Amphoteric Liposomes Serum Stability Nucleic Acid Delivery
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Solution Overview
Problem
Current liposomal systems face challenges with stability in human or animal serum, leading to inefficient drug delivery and potential toxicity, as cationic liposomes lack colloidal stability and exhibit toxicity, while anionic or neutral liposomes have low encapsulation efficiency and do not facilitate cellular uptake.
Innovation Solution
Development of amphoteric liposomes comprising a mixture of phosphatidylcholine and phosphatidylethanolamine with a specific molar ratio, combined with pH-sensitive anionic and cationic lipids, which provide improved serum stability and enhanced encapsulation efficiency for nucleic acid drugs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If cationic liposomes are used to provide high loading efficiency, then encapsulation efficiency is improved, but colloidal stability deteriorates due to aggregation with proteins and biopolymers
Solution Approach 1:
The patent combines cationic and anionic lipids into a single liposomal formulation, where the cationic component provides encapsulation efficiency while the anionic component provides colloidal stability. This merging of previously separate functional components resolves the contradiction between high loading efficiency and stability in body fluids.
Solution Approach 2:
The patent modifies the charge parameters of the liposomal membrane by incorporating both cationic and anionic lipids in specific ratios, creating an amphoteric system that maintains net positive charge for encapsulation while having reduced surface charge density to prevent aggregation with proteins and biopolymers.
2Productivity
If cationic lipids are used to achieve high loading efficiency, then encapsulation efficiency is improved, but toxicity increases
Solution Approach 1:
The patent merges cationic and anionic lipids to create an amphoteric system where the anionic component counteracts the toxic effects of cationic lipids. The combination maintains the encapsulation benefits of cationic lipids while the anionic lipids provide steric stabilization and reduce membrane permeability to harmful substances.
Solution Approach 2:
The anionic lipids act as intermediary components that mediate between the cationic lipids and the biological environment. They provide steric stabilization that reduces direct interaction with cellular membranes, thereby reducing toxicity while preserving encapsulation efficiency.
3Stability of the object's composition
If PEG is added to provide steric stabilization, then colloidal stability is improved, but cellular uptake is inhibited
Solution Approach 1:
The patent extracts the PEG component from the liposomal formulation and replaces it with anionic lipids that provide steric stabilization through their own molecular structure. This removal of PEG eliminates the inhibition of cellular uptake while maintaining colloidal stability through the alternative mechanism provided by the anionic lipids.
4Stability of the object's composition
If anionic or neutral liposomes are used to achieve colloidal stability, then stability in body fluids is improved, but encapsulation efficiency deteriorates
Solution Approach 1:
The patent merges anionic and cationic lipids in a way that preserves the colloidal stability provided by the anionic component while the cationic component provides the necessary encapsulation efficiency. The synergistic combination allows both functions to be achieved 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 amphoteric liposomes achieve improved stability and targeted delivery of nucleic acid drugs, reducing drug release in serum and enhancing cellular uptake, thus addressing the limitations of existing liposomal systems.
Implementation Method 1
a plurality of charged amphiphiles which in combination with one another have amphoteric character, said plurality of charged amphiphiles being negatively charged or neutral at pH 7.4 and positively charged at pH 4, and comprising at least one pH sensitive anionic lipid and at least one pH sensitive cationic lipid
Implementation Method 2
Liposomes are artificial single, oligo or multilamellar vesicles having an aqueous core and being formed from amphiphilic molecules having both hydrophobic and hydrophilic components (amphiphiles)
Implementation Method 3
After the injection of liposomes into the bloodstream, serum components interact with the liposomes and may lead to permeabilisation of the liposomal membrane
Data Source
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AI summary
A serum-stable mixture of lipids capable of encapsulating an active agent to form a liposome, said mixture comprising phosphatidylcholine and phosphatidylethanolamine in a ratio in the range of about 0.5 to about 8. The mixture may also include pH sensitive anionic and cationic amphiphiles, such that the mixture is amphoteric, being negatively charged or neutral at pH 7.4 and positively charged at pH 4. Amphoteric liposomes comprising such a mixture may be used for encapsulating nucleic acid therapeutics, such as oligonucleotides and DNA plasmids. The drug/lipid ratio may be adjusted to target the liposomes to particular organs or other sites in the body.