Membrane Separation
Membrane Separation - Related Videos
03:47
Separation of Inner and Outer Membrane Fractions of Gram-Negative Bacteria
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2025
Source: Cian, M. B. et. al., Separation of the Cell Envelope for Gram-negative Bacteria into Inner and Outer Membrane Fractions with Technical Adjustments for Acinetobacter baumannii. J. Vis. Exp. (2020)This video demonstrates the separation of the inner and outer membrane fractions of Gram-negative bacteria using sucrose gradient ultracentrifugation. The membrane fractions are purified and stored at low temperatures for targeted analysis of membrane-specific components.
06:14
Separation and Fractionation of Cell Wall and Cell Membrane Proteins from Mycobacterium tuberculosis for Downstream Protein Analysis
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2025
This protocol separates insoluble cell wall and membrane proteins into simple fractions (1-5 proteins) using preparative isoelectric focusing (IEF) based on isoelectric point, followed by separation by molecular weight. The resulting fractions can be used directly for immunological and proteomic analysis without further purification.
04:51
Size Exclusion Chromatography Based Separation of Bacterial Extracellular Vesicles: A Technique to Separate Heterogenous Population of Gram-Negative Bacterial Outer Membrane Vesicles Based on Their Size
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2025
In this video, we demonstrate a technique–size exclusion chromatography–to separate a heterogenous population of outer membrane vesicles or OMVs derived from bacteria. These vesicles are nanosized spherical structures and are separated into large and small subpopulations based on their size through Size Exclusion Chromatography.
07:29
Separating Protein with SDS-PAGE
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2023
Sodium Dodecyl Sulfate Poly-Acrylamide Gel Electrophoresis, or SDS-PAGE, is a widely-used technique for separating mixtures of proteins based on their size and nothing else. SDS, an anionic detergent, is used to produce an even charge across the length of proteins that have been linearized. By first loading them into a gel made of polyacrylamide and then applying an electric field to the gel, SDS-coated proteins are then separated. The electric field acts as the driving force, drawing the SDS...
05:26
Dialysis: Diffusion Based Separation
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2023
Dialysis is a common technique used in biochemistry for separating molecules based on diffusion. In this procedure, a semipermeable membrane allows the movement of certain molecules based on size. This method can be applied to the removal of buffer, known as desalting, or exchanging buffer molecules or ions from a protein solution. This video covers the principles of dialysis along with a general procedure. Several applications of dialysis are reviewed, including the removal of gradient...
FAQs
These molecular properties determine how readily each component interacts with and crosses the membrane. A difference in size may favor passage of smaller species, while differences in solubility, diffusivity, charge, or affinity can produce different transport rates for similarly sized molecules or ions. The resulting rate differences determine which components are enriched in the transmitted or retained portions.
Membrane composition governs how components interact with the membrane and therefore influences selectivity, flux, energy demand, and product quality. A composition that favors one component can improve separation, but operating conditions also affect the outcome. Chemists therefore consider membrane composition together with the mixture and applied driving force rather than treating the membrane as an isolated variable.
These gradients supply the driving force that moves molecules or ions through the membrane. Changing the type or magnitude of the gradient can alter transport rates and the balance between passage and retention. Because flux, selectivity, energy demand, and product quality depend on operating conditions, selecting an appropriate gradient is central to controlling the separation outcome.
First, identify the desired purification, concentration, or fractionation outcome and select a membrane composition suited to the mixture. Next, establish a pressure, concentration, or electrical-potential gradient. Components then move through the membrane at different rates, producing transmitted and retained portions. Chemists evaluate those portions to determine whether the required product quality and separation have been achieved.
The method supports purification, concentration, and fractionation across several chemical settings. The overview identifies water treatment, gas processing, pharmaceutical production, and reaction research as important application areas. Its value is especially apparent when researchers need to divide mixture components without necessarily introducing a phase change, while controlling membrane properties and operating conditions.
Chemists should assess selectivity, flux, energy demand, and product quality together. Selectivity indicates how effectively components are differentiated, while flux reflects transport through the membrane. Energy demand describes the cost associated with the driving force, and product quality shows whether purification, concentration, or fractionation met the intended objective. These measures reveal tradeoffs in process design.