Facile and cost-effective detection of multiple targets is essential for a variety of applications ranging from life sciences to environmental monitoring. Here, we report a versatile ratiometric fluorescence platform for multiple detection of various targets based on the conjugation of single-stranded DNA (ssDNA) with protonated graphitic carbon nitride nanosheets (Pg-C3N4 NSs). We demonstrate that intrinsic peroxidase-like activity of Pg-C3N4 NSs is enhanced by conjugating with ssDNA, and thus the oxidation of substrate o-phenylenediamine (OPD) is promoted in the presence of H2O2. The oxidation product 2,3-diaminophenazine (DAP) can deliver a new fluorescence signal at 564 nm, and concurrently quench the intrinsic fluorescence of conjugates ssDNA/Pg-C3N4 NSs at 443 nm upon excitation at 370 nm. The transformation of fluorescence provides us a novel strategy for ratiometric fluorescence-based analytical sensing. Taking ssDNA as the target-recognition element of the conjugates ssDNA/Pg-C3N4 NSs, we favorably present ratiometric fluorescence detection of various targets including heavy metal ions (Hg2+) and biomolecules (Aflatoxin B1 (AFB1) and adenosine triphosphate (ATP)) in real samples by varying the ssDNA sequences. The present work provides a new strategy to develop facile methods for quantitative determination of various analytes and uncovers an innovative horizon for Pg-C3N4 NSs-based sensing platform fabrication.
Keywords: Multiplex detection; Peroxidase-like activity; Protonated graphitic carbon nitride nanosheets (Pg-C(3)N(4) NSs); Ratiometric fluorescence; Single-stranded DNA (ssDNA); Versatile platform.
Copyright © 2019 Elsevier B.V. All rights reserved.