Membrane Permeation
Membrane Permeation - Related Videos
01:58
Studying the Permeation of FITC and FITC-Ferritin through an In Vitro Blood-Brain Barrier Model
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2025
This video demonstrates a method to study permeation through an in vitro blood-brain barrier (BBB) model using astrocytes and endothelial cells on a membrane insert, with free FITC and FITC-loaded ferritin. FITC-ferritin bound to receptors on endothelial cells and crossed the membrane barrier to the lower chamber while free FITC showed restricted permeation and remained in the upper chamber.
11:13
In Vitro Permeation of FITC-loaded Ferritins Across a Rat Blood-brain Barrier: a Model to Study the Delivery of Nanoformulated Molecules
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Cited by 15 •
2016
A method to establish an in vitro model of blood-brain barrier based on a co-culture of rat brain microvascular endothelial cells and astrocytes is described and validated. This system proved to be a valid tool to study the effect of nanoformulation on the trans-barrier permeation of fluorescent molecules.
07:32
Synthesis of Hydrogels with Antifouling Properties As Membranes for Water Purification
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Cited by 10 •
2017
This paper reports practical methods to prepare hydrogels in freestanding films and impregnated membranes and to characterize their physical properties, including water transport properties.
08:14
Determining Membrane Protein Topology Using Fluorescence Protease Protection (FPP)
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Cited by 18 •
2015
Here, we present a protocol to determine the orientation and topology of integral membrane proteins in living cells. This simple protocol relies on selective protease sensitivity of chimeras between the protein of interest and GFP.
05:54
Controlled Odor Mimic Permeation Systems for Olfactory Training and Field Testing
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Cited by 1 •
2021
The Controlled Odor Mimic Permeation System is a simple, field-portable, low-cost method of odor delivery for olfactory testing and training. It is constructed of an odorant retained on an adsorbent material and contained inside of a permeable polymer bag allowing controlled release of the odorant vapor over time.
FAQs
Size, polarity, and electrical charge strongly influence the route across a membrane. Small nonpolar molecules can diffuse through the lipid bilayer, while charged molecules and larger solutes generally cannot pass efficiently through that region alone. Instead, they typically depend on membrane proteins, allowing selective permeability to control which substances enter or leave a cell.
Gradients provide the directional driving force for many transport events. Passive diffusion and facilitated diffusion move substances down existing concentration or electrochemical gradients, so the membrane does not need to supply cellular energy for these processes. The direction and availability of a gradient therefore help determine whether a solute moves into or out of the cell.
Channels and carrier proteins provide alternative pathways for solutes that cannot readily cross the lipid bilayer. Their involvement is especially important for charged molecules and larger substances. Depending on the gradient and energy requirements, protein-assisted movement may remain passive, as in facilitated diffusion, or support active transport that maintains concentration differences.
Membrane permeation supports osmoregulation by controlling the movement of water-related solutes and ions between a cell and its surroundings. Selective passage helps preserve appropriate concentration differences rather than allowing all materials to equilibrate indiscriminately. This regulation is important for maintaining cellular conditions as the external environment changes.
Nutrient uptake depends on whether particular nutrients can cross the lipid bilayer or require protein-mediated transport. Facilitated diffusion can move suitable solutes along existing gradients, while active transport can use cellular energy to maintain differences that favor accumulation inside the cell. These mechanisms connect membrane selectivity with the cell’s access to nutrients.
Signaling depends partly on controlled movement of ions and other molecules across membranes. Because charged solutes generally require channels or carrier proteins, changing transport pathways can influence how cells exchange signaling-related materials with their surroundings. The resulting control over membrane passage helps link membrane behavior to cellular responses and communication.
In pharmacology, membrane permeation helps explain how drugs move across cells and interact with cellular compartments. In membrane-based biotechnology, the same principles guide attention to selective barriers, protein pathways, gradients, and energy use. Understanding these factors helps relate molecular movement to the performance of biological or engineered membrane systems.