Composite Dialysis Membrane Biocompatibility Water Permeability
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Solution Overview
Problem
Current dialysis membranes face challenges in achieving optimal biocompatibility and water permeability while maintaining the desired separation effect, particularly in the goal of miniaturizing dialyzers to the level of a kidney implant, which requires advancements in material composition and surface modification to enhance therapeutic efficacy.
Innovation Solution
The development of composite dialysis membranes comprising polysulfones with sulfonation, combined with layer-by-layer deposition of polyethylenimine and sulfated polysaccharides, such as dextran sulfate, to create a functional surface that improves water permeability and sieving coefficients, specifically tailored for hollow-fibre or flat-membrane geometries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional dialysis membranes are used, then basic separation function is achieved, but water permeability and biocompatibility are insufficient for miniaturized dialyzers
Solution Approach 1:
The patent uses composite materials by combining polysulfone base membrane with multiple functional layers including polyethylenimine and sulfated polysaccharides. This composite structure allows the base membrane to provide mechanical strength while the functional layers enhance water permeability and biocompatibility, resolving the contradiction between reliability and productivity.
Solution Approach 2:
The patent modifies membrane parameters through sulfonation of the polysulfone base membrane and controlled deposition of functional layers. These parameter changes (chemical modification, surface charge adjustment) improve both biocompatibility and water permeability simultaneously, addressing the contradiction for miniaturized dialyzer applications.
2Volume of moving object
If membrane thickness is reduced for miniaturization, then dialyzer size is decreased, but separation precision and control over sieving coefficients deteriorate
Solution Approach 1:
The patent applies local quality by creating functionally distinct layers within the membrane structure. The base membrane provides mechanical support while functional layers with specific pore structures and surface properties control separation precision. This localized functional differentiation maintains high separation precision even in miniaturized dialyzers with reduced overall thickness.
Solution Approach 2:
The multi-layer composite structure allows different regions of the membrane to specialize in different functions: mechanical strength, water permeability enhancement, and precise molecular sieving. This composite approach enables miniaturization while preserving separation precision through optimized local properties in each layer.
3Strength
If hydrophobic polymers are used for membrane structure, then mechanical strength is improved, but water permeability and hydrophily decrease
Solution Approach 1:
The patent uses hydrophilic polymers and sulfonated groups as intermediaries between the hydrophobic polysulfone base membrane and the aqueous dialysis environment. These intermediary layers improve water permeability and hydrophily without compromising the mechanical strength provided by the hydrophobic base membrane, resolving the contradiction between strength and productivity.
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 membranes exhibit enhanced water permeability and controlled sieving coefficients, suitable for dialysis applications, with improved hydrophily and surface charge management, achieving a wide range of water permeability from 10 to 2000 L/bar*h*m2 and sieving coefficients for bovine serum albumin between 0.5 to 0.0001, effectively addressing the need for high-performance dialysis membranes.
Implementation Method 1
US 2013/0 277 878 A1 describes a method for producing a hollow-fibre dialysis membrane with a spinning technique with phase inversion
Implementation Method 2
the functional layer is formed from at least one polymeric polycationic bonding agent and at least one polymeric polyanion
Implementation Method 3
achieve the therapeutically desired separation effect
Data Source
AI summary
A membrane for the purification of blood, or a dialysis membrane, in hollow-fiber membrane or flat membrane geometry, made of a composite assembled from at least a base membrane based on at least one polysulfone or a polyphenylsulfone with at least one pore-forming hydrophilic additive and at least one functional layer arranged on the base membrane, whereby the functional layer is formed from at least one polymeric polycationic bonding agent and at least one polymeric polyanion, whereby the base membrane is made of a material which is selected from: a polysulfone [PSU], a sulfonated polysulfone [SPSU], a polyethersulfone [PES], a sulfonated polyethersulfone [SPES], a polyphenylsulfone [PPSU], a sulfonated polyphenylsulfone [SPPSU]; and mixtures of these.