​Sci Adv Yan Feng's research team develops a new type of virus detection sensor

Editor-in-Chief | The diagnosis of Enzyme's new coronavirus is currently mainly divided into nucleic acid detection and antibody detection
.

Antibody testing plays an important role in many aspects
.

First of all, antibody testing can be used to screen for asymptomatic infections of the new crown and those with false negative nucleic acid infections
.

Secondly, antibodies play a key role in the process of patient treatment and neutralization of the virus
.

People with low antibody levels are at risk of secondary infections, and critically ill patients are even more threatened with death
.

Then, the production of detection antibodies is of great significance to the development and evaluation of vaccines
.

In addition, the study of seroepidemiology is also of great significance for analyzing the infection rate and population immunity rate in different regions
.

COVID-19 antibody detection mainly adopts enzyme-linked immunosorbent assay (ELISA) and lateral flow immunoassays (LFIAs) and other methods
.

Current antibody testing methods have challenges in achieving high sensitivity, simple operation, and portability at the same time
.

Therefore, for the detection of COVID-19 antibodies, it is necessary to develop a high-sensitivity, rapid, and easy-to-operate detection method in order to achieve on-site detection and large-scale population screening
.

In addition to serum-based detection methods, SARS-CoV-2 IgG can also be detected in saliva.
Saliva antibody detection has the possibility of non-invasive detection and self-collection of samples
.

Since the antibody concentration in human saliva is several orders of magnitude lower than that in serum, higher analytical sensitivity is required
.

Recently, the research team of Feng Yan from Hong Kong Polytechnic University reported a SARS-CoV-2 IgG biosensor based on organic electrochemical transistor (OECT).
The whole detection process can be completed quickly on a small test box, and it can be operated and collected by mobile phone.
Data
.

This result was published in Science Advances on September 16, titled: Ultrafast, sensitive, and portable detection of COVID-19 IgG using flexible organic electrochemical transistors
.

Since SARS-CoV-2 IgG is positively charged in the neutral and acidic electrolyte, after the SARS-CoV-2 IgG is fixed on the grid surface, an electric dipole is formed on the grid surface to make the surface potential of the gold gate electrode The change occurs, which changes the effective gate voltage of the transistor
.

The concentration or quantity of the antibody can be judged by testing the shift of the transfer curve of the transistor before and after the antibody reaction
.

The change of the effective gate voltage is not only affected by the amount of antibody (antibody concentration), but also related to the effective net charge of the antibody
.

The effective charge is related to the Debye shield length on the surface of the gate electrode and the pH of the electrolyte
.

By reducing the concentration of the electrolyte (PBS solution) used in the detection and increasing the Debye shield length, the detection limit of SARS-CoV-2 IgG can be reduced from 10 pM to 100 fM
.

By adjusting the pH of the electrolyte (pH 5), the net charge on the surface of the antibody can be increased, and the detection limit can be reduced to 1 fM.
In addition, during the antigen-antibody reaction, the reaction speed can be accelerated by applying a pulse voltage, thereby shortening the detection time , Test results can be obtained within 5 minutes
.

Due to the specificity of antigen-antibody binding and the use of blocking agents during the modification process, the detection of SARS-CoV-2 IgG can be well distinguished from other types of antibodies in serum.
This detection method has high specificity
.

This OECT-based portable detector can also realize the detection of new crown antibodies in serum and saliva, with a detection limit of 10 fM each
.

The serum detection range is 10 fM ~ 100 nM, showing a good linear relationship, matching the specific IgG level in the serum of COVID-19 patients
.

The extremely low detection limit in saliva can also meet the demand for high sensitivity for saliva antibody detection
.

This research is of great significance for the rapid detection and large-scale screening of new coronavirus antibodies, and it can also help with the detection and evaluation of vaccines
.

Original link https:// Platemaker: Notice for reprinting on the 11th [Non-original article] The copyright of this article belongs to the author of the article.
Personal forwarding and sharing are welcome.
Reprinting without permission is prohibited, the author Have all statutory rights and offenders must be investigated
.