Pathogenic bacteria secrete various virulence factors as their biochemical weapons to gain access to and destroy the target cells. They can directly interact with the outer lipid bilayer membrane of eukaryotic cells, inducing the premature cell death by either apoptosis or necrosis. Such virulence factors account for much of the toxic actions associated with bacterial infection; therefore the detection of such proteins could provide a methodology for sensing/detection of pathogenic bacteria in, for example, food or human tissue. Detection and identification of pathogenic bacteria by conventional methods such as plating and counting in laboratory is expensive and time consuming. With growing concerns over emergence and re-emergence of pathogenic bacteria with high resistant to current antibiotics, there is a potential need for effective detection of pathogenic toxins invitro.
On the other hand, artificially prepared lipid bilayer membrane on planar metallic surfaces provides the cell membrane mimics which are extremely useful in exploring the cellular functions and processes at the molecular level. Therefore in this work, an application of planar tethered bilayer lipid membrane (pTBLM) as a biomimetic sensing platform for the detection of clinically important pathogens, Staphylococcus aureus and Pseudomonas aeruginosa via their secreted virulence factors was presented. Planar TBLM was modified by incorporation of cholesterol and detection of bacterial toxins at human body temperature was examined by impedance and surface plasmon resonance methods. The results of pathogenic bacterial toxin detection were compared with those of Escherichia coli (DH5α), the human gut normal flora with non-pathogenic strain, as a control.
Additionally pTBLM was transferred onto single nanoporous Si3N4 membrane to enhance the toxin sensitivity and extend the lifetime for the possible realization of future membrane chips for ion channel characterizations and drug screenings. Then the single ion channel measurement was demonstrated with nanopore-suspended TBLM (Nano-psTBLM) using α-toxin of S. aureus. The results presented in this work therefore, may pave the more effective and efficient ways for future pathogenic bacterial detection in which the sensing mechanism was solely based on the nature of interactions as well as modes of action between bacterial toxins and artificial lipid bilayer membranes.
|Date of Award||1 Oct 2010|
|Supervisor||Toby Jenkins (Supervisor)|
- Pathogenic bacteria
- alpha hemolysin