Luciferin Analogues Near-Infrared Bioluminescence Imaging
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Solution Overview
Problem
Current bioluminescence imaging technologies face limitations in extending small animal imaging to larger animals due to absorption and scatter of yellow-green light by haemoglobin, preventing true tomographic and multi-parametric imaging, and existing genetically encoded near-infrared bioluminescence labels are lacking, restricting depth penetration and resolution.
Innovation Solution
Development of novel substrate analogues of luciferin that shift emission into the near-infrared range, allowing for higher resolution and deeper tissue imaging by reducing haemoglobin attenuation and scatter, and enabling multispectral bioluminescence imaging in larger animals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If yellow-green light emission from firefly luciferase is used, then high sensitivity and rapid detection are achieved, but light absorption and scatter by haemoglobin prevent deep tissue imaging and tomographic reconstruction
Solution Approach 1:
The patent applies parameter changes by modifying the emission wavelength of the bioluminescence system from yellow-green (557nm) to red (620nm and beyond). This is achieved through engineering firefly luciferase mutants with altered spectral properties and using red-shifted luciferin analogues. The wavelength shift moves the emission into the optical window where tissue attenuation is minimized, thereby resolving the contradiction between sensitivity and deep tissue penetration.
2Length of stationary object
If emission wavelength is shifted to near-infrared to overcome haemoglobin absorption, then depth penetration is improved, but genetically encoded nIR BLI labels do not currently exist
Solution Approach 1:
The patent extends the emission wavelength beyond the conventional red limit of 620nm into the far-red and near-infrared regions (650-900nm). This is accomplished through systematic mutagenesis of firefly luciferase to create red-shifted variants and through chemical modification of luciferin substrates. These parameter changes enable genetically encoded nIR BLI labels to exist for the first time, resolving the contradiction between depth penetration and label availability.
Solution Approach 2:
The patent creates composite bioluminescence systems by combining engineered firefly luciferase mutants with synthetic red-shifted luciferin analogues. This composite approach allows the system to achieve near-infrared emission that neither component could achieve alone, thereby providing reliable genetically encoded nIR labels for deep tissue imaging.
3Object-affected harmful factors
If red-shifted emission is achieved through enzyme engineering, then attenuation is reduced, but current systems are near the limit of red-shifting at ca. 620nm
Solution Approach 1:
The patent overcomes the 620nm red-shifting limit by implementing dual parameter changes: (1) engineering firefly luciferase mutants with extended red-shifted spectra, and (2) introducing luciferin analogues with inherently red-shifted emission properties. This combined approach pushes the emission wavelength into the 650-900nm range, further reducing tissue attenuation while managing the complexity through systematic molecular design.
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 novel luciferin analogues achieve enhanced depth penetration and resolution in bioluminescence imaging by emitting light in the near-infrared range, reducing haemoglobin absorption and scatter, and providing high sensitivity for imaging in larger animals such as dogs, cats, primates, and humans.
Implementation Method 1
Catalysis of a substrate (e.g. luciferin) by a bioluminescence (BLI) enzyme (e.g. luciferase) results in the release of light
Implementation Method 2
The chemical mechanism for the different colours observed with different mutant Flue and native LH2 is unknown
Implementation Method 3
luciferases emit light (yellow-green colour) that is largely absorbed by haemoglobin
Implementation Method 4
This causes scatter and differential attenuation depending on tissue density and light source depth
Data Source
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AI summary
The present invention relates to a compound having the formula (I): wherein ring A is an optionally substituted 5- or 6-membered heterocyclyl, or heteroaiyl ring; ring B is an optionally substituted 5- or 6-membered heterocyclyl, heteroaiyl, or hydrocarbon ring; R1 is hydrogen or an optionally substituted alkyl group; each R2, when present, is a group independently selected from optionally substituted hydroxyl, optionally substituted amino, optionally substituted thiol, optionally substituted alkyl, and optionally substituted aryl; R3 is an optionally substituted acyl group; M is a group selected from O, S, and NR4, wherein R4 is a group selected from hydrogen, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted aryl, optionally substituted heteroaiyl, and optionally substituted heterocyclyl; X is an optionally substituted unsaturated hydrocarbon group or an optionally substituted alkylene carbonyl; and n is 0, 1, 2, or 3. Such compound is a substrate of luciferase enzymes.