Ultrasensitive biosensor based on MXene-GO field-effect transistor for the rapid detection of endotoxin and whole-cell E. coli in human blood serum.

BACKGROUND

Sepsis is known as one of the deadliest and costliest diseases in the world, which can be caused by bacteria or toxins and affects more than 30 million people annually. Similar clinical symptoms and the lack of a specific laboratory test have challenged its diagnosis and treatment. The fast, accurate, and easy detection of sepsis pathogens such as E. coli using biosensors is essential. Here, a Field-effect-Transistor aptasensor based on MXene and graphene oxide (MXene-GO-Apt FET) was designed and fabricated for the whole cell of E. coli and its endotoxin (lipopolysaccharide) detection.

RESULTS

MXene (TiC was prepared by HF etching of TiAlC, and its composite was synthesized with GO. After the ATR-FTIR, XRD, EDX, and FESEM characterization and biosensor fabrication, the amino ssDNA aptamer was immobilized on the biosensor surface. The investigation of the drain-source current showed that the biosensor modification with MXene-GO composite results in suitable and stable electrical conductivity. E. coli detection occurs by binding aptamer to lipopolysaccharides in the outer membrane of bacteria, changing its conformation, and then reducing the biosensor current. The response of the biosensor was highly selective; its detection limit was 1 pg/ml and 3 CFU/ml for lipopolysaccharide and E. coli in PBS buffer and better compared to other studies. MXene-GO-Apt FET's response is stable after 30 days and detects endotoxin and E. coli in human blood serum without pretreatment to 10 ng/ml and 30 CFU/ml, respectively, in 300s.

SIGNIFICANCE AND NOVELTY

This study represents a MXene-GO-Apt FET nanobiosensor for detecting E. coli and its endotoxin in PBS buffer and human blood serum in 300s. The small sample volume required and the possibility of performing by an unskilled user with accurate and ultrasensitive detection of bacteria and its LPS are the advantages of MXene-GO-Apt FET, which can be used as a point-of-care sensor for detecting pathogens in patients.