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Related Concept Videos

Membrane Fluidity01:23

Membrane Fluidity

Cell membranes are composed of phospholipids, proteins, and carbohydrates loosely attached to one another through chemical interactions. Molecules are generally able to move about in the plane of the membrane, giving the membrane its flexible nature called fluidity. Two other features of the membrane contribute to membrane fluidity: the chemical structure of the phospholipids and the presence of cholesterol in the membrane.
Membrane Fluidity01:26

Membrane Fluidity

Membrane fluidity is explained by the fluid mosaic model of the cell membrane, which describes the plasma membrane structure as a mosaic of components—including phospholipids, cholesterol, proteins, and carbohydrates—that gives the membrane a fluid character.
Mosaic nature of the membrane
The mosaic characteristic of the membrane helps the plasma membrane remain fluid. The integral proteins and lipids exist as separate but loosely-attached molecules in the membrane. The membrane is a relatively...
Membrane Lipids01:32

Membrane Lipids

Lipids are an essential component of all biological membranes. The average lipid content in mammalian membranes is 50%, though it can be as low as 20% in the inner mitochondrial membrane or as high as 80% in the myelin sheath present around the nerve cells.
Phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, and sphingomyelin are the most common phospholipids present in mammalian membranes. At physiological pH, phosphatidylserine is negatively charged, while the other three...
Membrane Lipids01:32

Membrane Lipids

Lipids are an essential component of all biological membranes. The average lipid content in mammalian membranes is 50%, though it can be as low as 20% in the inner mitochondrial membrane or as high as 80% in the myelin sheath present around the nerve cells.
Phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, and sphingomyelin are the most common phospholipids present in mammalian membranes. At physiological pH, phosphatidylserine is negatively charged, while the other three...
Synthesis of Phosphatidylcholine in the ER Membrane01:27

Synthesis of Phosphatidylcholine in the ER Membrane

The ER synthesizes lipids for building cell membranes and performing cellular functions such as energy storage and signaling. The lipid synthesis machinery embedded in the ER membrane primarily collects all reactants from the cytosol. Following synthesis, the secretory pathway and the ER contact sites distribute these lipids to other cellular organelles. Additionally, the energy-rich triacylglycerides are transported from the ER via lipid droplets.
The major components of all eukaryotic cell...
What are Lipids?01:31

What are Lipids?

Lipids function as structural components of cellular membranes, in addition to acting as energy reservoirs and signaling molecules. They are thus crucial to all living organisms.  The three biologically important classes of lipids are triglycerides, phospholipids, and steroids.
Non-Polar and Hydrophobic Characteristics of Lipids
Lipids are a structurally and functionally diverse group of hydrocarbons—compounds consisting of carbon and hydrogen atoms. The carbon-carbon and carbon-hydrogen bonds...

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Updated: May 19, 2026

Fabrication Procedures and Birefringence Measurements for Designing Magnetically Responsive Lanthanide Ion Chelating Phospholipid Assemblies
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Fabrication Procedures and Birefringence Measurements for Designing Magnetically Responsive Lanthanide Ion Chelating Phospholipid Assemblies

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Well-defined cholesterol polymers with pH-controlled membrane switching activity.

Sema Sevimli1, Fatih Inci, Hadi M Zareie

  • 1School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, Australia.

Biomacromolecules
|August 25, 2012
PubMed
Summary
This summary is machine-generated.

New copolymers incorporating cholesterol show pH-responsive behavior for drug delivery. The 2% cholesterol copolymer demonstrated the strongest interaction with cell membranes, indicating potential for targeted intracellular delivery without toxicity.

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Fabrication Procedures and Birefringence Measurements for Designing Magnetically Responsive Lanthanide Ion Chelating Phospholipid Assemblies
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Phase Behavior of Charged Vesicles Under Symmetric and Asymmetric Solution Conditions Monitored with Fluorescence Microscopy

Published on: October 24, 2017

Area of Science:

  • Polymer Chemistry
  • Materials Science
  • Biotechnology

Background:

  • Cholesterol enhances drug delivery system penetration of cellular membranes.
  • Well-defined copolymers are needed for controlled therapeutic delivery.
  • pH-responsive polymers offer targeted intracellular drug release.

Purpose of the Study:

  • Synthesize and characterize poly(methacrylic acid-co-cholesteryl methacrylate) [P(MAA-co-CMA)] copolymers.
  • Investigate their pH-responsive behavior and interaction with lipid bilayers.
  • Evaluate their potential for pH-controlled intracellular drug delivery.

Main Methods:

  • Reversible addition-fragmentation chain transfer (RAFT) polymerization to synthesize copolymers with varying cholesterol content (2, 4, 8 mol %).
  • Dynamic light scattering (DLS) and atomic force microscopy (AFM) for structural analysis.
  • UV-visible spectroscopy, surface plasmon resonance (SPR), and liposome leakage assays to study pH-responsiveness and membrane interactions.
  • CellTiter-Blue assay to assess cytotoxicity.

Main Results:

  • Copolymers exhibited pH-dependent changes in size and assembly.
  • Phase transition pH increased with cholesterol content (3.9-5.4).
  • The 2 mol % CMA copolymer showed highest binding and membrane destabilization at pH 5.0.
  • Copolymers demonstrated no cytotoxicity up to 30 μM.

Conclusions:

  • P(MAA-co-CMA) copolymers are effective for pH-controlled drug delivery.
  • Cholesterol content influences copolymer assembly and membrane interaction.
  • The 2 mol % CMA copolymer shows promise for targeted intracellular delivery due to strong membrane interaction.