摘要
DNA-templated silver nanoclusters(D-AgNCs)have exhibited unique performance advantages for developing label-free fluorescence biosensors;however,most of them are constructed on various single-signal output strategies and how to enhance their detection sensitivity still faces a significant challenge.Herein,a novel crosslinked DNA network nanostructure decorated by chameleon D-AgNCs was developed for constructing an ultrasensitive label-free ratiometric fluorescence biosensing method.The DNA nanostructure was assembled from an aptamer recognition-triggered rolling circle amplification(RCA)reaction under the assistance of a quadruple-way DNA scaffold.This aptamer recognition also triggered a DNA walking reaction to highly release a D-AgNC with yellow fluorescence emission and a nonfluorescent D-AgNC.Through the proximity assembly of the two D-AgNCs at the DNA nanostructure to form a new D-AgNC with red fluorescence emission,the ratiometric signal transduction strategy was constructed for the method.Due to the RCA-assisted amplified assembly of the DNA nanostructure to capture abundant D-AgNCs and dramatically enhance the red fluorescence signal through its nanoconfinement effect,this method exhibited a very low detection limit of 6.55 fg mL^(-1)for selectively assaying the model antibiotic of kanamycin in a sixorder of magnitude wide linear range.In addition,the one-step homogeneous assay with no need to form a DNA hydrogel well simplified the assay manipulation and also effectively decreased the assay cost for practical applications.
基金
supported by the National Natural Science Foundation of China(22076043,22234005)
Natural Science Foundation of Hubei Province of China(2023AFD003)
Natural Science Foundation of Jiangsu Province of China(BK20222015)。
