Gas-Filled Microvesicles with Controlled Ligand Density for Cell Sorting
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Solution Overview
Problem
Existing cell separation methods using gas-encapsulated microvesicles face issues with ligand density leading to aggregation and destabilization, particularly when high ligand densities are used for buoyancy-based cell sorting.
Innovation Solution
A suspension of gas-filled microvesicles with a stabilizing envelope comprising specific ratios of phospholipids and pegylated phospholipids, with controlled ligand density, is developed to minimize aggregation and enhance binding efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high ligand density is used on microvesicles, then binding efficiency to target cells is improved, but microvesicle aggregation occurs and stability is reduced
Solution Approach 1:
The patent applies local quality by creating heterogeneous ligand distribution on the microvesicle surface through controlled association of ligands with pegylated phospholipids at specific molar ratios (1-8% for ligand-containing pegylated phospholipid and 1-12% for additional pegylated phospholipid). This localized arrangement ensures high binding efficiency at contact points while maintaining overall microvesicle stability through distributed phospholipid composition.
Solution Approach 2:
The patent changes the chemical parameters of the microvesicle envelope by incorporating specific ratios of phospholipids, pegylated phospholipids, and ligand-associated pegylated phospholipids. The molar percentage parameters are precisely controlled (ligand: 1-8%, additional pegylated phospholipid: 1-12%) to optimize both binding efficiency and stability, preventing aggregation while maintaining high ligand availability.
2Reliability
If high ligand density is used on microvesicles, then binding efficiency to target cells is improved, but microvesicle aggregation occurs
Solution Approach 1:
The patent uses pegylated phospholipids as intermediary molecules between the ligand and the microvesicle structure. The pegylated phospholipid with reactive moiety covalently binds the ligand while the PEG chains provide steric stabilization, acting as a mediator that enables high ligand density without direct ligand-ligand aggregation. The additional pegylated phospholipid further enhances this protective effect.
Solution Approach 2:
The microvesicle envelope is designed as a composite material system comprising phospholipid, pegylated phospholipid, and pegylated phospholipid with ligand. This composite structure combines the structural integrity of phospholipid with the steric stabilization and ligand-binding capabilities of pegylated phospholipids, creating a material that simultaneously achieves high binding efficiency and prevents aggregation.
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 solution provides stable microvesicles with high ligand density on the surface, enabling efficient buoyancy-activated cell sorting with reduced aggregation, allowing effective separation of cells from complex mixtures.
Implementation Method 1
Gas encapsulated microvesicles or microparticles are used as reagent for buoyancy-activated cell sorting (BACS)
Implementation Method 2
the microvesicle binding efficiency increases with ligand density
Data Source
AI summary
Formulations of gas-filled microvesicles comprising a ligand, which may advantageously be used in methods for separating cells or biological materials. The formulations comprise a phospholipid and a suitable mixture of a pegylated phospholipid and of a pegylated phospholipid comprising a ligand.