Aptamer AS1411 subjected to chemical modification and application thereof

The invention discloses an aptamer AS1411 subjected to chemical modification and application thereof. A modification strategy of isonucleoside or isonucleoside combined with 2'-deoxyinosine is adopted, and the nucleotide in different positions of the aptamer AS1411 is replaced, so that the partial spatial conformation of the aptamer AS1411 is changed, the space structure is optimized, and the purposes that the molecular stability is improved, the recognition capability for target molecules is strengthened, the acting force for the targets is strengthened, and the biological activity of the aptamer is improved are achieved. Study indicates that the AS1411 modified through the method can be combined with target proteins better, the breast cancer cell proliferation resistant and DNA replication resistant capacities are remarkably strengthened, the inhibitory effect on breast cancer transplantation tumor growth is more obvious, and the difference has statistical significance; the computer simulation shows that the combining capacity of the modified AS1411 with target protein pyrenin is obviously improved; besides, the modified AS1411 can specially regulate some functional miRNA, and can be hopefully developed into a biological network regulating instrument.