Strategies for highly sensitive biomarker detection by Rolling Circle Amplification of signals from nucleic acid composed sensors.

The use of nucleic acids as components in highly sensitive biosensors has attracted increasing interest during recent years, not least due to the ease by which nucleic acids can be synthesized, manipulated and signal-amplified. To date, several enzymatic reactions, including Polymerase Chain Reaction, Rolling Circle- and Strand Displacement Amplification for signal enhancement of nucleic acid biosensors, have been presented. Of these, the isothermal Rolling Circle Amplification, in which a small single-stranded DNA circle is replicated to generate long tandem repeat products, presents the advantage of allowing single molecule detection and easy quantification as well as of posing little requirement to equipment and personnel training. Rolling Circle Amplification has been used to enhance signals of nucleic acid based sensors specific for a large variety of important biomarkers, including nucleotide sequences, small molecules, proteins and enzyme activities, allowing detection of biomarkers even at the aM concentration level. Moreover, Rolling Circle Products have been adapted to a broad variety of low technological and cost efficient readout formats making the technique appealing for future basic discovery research as well as for at-point-of-care diagnostic or prognostic tests. This journal is © The Royal Society of Chemistry 2011