Sartorius Lab Ultrafilters

Sartorius offers ultrafilters with polyethersulfone (PES), regenerated cellulose (RC) and cellulose acetate (CA/CTA) membrane materials.

For most ultrafiltration and diafiltration applications, both PES and RC are good choices. PES can provide higher recoveries for negatively charged molecules, while RC typically supports higher recoveries for linear molecules, including oligonucleotides and peptides. For new targets, Sartorius recommends testing both materials as part of your routine process optimization.

Meanwhile, CTA is recommended for applications where the ultrafiltrate (permeate) is of primary interest.

Ultrafilters are versatile consumables that can be used for ultrafiltration applications, such as macromolecule concentration and enrichment, clarification and particle removal, and sample volume reduction. They can also be used for diafiltration, which is an efficient alternative to gel filtration and dialysis for buffer exchange and desalting. Diafiltration can also be used for polishing, binding studies, and screening buffers to assess molecular stability.

Thanks to the comprehensive range of operating methods, membrane materials and MWCOs, Sartorius ultrafilters can be used for virtually any type of molecule, including proteins, viruses, nucleic acids, extracellular vesicles (EVs) and particles (EPs), and more.

For nucleic acids and other linear molecules, we recommend using Vivacon^®. The horizontal Hydrosart^® RC membranes and option of PCR-grade ultrafilters provide worry-free, contamination-free processing, especially in critical applications such as crime scene sample concentration prior to DNA sequencing.

Vivaflow^®️ is ideal for concentrating pDNA, purifying mRNA and processing other nucleic acids when working with larger feed volumes.

Many viruses can be processed in a similar manner to proteins, but typically with MWCOs ≥100 kDa. For enveloped viruses and similar molecules with lipid membranes, such as lipid nanoparticles (LNPs) and extracellular vesicles (EVs) and particles (EPs), reducing the operating pressure and shear stress on the sample by using a lower centrifugal force or pump flow rate may result in improved recoveries.

Yes, you can. Vivaspin^® 100 is ideal for handling samples up to 100 mL, while Vivaflow^® TFF cassettes, including the next generation Vivaflow^® SU, are intended for ultrafiltration and diafiltration of >100 mL samples without the complexity usually associated with crossflow technology.

Proteins are commonly concentrated using ultrafiltration. Product design of ultrafiltration devices for laboratory use consists of ultrafiltration membranes placed within housings specially designed to enable concentration through centrifugal, positive pressure, solvent adsorption and tangential flow separation methods. These methods use controlled forces to pass solutes and non-targeted molecules through a semi-permeable ultrafiltration membrane, into the permeate - while retaining the larger molecule(s) of interest in the retentate. 

The same membrane material, MWCO, feed flow direction and operating method may not be ideal for every sample. Therefore, optimizing your ultrafiltration and diafiltration processes for each target molecule should be a priority. Start by selecting a MWCO up to 1/3 or 1/2 the size of the molecule to be retained. If possible, it is also recommended to test different membrane materials and operating methods. Finally, refining your process by using, for example, reduced differential pressures, membrane passivation, or a buffer rinse after retentate collection can also help maximize target recoveries.

Most Sartorius ultrafilters have dead stops or minimum recirculation volumes to prevent sample loss due to dryness. These correspond to the minimum volume that a sample can reach before the ultrafiltration process automatically stops.

For molecules that are prone to aggregate above a certain concentration, the dead stop can be increased in selected Vivaspin^® ultrafilters to prevent overconcentration. Simply prefilling the permeate tube with water or buffer before starting ultrafiltration is sufficient to stop ultrafiltration earlier. This technique is also useful when you need to concentrate multiple samples to the same final volume in a single run with a fixed spin time.

The performance of ultrafiltration membranes degrades with repeated use, so most ultrafilters are designed for single use. This helps to reduce hands-on time, improve laboratory safety, and eliminate the risk of carryover.

However, cleaning and storage procedures are provided for Vivaspin^® 100 and selected Vivaflow^® ultrafilters, so that they can be used multiple times.

Sartorius ultrafilters can be used in a wide range of applications and many of them are therefore classified as General Laboratory Use (GLU). Although they can be used for diagnostic sample preparation, because these products were not specifically developed for in vitro diagnostics (IVD), they are not required to be classified as IVD medical devices under the In Vitro Diagnostic Medical Devices Regulation (Regulation (EU) 2017/746).

Clinical scientists in Europe and the United Kingdom can continue to validate and use GLU ultrafilters for diagnostic sample preparation. For example, GLU Vivaspin^® or Vivapore^® ultrafilters can be useful tools to increase the concentration of disease markers from body fluid samples prior to semi-quantitative or quantitative analysis. Products for GLU do not provide diagnostic results.

A biomolecule purification workflow typically begins after cell harvest or lysis, using a series of steps to isolate and increase the purity of the molecule of interest (MOI).

First, cells and cell debris can be removed by dynamic body feed filtration, to produce a clarified sample. This sample is usually rebuffered to ensure optimal conditions for capture of the MOI in subsequent chromatography steps. While dialysis can be used for buffer exchange, diafiltration offers a faster alternative with reduced buffer consumption and, if needed, can be combined with ultrafiltration to simultaneously concentrate the sample. Next, ion exchange (IEX) or affinity chromatography (AC) are common purification methods that can be applied to a variety of MOIs. These techniques will remove contaminants such as host cell proteins and DNA from the sample, to increase the sample purity. Finally, the sample may undergo a further round of buffer exchange and/or concentration, and sterilized by microfiltration, making it ready for use in a wide range of structural and functional studies.

Polishing chromatography is the final chromatography step in a purification workflow, designed to achieve the highest possible purity of a molecule of interest (MOI).

Ion exchange chromatography is commonly used for polishing in protein purification and can be applied in either capture or flowthrough modes. In capture polishing, buffer conditions are selected to promote binding of the MOI on the stationary phase. This allows for selective retention of the MOI, followed by washing (to remove further impurities) and elution - a so-called bind, wash, elute process.

In contrast, flowthrough polishing uses buffer conditions that promote the binding of impurities on the stationary phase, while the MOI flows through unbound. The key advantage of flowthrough polishing is its simplicity - it allows the MOI to be collected during sample loading, eliminating the need for washing and elution steps. This can reduce process time, buffer consumption, and handling complexity.