Inorganic and organic linker layers to aid immobilisation for SPR biosensing.

Improvements to the immobilisation of bio-recognition elements to sensor surfaces are keenly sought. Surface Plasmon Resonance is a highly sensitive optical based sensing technique that is being used in this research as a means of evaluating novel immobilisation techniques. We report on the establishment of binding-sites at the sensor surface using two diverse methods. In the first method, well established deposition techniques were used to coat the gold surface with a silicon rich matrix. It is demonstrated that control of the depth of the material to within 10 nm was achieved. In a second method highly ordered arrays of genetically modified biological materials have been used to form attachment sites and are being investigated. Careful choice of amino acid placement at the apical domain could provide bioselective attachment, with control in three dimensions in the region of 10's of nanometres. Characterisation of the active surfaces in each instance is presented using a number of well established techniques such as Scanning Electron Microscopy, Raman, Profilometry and Atomic Force Microscopy. Investigations, although at an early stage, have shown promise. Initial results obtained for sensitivity to glucose are indicative of an overall improvement over conventional techniques taking into account the key aspects of metal layer thickness and penetration depth of the surface plasmon wave.