Cellulose Nanofiber Membrane Virus Separation
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Solution Overview
Problem
Current virus filtration methods face challenges in effectively separating viruses from proteins without damaging the biological sample or affecting protein integrity, particularly due to the reliance on pH and ionic strength in electrostatic trapping, and the high cost and complexity of existing materials like ceramic filters.
Innovation Solution
A filtration membrane made from cellulose fibers derived from green filamentous algae with a narrow pore size distribution, specifically a modal pore diameter between 10 nm and 20 nm, and a high degree of crystallinity, which allows for efficient virus removal while allowing proteins to pass through, using environmentally friendly cross-linking agents and a simple production method.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrostatic trapping is used for virus filtration, then virus removal efficiency is improved, but the process becomes highly dependent on pH and ionic strength, reducing robustness
Solution Approach 1:
The patent transitions from electrostatic trapping (which depends on pH and ionic strength parameters) to size-exclusion filtration based on pore size distribution. By changing the filtration mechanism from electrostatic to physical size-based separation, the process becomes independent of pH and ionic strength variations, thereby improving robustness while maintaining virus removal efficiency.
2Reliability
If ceramic filters are used for virus filtration, then filtration performance is improved, but cost and device complexity increase significantly
Solution Approach 1:
The patent employs disposable polymeric membrane filters instead of expensive, complex ceramic filters. These polymeric membranes can be manufactured cost-effectively and are designed for single-use applications, eliminating the need for complex cleaning and sterilization procedures associated with ceramic filters while maintaining adequate filtration performance.
Solution Approach 2:
The patent utilizes porous polymeric membrane materials with controlled pore size distributions to achieve virus filtration. These porous structures provide the necessary filtration performance through size-exclusion mechanisms while being simpler in structure and lower in cost compared to ceramic filter systems.
3Reliability
If narrow pore size distribution is achieved for virus removal, then virus separation efficiency is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent achieves narrow pore size distribution by controlling the molecular weight and composition of the polymeric materials used in membrane fabrication. By adjusting polymer parameters such as molecular weight, polydispersity, and blend ratios, the pore size distribution can be controlled during the phase inversion process, achieving the required narrow distribution without excessively stringent manufacturing precision requirements.
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 cellulose-based filtration membrane achieves a high virus removal probability log reduction value (LRV) of ≥5 for large viruses and ≥3 for small viruses, while maintaining protein integrity and being cost-effective and non-destructive, comparable to industrial synthetic or semi-synthetic polymer membranes.
Implementation Method 1
size-exclusion filtration is the preferred mode of removing a virus from a fluid because it is both non-destructive, i.e. does not compromise the integrity of the biolofical sample of interest, and non-interfering
Implementation Method 2
the cellulose fibres have elementary fibrils of diameter greater than 10 nm and/or at least half of the cellulose has a degree of crystallinity greater than 90%
Data Source
AI summary
A filtration membrane comprising cellulose fibres, the membrane having a pore size distribution such that the modal pore diameter is between 10 nm and 25 nm and/or wherein less than 5% of the pore volume comprises pores of greater than 40 nm and having a total porosity greater than 30%.