pH-Responsive Polymeric Micelles for Stable Protein Release
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Solution Overview
Problem
Existing protein delivery systems face challenges such as enzymatic degradation, renal excretion, and immunogenicity, with PEGylated proteins experiencing protein inactivation and insufficient spatial-temporal regulation of protein functions.
Innovation Solution
Development of pH-responsive polymeric micelles using a block copolymer with a pH-responsive maleic anhydride derivative to form reversible covalent bonds with proteins, stabilized by polyion complex formation, enhancing blood retention and efficient protein release under acidic conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PEGylation is applied to proteins, then enzymatic degradation and renal excretion are suppressed, but protein inactivation occurs due to irreversible chemical modifications
Solution Approach 1:
The patent employs pH-responsive maleic anhydride derivatives that change their chemical state based on pH conditions. At physiological pH, the maleic anhydride forms stable covalent bonds with amino groups to provide stability. At acidic pH (tumor microenvironment), the bonds become cleavable, releasing the protein. This parameter change (pH-dependent bond stability) resolves the contradiction between stability and inactivation.
Solution Approach 2:
The patent creates a dynamic delivery system where the protein-polymer conjugate can transition between bound and unbound states based on pH conditions. The reversible covalent bonding allows the system to adapt its state dynamically - stable in circulation (physiological pH) and release-activating in target tissue (acidic pH), thus avoiding permanent inactivation while maintaining stability where needed.
2Duration of action of moving object
If PEGylation is applied to proteins, then protein half-life is extended, but spatial-temporal regulation of protein functions is insufficient
Solution Approach 1:
The patent introduces pH-responsive maleic anhydride groups at specific locations within the polymer structure that can selectively interact with amino groups on the protein surface. This localized chemical modification creates regions of high affinity binding that can be selectively activated in specific spatial locations (tumor microenvironment with acidic pH), enabling spatial-temporal regulation while maintaining overall protein stability.
Solution Approach 2:
The system dynamically regulates protein release based on pH conditions. The reversible covalent bonds formed by maleic anhydride derivatives remain stable at physiological pH (extending half-life) but become cleavable at acidic pH (enabling release). This dynamic response to environmental pH changes provides temporal and spatial regulation of protein function, allowing the protein to remain stable in circulation but be released at target sites.
3Reliability
If pH-responsive maleic anhydride derivative is introduced into block copolymer, then reversible covalent bonds are formed with proteins, but micelle stability may be compromised under acidic conditions
Solution Approach 1:
The patent utilizes pH as a controlling parameter to achieve different micelle-stability states. At physiological pH, the maleic anhydride groups form stable covalent bonds maintaining micelle integrity for blood retention. At acidic pH, the same groups become protonated and bonds are cleaved, releasing the protein. This parameter-based control allows the system to switch between stable and release states as needed.
Solution Approach 2:
The micelle structure is designed to be dynamic rather than static. The reversible covalent bonding through pH-responsive maleic anhydride groups allows the micelle to maintain structural integrity under physiological conditions but transition to a protein-release state under acidic conditions. This dynamic behavior resolves the contradiction by making stability conditional rather than absolute.
4Duration of action of stationary object
If block copolymer with maleic anhydride derivative is used, then blood retention is enhanced, but device complexity increases
Solution Approach 1:
The patent merges multiple functions into a single block copolymer structure: the polymer provides both the structural framework for micelle formation and the pH-responsive chemical groups (maleic anhydride) for reversible bonding. This integration of structural and functional elements reduces overall system complexity while achieving enhanced blood retention through the combined effects of micelle formation and pH-responsive binding.
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 micelles provide increased stability and efficient protein release in target tissues, improving therapeutic efficacy by enhancing blood retention and accumulation in target tissues.
Implementation Method 1
introducing a pH-responsive maleic anhydride derivative into the core-forming chain of a block copolymer to thereby form reversible covalent bonds with amino groups in the protein
Implementation Method 2
PIC formation between amino groups in the core-forming chain of the block copolymer and carboxyl groups in the protein
Implementation Method 3
Stimuli-responsive nanocarriers are designed to detect physiologically active substances in target tissues... External stimuli to which polymeric micelles can respond may be exemplified by pH
Data Source
AI summary
The present invention provides a polymeric complex comprising a protein and a block copolymer represented by the following formula (1):