PEG Folded Chain Threshold for Lyophilized Microvesicle Stability
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Solution Overview
Problem
The variability in the percentage of folded polymeric chains in polyethylene glycol used in the preparation of lyophilized powders for gas-filled microvesicles can lead to a high rejection rate of vials, affecting the quality and effectiveness of ultrasound contrast agents in contrast-enhanced ultrasound imaging.
Innovation Solution
A freeze-dried powder composition with a polyethylene glycol having a percentage of folded polymeric chains higher than 35%, preferably at least 42%, is used, along with a phospholipid like DSPC and a fatty acid, to ensure consistent production of gas-filled microvesicles, which are then dispersed in a physiologically acceptable liquid for ultrasound imaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If polyethylene glycol with variable folded chain percentage is used in the lyophilized powder preparation, then manufacturing cost is reduced, but the rejection rate of vials increases significantly
Solution Approach 1:
The patent applies parameter changes by establishing a minimum threshold for the percentage of folded polymeric chains (≥35%) in the polyethylene glycol used for lyophilized powder preparation. This parameter specification resolves the contradiction by defining acceptable material characteristics that ensure both manufacturing feasibility and high vial acceptance rates, eliminating the variability that caused the rejection problem.
2Quantity of substance
If polyethylene glycol with low folded chain percentage is used, then material cost is reduced, but the number of rejected vials in manufacturing batch increases
Solution Approach 1:
The patent resolves this contradiction by specifying that the polyethylene glycol must have at least 35% folded polymeric chains. This parameter threshold ensures adequate batch yield by preventing the formation of rough cakes that lead to vial rejection, while still allowing cost-effective material selection within the defined specification range.
3Device complexity
If polyethylene glycol with insufficient folded chains is used, then formulation simplicity is maintained, but the freeze-dried cake quality deteriorates
Solution Approach 1:
The patent maintains formulation simplicity while improving manufacturing precision by specifying a minimum folded chain percentage (≥35%) for the polyethylene glycol. This single parameter specification ensures the formation of smooth freeze-dried cakes with consistent quality without requiring complex formulation modifications or additional processing steps.
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
This approach significantly reduces the number of rejected vials and enhances the quality of gas-filled microvesicles, resulting in more effective contrast-enhanced ultrasound imaging by maintaining a higher microbubbles volume concentration and improving the physical aspect of the freeze-dried cakes.
Implementation Method 1
different releases (even from a same manufacturer) of commercially available PEG4000 may have different amounts of folded polymeric chains in the polymeric material
Implementation Method 2
Freezing the solution; and removing the solvent by lyophilization
Data Source
Figure 1A~1B
Figure 2
Figure 3
AI summary
A freeze-dried powder composition comprising a phospholipid and a polyethylene glycol, said polyethylene glycol having a percentage of folded polymeric chains higher than a predetermined limit. The composition is suitable for preparing gasfilled microvesicles.