Oil emulsions and methods for manufacture and use thereof
The invention provides oil emulsion droplets and a general and facile method for providing same through the use of templating multilayer capsules. The oil emulsion droplets are further useful in fabricating liquid crystal droplet-based biosensors for the detection of target analytes such as bacteria or viruses in a sample.
1. A method for providing naked oil emulsion droplets, the method comprising:
(a) preparing multilayer capsules by:
(i) layer-by-layer (LbL) coating of sacrificial particles with one or more types of macromolecular assembly materials to yield sacrificial particles having a pH sensitive semipermeable multilayer coating sensitive to disassembling at a certain pH; and
(ii) etching the sacrificial particles having the pH sensitive semipermeable multilayer coating to remove the sacrificial particle thereby yielding the multilayer capsules, wherein the multilayer capsules have an internal cavity obtained by removal of the sacrificial particle and the pH sensitive semipermeable multilayer coating enclosing the internal cavity;
(b) infiltrating oil from outside of the multilayer capsules through the pH sensitive semipermeable multilayer coating into the internal cavity of the multilayer capsules to provide pH sensitive semipermeable multilayer-coated oil droplets; and
(c) disassembling the pH sensitive semipermeable multilayer-coating of said pH sensitive semipermeable multilayer-coated oil droplets by exposing to a solution having the pH at which the pH sensitive semipermeable multilayer coating is sensitive to disassembling; whereby the naked oil emulsion droplets are provided.
2. The method according to claim 1 , wherein the macromolecular assembly materials include at least one polycation and one polyanion that yield multilayer-coated sacrificial particles having alternating layers of said polycation and polyanion in the LbL coating step.
3. The method according to claim 1 , wherein the macromolecular assembly materials include at least two non-ionic polymers that yield multilayer-coated sacrificial particles having alternating layers of said non-ionic polymers in the LbL coating step.
4. The method according to claim 1 , wherein the diameter of the multilayer capsules is predetermined and ranges from about 10 nm to about 10 mm.
5. The method according to claim 1 , wherein said naked oil emulsion droplets are naked monodisperse oil emulsion droplets of a predetermined diameter of from about 10 nm to about 10 mm.
6. The method according to claim 1 , wherein said naked oil emulsion droplets are naked monodisperse liquid crystal emulsion droplets.
7. The method according to claim 6 , wherein the naked monodisperse liquid crystal emulsion droplets have a uniform predetermined diameter from about 0.1 μm to about 10 μm.
8. The method according to claim 6 , wherein said naked monodisperse liquid crystal emulsion droplets have a granulomeric distribution of about 30% or less.
9. The method according to claim 8 , wherein said naked monodisperse liquid crystal emulsion droplets have a granulomeric distribution of about 10% or less.
10. The method according to claim 1 , wherein said naked oil emulsion droplets are monodisperse and have a granulomeric distribution of about 10% or less.