Targeted LPEI-PEG Polyplexes With Defined Conjugation for Cell Selectivity
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Solution Overview
Problem
Existing cationic polymer-based polyplexes for nucleic acid delivery suffer from aggregation and interaction with serum proteins, leading to heterogeneity and reduced biocompatibility, and random PEG conjugation to LPEI results in unpredictable structure-activity relationships.
Innovation Solution
The formation of LPEI-PEG conjugates through defined chemoselective reactions, using discrete molecular weight PEG fragments and specific linkages, ensures homogeneous and linear conjugates with predictable ratios, further linked to targeting fragments for selective cell uptake.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PEG fragments are conjugated to LPEI through covalent bonding formation, then the polyplexes show improved biocompatibility and blood circulation, but the conjugates become heterogeneous with random PEG inclusion density and undefined structure-activity relationships
Solution Approach 1:
The patent segments the conjugation process into discrete, controlled steps using specific chemical linkers (such as maleimide or hydrazone groups) that attach PEG fragments to defined positions on the LPEI backbone. This segmentation allows precise control over PEG inclusion density and conjugate structure, eliminating the randomness of conventional covalent bonding while maintaining biocompatibility.
Solution Approach 2:
The patent applies local quality by introducing specific functional groups at defined locations on the LPEI molecule to enable selective PEG attachment. By placing reactive groups at specific positions rather than allowing random conjugation, the patent achieves homogeneous conjugates with consistent local structure-activity relationships while preserving the overall biocompatibility benefits of PEG.
2Productivity
If multiple PEG fragments are bonded orthogonally to LPEI fragment, then the conjugates show improved polyplex formation, but the random synthesis leads to undefined structure-activity relationships
Solution Approach 1:
The patent employs preliminary action by pre-defining the attachment sites on the LPEI backbone before PEG conjugation. Using protected or activated groups at specific positions, the patent ensures that PEG fragments attach in predetermined locations, allowing complete definition of the conjugate structure before biological activity assessment, thus eliminating the information loss associated with random conjugation.
3Ease of manufacture
If LPEI is used alone for nucleic acid delivery, then the polyplexes can be formed, but aggregation and interaction with serum proteins occur
Solution Approach 1:
The patent creates composite materials by combining LPEI with PEG fragments through controlled conjugation. This composite structure leverages the cationic properties of LPEI for polyplex formation while the PEG segments provide steric shielding that prevents aggregation and reduces interaction with serum proteins, thus resolving the harmful effects of LPEI alone.
Solution Approach 2:
The patent uses PEG fragments as intermediary elements between the LPEI backbone and the surrounding biological environment. The PEG segments act as a protective interface that mediates interactions with serum proteins and prevents direct contact between LPEI and harmful biological molecules, reducing aggregation while maintaining polyplex formation capability.
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 resulting conjugates and polyplexes exhibit reduced heterogeneity, maintain or enhance biological activity, and achieve selective delivery of nucleic acids to target cells, including high expression and efficient protein translation.
Implementation Method 1
LPEI is protonated at physiological pH and therefore carries a net positive charge. When LPEI is incubated with a nucleic acid, which carries a net negative charge at physiological pH, LPEI and the nucleic acid can form polyplexes that are held together by electrostatic interaction.
Implementation Method 2
The chemoselective bonding of the LPEI fragments to the specifically defined discrete PEG fragments can take place using any suitable chemical precursors that can form a chemoselective bond.
Implementation Method 3
the chemoselective bonding of LPEI fragments to the specifically defined discrete PEG fragments takes place by means of a [3+2] cycloaddition between an azide and an alkyne or alkene leading to a 1,2,3-triazole or a 4,5-dihydro-1H-[1,2,3]triazole
Data Source
AI summary
The present invention relates to polyplexes comprising linear conjugates of LPEI and PEG. The LPEI and PEG fragments of the linear conjugates are preferably linked by a [3+2] cycloaddition between an azide and an alkene or an alkyne to produce a 1, 2, 3 triazole or a 4,5-dihydro-1H-[1,2,3]triazole. The linear conjugates are preferably further conjugated to a targeting fragment to enable selective interaction with a particular cell type. The conjugates can form polyplexes with therapeutic agents such as nucleic acids to deliver the therapeutic agents to cells.