Monocationic Cyanine Dyes for Live Cell DNA Detection
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Solution Overview
Problem
Current fluorescent dyes face limitations such as toxicity, carcinogenicity, restricted live cell permeability, and interference from UV light, which hinders their application in live cell analysis and genomics due to high fluorescence background and poor spectral properties.
Innovation Solution
Development of novel monocationic nitrogen-containing cyanine dyes with a simple structure, high sensitivity, long wavelength, and live cell permeability, synthesized through specific reaction steps involving quaternary ammonium salts and N,N′-diphenylformamidine, which exhibit enhanced fluorescence quantum yield upon binding to nucleic acids and reduced background interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If commercially available fluorescent dyes (TOPRO, TOTO, EB, PI) are used for DNA labeling, then DNA detection capability is achieved, but membrane permeabilization is required which produces undesired artifacts
Solution Approach 1:
The invention changes the charge parameter of the cyanine dye from multicationic (2+ or 3+) to monocationic (1+), which fundamentally alters the dye's interaction with cell membranes. This parameter change enables the dye to penetrate intact cell membranes without requiring permeabilization, thereby avoiding artifacts while maintaining DNA detection capability
Solution Approach 2:
The invention creates a composite fluorescent probe by conjugating monocationic cyanine dyes with specific nucleic acid-binding moieties. This composite structure combines the membrane-permeable properties of the monocationic dye with the DNA-specific binding capability, achieving both cell penetration and specific detection
2Measurement precision
If acridine and phenanthridine dyes (EB) are used for DNA staining, then DNA detection is achieved, but toxicity and carcinogenicity increase
Solution Approach 1:
The invention changes the chemical structure parameter by replacing acridine/phenanthridine cores with cyanine dye structures containing benzothiazole, benzoxazole, or indoline rings. This structural parameter change maintains DNA binding capability while eliminating the toxic and carcinogenic properties associated with acridine and phenanthridine dyes
3Measurement precision
If UV illumination is used to excite crescent-shaped dyes (DAPI, Hoechst), then blue fluorescence emission is achieved, but cellular DNA and protein damage occurs
Solution Approach 1:
The invention changes the excitation wavelength parameter from UV range (300-400 nm) to visible red range (530-680 nm). The cyanine dyes are designed to be excited by red light and emit in the far-red to near-infrared range, eliminating UV-induced damage to cellular components while maintaining DNA detection capability
Solution Approach 2:
The invention shifts the operational dimension from UV excitation to visible/red light excitation. By designing dyes with absorption maxima in the 530-680 nm range and emission in the 650-900 nm range, the system operates in a different spectral dimension that avoids the harmful effects of UV radiation while achieving the same detection function
4Measurement precision
If UV light is used for excitation, then fluorescence emission is achieved, but light penetration into biological tissues is restricted
Solution Approach 1:
The invention changes the wavelength parameter of both excitation and emission light to the red and near-infrared range (530-900 nm). This parameter change exploits the optical window in biological tissues where absorption and scattering are minimized, enabling deep tissue penetration while maintaining fluorescence detection capability
5Measurement precision
If multicationic asymmetric cyanine dyes (TOTO, YOYO) are used for nucleic acid detection, then high affinity binding is achieved, but live cell impermeability occurs
Solution Approach 1:
The invention changes the charge parameter from multicationic (2+ or 3+) to monocationic (1+), which reduces the electrostatic repulsion with the negatively charged cell membrane. This parameter change enables passive diffusion through the membrane while maintaining high nucleic acid binding affinity through optimized structural features
Solution Approach 2:
The invention segments the dye molecule into distinct functional domains: a monocationic head group for membrane interaction, a polymethine bridge for electronic conjugation, and heterocyclic end groups for nucleic acid binding. This segmentation allows each domain to independently optimize its function while working together as a unified probe
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The new dyes demonstrate significant fluorescence enhancement upon binding to nucleic acids, improved live cell membrane permeability, and reduced interference from biological samples, enabling more sensitive and specific nucleic acid detection with lower toxicity and cost-effective production.
Implementation Method 1
The interaction modes of these asymmetric cyanine dyes with nucleic acids are intercalation to base pairs, groove binding and electrostatic attraction
Implementation Method 2
The interaction modes of these asymmetric cyanine dyes with nucleic acids are intercalation to base pairs, groove binding and electrostatic attraction
Implementation Method 3
acridine and phenanthridine dyes such as EB are toxic and carcinogenic. Secondly, there are a considerable number of fluorescent dyes need ultraviolet illumination as excitation light source, such as DNA specific crescent-shaped dyes 4′,6-diamidino-2-phenylindole (DAPI), Hoechst33258, Hoechst34580, which emit blue fluorescence upon binding to DNA
Data Source
AI summary
The present invention provides a category of cyanine dyes having the following general structural Formula I, wherein X is defined as C(CH3)2, O, S or Se; m is an integer from 1 to 18, R1 and R2 are each independently chosen from H, C1-18alkyl, OR7, C1-6alkyl-OR7 or halogen; R3 is pyrrolyl, imidazolyl, piperidinyl, piperazinyl, morpholinyl, guanidino, NHR5 or N(R6)2; R4 is C1-18alkyl, benzyl or (CH2)mR3; R5 is saturated and/or unsaturated, straight-chained and/or branched-chained C1-18alkyl, hydroxy alkyl, mercapto-alkyl, amino alkyl, acyl, phenyl, naphthyl or benzyl; R6 is a C2-18alkyl; R7 is H or a C1-18alkyl; Y− is an anion. The mentioned compounds can be applied to staining biological samples, to the fields of nucleic acids labeling, blood cell analysis, clinical diagnosis, immunological assays and etc.