Improvement of MNAzyme derived from 17EV1 by modification on the split catalytic core for biosensor design

MNAzymes were derived from catalytic DNAzymes (10–23, 8–17, 17E, et al) with a split catalytic core at certain positions, an extra oligonucleotide (termed as initiating oligonucleotide) was introduced to recover the catalytic core and the catalytic activity. With this initiating oligonucleotide, thus, the applications of MNAzymes as the detection biosensors have been expanded dramatically to a wide range of analytes of interest. However, the split catalytic core of MNAzymes is less active than the intact DNAzymes, many designs were concentrated on the signaling methods for a better performance. Here, MNAzymes from 17EV1 were constructed with miR-21 and miR-155 as the initiating oligonucleotides, and chemical modification on the split catalytic core was conducted, by the substitution of the residue A15 with 6-(3-aminopropyl)-2′-deoxyadenosine (compound 1), two modified MNAzymes (MNAzyme-21-1 and MNAzyme-155-1) were obtained. With fluorescence signaling method, the limit of detection for miR-21 and miR-155 could be improved for about 4.9 and 12-fold, respectively. With this critical element, the modified MNAzyme could be further adapted for other analytes and combined with other detection methods for better performance, due to the programmability of MNAzyme components.