Hydrophobic peptides associated with neurodegenerative conditions could now be separated using a microfluidic device technique that utilizes the common surfactant sodium dodecyl sulphate (SDS).

Christopher Culbertson and his team at Kansas State University, US, have developed a method for separating hydrophobic mixtures on poly(dimethylsiloxane) (PDMS) microfluidic devices using the technique known as micellar electrokinetic chromatography.

PDMS is commonly used to make microfluidic devices. However, hydrophobic molecules are generally absorbed into the material making it difficult for molecules to travel through the microfluidic channels. Culbertson and his colleagues added the well-known surfactant SDS which is the soap found in shampoos. SDS selectively binds to the PDMS surface and changes the electro-osmotic flow generated in the channels. As the hydrophobic molecules move through the channels in the device, some of them separate from solution and become incorporated into the structures formed by the SDS. Using a serpentine pattern of channels and tapered turns, the device shows high separation efficiencies and very low detection limits.

Using their device the group have successfully separated a range of charged and neutral molecules including Rhodamine B, labelled amino acids and labelled E. coli homogenates. Culbertson hopes to use the device to separate the hydrophobic peptides associated with neurodegenerative conditions such as Alzheimer's disease and to examine the changes in the neuropeptides of insects during growth and metamorphosis.

Rebecca Lavender