NIR Quenching Cyanine Dyes for Protease Assay Background Reduction
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Solution Overview
Problem
Current protease assays using visible-range fluorophores suffer from high background fluorescence and low sensitivity due to undesired background fluorescence and scattering photons, limiting their utility in detecting specific protease activity and enzyme activity modulation.
Innovation Solution
Development of near-infrared (NIR) quenching cyanine dyes with absorption wavelengths between 650-900 nm that are essentially non-fluorescent, providing good water solubility and spectral overlap with NIR fluorophores, used in conjunction with NIR reporter dyes for enhanced fluorescence quenching and reduced background interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If visible-range fluorophores are used in protease assays, then fluorescence detection can be achieved, but background fluorescence and scattering photons increase, reducing assay sensitivity
Solution Approach 1:
The patent changes the wavelength parameter of the fluorophore from visible range to near-infrared range (650-900 nm). This parameter change shifts the detection window to a region where biological autofluorescence is minimal and light scattering is reduced, thereby improving assay sensitivity while maintaining fluorescence detection capability
Solution Approach 2:
The patent converts the limitation of available laser wavelengths into a benefit by selecting NIR fluorophores that match the discrete wavelengths of commercial diode lasers (e.g., 780 nm, 808 nm, 830 nm, 850 nm, 940 nm). This alignment ensures optimum excitation while operating in the low-background NIR region
2Object-generated harmful factors
If NIR fluorophores are used to reduce background fluorescence, then assay sensitivity improves, but matching laser wavelengths becomes limited due to discrete commercial laser availability
Solution Approach 1:
The patent develops a series of NIR cyanine dyes with absorption maxima at specific wavelengths (705 nm, 750 nm, 780 nm, 800 nm, 830 nm, 850 nm, 940 nm) that correspond to commonly available diode laser wavelengths. This enables universal compatibility with commercial laser sources while maintaining operation in the optimal NIR detection window
Solution Approach 2:
The patent modifies the chemical structure of cyanine dyes by varying the polymethine chain length and substituent groups to precisely tune the absorption maximum to match specific laser wavelengths, ensuring optimum excitation efficiency for each available laser source
3Quantity of substance
If cyanine dyes are used for labeling biomolecules, then high molar absorptivity and biocompatibility are achieved, but fluorescence quenching capability is insufficient for modulation applications
Solution Approach 1:
The patent introduces a nitro group substituent at specific positions on the cyanine dye structure. This local modification creates a 'dark' state that quenches fluorescence while maintaining the overall high molar absorptivity of the cyanine core, enabling both strong absorption and controllable quenching in the same molecule
Solution Approach 2:
The patent creates composite dye structures by combining the cyanine chromophore (providing high molar absorptivity) with nitro-substituted quenching groups (providing fluorescence quenching capability). This composite structure integrates both functions into a single molecule suitable for modulation applications
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 NIR quenching cyanine dyes efficiently quench fluorescence with minimal background interference, improving assay sensitivity and specificity for detecting protease activity and enzyme modulation, particularly in protease assays.
Implementation Method 1
near IR quenching cyanine dyes having formulae I-Id that 1) have absorption wavelengths in the near-infrared region of about 650-900 nm
Implementation Method 2
The NIR quenching cyanine dyes efficiently quench fluorescence with minimal background interference
Data Source
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Figure 1C
AI summary
The present invention provides for cyanine dyes as near IR quenchers. The cyanine dyes have absorption wavelengths in the near-infrared region of about 650-900 nm and are essentially non-fluorescent. The dyes of the invention have at least one linking group. The present invention also provides substantially non-fluorescent, NIR probes. Biological assays based on these novel, substantially non-fluorescent, NIR probes are also provided.