearable devices. 1,14,15 The massive work carried out during the last three decades on the development of novel organic semiconductors, their controlled processing and device optimization made it possible to increase field-effect mobilities in organic transistors, reaching values up to 20 cm 2 V −1 s −1 .…”