Principle And Application Of Tangential Flow Filtration Technology

Tangential flow filtration is an effective method for concentrating and desalting 10ml to thousands of liters of sample solution. It can be used to separate large biomolecules from small biomolecules, capture cell suspensions, and clarify fermentation broth and cell lysates. TFF can be applied to a range of applications, including protein chemistry, molecular biology, immunology, biochemistry and microbiology. This paper will focus on the principle, main parameters and application of tangential flow filtration technology.

How to choose an appropriate tangential flow filtration system

TFF is tangential flow filtration, which is a pressure driven membrane separation process according to molecular size. With TFF, the sample mixture is not forced through a single path to pass through the membrane like DC filtration. Instead, the fluid circulates tangentially through the surface of the membrane through multiple times. This "sweeping" behavior caused by applied pressure reduces the accumulation of initial samples on the membrane surface. The target molecules with larger molecular weight than that intercepted by the membrane were retained, but the small molecules and buffer passed through the membrane. Tangential flow filtration is an effective method for concentrating and desalting 10ml to thousands of liters of sample solution. It can be used to separate large biomolecules from small biomolecules, capture cell suspensions, and clarify fermentation broth and cell lysates. TFF can be applied to a range of applications, including protein chemistry, molecular biology, immunology, biochemistry and microbiology. This paper will focus on the principle, main parameters and application of tangential flow filtration technology.

Conventional filtration means that under the action of pressure, the liquid directly passes through the filter membrane and enters the downstream, while large particles or molecules are intercepted upstream or inside the membrane, and small particles or molecules enter the downstream through the membrane. In this operation mode, the flow direction of the liquid is perpendicular to the membrane surface and enters the downstream, so it is also called "dead end filtration". The application of conventional filtration includes clarification filtration, sterilization filtration and virus removal filtration, which is not the focus of this paper. Tangential flow filtration means that the flow direction of the liquid is parallel to the membrane surface. Under the action of pressure, only part of the liquid passes through the membrane and enters the downstream. This operation mode is also known as "cross flow filtration". Because the tangential flow continuously "washes" the surface of the membrane package during the filtration process, this operation mode can effectively alleviate the accumulation of large particles and molecules on the membrane, which makes this operation mode have unique advantages in many applications.

In tangential flow (also known as "cross flow") filtration, the pump pushes the fluid through the surface of the filter membrane to wash away the trapped molecules, so as to minimize the scale on the surface of the filter membrane. At the same time, tangential fluid will also generate pressure perpendicular to the filter membrane, pushing solutes and small molecules through the filter membrane. In this way, the filtering can be completed. The simulation test of separating sand and pebbles by subdivision screen is helpful to understand the mechanism of tangential flow filtration: the screen hole symbolizes the pores on the filter membrane, while sand and pebbles symbolize the molecules to be separated. In DC filtration, the sand pebble mixture is forced to move towards the screen hole, and a pebble layer is formed on the screen surface as some smaller sand particles fall through the screen hole, Prevent the top sand from moving towards the screen and passing through the screen mesh (Fig. 1). In DC filtration, increasing the pressure can only exert pressure on the mixture, which is not conducive to the promotion of separation; In contrast, in the tangential flow filtration mode, the formation of the limiting layer is prevented by recirculation of the mixture, which is similar to vibration to remove the pebbles blocking the screen mesh, so that the sand at the top of the mixture falls and passes through the screen mesh. Therefore, the use of tangential flow filtration for biomolecular separation has higher efficiency and faster concentration or filtration speed.