Nucleic acid sensing by regenerable surface-associated isothermal rolling circle amplification

A novel method for regenerating biosensors has been developed in which the highly specific detection of nucleic acid sequences is carried out using molecular padlock probe (MPP) technology and surface-associated rolling circle amplification (RCA). This technique has a low occurrence of false positive results when compared to polymerase chain reaction, and is an isothermal reaction, which is advantageous in systems requiring low power consumption such as remote field sensing applications. Gold-sputtered 96-well polystyrene microplates and a fluorescent label were used to explore the detection limits of the surface-associated RCA technique, specificity for different MPP, conditions for regeneration of the biomolecular sensing surface, and reproducibility of measurements on regenerated surfaces. The technique was used to create highly selective biomolecular surfaces capable of discriminating between DNA oligonucleotides with sequences identical to RNA from infectious salmon anemia (ISA) and infectious hematopoietic necrosis (IHN) virus. As little as 0.6 fmol of circularized MPP was detectable with this fluorimetric assay. The sensing layers could be reused for at least four cycles of amplification using thermal denaturation, with less than 33% decrease in RCA response over time. Because the nucleic acid product of the test is attached to a surface during amplification, the technique is directly applicable to a variety of existing sensing platforms, including acoustic wave and optical devices.