Related Experiment Video
Updated: Jul 5, 2026
07:55
Ion-Exchange Membranes for the Fabrication of Reverse Electrodialysis Device
Published on: July 20, 2021
Desalting, concentration, and buffer exchange by dialysis and ultrafiltration
Allen T Phillips1, Mark W Signs1
1Pennsylvania State University, University Park, Pennsylvania.
Current Protocols in Protein Science
|April 23, 2008
Summary
This study details dialysis and ultrafiltration methods for sample preparation, including desalting, concentration, and buffer exchange. These techniques are crucial for various biochemical and biophysical applications.
Area of Science:
- Biochemistry
- Biophysics
- Molecular Biology
Background:
- Effective sample preparation is critical for downstream biochemical and biophysical analyses.
- Traditional methods for desalting, concentration, and buffer exchange can be time-consuming and may lead to sample loss.
Purpose of the Study:
- To describe various dialysis and ultrafiltration techniques for biological sample preparation.
- To outline the applications of these techniques in desalting, concentration, and buffer exchange.
Main Methods:
- Standard dialysis using cellulose tubing for diffusion-based separation.
- Pressure-driven ultrafiltration for sample concentration or diafiltration (buffer exchange).
- Tangential flow filtration and centrifugal microconcentrators for large-volume and small-volume processing, respectively.
Main Results:
- Dialysis effectively removes small molecules and exchanges buffers.
- Ultrafiltration efficiently concentrates protein solutions.
- Diafiltration using ultrafiltration allows for seamless buffer exchange.
- Tangential flow filtration is advantageous for processing large solution volumes.
- Centrifugal microconcentrators enable rapid concentration of minute sample volumes.
Conclusions:
- A range of dialysis and ultrafiltration methods are available for diverse sample preparation needs.
- The choice of technique depends on sample volume, concentration requirements, and buffer exchange needs.
- These methods are essential tools for researchers in molecular biology, biochemistry, and biophysics.
Related Concept Videos
01:15Dialysis
Dialysis is a diffusion-based purification process that separates analyte molecules from a complex matrix. This is accomplished by allowing molecules in the solution to pass through a semipermeable membrane into a liquid on the other side. The membrane is usually made of cellulose acetate or cellulose nitrate, and the second liquid must be miscible with the solution. Ions (e.g., chloride or sodium) or organic molecules (e.g., glucose) can pass through the membrane pores, which generally have...
01:17Ion Exchange
Ion exchange chromatography separates charged molecules from a solution by reversibly exchanging them with mobile, or 'active', ions associated with the oppositely charged stationary phase. This method can be used to separate ions, soften and deionize water, and purify solutions. The polymers comprising the ion-exchange column are high-molecular-weight and chemically stable polymers, crosslinked to be porous and essentially insoluble. They are also functionalized with either acidic or basic...
01:29Downstream Processing
Downstream processing begins once fermentation is complete and involves a series of steps to recover and purify products such as acids, vitamins, antibiotics, or proteins.Cell HarvestingFor example, for intracellular protein-based products, the first step is harvesting the cells. This is typically achieved using centrifugation or filtration to separate the cells from the liquid phase.Cell Disruption for Intracellular ProductsIf the target product is intracellular, the harvested cells must be...
01:09Ion-Exchange Chromatography
Ion-exchange chromatography, or IEC, is a technique for separating ions based on their affinity for the stationary phase. The stationary phase is a cross-linked polymer resin with covalently attached ionic functional groups. The functional groups can be either positively charged (cation exchangers) or negatively charged (anion exchangers). A cation exchanger consists of a polymeric anion and active cations, while an anion exchanger is a polymeric cation with active anions. The choice of...
01:30Peritoneal Dialysis I: Introduction and Procedure
Peritoneal dialysis (PD) is a procedure that facilitates the exchange of solutes, waste products, electrolytes, and excess fluid between the blood in the peritoneal capillaries and a dialysis solution introduced into the peritoneal cavity.Principles of Peritoneal Dialysis (PD)Diffusion: Waste products such as urea and electrolytes move from high concentrations in the blood to low concentrations in the dialysate across the peritoneal membrane. This mechanism is driven by the concentration...
02:40Osmosis and Osmotic Pressure of Solutions
A number of natural and synthetic materials exhibit selective permeation, meaning that only molecules or ions of a certain size, shape, polarity, charge, and so forth, are capable of passing through (permeating) the material. Biological cell membranes provide elegant examples of selective permeation in nature, while dialysis tubing used to remove metabolic wastes from blood is a more simplistic technological example. Regardless of how they may be fabricated, these materials are generally...