Zwitterionic Covalent Modification of Micro/Nano Surfaces
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Solution Overview
Problem
Current methods for covalently modifying micro/nano materials with hydrophilic compounds face challenges such as insufficient reduction of non-specific adsorption, limited modification density, and steric hindrance issues, particularly with bulky modification agents, which affect the biological activity and stability of immobilized biomolecules.
Innovation Solution
A systematic optimization approach involving the use of special organic monomers to generate active esters on the surface, a hydrophilic modification agent with primary and/or secondary aliphatic amines, pro-zwitterion groups, and flexible linking arms, and multilayer covalent modification to achieve high-density, uniform modification layers that reduce non-specific adsorption and enhance biomolecule activity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If PEG modification is used to reduce non-specific adsorption, then adsorption resistance is improved, but modification density is limited due to steric hindrance and chain flexibility
Solution Approach 1:
The patent changes the chemical structure parameter of the modification agent from PEG to zwitterionic compounds, which have different steric and electronic properties. This allows achieving high modification density without the steric hindrance limitations of PEG chains, while simultaneously maintaining or improving anti-adsorption performance
Solution Approach 2:
The patent uses composite modification by combining zwitterionic compounds with hydrophilic polymers or small molecules. This composite approach creates a synergistic effect where the zwitterionic groups provide high-density surface coverage and electrostatic repulsion, while the hydrophilic components contribute to steric stabilization and hydration layers, collectively achieving superior anti-adsorption performance
2Object-affected harmful factors
If zwitterionic modification agents are used to reduce non-specific adsorption, then adsorption resistance is improved, but modified area is limited due to small agent size
Solution Approach 1:
The patent merges zwitterionic modification agents with hydrophilic polymers or small molecules to create composite modification systems. This merging allows the small zwitterionic groups to be carried by larger hydrophilic structures, thereby expanding the modified area and coverage on the micro/nano material surface while maintaining the strong anti-adsorption properties of zwitterions
3Quantity of substance
If high PEG density is achieved on surface, then modification coverage is improved, but non-specific adsorption of proteins and hydrophobic molecules increases
Solution Approach 1:
The patent inverts the conventional approach by using zwitterionic compounds instead of PEG as the primary modification agent. Zwitterions provide anti-adsorption through electrostatic repulsion and hydration mechanisms rather than solely through steric barriers, allowing high surface coverage without the adverse effect of increased non-specific adsorption that occurs with high PEG density
4Quantity of substance
If bulky modification agents are used to increase modification density, then coverage is improved, but biological activity of immobilized biomolecules decreases
Solution Approach 1:
The patent segments the modification system into two functional parts: small zwitterionic compounds that provide high-density surface coverage and anti-adsorption properties, and separate hydrophilic polymer chains that provide steric stabilization. This segmentation allows achieving high modification density without using bulky agents that would interfere with biomolecule activity
Solution Approach 2:
The patent introduces flexible linking arms as intermediaries between the micro/nano material surface and the modification agents or biomolecules. These linking arms provide sufficient flexibility and distance to prevent steric hindrance to biomolecule function while still allowing high-density anchoring of modification agents on the surface
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 approach results in micro/nano materials with negligible non-specific adsorption of proteins and hydrophobic small molecules, maintaining high biological activity of immobilized biomolecules and improving the hydrophilicity of the surface.
Implementation Method 1
a carboxyl group is easily activated into an active ester at a high yield, and then reacts with a primary or secondary aliphatic amine to form an amide bond
Implementation Method 2
Zwitterions, also known as amphoteric ions, refer to functional groups/compounds with equal amounts of positive and negative charges. The zwitterions modification agent coated on the surface of the micro/nano material can significantly reduce non-specific adsorption.
Implementation Method 3
a mixture of a large number of intermolecular ion pairs also has a strong hydration ability and a weak non-specific adsorption
Data Source
AI summary
Micro-nano materials, products obtained by covalently modifying the surfaces of micro/nano materials with hydrophilic materials, and methods for making the same. The micro/nano materials on the surfaces have carboxyl groups or/and pro-carboxyl groups which are converted into their active esters. The products are covalently modified by forming amide bonds between the active esters on the surfaces and the modification agents; where the modification agents are hydrophilic compounds and/or hydrophilic polymers bearing primary and/or secondary aliphatic amines. Monomers bearing carboxyl groups and/or pro-carboxyl groups are used to produce an adequate number of carboxyl groups and/or pro-carboxyl groups on the surface of a polymer material to be modified. The carboxyl groups and/or pro-carboxyl groups are converted into active esters. A reasonably-sized modification agent bearing primary and/or secondary amines, zwitterions and hydrophilic linear spacer arms is used to form amide bonds and obtain a covalently modified surface layer.