Just came across a new method, developed by Steven Lenhart, for creating gratings using lipid multilayers that can be used as label free optical biosensors. Now. the grating based label-free biosensors have been around for long time but the new method has few novel features not found in conventional grating based sensors. First, the gratings are fabricated using Dip Pen Nanolithography (DPN) that allows gratings of different pitch and thickness to be fabricated on a single device using parallel DPN tip arrays. By changing the period and thickness of lipid multilayer the optical properties can be modulated and potentially the biosensor response. Second feature of the sensor is that the biological element for detection can be incorporated right into the lipids, eliminating the need for separate biofunctionalization step. Third feature is that the lipid membranes will be protein friendly layer, possibly reducing the protein denaturation associated with conventional protein capture methods. Finally, lipid bilayers have been used for capturing membrane proteins and hence this sensor should be useful for membrane protein functional assays something that can’t be done easily on conventional biosensors.
The way the biosensor works is that interaction of protein and lipid multilayer result in intercalation, spreading or dewetting of lipid grating and a proportional change in optical properties. Authors incorporated biotin in the lipids before fabricating grating and show changes in optical properties even in presence of 0.5nM streptavidin.
DPN has been around for a while now but the potential for creating commercial devices using this technology is still to be realized. Let’s wait and see what will happen with this biosensor!