Label-free and non-enzymatic detection of DNA based on hybridization chain reaction amplification and dsDNA-templated copper nanoparticles.

A label-free and non-enzymatic amplification fluorescent method for detection of DNA has been developed by using hybridization chain reaction (HCR) and dsDNA-templated copper nanoparticles (CuNPs). First, the biotinylated capture DNA probes were immobilized on the streptavidin-modified beads through the interaction of biotin and streptavidin. Then, target DNA hybridized with the capture DNA probes, which formed a hybridized DNA with sticky end. The sticky end triggered the HCR process and formation of dsDNA polymers while two hairpin probes coexisted. Subsequently, the dsDNA polymers were employed as template for synthesis of CuNPs with excellent fluorescent properties, which provided a label-free, non-enzymatic signal response. Meanwhile, the fluorescence sensing depended on the target DNA triggered HCR, which render this method a high selectivity against single-base mismatch sequences. The concept and methodology developed in this work show great promise in the quantitative detection of DNA in biological and medical applications.