pH-Responsive Block Copolymer for Endosomal Escape

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Solution Overview

Problem

Current methods for intracellular delivery of macromolecular therapeutics, such as nucleic acids and proteins, face significant challenges due to inefficient endosomal escape, with viral vectors posing immunogenicity and safety concerns, and non-viral systems being less efficient and prone to lysosomal degradation.

Innovation Solution

A synthetic block copolymer that mimics the adenovirus mechanism for efficient endosomal escape, comprising a hydrophilic block for solubility and a pH-responsive, hydrophobic block with a membrane-lytic entity, which self-assembles to reduce lytic potential extracellularly and exposes the membrane-lytic entity at acidic pH for endosomal release.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If membrane-active peptides are incorporated to enhance endosomal release, then endosomal escape efficiency is improved, but cell membrane disruption and off-site toxicity increase

Engineering Contradiction:

Improveendosomal escape efficiencyVSAvoidcell membrane disruption and toxicity

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The membrane-active peptide is pre-concealed within the hydrophobic block at neutral pH before cellular internalization, preventing premature membrane disruption. The peptide is only activated and exposed after the polymeric carrier reaches the acidic endosomal compartment, where pH-induced conformational change unveils the peptide for targeted endosomal membrane disruption.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The pH-responsive hydrophobic block acts as an intermediary that mediates between the membrane-active peptide and the cellular environment. It shields the peptide from interacting with cell membranes at neutral pH, then facilitates peptide exposure and activation in response to acidic pH conditions within endosomes, enabling controlled and targeted action.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If proton sponge effect is used for endosomal buffering, then endosomal release is enhanced, but significant accumulated polymer concentrations are required that are difficult to achieve in vivo

Engineering Contradiction:

Improveendosomal release efficiencyVSAvoidpolymer concentration

Core Design Contradiction:

ProductivityVSQuantity of substance

Solution Approach 1:

The invention exploits pH as a critical parameter change to trigger the conformational transition of the pH-responsive hydrophobic block. At neutral pH, the block remains hydrophobic and conceals the membrane-active peptide. Upon encountering acidic pH in endosomes, the block undergoes conformational change to expose the peptide, enabling pH-triggered activation without requiring high polymer concentrations.

Inventive Principle:

Principle #35Parameter changes

3Productivity

If viral vectors are used for intracellular delivery, then gene transfer efficiency is high, but immunogenicity and safety concerns arise

Engineering Contradiction:

Improvegene transfer efficiencyVSAvoidsafety and immunogenicity profile

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The invention copies the endosomal escape mechanism of adenovirus through the pH-responsive conformational change that unveils membrane-active peptides, mimicking viral behavior. However, it uses a synthetic polymeric carrier instead of actual viral components, achieving viral-like efficiency without the immunogenicity and safety issues associated with viral vectors.

Inventive Principle:

Principle #26Copying

4Reliability

If non-viral polymeric carriers are used, then safety and manufacturing cost are improved, but gene transfer efficiency is orders of magnitude lower than viral systems

Engineering Contradiction:

Improvesafety and cost profileVSAvoidgene transfer efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The invention creates a composite polymeric carrier combining a hydrophilic block for solubility and cargo complexation with a pH-responsive hydrophobic block containing concealed membrane-active peptides. This composite structure enables the carrier to exhibit both the safety advantages of synthetic polymers and the efficient endosomal escape capability previously only achieved by viral systems.

Inventive Principle:

Principle #40Composite materials

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 block copolymer effectively facilitates the intracellular delivery of nucleic acids and proteins by enhancing endosomal escape, demonstrating improved transfection efficiency and reduced cytotoxicity compared to existing systems, with potential for in vivo gene transfer and therapeutic applications.

Implementation Method 1

a pH-responsive block comprising repeating units that are hydrophobic at about neutral pH... At certain acidic pH (that is encountered after internalization into the acidifying endosomes), the second block becomes hydrophilic

Methodology Applied

Scientific EffectpH-responsive hydrophobic to hydrophilic transition: Phase Change

Implementation Method 2

At extracellular pH, the second block is hydrophobic, resulting in self-assembly of the hydrophobic block, reducing the lytic potential of the material before internalization

Methodology Applied

Scientific EffectSelf-assembly: Self-Assembly