Purification is key when it comes to isolating biomolecules. Here we look at the best of the latest filtration and purification technologies aimed at the biotech lab worker.
Pall Corporation's new Acrodisc MS syringe filter is the first syringe filter certified for low extractables in high performance liquid chromatography/mass spectrometry (LCMS) applications.
Designed specifically for LCMS, the Acrodisc MS syringe filter improves the accuracy of testing, enhances LCMS performance, and extends the longevity of testing instrumentation. The filter's low extractable levels minimise interference with the ionisation process and reduce the need for retesting. This lowers costs while reducing downtime due to unexpected contamination. To ensure high performance, product tubes are packaged individually so that filters not currently in use remain sealed and protected from external contamination.
Constructed with Pall's new WWPTFE membrane in a high density polyethylene housing, the Acrodisc MS syringe filter can be used with both organic and aqueous solvents. It offers excellent chemical resistance, good particulate retention, and minimal protein adsorption. This protects instrument columns from particulate build-up and reduces the frequency and cost of replacement. It also enables more consistent LCMS testing performance.
"Pall's Acrodisc MS syringe filter is the newest innovation in our comprehensive line of syringe filters and the first LCMS-certified syringe filter that is low in extractables," said Larry O'Connell, senior vice president, Pall Global Lab Products. "Coupled with our other well-known filtration products, the Acrodisc MS filter will continue our tradition of improving efficiencies and profitabilities of laboratory processes at all levels."
Another new innovation from Pall is AcroPrep Advance filter plates. These provide high performance membranes in an optimised filter plate configuration for diagnostic, genomic and protein applications. New sealing technology and advanced tip design result in faster, uniform filtration rates, improving well-to-well, plate-to-plate and lot-to-lot consistency (Fig. 1).
In addition, the company's new Microsep Advance and Macrosep Advance ultrafiltration centrifugal devices simplify many common nucleic acid and protein handling procedures. This facilitates higher volumes of pure product and high recovery rates of up to 90 per cent. Ultrafiltration reduces the amount of handling that can cause damage to samples, leaving concentrated samples ready for direct incorporation into downstream applications at critical stages in the discovery process. Pall's microfiltration centrifugal devices are used in separation and small-scale general filtration procedures, and can be combined with chromatography resins to create a fast, efficient method for purifying proteins.
Antibody polishing
Polishing in antibody production is usually performed on quaternary ammonium (Q) membranes in flow-through mode, since the overall speed and productivity is much higher than on traditional anion-exchange columns. However, the binding capacity of Q ligands is reduced at higher conductivities, so concentrated feed streams must be diluted to adequately remove contaminants such as DNA, host cell proteins, viruses and endotoxins.
The Sartobind STIC PA (primary amine) anion-exchange membrane from Sartorius Stedim Biotech overcomes this limitation and binds contaminants at high conductivities under high-salt conditions at up to 20mS/cm. The salt-tolerant anion exchanger can directly process cation-exchange pools without further dilution. Buffer consumption and buffer tank investments can be reduced.
Sartobind pico with 0.08ml is the latest member of the Sartobind STIC family with nano, 5-in, 10-in, 30-in and mega capsules. Since all devices are used for flow-through polishing, a 4mm bed height is kept constant to scale to larger devices up to 1.6 litres. The small membrane volume of 0.08ml reduces material consumption during testing and virus spiking studies to save cost during the initial development phases (Fig. 2).
All membrane adsorber capsules are 'plug and play' devices and can be used like filters. As the materials are disposed of after a single use, this saves validation costs.
New from GE Healthcare Life Sciences are Streptavidin Mag Sepharose magnetic beads. These have a high binding capacity for purification of biotinylated biomolecules and enrichment of target proteins. The magnetic beads help simplify handling, and rapid capture is facilitated by magnetic devices while delivering scalability and high yield, from low microlitre to high millilitre scale sample volumes.
Streptavidin Mag Sepharose beads support reliable sample preparation for downstream analysis and have a more than 400-fold enrichment factor to promote an increased identification rate of target proteins. The magnetic beads are hydrophilic with a high density to ensure the beads do not aggregate. They are available in two pack sizes, 2 x 1mL and 5 x 1mL. In addition, the MagRack Maxi has been launched to facilitate handling and to support sample capacities of up to 50mL.
From the same company, the rProtein A GraviTrap, Protein G GraviTrap, and rProtein A/Protein G GraviTrap gravity-flow columns enable single-step manual purification of monoclonal and polyclonal antibodies from various species in milligram scale. The purification run time is approximately 30 minutes (dependent on sample).
Designed for small-scale antibody purification, the product package contains everything needed for manual purification, as it converts into a column stand (Workmate) with a plastic tray to collect liquid waste. Each pack contains ten pre-packed columns to facilitate multiple samples to be purified simultaneously, using a gravity format. Columns contain 1 mL bed volume and can bind milligram amounts of antibodies. The columns are reusable up to five times depending on the sample.
For its part, Phenomenex has introduced the Phenex-GF/NY dual-membrane syringe filter for viscous, particulate-laden samples. The new filter incorporates a glass layer, through which the sample passes first for elimination of heavy particulates, increasing the effectiveness of the second, nylon fibre membrane. By removing particulates from the sample, the syringe filter prevents build-up and blockage of chromatography columns and frits while minimising wear and tear on injection valves. Proper sample filtration can ultimately reduce system downtime and component replacement.
Ideal for any applications with highly viscous or heavily particulate-laden samples, such as foods, biological fluids, soil and fermentation broths, Phenex-GF/NY performs at higher capacity than nylon-only filters, and requires less hand pressure to filter the sample. Phenex syringe filters are optimised for superior flow rates and high throughput.
Finally, designed to meet the pressure-flow requirements of commercial-scale bioprocesses, Nuvia Q high-capacity anion exchange media from Bio-Rad exhibits a binding capacity of greater than 170mg/mL at a flow rate of 300cm/hr. By maintaining high binding capacity even at fast flow rates, Nuvia Q can help improve productivity while reducing cycle time for downstream biotherapeutics purification. Moreover, less media is required for a given unit operation. Nuvia Q targets the purification of mAbs, recombinant proteins, and vaccines
Bio-Rad purchases QuantaLifeBio-Rad Laboratories has purchased QuantaLife for US$162m (EUR124m) in cash plus potential future milestone payments. QuantaLife has developed an innovative digital polymerase chain reaction (PCR) system that provides quantification of target molecules with unprecedented precision and sensitivity.
This next generation PCR technology builds on the well-established method of amplifying DNA that is used in research laboratories around the world. Digital PCR provides researchers with a new tool for the detection of rare mutations including distinguishing rare sequences in tumours, precise measurement of copy number variation, and absolute quantification of gene expression.
"We are impressed with QuantaLife's digital PCR technology and believe it will complement Bio-Rad's existing amplification business," said Norman Schwartz, Bio-Rad president and ceo. "This elegant solution expands the current state of the art methods of quantitative PCR (qPCR), and we look forward to its adoption in life science research."
Based in Pleasanton, California, QuantaLife was a privately-held life sciences company that provides advanced genetic analysis systems for research. QuantaLife has commercialised the droplet digital (ddPCR) system, the most accurate genetic analysis platform available today. The system is the first cost-effective, high-resolution platform available for the validation of next-generation sequencing discoveries. The company says it is easy to use, easy to automate, and easy to integrate into existing workflows in both life science and clinical research labs. With the ddPCR system, researchers can explore complex genetic landscapes in high-definition, discover new disease associations, and define a new category of improved molecular diagnostic tests
