Label-free DNAzyme for highly sensitive detection of multiple biomolecules in real samples through target-triggered catalytic cleavage reactions with auramine O’s discriminated fluorescence emission

Abstract

A universal enzyme strand (E-DNA) recyclable L-histidine (L-His), melamine (MA), and cisplatin (CP) biosensor was fabricated on the basis of a target-specific RNA-cleaving DNAzyme with specific auramine O (AuO) dye instead of thioflavin T. In this strategy, the substrate strand (S-DNA) of the RNA-cleaving site was constructed as an intramolecular stem-loop structure, and a GT-rich sequence was imprisoned in the double-stranded stem which inhibits the formation of stable G-quadruplex (G4cpx) with AuO. The presence of L-His initiates a catalytic reaction for cleaving the RNA site of the S-DNA hydrolytically releasing the GT-rich portion, which subsequently combines with AuO and forms a G4cpx for enhanced fluorescent signal. The subsequent addition of MA uncoils the G4cpx to form T-MA-T dsDNA, or addition of CP unwound the G4cpx to form CP-DNA leading to an intensive decrease of AuO emission. Remarkably, the liberated L-His can ultimately cause several rounds of cleavage, and the liberated E-DNA can catalyze the subsequent reaction with the other S-DNA. The use of L-His and E-DNA repeatedly induces S-DNA cleavage and intensifies the emission signal. The results show that the proposed biosensor is extremely sensitive to L-His, MA, and CP with a detection limit of 0.98, 10, and 3.4 nM respectively. To the best of our knowledge, the utilization of AuO as the G4cpx inducer and stabilizer for L-His, MA, and CP detection in real milk and urine samples has never been reported.

A dual-color fluorescent biosensing platform based on amine functionalized 3D copper Prussian blue nanocubes and exonuclease I activity for simultaneous detection of kanamycin and streptomycin

“…The oligosensor, a different type of sensor, is an extremely effective detector that captures the target using oligomers as an identification element. [11][12][13] The oligomer is a nucleic acid fragment that is selected from a random oligonucleotide library and specifically binds to the target. The oligomer has several benefits as an identification element: it has high specificity and affinity for the target; it is stable and high temperature has little effect on its activity; it is simple to prepare and transform; it is convenient for transportation, long-term storage, low cost, and has no or low poisonousness and immunogenicity.…”

Rapid Indentification of Auramine O Dyeing Adulteration in Dendrobium officinale, Saffron and Curcuma by SERS Raman Spectroscopy Combined with SSA-BP Neural Networks Model

“…At present, the detection methods of AO in food and medicine mainly include chromatography [2,27] and fluorescence [28][29][30], which have the advantages of high accuracy and good detection sensitivity. In addition, adsorptive stripping voltammetry [31], bionanosorbent [32], and terahertz spectroscopy [33,34] have also been applied for the determination of AO in foods and herbs.…”