In March 2025, the "Global Biopharmaceutical Process White Paper" released by the Jinan International Biofermentation Exhibition (BioChina) showed that the application coverage of filtration technology in cell culture and fermentation has reached 98%, which directly affects product purity, production efficiency and compliance. The perfluorinated capsule filter exhibited by Hangzhou Hanzhikang Purification Equipment Co., Ltd. has been verified by a third party to increase the cell debris removal rate to 99.9%, while maintaining the target protein recovery rate of over 95%. This article combines the latest industry trends and analyzes the core value of different filters in bioprocessing from four dimensions: filtration type, technical principle, application scenario, and maintenance strategy.
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Differences between glass fiber and cellulose media
Optimization of dirt holding capacity of gradient pore size design
Aperture selection for microfiltration (MF) and ultrafiltration (UF)
Chemical compatibility of polyethersulfone (PES) and polytetrafluoroethylene (PTFE)
Sterility assurance of hydrophobic PTFE membranes
Necessity of online integrity testing
Bacterial interception verification of 0.22μm PES membranes
Compliance design of redundant filtration systems
Application cases of virus filtration (20nm membrane)
Technical challenges of mycoplasma removal (0.1μm membrane)
Filter cleaning and sterilization procedures
Core parameters of FDA and EU CE certification
Deep filtration: efficient clarification of complex systems
Differences between glass fiber and cellulose media
In CHO In cell culture, deep filtration is a key step to remove cell debris and metabolites. Hangzhou Hanzhikang's P43 deep filter uses glass fiber media to reduce the turbidity of the fermentation broth from 120NTU to below 0.5NTU, while maintaining an antibody activity recovery rate of more than 95%. In contrast, cellulose media (such as Sartoclear® from Sartorius) are more suitable for virus-like particles (VLPs) that are sensitive to shear forces. Data from an mRNA vaccine production project showed that after using cellulose filters, VLP integrity increased from 78% to 92%.
Optimization of dirt holding capacity by gradient pore size design
The multi-layer gradient pore size design of the deep filter medium (upper layer coarse pore 50μm, lower layer fine pore 5μm) can significantly improve the dirt holding capacity. Hangzhou Hanzhikang's DepthPlus series reduces host cell protein (HCP) residues from 500ppm to below 10ppm in gene editing plasmid purification, while maintaining a 95% plasmid recovery rate. Compared with traditional single-layer filter materials, the gradient design extends the service life of the filter element by 3 times and shortens the purification time of a single batch by 2 hours.
Membrane filtration: the core technology of precise interception
Selection of pore size for microfiltration (MF) and ultrafiltration (UF)
Microfiltration (0.1-10μm): 0.22μm PES membrane is the "gold standard" for sterile filtration. After a monoclonal antibody manufacturer used it, the endotoxin residue in the finished product dropped from 0.05EU/μL to 0.005EU/μL, which meets FDA standards.
Ultrafiltration (10-100kDa): 10kDa molecular weight cutoff membrane is used for antibody concentration. After a pharmaceutical company used Hangzhou Hanzhikang's PA series filter element, it concentrated 100L fermentation broth to 5L while maintaining 95% antibody activity, which reduced energy consumption by 60% compared with centrifugation.
Chemical compatibility of polyethersulfone (PES) and polytetrafluoroethylene (PTFE)
PES membrane: highly hydrophilic, suitable for sterilization of buffer and culture medium. Tests in a university laboratory show that it remains stable in the pH range of 2-12, and the detection value of dissolved matter is less than 0.1μg/mL.
PTFE membrane: good hydrophobicity, strong acid and alkali resistance. Hangzhou Hanzhikang's HPTG series filter element can withstand 75% ethanol immersion for 48 hours without dissolved matter in amino acid fermentation, which is significantly better than ordinary industrial-grade filter materials.
Gas filtration: "Breathing Guardian" of bioreactor
Sterility guarantee of hydrophobic PTFE membrane
Hydrophobic PTFE membrane filter is required at the air inlet of the bioreactor to intercept fungal spores (≥0.3μm) in the air. Hangzhou Hanzhikang's HPTG filter element uses a hydrophobic PTFE membrane with a bubble point pressure of ≥3.0bar, which can withstand steam sterilization (121℃, 30 minutes). Therefore, a yeast fermentation project can control the contamination rate below 0.1%.
Necessity of online integrity testing
The gas filtration system needs to be tested for diffusion flow every week to ensure the sealing of the membrane. After a biopharmaceutical factory used Hangzhou Hanzhikang's IntegrityTest system, the number of microbial culture colonies in the filtered product dropped from 10CFU/mL to below the detection limit, avoiding pollution losses of more than 20 million yuan per year.
Sterile Filtration: Safety Barrier for End Products
Bacterial Retention Verification of 0.22μm PES Membrane
In the production of mRNA vaccines, the retention rate of 0.22μm PES membrane for bacteriophage (MS2) reaches 10^6 log. The actual test of a vaccine company shows that after using Hangzhou Hanzhikang's Bioaxenic series filter element, the pass rate of sterility test of finished products has increased from 92% to 100%.
Compliance design of redundant filtration system
In order to meet the stringent requirements of FDA for injections, a pharmaceutical company adopts a three-stage filtration scheme of "deep filtration (removal of cell debris) → ultrafiltration (concentration of LNP) → terminal sterilization filtration (0.22μm PES membrane)" to control the residual impurities to:
Host cell DNA: <100pg/dose (far exceeding the FDA requirement of <10ng/dose)
Endotoxin: <0.01EU/dose (better than the European Pharmacopoeia's <0.2EU/dose)
Special scenario filtration: customized solutions
Application case of virus filtration (20nm membrane)
In CAR-T cell therapy, 20nm PVDF membrane can effectively intercept adeno-associated virus (AAV, diameter 20-26nm). After a company used it, the residual virus was reduced from 10^4 copies/mL to below the detection limit, while maintaining a CAR-T cell activity recovery rate of 90%.
Technical challenges of mycoplasma removal (0.1μm membrane)
The removal of mycoplasma (diameter 0.1-0.3μm) requires the use of 0.1μm PES membrane. In a CRISPR-Cas9 experiment, a research institute reduced the mycoplasma contamination rate from 8% to 0.5% by combining Hangzhou Hanzhikang's ZetaCARE deep filter with a 0.1μm membrane.
Maintenance and compliance: full life cycle management
Cleaning and sterilization procedures for filters
Cleaning cycle: After every 5 batches, use 0.1M NaOH for online cleaning (CIP) to ensure that the membrane flux recovery rate is ≥95%.
Sterilization method: Online steam sterilization requires a temperature of 121℃ and a pressure of 3.5bar, and the offline radiation sterilization dose must be ≥25kGy.
Core parameters of global certification standards
FDA requirements: filter materials used for injections must pass the test of the horseshoe crab reagent gel method, and the endotoxin residue must be ≤0.05EU/μL.
CE certification: mechanical strength must withstand 50N axial tension without deformation (EN 10204 3.1B), and chemical compatibility must pass 75% ethanol immersion for 48 hours without dissolution (ISO 10993-1).
Summary
Industry practices in 2025 show that filtration technology has been upgraded from an "auxiliary step" to a "core process" for cell culture and fermentation. International mainstream laboratories adopt a "medium + membrane + gas" trinity filtration strategy. For example, in the biopharmaceutical field, glass fiber deep filtration + 0.22μm PES membrane + hydrophobic PTFE gas filtration is preferred, while gene editing experiments tend to use gradient pore depth filters + 0.1μm mycoplasma removal membranes. In the future, with the popularization of AI technology, intelligent filtration systems with integrated sensors will realize the closed loop of the entire process of "real-time monitoring - automatic optimization - data traceability", further improving production efficiency and compliance. Laboratory managers should establish standardized filtration management procedures and conduct performance verification regularly to ensure the accuracy and reliability of experimental results.