Membrane Separation

Aside from chromatography and protein precipitation, membrane separation is another potent technique in protein purification. It is based on artificial semipermeable membranes that selectively allow molecules to penetrate. The high surface area/volume ratio offers an edge of high throughput. Traditional membranes separate molecules solely according to the molecular sizes, and it suffers from a low resolution. With the advances in membrane modification and manufacturing, membranes with charges and other desirable properties are now available for a better resolution.

Creative BioMart Nanocage is highly experienced in a wide range of membrane technologies for protein nanocage purification. We have well-trained technicians and membrane separation experts to support our customer's research and meet all the needs. In our laboratories, we possess a variety of advanced instruments performing microfiltration, ultrafiltration, and membrane chromatography.

Microfiltration and Ultrafiltration Service

Microfiltration and ultrafiltration are both pressure-driven filtration processes, but differ in membrane pore sizes and are used for different purposes. Currently, there are two filtration modes, dead-end/direct flow and cross-flow/tangential flow. Dead-end filtration is a batch type whilst cross-flow mode is more continuous and usually preferred because of its high efficiency. Creative BioMart Nanocage offer microfiltration and ultrafiltration modules in hollow fiber, spiral wound cartridges, flat-sheet cassettes, spiral-wound cartridges, and tubular modules. Different molecular cut-off membranes are available for selection.

Fig 1. Mechanism of Dead-end and Cross-flow Filtration Modes (Silverwood, A., et al., 2016)

Microfiltration separates particles sized from 0.1 to 10.0 μm, therefore, is well-suited to separate cells, viruses with proteins. It is mainly used as an auxiliary step in the protein purification pathway. At Creative BioMart Nanocage, we primarily employ this technique for 2 aims, 1) capturing the secreted recombinant protein nanocages in fermentation broth as a pretreatment of further purification and, 2) removing bacterial before in vitro and in vivo application of recombinant protein nanocages.

Ultrafiltration typically separates particles between 5-100 nm. It is more extensively used than microfiltration. Main usages of it include sample concentration, buffer exchange, and protein purification. Except for the traditional pressure-driven ultrafiltration, we provide electro-ultrafiltration, ultrafiltration under ultrasonic field, and high-performance tangential flow ultrafiltration (HPTFF).

Membrane Chromatography Service

Membrane chromatography is similar to resin-based chromatography in the purification mechanism. Membranes are conjugated with functional groups to selectively and reversibly bind to molecules through electrostatic attraction, hydrophobic interaction, or specific affinity. Compared with resin-based chromatography, membrane chromatography is advantageous in purifying large proteins such as protein nanocages because of the shorter diffusion time and higher diffusion efficiency. It also has the merits of high scalability and fast process. Creative BioMart Nanocage utilizes a wide selection of membrane absorbents manufactured by Saturious for different purification aims.

Table 1. Membrane chromtagraphy service

Creative BioMart Nanocage is a leading company in protein nanocage purification. We provide a wide range of purification techniques capable of purifying all types of proteins. We specialize in the purification of protein nanocages, such as ferritin, ferritin mutants, ferritins inserted with foreign peptides, VLPs, and chimeric VLPs. Our membrane separation can be used alone or be combined with other purification techniques. This service is guaranteed to be fast, reliable, and to meet our customer's expectations. Various levels of final product purity and purification scale are available. If you are interested in our membrane separation service, please feel free to contact us through online inquiry.

Reference

• Silverwood, A., et al. (2016). "Cross-flow microsand filtration for membrane pre-treatment." Desalination and Water Treatment. 57(55), 26548-26551.