The Enhanced Enzymolysis Resistance of Surface-Immobilized DNA Caused by Hybridizing with Morpholino

The anti-enzymolysis capability of surface attached DNA, morpholino (MO) single strands, and DNA-DNA, MO-DNA double strands are studied using cyclic voltammetry. Results show that MO, the neutral analog of DNA, bears strong anti-enzymolysis capability against DNase I and can protect its complementary DNA from being decomposed. Only 15 % of the DNA in the MO-DNA double strands is decomposed within 20 min, which is much lower than that for DNA-DNA double strands (100 % in 400 s). Fluorescence polarization measurements suggest that the steric hindrance of MO is the main cause of the improved anti-enzymolysis ability of DNA in MO-DNA double strands.