Polymer Micelle Solubilization of Cyanin IR-780 Photosensitizer
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Solution Overview
Problem
Current drug delivery systems for photodynamic therapy face challenges in stabilizing hydrophobic photosensitizers like cyanins, which are insoluble in water and sensitive to light and temperature, leading to premature degradation and reduced therapeutic efficacy due to their hydrophobicity and size limitations, necessitating the development of stable and targeted carriers for effective tumor cell delivery.
Innovation Solution
The use of polymer micelles based on block copolymers, specifically Pluronic P123, produced via thin film hydration, encapsulating cyanin IR-780, which achieves high solubilization and stability with low polydispersity and nanoscopic size, enhancing photocytotoxicity and reducing cytotoxicity, allowing for controlled drug release and targeted tumor therapy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hydrophobic photosensitizers like cyanins are used directly, then they exhibit high effectiveness as photosensitizers, but their hydrophobicity and insolubility in water preclude their direct use in photodynamic therapy
Solution Approach 1:
The patent uses polymer micelles as intermediary carriers to solubilize hydrophobic cyanin photosensitizers in aqueous environments. The micelles have a hydrophobic core that accommodates the cyanin molecules and a hydrophilic outer shell that enables water solubility, thus acting as a mediator between the incompatible hydrophobic drug and hydrophilic biological environment
Solution Approach 2:
The patent creates composite structures by combining cyanin photosensitizers with polymer micelle carriers. The resulting composite system integrates the photosensitizing properties of cyanin with the solubilizing properties of the polymer micelles, achieving both effectiveness and water solubility simultaneously
2Ease of operation
If polymer micelles are used to solubilize photosensitizers, then water solubility is improved, but the micelles must maintain stability under highly diluted conditions during injection
Solution Approach 1:
The patent optimizes the polymer-to-photosensitizer ratio and selects specific block copolymer compositions to achieve low critical micelle concentration (CMC) values. By adjusting these parameters, the micelles maintain structural integrity and stability even when highly diluted in blood circulation, preventing premature drug release
3Quantity of substance
If the micelle core has high loading capacity for photosensitizers, then drug delivery efficiency is improved, but the micelle size must not exceed 100 nm to avoid reticuloendothelial system reactions
Solution Approach 1:
The patent utilizes the flexible micellar structure where the polymer chains dynamically adjust to accommodate photosensitizer molecules in the core. This flexible shell structure allows high drug loading capacity while maintaining a compact overall size below 100 nm, avoiding recognition by the reticuloendothelial system
Solution Approach 2:
The patent creates local concentration of photosensitizers in the hydrophobic core region while maintaining a small overall micelle size. The local quality of the core provides high loading capacity, while the global structure remains small enough to evade immune detection
4Illumination intensity
If cyanins are used as photosensitizers, then they absorb light in the phototherapeutic window (600-1000 nm) with low tissue dispersion, but their sensitivity to light and temperature causes premature degradation
Solution Approach 1:
The patent provides beforehand protection by encapsulating cyanin molecules within the hydrophobic core of polymer micelles before administration. This pre-protection shields the sensitive cyanin from environmental factors like light and temperature that would cause degradation, allowing stable storage and handling
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 micelles demonstrate high solubilization efficiency (86.5%) and low cytotoxicity, effectively penetrating tumor cells and exhibiting increased photocytotoxicity, making them suitable for photodynamic therapy with improved therapeutic outcomes compared to free cyanins.
Implementation Method 1
They differ from other drug carriers by their small size, extensive transparency of solutions, an internal hydrophobic phase, and protective activity for the external polymer chains
Implementation Method 2
the thin film formed is hydrated at a temperature of 25-60°C for 0.5-2h and an aqueous solution of micelles is obtained
Data Source
Figure 1A~1B
Figure 2
Figure 3
AI summary
The subject of the present invention are nanocarriers of the polymer micelle type based on block copolymers, made using thin film hydration and meant for use in w pharmaceutical formulations as active ingredient carriers, i.e. for photosensitizers used in the photodynamic therapy of tumours, a method of making them and their use.