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Impedimetric immunosensor for the detection of circulating pro-inflammatory monocytes as infection markers
Armelle Montrose1, Sébastien Cargou, Françoise Nepveu
1Université de Toulouse; UPS; UMR 152 Pharma-Dev; Université Toulouse 3, Faculté des Sciences Pharmaceutiques, F-31062 Toulouse cedex 09, France.
Abstract:
Circulating blood monocytes belong to the first line of defense against pathogens and inflammation. Monocytes can be divided into three populations defined by the expression of the cell surface molecules, CD 14 and CD 16. The CD 14(++) CD 16(-) cells, called "classical" monocytes, represent 85% to 95% of the total monocytes in a healthy person whereas CD 14(-) CD 16(+), called "proinflammatory" monocytes, are found in greater numbers in the blood of patients with acute inflammation and infectious diseases. This increase in the concentration of proinflammatory monocytes can be a good indicator of an infectious state. This study presents an immunosensor based on impedance detection for specific cell trapping of classical and proinflammatory monocytes. The grafting of specific antibodies (CD 14 or CD 16) was based on the use of mixed SAM associated with protein G. Each step of the functionalization was characterized by electrochemical methods, quartz crystal microbalance and atomic force microscopy. Faradaic electrochemical impedance spectroscopy and voltametric analysis confirmed the success of the modification process with a surface coverage reaching 92% for the antibody layer. The increase in the deposited mass at each step of the modification process confirmed this results revealing that one protein G in two was bound to an antibody. The cell trapping capacity, evaluated by the variation in the film resistance using non-faradaic impedance spectroscopy revealed that the cell trapping is selective, depending on the specific antibody grafted and quantitative with the range of detection being 1000 to 30,000 infected cells. This range of detection is consistent with the application targeted.
Insights
This study developed an immunosensor for detecting classical and proinflammatory monocytes, key immune cells. The device uses specific antibodies for selective cell trapping, offering a quantitative indicator for infectious diseases.
Area of Science:
- Biomedical Engineering
- Immunology
- Biosensors
Background:
- Circulating monocytes are crucial for pathogen defense and inflammation.
- Monocyte populations (CD 14++ CD 16- classical, CD 14- CD 16+ proinflammatory) differ in disease states.
- Increased proinflammatory monocytes indicate infection or inflammation.
Purpose of the Study:
- To develop an immunosensor for specific trapping of classical and proinflammatory monocytes.
- To utilize impedance detection for sensitive and selective cell identification.
Main Methods:
- Fabrication of an immunosensor using mixed self-assembled monolayers (SAMs) and Protein G.
- Grafting of CD 14 or CD 16 antibodies for specific monocyte capture.
- Characterization via electrochemical methods, quartz crystal microbalance, and atomic force microscopy.
- Evaluation of cell trapping using non-Faradaic electrochemical impedance spectroscopy.
Main Results:
- Successful functionalization with 92% antibody layer surface coverage.
- Confirmation of antibody layer integrity and mass increase through electrochemical analysis.
- Demonstrated selective and quantitative cell trapping of monocytes.
- Established a detection range of 1000 to 30,000 cells, suitable for diagnostic applications.
Conclusions:
- The developed immunosensor enables selective and quantitative detection of classical and proinflammatory monocytes.
- Impedance-based detection provides a viable method for identifying immune cell populations.
- This technology shows potential as a diagnostic tool for infectious and inflammatory conditions.
