Signal amplification by rolling circle amplification on DNA microarrays

While microarrays hold considerable promise in large-scale biology on accou nt of their massively parallel analytical nature, there is a need for compa tible signal amplification procedures to increase sensitivity without loss of multiplexing. Rolling circle amplification (RCA) is a molecular amplific ation method with the unique property of product localization. This report describes the application of RCA signal amplification for multiplexed, dire ct detection and quantitation of nucleic acid targets on planar glass and g el-coated microarrays. As few as 150 molecules bound to the surface of micr oarrays can be detected using RCA. Because of the linear kinetics of RCA, n ucleic acid target molecules may be measured with a dynamic range of four o rders of magnitude. Consequently, RCA is a promising technology for the dir ect measurement of nucleic acids on microarrays without the need for a pote ntially biasing preamplification step.