A team led by Prof. WU Zhengyan from the Hefei Institutes of Physical Science of the Chinese Academy of Sciences developed a high-sensitivity electrochemical aptasensor to detection of thrombin in serum.

Using synchronous coordination of triple signal amplification strategy, they developed this ultrasensitive electrochemical aptasensor for picomolar thrombin detection. Results were published in Biosensors & Bioelectronics.

Thrombin is a proteolytic enzyme that catalyzes the conversion of fibrinogen to fibrin and promotes blood clotting.  It is closely related to leukemia, thrombotic diseases, vascular wall inflammation, Alzheimer's disease and many other diseases. Thrombin is not normally present in the blood of humans and other animals. It is converted from prothrombin during coagulation. Therefore, accurate detection of low concentration thrombin is of great significance for the diagnosis, treatment and evaluation of drug efficacy of related diseases.   

When designing the sensor, the researchers chose a Ti₃C₂Tx (titanium carbide) MXene multilevel porous structure as the sensing material and a metallic nanoprobe as the signal amplifier. The porous structure has more electronic transport channels and the nanoprobe has higher electrocatalytic effect, which is helpful to promote the response signal of sensor.

YANG Pengqi, a PhD student who conducted the research, further explained the process. Under the exsistence of picomolar-level thrombin, catalytic hairpin assembly reactions of DNA was triggered to bridge thionine labelled Au nanorob or hollow Cu-Pt alloy nanoprobes on the hierarchically porous Ti₃C₂Tx MXene framework with controllablly scondary pore structures. The sandwich-typed aptasensor showed an excellent performance with a wide linear range from 2 pM to 10 nM for thrombin, and a low limit of detection of 0.67 pM.

When they applied the sensor to the detection of a low concentration thrombin in blood, they found that it could not only detect thrombin at picomolar concentration, but also showed excellent anti-interference and stability against various physiological substances.

"The sensing platform established in this study can be customized to analyze other biological or environmental substances," said YANG, "what's required is to rationally design the DNA sequences of target-binding aptamer."

This research was supported by the University Synergy Innovation Program of Anhui Province, the Special Project of Central Government for Local Science and Technology Development of Shandong Province, and the Open Research Fund of Key Laboratory of Environmental Toxicology and Pollution Control Technology of Anhui Province.

Schematic illustration of detection mechanism based on self-prepared aptasensor. (Image by YANG Pengqi)