Luminogenic Transition Metal Pyridyl Complex for Bioorthogonal Imaging
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Solution Overview
Problem
Current bioorthogonal probes, primarily organic dyes, face limitations such as high photobleaching rates, self-quenching, pH dependence, and short-lived fluorescence, which restrict their application in live cell and organism imaging, particularly due to susceptibility to thiols in biological systems.
Innovation Solution
Development of luminogenic transition metal-based pyridyl complexes containing a nitrone moiety that acts as both a bioorthogonal functional group and an emission quencher, enabling strain-promoted alkyne-nitrone cycloaddition reactions and providing enhanced photostability and long-lived phosphorescence suitable for fluorescence-lifetime imaging microscopy (FLIM).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If organic dye-based fluorescent probes are used for bioorthogonal labeling, then strong fluorescence signal is achieved, but photobleaching rate increases and photostability decreases
Solution Approach 1:
The patent transitions from organic fluorophores to transition metal complexes (e.g., ruthenium, iridium) which fundamentally changes the emission mechanism from fluorescence to phosphorescence. This parameter change enables long-lived emission (microsecond to millisecond timescale) with inherently higher photostability, as the triplet state emission is less susceptible to photobleaching compared to singlet state fluorescence of organic dyes
Solution Approach 2:
The patent creates composite structures by coordinating transition metal centers with organic ligands containing nitrone or azide groups. This composite approach combines the photostability and long-lived phosphorescence of transition metals with the bioorthogonal functionality of the organic moieties, achieving both strong signal and high reliability
2Measurement precision
If azide-containing fluorogenic probes are used, then emission turn-on after labeling is achieved, but susceptibility to thiol reduction increases causing false positive signals
Solution Approach 1:
The patent changes the bioorthogonal functional group from azide to nitrone, which fundamentally alters the chemical stability profile. Nitrone groups are resistant to thiol reduction while maintaining reactivity with strained alkynes, eliminating the false positive issue. The emission turn-on mechanism is preserved through the quenching effect of the nitrone group on the phosphorescent metal complex
Solution Approach 2:
The patent replaces the unstable azide group with a more stable nitrone group that is not susceptible to reduction by cellular thiols. This substitution makes the probe robust for in vivo applications where thiol concentrations are high, ensuring that signal activation occurs only through the intended cycloaddition reaction with the target biomolecule
3Duration of action of moving object
If conventional fluorescent probes are used, then real-time monitoring is possible, but emission lifetime is too short for FLIM compatibility
Solution Approach 1:
The patent exploits the parameter change from fluorescence (nanosecond lifetime) to phosphorescence (microsecond to millisecond lifetime) by using transition metal complexes. The heavy atom effect in these complexes enables efficient triplet state population and long-lived phosphorescent emission, making the probes inherently compatible with FLIM techniques that require microsecond-timescale emission lifetimes for accurate lifetime measurements
4Illumination intensity
If highly fluorescent organic probes are used, then strong signal is obtained, but self-quenching increases reducing detection sensitivity
Solution Approach 1:
The patent changes the emission mechanism from fluorescence to phosphorescence, which fundamentally alters the quenching behavior. Phosphorescent transition metal complexes exhibit different self-quenching characteristics compared to fluorescent organic dyes, and the long-lived triplet state emission allows for detection even at lower concentrations, reducing the impact of self-quenching effects
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
These complexes offer improved photostability, reduced self-quenching, and extended emission lifetimes, enabling effective bioorthogonal labeling and imaging of biomolecules with enhanced sensitivity and specificity, even in the presence of thiols, thus overcoming the limitations of existing probes.
Implementation Method 1
The nitrone moiety can undergo cycloaddition reaction with a complementary bioorthogonal functional group coupled to a substrate
Implementation Method 2
providing enhanced photostability and long-lived phosphorescence suitable for fluorescence-lifetime imaging microscopy (FLIM)
Implementation Method 3
a nitrone moiety that acts as both a bioorthogonal functional group and an emission quencher
Data Source
AI summary
The present invention provides a luminogenic, in particular a phosphorogenic transition metal-based pyridyl complex containing a nitrone moiety, which nitrone moiety acts as a bioorthogonal functional group and an emission quencher, and can undergo cycloaddition reaction with a complementary bioorthogonal functional group coupled to a substrate. The transition metal is can be selected from iridium or ruthenium. Also disclosed is a method for preparing the transition metal-based pyridyl complex and a pharmaceutical composition comprising it. Still further provided is a method for bioorthogonal labeling of a biomolecule, a method for staining of a cell structure, a method for in vivo imaging of an organism, and a kit for in vivo imaging of an organism. The luminogenic properties and high reactivity of the complexes are highly advantageous for bioorthogonal labeling and imaging of biomolecules in their native biological environments at much lower costs than those of the existing commercial products.