Coordination polymer nanobelts for nucleic acid detection

Herein, coordination polymer nanobelts (CPNBs) were prepared rapidly and on a large scale, by directly mixing aqueous AgNO3 solution and an ethanol solution of 4,4'-bipyridine at room temperature. The application of such CPNBs as a fluorescent sensing platform for nucleic acid detection was further explored. CPNB is a pi-rich structure, the strong pi-pi stacking interactions between unpaired DNA bases and CPNB leads to adsorption of fluorescently labeled single-stranded DNA (ssDNA) accompanied by 66% fluorescence quenching. However, the presence of target ssDNA will hybridize with the probe. The resultant helix cannot be adsorbed by CPNB due to its rigid conformation and the absence of unpaired DNA bases. Thus, a significant fluorescence enhancement, 73% fluorescence recovery, was observed in DNA detection as long as the target exists. The present system has excellent sensitivity; a substantial fluorescence enhancement was observed when the concentration of the target was as low as 5 nM. It also exhibits outstanding discrimination ability down to a single-base mismatch.