Polyoxazoline Polymer for Photoacoustic Contrast Agent
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Solution Overview
Problem
Near-infrared fluorescent dye-bound PEG exhibits high tumor accumulation but has a low tumor/blood ratio due to high retentivity in blood, limiting its effectiveness as a contrast agent for photoacoustic imaging.
Innovation Solution
A polymer with a polyoxazoline main chain and a near-infrared dye bound to its terminal, which accumulates in tumors and is rapidly excreted from the blood, enhancing the tumor/blood ratio for selective tumor detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If PEG is covalently bound to near-infrared dye to prolong half-life in blood, then the half-life in blood is prolonged, but the tumor/blood ratio becomes low due to high retentivity in blood
Solution Approach 1:
The patent changes the chemical structure parameter from PEG to polyoxazoline main chain, which fundamentally alters the pharmacokinetic behavior. This parameter change enables the contrast agent to achieve both prolonged blood circulation (improved half-life) and rapid tumor accumulation with clearance from blood (improved tumor/blood ratio), resolving the contradiction between duration of action and quantity distribution.
2Adaptability or versatility
If ICG is used as contrast agent, then light absorption in near-infrared region is achieved with high permeability to living body, but the half-life in blood is very short (several minutes)
Solution Approach 1:
The patent creates a composite contrast agent by conjugating ICG dye with polyoxazoline polymer. This composite structure combines the excellent light absorption and permeability properties of ICG with the prolonged circulation and tumor accumulation capabilities of polyoxazoline, achieving both high adaptability to living body and extended half-life simultaneously.
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 polymer achieves a high tumor/blood ratio, allowing for selective tumor detection by accumulating in tumors and reducing blood concentration, thereby improving the effectiveness of photoacoustic imaging.
Implementation Method 1
measuring the intensity and the time of generation of a photoacoustic signal emitted from a substance (optical absorber) that absorbs light in the object
Implementation Method 2
the polymer... accumulates in a tumor
Implementation Method 3
excreted from blood with the lapse of time
Data Source
AI summary
To provide a polymer having a high tumor/blood ratio. The present invention provides a polymer represented by the following formula (P1):wherein in the formula (P1), R0 represents any of a residue or a functional group derived from a cationic polymerization initiator; L represents a linker and L may not be present; n represents an integer of 1 or more; D represents a dye backbone of a dye having absorption in the near-infrared region.