Ionic Neutral Lipid Composition for Endosomal Phase Transition
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Solution Overview
Problem
The phase transition of lipid nanoparticles containing pH-sensitive cationic lipids is inhibited by neutral phospholipids like phosphatidylcholine, which hinders efficient uptake into cells.
Innovation Solution
A compound with a hydrocarbon chain bonded to each hydroxyl group of Tris and a hydrophilic group with a cationic moiety and an anionic group at the terminal, forming an ionic neutral lipid, is used as a constituent lipid in lipid nanoparticles to suppress the inhibition of phase transition by phosphatidylcholine.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If phosphatidylcholine is used as a neutral phospholipid in lipid nanoparticles, then the lipid bilayer is stabilized, but the phase transition is inhibited and uptake efficiency into cells is reduced
Solution Approach 1:
The patent introduces a novel neutral lipid with a specific molecular structure (containing a hydroxyl group and a hydrophobic chain with 15-22 carbon atoms) that changes the physical parameters of the lipid bilayer. This structural parameter change allows the membrane to undergo phase transition while maintaining stability, resolving the contradiction between stabilization and phase transition capability
Solution Approach 2:
The patent creates a composite lipid system by combining phosphatidylcholine with the newly discovered neutral lipid (having formula (I) with specific hydrophobic chain length). This composite material exhibits both the stabilizing effect of phosphatidylcholine and the phase transition-promoting effect of the novel lipid, simultaneously achieving both improved stability and uptake efficiency
2Productivity
If pH-sensitive cationic lipids are used to enable endosomal escape, then nucleic acid delivery is improved, but non-specific interaction with plasma proteins occurs and rapid clearance by the reticuloendothelial system happens
Solution Approach 1:
The patent applies local quality by using pH-sensitive cationic lipids only in the endosomal compartment where they are needed for escape, while the neutral lipid composition of the outer membrane maintains blood circulation stability. The cationic lipids remain neutral at physiological pH (avoiding plasma protein interaction) but become cationic in the acidic endosomal environment (enabling membrane escape)
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 ionic neutral lipid enhances the uptake efficiency of lipid nanoparticles into cells by reducing the stabilizing action of phosphatidylcholine on the lipid bilayer, facilitating effective delivery of nucleic acids.
Implementation Method 1
phosphatidylcholine (PC), the main constituent lipid of the endosomal membrane, takes a cylindrical shape and thus stabilizes the lamellar (L) phase of the lipid bilayer (planar membrane) and strongly inhibits the transition to the inverse hexagonal (HII) phase
Implementation Method 2
it is traditionally known that DOPE, a constituent lipid commonly used in lipid nanoparticles, takes a cone shape and thus promotes the transition from the lamellar phase to the inverse hexagonal phase
Implementation Method 3
Lipid nanoparticles are taken up into cells by endocytosis. Therefore, it is essential for improving the efficiency of uptake of lipid nanoparticles into cells that the lipid nanoparticles easily fuse with the endosomal membrane
Implementation Method 4
a neutral lipid having a hydrophobic chain and a hydrophilic group
Data Source
AI summary
The present invention provides: a neutral lipid capable of suppressing the phase transition of endosomal membranes caused by phosphatidylcholine from being inhibited; and a lipid nanoparticle containing the neutral lipid. The present invention pertains to an ionic neutral lipid comprising a compound represented by general formula (I). [In formula (I), R1 is a C1-22 hydrocarbon group; three R1 groups in one molecule may be the same as or different from each other; a1 and a2 are each independently an integer of 0 to 4; b1 and b2 are 0 or 1, satisfying b1+b2=1; R2 and R3 are each independently a hydrogen atom or a C1-3 alkyl group; and R4 is an anionic group.]