Ratiometric Quantum Dot–Ligand System Made by Phase Transfer for Visual Detection of Double-Stranded DNA and Single-Nucleotide Polymorphism

Abstract

We have developed a proof-of-concept quantum dot-ligand (QD-L) system for visual selective detection of nucleic acids, in combination with a ratiometric fluorescence technique. This system comprises a dual-emission QDs nanohybrid formed by embedding a red-emission QD (rQD) in a silica nanoparticle and electrostatically assembling green-emission QDs (gQDs) onto the silica surface, as the signal displaying unit, and a hydrophobic compound, dipyrido[3,2-a:2',3'-c]phenazine (dppz), attached onto the gQDs surface via phase transfer, as the ligand as well as fluorescence quencher of gQDs. This system is successfully used for quantification of double-stranded DNA (dsDNA). Because of its avid binding with dppz, dsDNA can break up the QD-L system, displacing the dppz ligand from the gQDs surface and restoring the gQDs emission. Since the red emission of embedded rQDs stays constant, variations of the dual-emission intensity ratios display continuous color changes from orange to bright green, which can be clearly observed by the naked eye. More importantly, this system is advantageous in terms of specificity over a QD ionic conjugate, because the electrical neutrality of dppz excludes its nonspecific electrostatic association with dsDNA. The QD-L system also is capable of detecting single-nucleotide polymorphism, exhibiting sequence-specific ratiometric fluorescence as a QD-bioconjugate does, but possessing the obvious advantage in terms of low cost, with the avoidance of modification, labeling, and purification processes. Therefore, the QD-L system provides an extremely simple but general strategy for detecting nucleic acids in a facile, sensitive, and specific manner.

DNA Three‐Way Junction for Differentiation of Single‐Nucleotide Polymorphisms with Fluorescent Copper Nanoparticles

“…With the development of chemical modification techniques, new strategies for SNPs detection have gradually emerged. Some are based on the labeling of DNA with fluorophores, organic molecules, or metal complexes, whereas some rely on the modification of certain spacer groups that connect the DNA to electrodes, nanochannels, or nanomaterials through chemical bonds, thereby exploiting fluorescent, electrical, or color signals . Although enzymes are avoided in these methods, the complicated process of chemical modification is tedious and expensive.…”

“…Some are based on the labeling of DNA with fluorophores, organic molecules, or metal complexes, [6][7][8] whereass ome rely on the modification of certain spacer groups that connect the DNA to electrodes, nanochannels, or nanomaterials through chemical bonds, [9][10][11] thereby exploiting fluorescent, electrical, or color signals. [11][12][13] Althoughe nzymes are avoided in these methods, the complicated process of chemical modification is tedious and expensive. Therefore, as imple, rapid, and cost-effective design is urgently neededf or SNPs detection.The emerging fluorophores of noble-metaln anoclusters, especially fluorescent silver nanoclusters (AgNCs), [14] are potential new tools for the identification of SNPs.…”

A ratiometric fluorescence sensor based on UiO-66-CdTe@ZIF-8 core-shell nanocomposites for the highly selective detection of NO

“…Quantum dots (QDs) are better than their organic uorophore counterparts because of their unique electro-optical properties and photophysical features, such as high quantum yields, long uorescence lifetimes, large extinction coe cients, higher brightness and stability against photobleaching, and broad absorption spectra coupled with narrow photoluminescent (PL) emission spectra 11,12 ; thus, QDs are more suitable for constructing multi-coloured uorescence systems 13,14 . In recent years, great efforts have been made to construct dual-colour QD-based ratiometric uorescent sensing system for the highly sensitive detection of various substances, such as TNT 15 , metal ions 16 , amino acids 17 and duplex DNA molecules 18 .…”

Activatable QD-Based Near-Infrared Fluorescence Probe for Sensitive Detection and Imaging of DNA

“…Aberrant DNA levels can generally indicate disease states. As such, accurate detection of DNA can enable distinguishing different cell types or reporting on a different cell status, which is helpful for the precise diagnosis of disease. , To date, a large number of analytical methods have been developed for the determination of DNA, such as fluorescence, phosphorescence, electrochemistry, resonance Rayleigh scattering, surface plasmon resonance, , and chemiluminescence . Among these, fluorescence, which can offer prominent merits in terms of sensitivity and easy operation, has attracted much attention.…”