High-throughput assays on the chip based on metal nano-cluster resonance transducers

High throughput transducers using metal cluster resonance technology are ba sed on surface-enhancement of metal cluster light absorption. These devices can be used for detection of biorecognitive binding, as well as structural changes of nucleic acids, proteins or any other polymer. The optical prope rty for the analytical application of metal cluster films is the so-called anomalous absorption. An absorbing film of clusters positioned 10 400 nm to a mirror surface reacts in a similar way to a reflection filter. At a cert ain distance of the absorbing layer to the mirror the reflected electromagn etic field has thc same phase at the position of the absorbing cluster as t he incident fields. This feedback mechanism strongly enhances the effective cluster absorption coefficient. The system is characterised by a narrow re flection minimum whose spectral position shifts sensitively with the interl ayer thickness, because a given cluster mirror distance and wavelength defi nes the optimum phase. Based on this principle a set of novel tools includi ng biochips and micro arrays is presented, which enabled us to transduce bi nding, as well as changes of protein-, DNA- and polymer-conformation, quant itatively into an optical signal which can be observed directly as a colour change of a sensor-chip surface. (C) 2001 Elsevier Science B.V. All rights reserved.