Liquid crystal (LC) based sensors offer several advantages over traditional devices because they offer fast, label-free detection of molecules at the aqueous-LC interface through the observation of LC alignment. For example, phospholipids will spontaneously adsorb at the interface, realigning the LC and changing the optical properties of the sample. This spontaneous liposome fusion can be inhibited by the presence of poly(ethylene glycol) (PEG), which acts as a steric barrier at the LC interface. Complementary DNA strands incorporated at the interface and in the liposomes can be used to control specific fusion events.  Hybridization of these DNA oligonucleotides leads to vesicle rupture and fusion with the LC interface, increasing the local phospholipid concentration and modifying the LC orientation and optical signal. To expand the scope of our system, we can employ DNA aptamers as molecular recognition elements to detect a number of molecular targets. <br/><br/>We have performed a systematic study of system parameters to optimize the conditions required for fast and specific liposome fusion at the LC interface. This study focused on liposome composition, the steric barrier at the interface, and the DNA oligonucleotide recognition element. Results show that all of these parameters will affect the kinetics of vesicle fusion with the interface. Optimization of these conditions suggests the ideal system contains a liposome mixture of unsaturated phospholipids and cholesterol along with a DNA recognition element that is 30-40 base pairs in length. These properties improve the current design of our LC-based sensor by increasing the kinetics of the system, while still maintaining high sensitivity and selectivity. Exploring these parameters is also important to improve understanding of the mechanism of liposome fusion with a soft interface. Future work will attempt to pinpoint specific parameters (e.g. oligonucleotide length, lipid composition) and observe their influence on individual steps in the fusion mechanism.

Studying receptor-mediated liposome fusion kinetics at aqueous/liquid crystal interfaces

249th National Meeting (2015)

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