Speeding Up the Separation of Proteins

Conventional separation methods employ gels, which are slower and more labour-intensive to process. The new microchip system could sort proteins in minutes, as compared to the hours necessary for gel-based systems.

The researchers have designed an anisotropic sieve in two orthogonal dimensions (at a right angle), which enables rapid continuous-flow separation of the biological sample. This allows continuous isolation and harvesting of subsets of biomolecules that researchers want to study. And that increases the probability of detecting even the smallest number of molecules in the sample.

The anisotropic sieve is embedded into a silicon chip. A biological sample containing different proteins is placed in a sample reservoir above the chip. The sample is then run through the sieve of the chip continuously. The chip is designed with a network of microfluidic channels surrounding the sieve, and the anisotropy (directional property) in the sieve causes proteins of different sizes to follow distinct migration trajectories, leading to efficient continuous-flow separation. The current sieve has an array of nanofluidic filters of about 55 nanometers, or billionths of a meter, wide.

"The proteins to be sorted are forced to take two orthogonal paths. Each path is engineered with different sieving characters. When proteins of different sizes are injected into the sieve under applied electric fields, they will separate into different streams based on size," Jongyoon Han, the Karl Van Tassel Associate Professor of Electrical Engineering and associate professor of biological engineering at Massachusetts Institute of Technology (MIT) and head of the MIT team explained. At the bottom of the chip the separated proteins are collected in individual chambers. Scientists then can test the proteins.

COMPAMED.de; Source: Massachusetts Institute of Technology