Various DNA assembly techniques and structures have emerged with the continuous progress of DNA nanotechnology. DNA hybridization chain reaction (HCR) is a representative example owing to isothermal and enzyme-free features. However, HCR is time consuming and is inhibited by nucleases present in biological samples. Herein, we demonstrated that a cationic copolymer, poly(l-lysine)-graft-dextran (PLL-g-Dex), significantly facilitated HCR and increased its initiator sensitivity by 40-fold. PLL-g-Dex promoted the generation of HCR products with high molecular weight by accelerating the initiation and the subsequent growth steps of HCR. Moreover, PLL-g-Dex protected the HCR system from nucleases, permitting HCR in the presence of serum components. Addition of PLL-g-Dex is a universal and efficient strategy that does not require optimization of the reactor setup or DNA sequences, thus laying a solid foundation for the wider application of HCR.
Keywords: DNA hybridization chain reaction; cationic copolymer; enzyme-free assay; isothermal amplification; toehold-mediated strand displacement.