Nucleic Acid Encapsulation in Lipid Nanoparticles Using Acidic Buffers

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Solution Overview

Problem

Existing methods for encapsulating nucleic acids in lipid nanoparticles face challenges in efficiency and stability, particularly with ionic lipids having tertiary amines, as they do not electrostatically interact with nucleic acids due to weak or neutral surface charges, and require complex lyophilization steps.

Innovation Solution

A method involving the preparation of lipid nanoparticles in an acidic buffer without nucleic acids, followed by addition of an aqueous nucleic acid solution, and optional incubation and buffer exchange, to achieve high-efficiency encapsulation without lyophilization.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If ionic lipids having tertiary amine are used to prepare lipid nanoparticles, then the nanoparticles can be formed with neutral or weakly negative surface charge, but they do not electrostatically interact with nucleic acids due to the lack of positive charge

Engineering Contradiction:

Improvesurface charge stabilityVSAvoidelectrostatic interaction with nucleic acid

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

The patent changes the pH parameter of the buffer solution to acidic conditions (pH 3-6), which causes the tertiary amine groups in the ionic lipid to become protonated and acquire positive charge. This parameter change enables electrostatic interaction with negatively charged nucleic acids while maintaining the structural integrity of the lipid nanoparticles.

Inventive Principle:

Principle #35Parameter changes

2Stability of the object's composition

If lyophilization step is used to prepare lyophilized lipid nanoparticle composition, then storage stability is improved, but the production process becomes complex

Engineering Contradiction:

Improvestorage stabilityVSAvoidproduction process complexity

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The patent extracts the lyophilization step from the production process, achieving storage stability through alternative means. By formulating the lipid nanoparticles with appropriate lipid composition and preparing them in acidic buffer, the nanoparticles maintain stability without requiring lyophilization, thus simplifying the production process while still achieving reliable storage.

Inventive Principle:

Principle #2Taking out (Extraction)

3Reliability

If cationic lipids with quaternary amine are used, then electrostatic interaction with nucleic acid is strong, but cytotoxicity increases due to positive charge

Engineering Contradiction:

Improveelectrostatic interaction with nucleic acidVSAvoidcytotoxicity

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent uses ionic lipids with tertiary amine groups that dynamically change their charge state based on environmental pH. At acidic pH during preparation, the lipids are positively charged for strong nucleic acid binding. At physiological pH after administration, the lipids become neutral or weakly negative, reducing cytotoxicity. This dynamic charge transition resolves the contradiction between effective gene delivery and cellular safety.

Inventive Principle:

Principle #15Dynamics

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 method enables efficient encapsulation of nucleic acids in lipid nanoparticles with improved gene transfer efficiency and simplified production process compared to conventional techniques.

Implementation Method 1

ionic lipids having a tertiary amine—which is positively charged under acidic conditions and has no electric charge under near neutral conditions

Methodology Applied

Scientific EffectProtonation:

Implementation Method 2

cationsic liposomes using cationic lipids with quaternary amine are positively charged, they can form a complex (lipoplex) by electrostatic interaction with negatively-charged nucleic acids

Methodology Applied

Scientific EffectElectrostatic interaction: Electrostatics

Data Source

PatentUS20250205168A1Method for producing nucleic acid-encapsulated lipid nanoparticles, method for producing pharmaceutical composition containing said lipid nanoparticles, and method for introducing nucleic acid into cell or target cell

Publication Date: 2025.06.26 NOF CORP

AI summary

The present invention provides a method for producing nucleic acid-encapsulated lipid nanoparticles, which can encapsulate any nucleic acid with high efficiency and with ease. A method for producing nucleic acid-encapsulated lipid nanoparticles, including the following steps: a) a step of preparing a suspension of lipid nanoparticles not containing a nucleic acid, by mixing an alcohol solution containing ionic lipid, sterol and PEG lipid with an acidic buffer having a buffering action at pH 1 to 6.5, and b) a step of mixing, without lyophilization, the suspension of the lipid nanoparticles obtained in step a with an aqueous solution containing a nucleic acid and optionally containing 0 to 25 v/v % alcohol, and optionally incubating the mixture at 0 to 95° C. for 0 to 60 min to obtain nucleic acid-encapsulated lipid nanoparticles.