Cyclodextrin-RNA Conjugates for Membrane Penetration
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Solution Overview
Problem
Current methods for delivering RNA therapeutics face challenges in penetrating the cell membrane and achieving effective gene knockdown due to the polyanionic nature of RNAs and the large size of oligonucleotides, which hinders their therapeutic potential in treating diseases.
Innovation Solution
Cyclodextrin conjugates are used to form nanoparticulate complexes with RNA, incorporating amphiphilic cyclodextrins and additional modifying groups to facilitate membrane penetration and protect RNA from degradation, enabling targeted delivery and efficient gene knockdown.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cationic lipids or polymers are used to complex with RNA and neutralize negative charges, then electrostatic repulsion is overcome and membrane penetration is facilitated, but the large size and polar nature of the oligonucleotide still hinder effective delivery
Solution Approach 1:
The invention segments the delivery system by separating the RNA cargo from the delivery vehicle. Instead of using large cationic lipids or polymers that complex with RNA, the invention uses small cyclodextrin molecules (7-9 glucose units) that can penetrate membranes efficiently. The RNA is delivered in its native form without being bound to large delivery vehicles, thus reducing the effective size barrier while maintaining delivery functionality.
Solution Approach 2:
The invention introduces cyclodextrin as an intermediary molecule that mediates RNA delivery. Cyclodextrins serve as a bridge between the RNA and the cell membrane, using their unique amphiphilic structure (hydrophobic interior, hydrophilic exterior) to facilitate membrane penetration. The cyclodextrin-RNA conjugate allows the RNA to be delivered without requiring large cationic carriers, thus resolving the size-complexity contradiction.
2Reliability
If RNA is delivered into the cytoplasm to enable endogenous biology to effect therapy, then therapeutic effectiveness is achieved, but RNA degradation en route to the target reduces delivery reliability
Solution Approach 1:
The invention applies preliminary protection by conjugating RNA to cyclodextrin before delivery. This conjugation creates a protective complex that shields the RNA from nucleases and degradation during transit to the target cell. The cyclodextrin moiety acts as a protective cloak, allowing the RNA to reach the cytoplasm intact and maintain its therapeutic effectiveness.
Solution Approach 2:
Cyclodextrin serves as a protective intermediary during RNA transport. The conjugate structure provides a steric and chemical barrier that prevents nuclease access to the RNA phosphodiester bonds. This intermediary protection ensures the RNA remains stable during circulation and cellular uptake, resolving the contradiction between therapeutic effectiveness and stability.
3Reliability
If cyclodextrins are modified with hydrophilic and lipophilic groups to make them amphiphilic, then self-assembly properties and membrane penetration are improved, but the complexity of maintaining liquid crystalline properties increases
Solution Approach 1:
The invention applies local quality modification by functionalizing cyclodextrin at specific positions (2-, 3-, or 6-positions of glucose units) rather than uniformly modifying the entire structure. This localized functionalization allows precise control over amphiphilic properties while maintaining the core cyclodextrin self-assembly capability. The modified positions create specific interaction zones that facilitate membrane penetration without disrupting overall structural organization.
Solution Approach 2:
The invention systematically varies parameters such as the degree of substitution, position of substitution, and type of functional groups to optimize the balance between self-assembly and membrane penetration. By controlling these parameters, the invention achieves reliable nanoparticle formation and cellular delivery without requiring overly complex structural modifications, thus resolving the contradiction between self-assembly capability and modification complexity.
4Adaptability or versatility
If ligands are conjugated to cyclodextrin for targeting to specific cell types, then cellular specificity is improved, but the size and polarity of the conjugate may hinder spontaneous assembly
Solution Approach 1:
The invention segments the targeting function from the self-assembly function. The cyclodextrin core maintains its inherent self-assembly properties, while ligands are attached as separate functional modules at specific positions. This segmentation allows the core structure to spontaneously assemble into nanoparticles while the attached ligands provide targeting specificity without interfering with the assembly process.
Solution Approach 2:
The cyclodextrin conjugate structure serves multiple functions simultaneously: the cyclodextrin core provides self-assembly and membrane penetration capabilities, while the attached ligands provide cellular targeting specificity. This multi-functionality is achieved within a single molecular architecture that maintains spontaneous assembly properties, thus resolving the contradiction between targeting versatility and assembly difficulty.
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 cyclodextrin-RNA conjugates effectively deliver RNA into cells, achieving significant gene knockdown and therapeutic outcomes by overcoming the challenges of membrane penetration and stability, as demonstrated in various cellular models.
Implementation Method 1
Nanoparticulate inclusion of the RNA also protects it from degradation en route to its target
Implementation Method 2
The modified cyclodextrins which are the subject of these patents form molecular complexes which adopt the nanoparticulate structure that encapsulates the RNA. These modified cyclodextrins are capable themselves of forming bilayers or vesicles in aqueous solutions.
Implementation Method 3
incorporation of cationic groups to neutralise the anionic charges of RNA and promote complexation
Data Source
AI summary
A cyclodextrin-RNA conjugate is described in which the cyclodextrin molecule is conjugated at its glucosyl 6-, 2- or 3-positions, optionally via a linker, to at least one RNA molecule at the RNA 3' terminal base. The at least one RNA molecule may be an siRNA molecule.