CA-IX Fluorescent Probes With Cyanine-Acetazolamide Targeting
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Solution Overview
Problem
Current fluorescent probes targeting Carbonic Anhydrase IX (CA-IX) for biomedical imaging suffer from low specificity, high non-specific accumulation, and instability, limiting their effectiveness in diagnosing and treating hypoxic tumors.
Innovation Solution
Development of heptamethine cyanine dyes conjugated to an acetazolamide moiety at position 5 of the indolenine ring, providing high affinity and stability for CA-IX, with improved water solubility and reduced non-specific interaction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional fluorescent probes (ICG, Fluorescein) are used for tumor imaging, then they can distribute in tumor tissues through passive diffusion and EPR effect, but they require large mass doses (>1 mg/kg) and produce false positive/negative responses due to low specificity
Solution Approach 1:
The patent introduces an acetazolamide moiety as a targeting intermediary that specifically binds to Carbonic Anhydrase IX (CA-IX) enzyme overexpressed on hypoxic tumor cells. This mediator enables the fluorescent probe to selectively accumulate at the tumor site through active targeting, replacing the non-specific passive diffusion mechanism and eliminating the need for large mass doses.
Solution Approach 2:
The patent modifies the fluorescent probe structure by conjugating acetazolamide at specific positions (position 5 of indolenine ring) to create localized high-affinity binding capability. This local modification enables the probe to recognize and bind specifically to CA-IX receptors on tumor cells, achieving high detection precision with minimal dosage.
2Measurement precision
If cyanine dyes are conjugated to targeting agents to improve sensitivity and specificity, then detection precision improves, but in vivo behavior is strongly affected by biological properties of the fluorescent moiety leading to non-specific accumulation
Solution Approach 1:
The patent systematically varies structural parameters of the cyanine dye including the polymethine chain length (n=3,4,5), substituent groups (R1, R2, R3), and conjugation position (position 5 of indolenine ring) to optimize the balance between targeting efficiency and non-specific accumulation. These parameter changes enable fine-tuning of hydrophobicity, molecular size, and binding affinity to minimize off-target effects.
Solution Approach 2:
The patent creates a composite structure combining heptamethine cyanine dye (for fluorescence) with acetazolamide moiety (for CA-IX targeting) through covalent conjugation. This composite probe integrates the advantages of both components: high fluorescence quantum yield and specific enzyme targeting, while the careful design of the conjugation structure minimizes interference with biological properties.
3Measurement precision
If structural modifications of cyanine dyes are made to improve targeting, then specificity improves, but stability and solubility are affected
Solution Approach 1:
The patent explores different structural parameters including polymethine chain length (n=3,4,5), substituent types (sulfonate, carboxylate, amino groups), and conjugation positions to optimize the balance between CA-IX binding affinity and chemical stability. The acetazolamide conjugation at position 5 of the indolenine ring provides both high specificity and enhanced stability compared to other positions.
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 probes achieve high signal-to-noise ratio imaging with low mass doses, enabling precise tumor visualization and surgical guidance with enhanced specificity and stability.
Implementation Method 1
Dyes are chemical entities that absorb photons of a specific wavelength upon light excitation and re-emit some of that energy, depending on quantum efficiency, usually at a longer wavelength. Particularly, cyanine dyes are fluorescent organic molecules characterized by a delocalized electron system that spans over a polymethine bridge
Implementation Method 2
CA-IX is a homo-dimeric glycoprotein located on the cell surface and is a member of the large carbonic anhydrases (CAs) family of zinc metalloenzymes. The new probes achieve high signal-to-noise ratio imaging with low mass doses, enabling precise tumor visualization
Data Source
AI summary
The present invention relates to the field of optical imaging. More particularly, it relates to fluorescent probes targeting carbonic anhydrase nine (CA-IX) comprising near-infrared (NIR) dyes of the cyanine. The invention also relates to the methods for preparing these compounds, to pharmaceutical compositions and kits incorporating them and to methods of use them as optical diagnostic agents in imaging or therapy of diseases such as solid tumors with hypoxic tissues involving cells expressing CA-IX. The compounds have formula (I).