NILbiochip

Providing parallel assay format and high throughput ability biochips have revolutionized the areas of genomics and proteomics. However, to move biochips from the bench to analysis laboratories significant improvements in sensitivity need to be made. Especially in this context nanoimprint lithography (NIL) promises to find its use in many aspects of biochips. In NILbiochip emphasis is placed on three main approaches: micro/nanostructuring of the biochip surface; integration of optical elements; and surface enhanced fluorescence (SEF) detection.

Micro/nanostructuring of photoresist coated chips is aimed to increase the chip surface area and thus enhance the amount of protein that can be bound to the chip. Increased amount of immobilized protein is able to bind more analyte of interest which in turn requires more fluorophor labeled antibody for detection. As the fluorescence of the on-chip immunoassay is directly related to the amount of immobilized protein, enhanced fluorescence signals will be generated.

Microoptical elements fabricated by Nanoimprint Lithography will be integrated in the biochip to minimize the loss of fluorescence light which is emitted in all directions and redirect it towards the detector.

Immobilization techniques for proteins on metal cluster coated biochips will be established to exploit a distance-dependent phenomenon that occurs between a fluorophor and a metal cluster for surface enhanced fluorescence (SEF) detection. If fluorophor and metal cluster are in a certain distance surface plasmons are generated resulting in enhanced fluorescence. If fluorophor and metal are too close to each other, the fluorescence signals are quenched. To fabricate such metal clusters onto which the proteins are then immobilized electrochemical pulse plating processes are employed on NIL prestructured biochips.

The challenge in NILbiochip is to handle the materials which have so far not been used for NIL and develop processes which are compatible with the biochip functionality. These will then be evaluated using a model protein chip for detection of sepsis.

From the biochip point of view it is expected that a significant improvement in sensitivity will be achieved. The optimal design of the structures taking also the constraints of NIL into account is a challenge which will push further both NIL and biochip design.