Understanding the Options

Cell Culture Media Preparation:
Bacterial and Mycoplasma Retention

Prefiltration

(If sterile filter capacity is <1,000 L/m2 then a prefilter should be considered.)

Essential Process Requirements

• Protect sterilizing-grade filters by effectively removing lipids, colloids and particles without binding vital media constituents
• Cost effectiveness and timely separation
• Needs to work irrespective of variation from batch to batch
• Preserve cell growth properties

Recommended Filter	Filter Characteristics
Triple-layer Millistak+ HC Filters (Grade A1HC) Disc Filters Pod Filters	Triple-layer configuration includes a membrane bottom layer to enhance filter loading capacity and retention Higher filtrate quality allows smaller size requirements for downstream sterilizing-grade filtration step Unique design enables the compression of multiple process steps into one, lowering overall filtration costs ALTERNATIVE: If media stream is less plugging, Millipore suggests testing single-layer Grade 75DE Millistak+ Filters in your small-scale trials.
Triple-layer Polysep II Filters (Grade W1, 1.0 µm + 0.2 µm + 0.1 µm) Cartridge Filters Opticap Capsules Optiscale Capsules	Designed for the protection of downstream 0.1 µm sterilizing-grade filters Triple layer construction ensures high particle loading and capacity Validated for multiple sanitization and SIP cycles Higher filtrate quality allows smaller size requirements for downstream sterilizing-grade filtration step Non-fiber releasing structure preserves product purity Cell growth studies confirm growth properties are preserved

Sterile Filtration

• Remove bacteria and mycoplasma to preserve the aseptic barrier around the bioreactor
• Filter material must have low cytotoxicity, low extractables and low binding of key nutrients
• Preserve cell growth components

Recommended Filter

Filter Characteristics

Millipore Express SHR Filters (0.1 µm or 0.1 µm + Prefilter Layer) Cartridge Filters Opticap Capsules Optiscale Capsules

Sterilizing-grade membrane designed to remove high levels of mycoplasma and bacteria over a range of moderately plugging to highly fouling streams Asymmetric pore structure delivers extremely high flow rates at low pressure drop PES membrane provides broad chemical compatibility across a wide pH range (1–14) 100% integrity tested to ensure quality Robust construction validated for multiple SIP cycles Can be integrity tested on-site Available in single-layer 0.1 µm or double-layer 0.1 µm with prefilter layer. The degree of protection required for the downstream process and the plugging characteristics of the fluid will guide this selection. Choice should be based on small-scale testing.