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Gravimetric antigen detection utilizing antibody-modified lipid bilayers.
Charlotte Larsson1, Hanna Bramfeldt, Christer Wingren
1Department of Applied Physics, Chalmers University of Technology and Göteborg University, 41296 Göteborg, Sweden.
Analytical Biochemistry
|September 6, 2005
Summary
Researchers developed a novel method to immobilize antibody fragments onto lipid bilayers for cholera toxin detection. This technique simplifies protein purification and enhances detection sensitivity, even in complex samples like serum.
Area of Science:
- Biotechnology
- Biosensing
- Immunochemistry
Background:
- Lipid bilayers offer a versatile platform for biomolecule immobilization.
- Oligohistidine-tagged proteins are commonly used in bioconjugation strategies.
- Cholera toxin detection is crucial for public health diagnostics.
Purpose of the Study:
- To develop an efficient method for immobilizing single-chained antibody fragments (scFvs) against cholera toxin on nitrilotriacetic acid (NTA)-functionalized lipid bilayers.
- To assess the feasibility of using unpurified protein samples for immobilization, bypassing extensive purification.
- To enhance the sensitivity and robustness of cholera toxin detection using this biosensor platform.
Main Methods:
- Fabrication of SiO2-supported lipid bilayers incorporating 5% nitrilotriacetic acid (NTA) lipids.
- Immobilization of oligohistidine-tagged scFvs onto NTA-Ni2+-functionalized lipid bilayers from both purified and unpurified samples.
- Detection of cholera toxin using quartz crystal microbalance with dissipation monitoring (QCM-D) and secondary amplification with GM1-containing lipid vesicles.
Main Results:
- Histidine-tagged scFvs efficiently coupled to the NTA-lipid bilayer from unpurified expression supernatant, eliminating the need for protein prepurification.
- The biosensor template demonstrated efficient cholera toxin detection, with a detection limit below 750 pM when amplified with GM1 vesicles.
- Bivalent anchoring of scFvs (using two histidine tags) significantly improved resistance to displacement in complex biological matrices like serum.
Conclusions:
- A simplified and efficient method for antibody fragment immobilization on NTA-lipid bilayers was established, suitable for direct use of unpurified samples.
- The developed biosensor platform shows high sensitivity and specificity for cholera toxin detection.
- The bivalent anchoring strategy enhances the stability and reliability of the biosensor in complex sample matrices.