Multiplexed Functionalities

Using the soft lithographic techniques described above, I am attempting to multiplex functionalities in a supported membrane to create high throughput microarrays.












Microfluidics

The use of microfluidic devices have proven useful in a number of materials and biological research applications. We have been using these flexible PDMS devices to create gradients of different lipid species on a glass substrate.  We have also incorporated cholesterol and proteins into these supported lipid membranes to produce functional gradients across a glass surface in order to conduct high through-put chemical and biological assays.


To the left is an example of a microfluidic mixing channel, a design produced by the Noo Li Jeong Group at UC Irvine.  Solutions are injected from the top using a syringe and a rate determining syringe pump. As the solutions travel through the channels, they are forced to meet at a number of junctions followed by saw-tooth channels that thoroughly mix the solutions.  These mixing channels end with one long channel that can be used for assaying.


Below are four images at the beginning of the assaying channel.  The first is a bright field image of the channel, which is followed by fluorescence images of lipid gradients. One solution has red dye and the other green.  The last image shows an intensity map of the two color gradient.  These colors are used to depict the possible gradients that can be created using proteins and other molecules of interest.











 

Other Work:

Lithography, Assays, & Microfluidics

Membrane Photolithography

Surface patterning of physical, chemical, and biological functions using standard photolithographic methods in the dry solid state is leading to new high throughput approaches in materials synthesis, sensor microarrays, genomics, drug screening, and proteomics. Extending this strategy to fluidic biomembrane functions that require cooperative dynamics and wet environments is desirable in order to understand, emulate, pattern, and exploit many functions of cell membranes for fundemental biological research as well as many biomedical and sensing technologies.  To the left is shown a wet photolithographic route for micropatterning fluid phospholipid

bilayers in which spatially directed illumination with deep-ultraviolet radiation results in highly localized photodecomposition of the exposed lipids. Unexposed lipids retain their material fluidity and exhibit bio-specific recognitions inhibiting non-specific interactions. Using this method, we can directly engineer stable patterns of hydrophilic voids (with dimensions >2um) within a fluid membrane. Furthermore, the voids can be refilled by fusion of secondary lipid vesicles, establishing contiguity with the existing membrane, or creating long-lived, metastably phase-separated states, therby providing a synthetic means for probing 2D reaction-diffusion processes, manipulating membrane compositions, and designing functional membrane arrays.



Click on the Advanced Material Cover to view the article.