Bits and Pieces_01/18/10

 3D Microfluidic Devices on the Cheap

In my previous post I wrote about Microfluidic Paper Based Analytical Devices (PADs). These devices use lithography or wax based techniques to create microfluidic channels in the paper to transport minute amount of reagents or sample for sensing. These methods for creating channels can become expensive but a cheaper solution may be lowly cotton thread according to a recent paper published by Wei Shen of Australian Pulp and Paper Institute. The technology leverages wicking properties of cotton thread to move and mix liquid for sensing.


Thread based microfluidic device. Credit: ACS Appl. Mater. Interfaces

In this paper thread based microfluidic device was used for sensing of NO2and uric acid but I believe biosensing applications for diagnostics will follow soon.

Giant Magnetoresistive based Immunoassay

Few months back I wrote about the Biosensors based on Giant-Magnetoresistive sensors. Same team of scientists has published another proof-of-principle of GMR biosensors for multiplexed mycotoxin detection. Mycotoxins are secondary metabolites of fungi and are associated with contamination in food industry. GMR based biosensors are sandwich immunoassays where the tag used in magnetic nanotags instead of enzyme in conventional ELISAs. Sensor is claimed to be sensitive, specific and suitable for point-of-care testing but with three step assay this is easier said than done.

Photonic Crystal Biosensor for Protein-Protein Interactions

I wrote earlier about Photonic Crystal biosensors for multiplexed bioassay. Now Prof. Cunningham and his collaborators have used PC biosensors for label free protein-protein interaction studies. Prof. Cunningham is also founder and CTO of SRU Biosystems that is commercializing PC based biosensors. HIS tagged bait proteins are immobilized at the biosensor surface and binding of the prey partner protein in the presence or absence of small molecule modulator is detected using PC biosensors. Nothing new here!

Several other platforms including Corning’s EPIC, multiplexed Surface Plasmon Resonance Biosensors and protein arrays have been used for protein interaction studies and a side-by-side comparison at some point will be needed.

Binding event on PC Biosensor result in shift in reflectance. Credit: J. Am. Chem. Soc., 2009, 131 (51), pp 18202–18203

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