Immunodetection of inactivated Francisella tularensis bacteria by using a quartz crystal microbalance with dissipation monitoring.
Francisella tularensis are very small, gram-negative bacteria which are capable of infecting a number of mammals. As a highly pathogenic species, it is a potential bioterrorism agent. In this work we demonstrate a fast immunological detection system for whole F. tularensis bacteria. The technique is based on a quartz crystal microbalance with dissipation monitoring (QCMD), which uses sensor chips modified by a specific antibody. This antibody is useful as a capture molecule to capture the lipopolysaccharide structure on the surface of the bacterial cell wall. The QCMD technique is combined with a microfluidic system and allows the label-free online detection of the binding of whole bacteria to the sensor surface in a wide dynamic concentration range. A detection limit of about 4 × 10(3) colony-forming units per milliliter can be obtained. Furthermore, a rather short analysis time and a clear discrimination against other bacteria can be achieved. Additionally, we demonstrate two possibilities for specific and significant signal enhancement by using antibody-functionalized gold nanoparticles or an enzymatic precipitation reaction. These additional steps can be seen as further proof of the specificity and validity.
Biosystems Technology, Technical University of Applied Sciences Wildau, Wildau, Germany. kleo@th-wildau.de
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K
Kleo
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D
Schäfer
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S
Klar
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D
Jacob
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R
Grunow
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F
Lisdat
D055910:Antibodies, Immobilized / Q000737:chemistry* / Q000276:immunology; D015374:Biosensing Techniques; D005604:Francisella tularensis / Q000737:chemistry / Q000276:immunology / Q000302:isolation & purification*; D006046:Gold / Q000737:chemistry; D057230:Limit of Detection; D008070:Lipopolysaccharides / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry; D046210:Microfluidic Analytical Techniques; D058525:Quartz Crystal Microbalance Techniques / Q000295:instrumentation / Q000379:methods*; D013234:Stem Cells
D055910:Antibodies, Immobilized; D008070:Lipopolysaccharides; D006046:Gold