Label-Free Fluorescence Molecular Beacon Probes Based on G-Triplex DNA and Thioflavin T for Protein Detection

Abstract

Protein detection plays an important role in biological and biomedical sciences. The immunoassay based on fluorescence labeling has good specificity but a high labeling cost. Herein, on the basis of G-triplex molecular beacon (G3MB) and thioflavin T (ThT), we developed a simple and label-free biosensor for protein detection. The biotin and streptavidin were used as model enzymes. In the presence of target streptavidin (SA), the streptavidin hybridized with G3MB-b (biotin-linked-G-triplex molecular beacon) perfectly and formed larger steric hindrance, which hindered the hydrolysis of probes by exonuclease III (Exo III). In the absence of target streptavidin, the exonuclease III successively cleaved the stem of G3MB-b and released the G-rich sequences which self-assembled into a G-triplex and subsequently activated the fluorescence signal of thioflavin T. Compared with the traditional G-quadruplex molecular beacon (G4MB), the G3MB only needed a lower dosage of exonuclease III and a shorter reaction time to reach the optimal detection performance, because the concise sequence of G-triplex was good for the molecular beacon design. Moreover, fluorescence experiment results exhibited that the G3MB-b had good sensitivity and specificity for streptavidin detection. The developed label-free biosensor provides a valuable and general platform for protein detection.

Fluorescent Investigation of Proteins Using DNA-Synthetic Ligand Conjugates

“…Binding of the FA-modified DNAzyme to FR protects it from being degraded by Exos, retaining its catalytic activity. Similar amplifiable systems were recently developed, distinguished by their “label-free” setup. , Instead of using fluorophore-DNA conjugates, these platforms implement G-triplex-based MBs to generate fluorescent output. In a different catalytic amplification sensory system, protein detection was mediated by the CRISPR-Cas system .…”

Determination of ciprofloxacin using the Ziziphus mauritania derived fluorescent carbon dots based optical sensor

“…On contrast, the uorescence sensor or optical sensor approach offers the bene ts of non-destructive, simple, and cost effective . Owing to its rapid, lack of pre-processing, and high sensitivity detection, uorescence based optical sensors have been extensively applied to detect many analytes that includes biomolecules (Chai et al 2021); proteins (Xue et al 2021); and metal ions (Wang et al 2021).…”