siRNA Multi-Conjugate for Stable Gene Delivery
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Solution Overview
Problem
Conventional siRNA is unstable and difficult to deliver effectively due to its anionic nature and stiff structure, leading to low intracellular delivery efficiency and potential non-specific cytotoxicity from strong cationic gene carriers.
Innovation Solution
A multi-conjugate of siRNA is prepared through direct or indirect covalent bonding of double-stranded sense/antisense siRNA monomers mediated by a cross-linking agent or polymer, forming a stable ionic complex with cationic gene carriers, which increases molecular weight and charge density without inducing severe immune responses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional siRNA is used for gene delivery, then gene selectivity is maintained, but intracellular delivery efficiency is low due to anionic nature and stiff structure
Solution Approach 1:
The patent merges multiple siRNA monomers (comprising sense strand, antisense strand, and spacer sequences) into a single multi-conjugate molecule. This combining approach increases molecular weight and creates a more flexible structure that can form stable complexes with cationic gene carriers, thereby improving intracellular delivery efficiency while maintaining gene selectivity through specific target binding.
Solution Approach 2:
The invention creates a composite structure by covalently bonding multiple different siRNA components (sense strand with specific sequence, antisense strand with complementary sequence, and spacer sequences) into an integrated multi-conjugate molecule. This composite design provides both the stability needed for delivery and the specificity required for target gene recognition.
2Reliability
If molecular weight of siRNA is increased to improve stability and complex formation, then delivery efficiency increases, but non-specific cytotoxicity increases due to strong cationic groups
Solution Approach 1:
The patent changes the molecular parameters of siRNA by increasing molecular weight through multi-monmer conjugation and adjusting charge density through optimized nucleotide composition and spacing. This creates a balance where the molecule forms stable complexes with cationic carriers without requiring excessive strong cationic groups, thereby reducing non-specific cytotoxicity while maintaining complex stability.
Solution Approach 2:
The invention introduces local variations in charge distribution and molecular properties at different regions of the multi-conjugate structure. The sense strand, antisense strand, and spacer sequences have different local characteristics that collectively provide stable complex formation while distributing charge interactions to minimize non-specific cytotoxic effects.
3Stability of the object's composition
If additional nucleotides are added to sense strand to increase molecular weight, then complex stability improves, but complementary binding becomes unstable and cannot be confirmed by electrophoresis
Solution Approach 1:
The patent segments the siRNA structure into distinct functional modules: sense strand sequences, antisense strand sequences, and spacer sequences. By dividing the molecule into these segments with specific functions, the invention achieves overall complex stability through the collective contribution of each segment while maintaining reliable complementary binding between sense and antisense strands through optimized segment design.
Solution Approach 2:
The spacer sequences act as intermediaries between the sense and antisense strands, providing structural support and facilitating proper orientation for complementary binding. These intermediary elements help stabilize the overall complex structure without interfering with the specific base-pairing interactions between sense and antisense sequences.
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 multi-conjugate demonstrates higher gene delivery efficiency and target gene inhibition with reduced cytotoxicity, forming stable and small nano-sized complexes that effectively inhibit genes like VEGF, making it suitable for cancer and angiogenesis-related disease treatments.
Implementation Method 1
a nano-sized ion-complex is generally used which is prepared by ionic bonding of siRNA and diverse functional cationic polymers, lipids or cationic peptides
Implementation Method 2
direct or indirect covalent bonding of double-stranded sense/antisense siRNA monomers mediated by a cross-linking agent or a polymer
Data Source
AI summary
The present invention relates to a multi-conjugate of small interfering RNA (siRNA) and a preparing method of the same, more precisely a multi-conjugate of siRNA prepared by direct binding of double stranded sense/antisense siRNA monomers or indirect covalent bonding mediated by a cross-linking agent or a polymer, and a preparing method of the same. The preparing method of a siRNA multi-conjugate of the present invention is characterized by simple and efficient reaction and thereby the prepared siRNA multi-conjugate of the present invention has high molecular weight multiple times the conventional siRNA, so that it has high negative charge density, suggesting that it has excellent ionic interaction with a cationic gene carrier and high gene delivery efficiency.