Evaluation of the application potential of electrical biosensors for the continuous measurement of protease biomarkers

• Applicant: Professor Dr. Alexey Tarasov
• Subject Area: Biomedical Systems Technology
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 558246875

Proteases are enzymes that cleave peptides and proteins in the human body. Abnormal levels of proteases in the blood have been associated with pathophysiological conditions such as cancer, cardiovascular disease, and psychiatric disorders. Levels of proteases can also change over time as a result of disease progression or therapeutic intervention. To better understand the mechanisms of disease progression and to develop new treatment options, there is a growing need for analytical tools that can continuously monitor protease biomarkers over time. Currently, there is no direct method for simple online protease detection from complex samples. Electrical sensors combine high sensitivity and selectivity with ease of use, miniaturization and integration into compact and low-cost biosensing systems. Existing biosensors for protease activity typically rely on protease cleavage of immobilized peptides. These sensors cannot be easily regenerated and are not directly applicable to continuous monitoring of a protease level over time. However, electrical sensors such as ion-sensitive field-effect transistors (ISFETs) and potentiometric ion-selective electrodes (ISEs) are widely used for the detection of ions such as hydrogen, sodium, and potassium, and are easily adaptable to continuous monitoring. The main goal of this project is to develop a method for continuous monitoring of protease activity using electrical biosensors, taking advantage of their ion sensing capabilities. We will focus on two biomarkers, matrix metalloproteinases, MMP-9 and MMP-12, because of their importance in several diseases, including cancer and vascular pathologies. The sensing principle is based on the quantification of the ionic cargo released from microcapsules in response to protease activity. The released ions are detected by two types of transducers: graphene ISFETs and mesoporous carbon-based potentiometric ISEs. Graphene ISFETs are expected to offer higher sensitivity and lower detection limits, while ISEs potentially offer lower cost and ease of fabrication. Both sensor types will be evaluated and compared. A DFG-funded e-beam evaporator will be extensively used as part of a process line for the fabrication of novel electrochemical biosensor chips. This evaporator will be also used to develop a new method for the fabrication of mesoporous carbon, which will be simpler and require less dangerous and hazardous chemicals compared to reported methods. Ion-loaded microcapsules will be synthesized using a polymerization reaction. The microcapsules will contain MMP-selective peptides in the shell and will be loaded with lithium or potassium ions. The correlation between protease activity and the amount of released ions will be studied. A microfluidic chip will be developed to demonstrate liquid handling including continuous feeding of microcapsules. Finally, the biosensor system will be validated in serum samples and compared with state-of-the-art protease detection tools.

• DFG Programme: Research Grants