Filters rated at 0.1 µm have been increasingly used for cell culture media filtration due to concerns about mycoplasma contamination of cell cultures. Sartorius Stedim Biotech has recently launched a new 0.1-µm, mycoplasma-retentive, sterilizing grade filter: Sartopore® 2 XLM. it is a heterogeneous, double-layer PES membrane filter with a highly asymmetric 0.2-µm prefilter layer in-built with the same 0.1 µm mycoplasma-retentive final membrane as its predecessor, Sartopore® 2 0.2/0.1. Sartopore® 2 0.1-µm. 10″ cartridges have been validated as mycoplasma-retentive by testing at a third-party laboratory using a modified AStM F838-05 method to show removal of Acholeplasma Iaidlawii at LRV = 7/cm2.
We have tested Sartopore® 2 XLM filters extensively in different media applications. Two examples of its excellent performance are presented here. one is for serum-free media specifically developed for adherent cell lines used in vaccine production (e.g., Ex-CELL Ebx GRO-I from SAFC), and the other is for a fully chemically defined medium. These tests were conducted on 47-mm disks (in duplicate for Ebx GRO) with unprotected 0.1-µm filters at 12 psig constant upstream pressure. the number of 10″ elements needed was also calculated for each filter, assuming 5,000 l batch size and two-hour filtration time. Media were prepared from powders in accordance with manufacturer instructions.
In Figure 1: For serum free Ebx GRO-I media, next-generation 0.1-µm filters from three premier filter manufacturers performed well with v∞ values ≥3,000 L/m2. Sartopore® 2 XLM led the pack with v∞ ~ 5,100 L/m2 followed by competitive PeS and PeS/PvdF 0.1-µm membranes at about 3,700 and 3,000 L/m2, respectively. Sartopore® 2 XLM needed five 10″ elements followed by competitive PES/PVDF and PES 0.1-µm filters needing six and seven 10″ elements, respectively. Classical PVDF and CA membranes exhibited lower throughputs by 3–4×, with v∞ ~ 400-L,200 L/m2 range.
In Figure 2: the second medium tested was fully chemically defined with high lipid content. this was difficult to filter with all 0.1-µm filters showing ~5–10× less throughput. Sartopore® 2 XLM and competitor B PES/PVDF 0.1 were the lead candidates (v∞~ 530 and 550 L/m2, respectively) closely followed by competitor A PES 0.1 at v∞~ 425 L/m2. Classical PVDF and CA membranes exhibited lower throughputs with v∞ in 100–175 L/m2 range. the number of 10″ elements needed for a 5,000-L batch are not significant here because such low throughputs require prefilters for a cost-effective filter train.
In conclusion, Sartopore® 2 XLM 0.1-µm mycoplasma-retentive filters showed outstanding performance in two different types of important media filtration applications. its more effective, 0.2-µm, highly asymmetric prefilter layer coupled with 30% higher surface area (0.8 m2/10″) compared with other 0.1-µm filters deliver desired results.
We would like to acknowledge SaFC Biosciences for providing different media formulations for this testing.
Author Details
Chris Sullivan is an applications specialist, and Mandar Dixit is the director of product management, filtration technologies in North America for Sartorius Stedim North America Inc., 5 Orville Drive, Suite 200, Bohemia, NY 11716; 1-631-254-4249, bttechsupport@sartorius-stedim.com.