pH-Responsive Polymeric Nanoparticles for siRNA Delivery
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Solution Overview
Problem
Current methods for delivering siRNA and plasmids face challenges such as poor filtration, susceptibility to enzymes, poor membrane permeability, and rapid burst release, leading to instability and cytotoxicity, limiting their clinical application in gene silencing and therapy.
Innovation Solution
Development of pH-responsive polymeric nanoparticles comprising a hydrophilic outer shell and a cationic-hydrophobic core, where siRNA is bound to cationic monomers, allowing for controlled release and enhanced intracellular delivery by disassembling at lower pH, thereby improving stability and cytocompatibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If cationic lipoplexes or nanoparticles are used for intravenous administration, then intracellular delivery is improved, but particle instability and nonspecific interactions with blood components occur leading to aggregation and cytotoxicity
Solution Approach 1:
The patent applies parameter changes by utilizing pH-responsive behavior of the cationic polymer blocks. The polymers remain neutral at physiological pH (7.4) for stable circulation, then become cationic at endosomal pH (5.0-6.0) to enable intracellular delivery. This dynamic parameter change resolves the contradiction by allowing the same material to provide both stability in blood and effective intracellular delivery.
Solution Approach 2:
The invention employs dynamic properties through pH-responsive polymer blocks that change their charge state based on environmental pH. The cationic blocks are protonated at endosomal pH but neutral at physiological pH, creating a dynamic system that adapts its properties to different biological environments, thereby achieving both stability and delivery efficacy.
2Ease of operation
If known polymer siRNA carriers are used, then delivery is achieved, but cytotoxicity occurs
Solution Approach 1:
The patent uses parameter changes by designing polymers that switch from cationic to neutral charge states based on pH. This eliminates continuous cytotoxicity while maintaining delivery capability at the target site, as the cationic charge is only activated within endosomes after cellular uptake.
Solution Approach 2:
The invention extracts the harmful continuous cationic charge from the polymer structure and replaces it with pH-responsive charge activation. The cationic charge is 'taken out' from being permanently present and instead activated only when needed within endosomes, eliminating cytotoxicity while preserving delivery function.
3Productivity
If siRNA is delivered using conventional methods, then gene silencing is achieved, but rapid burst release occurs reducing controlled delivery
Solution Approach 1:
The patent applies parameter changes through pH-responsive disassembly of the nanoparticle structure. The particles remain intact during circulation (stable configuration) then disassemble in response to endosomal pH changes, enabling controlled release kinetics rather than rapid burst release.
Solution Approach 2:
The invention implements periodic action through sequential events: stable circulation phase followed by pH-triggered disassembly phase. This periodic behavior between stable circulation and controlled release resolves the contradiction by providing both sustained delivery capability and controlled release kinetics.
4Reliability
If materials are used to protect siRNA from nucleases, then stability is improved, but membrane permeability and intracellular cytosolic delivery worsen
Solution Approach 1:
The patent employs dynamics through pH-responsive polymer blocks that change their conformation and charge state. The polymers provide protective coating at physiological pH, then become cationic and conformationally change at endosomal pH to facilitate membrane interaction and permeability, resolving the stability-permeability contradiction.
Solution Approach 2:
The invention uses periodic action with distinct phases: protective stabilization phase during circulation, followed by pH-triggered conformational change phase that enables membrane permeability. This sequential behavior allows the same material to provide both protection and permeability at different times.
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 nanoparticles achieve efficient and controlled delivery of siRNA, enhancing gene silencing efficacy while minimizing cytotoxicity and improving circulation time, leading to effective treatment of diseases like cancer and tissue restoration.
Implementation Method 1
siRNA is bound to cationic monomers
Implementation Method 2
allowing for controlled release and enhanced intracellular delivery by disassembling at lower pH
Data Source
AI summary
The presently-disclosed subject matter includes nanoparticles that comprise a plurality of assembled polymers. In some embodiments the polymers comprise a first block that includes hydrophilic monomers, the first block substantially forming an outer shell of the nanoparticle, and a second block that includes cationic monomers and hydrophobic monomers, the second block substantially forming a core of the nanoparticle. In some embodiments a polynucleotide is provided that is bound to the cationic monomers of the nanoparticle. The presently-disclosed subject matter also comprises methods for using the present nanoparticles to include RNAi in a cell as well as methods for making the present nanoparticles.