Stable Cyanine Dyes for Near-Infrared Bioimaging
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Solution Overview
Problem
Existing cyanine dyes lack stability in the presence of common bioassay reagents and suffer from thermal and photostability issues, making them unsuitable for applications like DNA sequencing and in vivo imaging, and are often difficult to synthesize in high purity and yield due to asymmetry.
Innovation Solution
Development of stable and symmetric cyanine dyes with specific polymethine bridge structures and bioconjugates that can be used for labeling biomolecules and in vivo imaging, including compounds of Formula I and II, which are designed to be more robust and versatile.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional cyanine dyes are used for labeling biomolecules, then fluorescence imaging in the near-infrared region can be achieved, but the dyes lack stability in the presence of common bioassay reagents and have poor thermal and photostability
Solution Approach 1:
The patent modifies the chemical structure of cyanine dyes by introducing specific substituents (such as sulfur-containing groups and cyclic structures) to enhance stability. The polymethine bridge is designed with specific configurations (e.g., 5-membered rings with sulfur atoms) that increase resistance to reagents like ammonium hydroxide, DTT, and APS while maintaining near-infrared fluorescence properties.
Solution Approach 2:
The invention creates composite dye structures by combining multiple functional groups within the cyanine molecule - including heterocyclic rings, polymethine bridges, and stabilizing substituents - to achieve both stability and versatility. These composite structures integrate multiple properties: photostability, chemical stability, and biomolecule compatibility within a single molecular framework.
2Adaptability or versatility
If asymmetric cyanine dyes are synthesized, then structural diversity can be achieved, but synthesis difficulty increases and purity/yield decreases
Solution Approach 1:
The patent employs asymmetric substitution patterns on the cyanine core structure, where different substituents are placed at different positions of the polymethine bridge or heterocyclic rings. This controlled asymmetry generates structural diversity for various applications while maintaining synthetic feasibility through systematic design rules.
Solution Approach 2:
The synthesis approach divides the complex cyanine dye synthesis into modular steps: first constructing the core polymethine bridge structure, then adding substituents in separate stages. This segmentation allows for better control over purity and yield while achieving diverse final structures.
3Object-affected harmful factors
If cyanine dyes are used for in vivo imaging, then near-infrared fluorescence can be achieved with reduced autofluorescence interference, but photostability and thermal stability are insufficient
Solution Approach 1:
The patent optimizes the conjugation length and substitution patterns of the polymethine bridge to shift emission wavelengths into the near-infrared region (600-1000 nm), where biological autofluorescence is minimal. Simultaneously, stabilizing groups are incorporated to enhance photostability, allowing prolonged imaging sessions without rapid signal degradation.
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 cyanine dyes provide enhanced stability and photostability, enabling effective labeling and imaging applications, including improved performance in Western blotting and in vivo imaging, with balanced charge and suitable absorption and emission spectra for biomedical use.
Implementation Method 1
many of these dyes fluoresce in the near-infrared (NIR) region of the spectrum (600-1000 nm)
Implementation Method 2
cyanine dyes strongly absorb and fluoresce light
Data Source
Figure 1A~1D
Figure 2A~2D
Figure 3A~3B
AI summary
Compounds and methods are disclosed that are useful for noninvasive imaging in the near-infrared spectral range. The cyanine compounds of Formula (I) are presented: (I). wherein Q is a portion of a polymethine bridge selected from the group consisting of: (a) and (b). Also included are bioconjugates of the compounds of Formula (I), methods of labeling biomolecules with the compounds, and methods of imaging.