A Homogeneous Multicomponent Nucleic Acid Enzyme Assay for Universal Nucleic Acid Detection by Single-Particle Inductively Coupled Plasma Mass Spectrometry

Single-particle inductively coupled plasma mass spectrometry (SP-ICP-MS) has great potential for sensitive analysis of nucleic acids; however, it usually requires separation of target-induced nanoparticle reporters, and the sequence of probes on nanoparticle reporters has to be tuned for each target accordingly. Here, we developed a homogeneous multicomponent nucleic acid enzyme (MNAzyme) assay for universal nucleic acid detection. The two components of MNAzyme contain target recognition sites, substrate binding sites, and a catalytic core. Only in the presence of a specific nucleic acid target, the MNAzyme will assemble to trigger its nucleic acid enzyme activity and cleave its substrate (Linker DNA). The Linker DNA could link gold nanoparticle (AuNP) probes to form a larger assembled particle, while the cleavage of Linker DNA will disturb the linkage between probes, inducing a smaller assembled particle. The assembled particles with different sizes could be differentiated and sensitively detected in SP-ICP-MS, which also enables the tolerance of a complex matrix. By simply altering the sequences of the target recognition sites in MNAzyme, we applied the assay for two types of nucleic acids (long strand DNA and short strand RNA), malaria DNA and miRNA-10b. With increasing the target concentration, the signal intensity of each assembled particle decreases, but the frequency of assembled particle pulse increases. Both targets could be quantitatively detected from 0.1 to 25 pmol L^-1 with high specificity in serum samples. The developed MNAzyme-SP-ICP-MS assay possesses simple operation in a homogeneous reaction, easy tunability for multiple types of nucleic acid targets, and good compatibility with clinic samples.