posted on 2018-06-15, 00:00authored byYishen Tian, Chen Xin, Shuang Liu, Ying Liu, Shufeng Liu
Herein, a general
protein conversion and analysis strategy was
developed for homogeneous, label-free, and sensitive protein detection,
on the basis of the affinity binding-induced Hg2+ release
for protein conversion, and the succeeding Hg2+ doping-induced
ZnSe quantum dot (QD) photoluminescence for signal readout. Two DNA
motifs were designed, each of which was conjugated with a protein-specific
recognition ligand. The mercury ions were initially introduced into
one DNA motif by T-Hg2+-T interaction. The Hg2+ releasing was then accomplished after protein recognition-initiated
strand exchange reaction between two DNA motifs. Then, the simultaneous
incorporation of the released Hg2+ into ZnSe QD resulted
in a doping-dependent fluorescence emission at 560 nm correlated with
protein analysis. The protein assay is outperformed only by a simple
one-step mixing operation but no separation or washing steps. Also,
the use of doped QD as a fluorogenic reporter can avoid the fluorophore
and/or quencher labeling, and eliminate complex DNA manipulation procedures
for signal readout or amplification involved in most existing nucleic
acid-based protein conversion and analysis methods. The versatile
and sensitive detection toward multivalent proteins was verified with
the detection limits achieved at 0.034 nM for anti-Dig antibody, 0.012
nM for streptavidin, and 0.025 nM for thrombin. Thus, it shows great
promise for protein analysis to accommodate the applications in disease
diagnosis, biomarker screening, and clinical medicine.