A novel label-free fluorescent detection of histidine based upon Cu2+-specific DNAzyme and hybridization chain reaction

A novel label-free fluorescent sensor for histidine was developed based upon Cu 2+ -specific DNAzyme, hybridization chain reaction(HCR) and triplex DNA . Cu 2+ can bind to the histidine, in the presence of histidine, leading to the inhibition of the cleavage of substrate strand of Cu 2+ -dependent DNAzyme, then the intact substrate strand trigger the HCR between H1 and H2. The HCR product can be recognized by triplex-forming oligonucleotide (TFO) through triplex formation and reported by the fluorescence of berberine , the fluorescence intensity of the sensing system was proportional to the concentration of histidine during the range of 5.7–455 nmol L −1 , with a detection limit of 2.0 nmol L −1 .