Ratiometric fluorescence detection of bleomycin based on proximity-dependent fluorescence conversion of DNA-templated silver nanoclusters

We design a ratiometric fluorescent sensing platform for bleomycin (BLM) by using proximity-dependent DNA-templated silver nanoclusters (DNA-AgNCs) probe. This ratiometric sensing system is constructed with DNA-AgNCs as single fluorophore. The proposed strategy is based on the two following facts: (1) a covert DNA can approach and transform the DNA-AgNCs with green emission (G-DNA-AgNCs) into red emission through hybridization reaction. (2) The specific cleavage of the convert DNA by BLM in the presence of Fe(II) inhibits the discoloration of G-DNA-AgNCs. Thus, benefiting from the specific recognition of BLM and unique properties of G-DNA-AgNCs, a highly-sensitive ratiometric sensor for BLM has been successfully developed. The detection limit is as low as 30 pmol/L. This label-free fluorescence probe possesses advantages of convenient synthetic process and low cost. Moreover, this ratiometric method has been applied to the detection of BLM in human serum samples, illustrating a promising tool for analysis of BLM in cancer therapy.