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Encyclopedia > Amphiphile

Amphiphile (from the Greek αμφις, amphis: both and φιλíα, philia: love, friendship) is a term describing a chemical compound possessing both hydrophilic and hydrophobic properties. Such a compound is called amphiphilic or amphipathic. This forms the basis for a number of areas of research in chemistry and biochemistry, notably that of lipid polymorphism. A philia is the love or obsession with a particular thing or subject. ... A chemical compound is a chemical substance consisting of two or more different chemically bonded chemical elements, with a fixed ratio determining the composition. ... The adjective hydrophilic describes something that likes water (from Greek hydros = water; philos = friend). ... In chemistry, hydrophobic or lipophilic species, or hydrophobes, tend to be electrically neutral and nonpolar, and thus prefer other neutral and nonpolar solvents or molecular environments. ...

Contents

Structure

The hydrophobic group is typically a large hydrocarbon moiety, such as a long chain of the form CH3(CH2)n, with n > 4. The hydrophilic group falls into one of the following categories: In chemistry, hydrophobic or lipophilic species, or hydrophobes, tend to be electrically neutral and nonpolar, and thus prefer other neutral and nonpolar solvents or molecular environments. ... Hydrocarbons are refined at oil refineries and processed at chemical plants A hydrocarbon is a chemical compound that consists only of the elements carbon (C) and hydrogen (H). ... Look up moiety in Wiktionary, the free dictionary. ... The adjective hydrophilic describes something that likes water (from Greek hydros = water; philos = friend). ...

  1. Charged groups
  2. Polar, uncharged groups. Examples include phospholipids, one of the main constituents of biological membranes, and alcohols with large R groups.

Often, amphiphilic species have several hydrophobic parts, several hydrophilic parts, or several of both. Proteins and some block copolymers are such examples. In chemistry, an anionic species is one that contains a full negative charge. ... Structure of a carboxylic acid Carboxylic acids, also known as alkanoic acids, are organic acids characterized by the presence of a carboxyl group and have the general chemical formula R-C(=O)-OH, also written as R-COOH, where R is a hydrogen or an alkyl group. ... In inorganic chemistry, a sulfate (IUPAC-recommended spelling; also sulphate in British English) is a salt of sulfuric acid. ... A sulfonate anion consists of sulfur double bonded to two oxygens and bonded to an R group and an oxygen anion. ... In chemistry, a cationic species is one that contains a full positive charge. ... Phospholipid Two schematic representations of a phospholipid. ... A biological membrane or biomembrane is an enclosing or separating tissue which acts as a barrier within or around a cell. ... Functional group of an alcohol molecule. ... A representation of the 3D structure of myoglobin, showing coloured alpha helices. ... The introduction of this article does not provide enough context for readers unfamiliar with the subject. ...


How is it possible?

Molecules of amphiphilic compounds have hydrophobic (usually of hydrocarbon nature) and hydrophilic (represented by either ionic or uncharged polar functional groups) structural regions.


As a result of having both hydrophobic and hydrophilic structural regions, some amphiphilic compounds may dissolve in water and to some extent - in non-polar organic solvents. Hydrophobe (from the Greek (hydros) water and (phobos) fear) in chemistry refers to the physical property of a molecule that is repelled by water. ... A solvent is a liquid that dissolves a solid, liquid, or gaseous solute, resulting in a solution. ...


When placed in an immiscible biphasic system consisting of aqueous and hydrophobic solvent the amphiphilic compound will partition the two phases. The balance between hydrophobic and hydrophilic natures defines the extent of partitioning.


Biological role

Phospholipids, a class of amphiphilic molecules, are the main components of biological membranes. The amphiphilic nature of this molecules defines the way in which they form membranes. They arrange themselves into bilayers, by positioning their polar groups towards the surrounding aqueous medium, and their hydrophobic chains towards the inside of the bilayer, defining a non-polar region between two polar ones. Two schematic representations of a phospholipid. ... A diagonal molecular slab from the DPPC lipid bilayer simulation1; color scheme: PO4 - green, N(CH3)3 - violet, water - blue, terminal CH3 - yellow, O - red, glycol C - brown, chain C - grey. ...


Although phospholipids are principal constituents of biological membranes, there are other amphiphilic molecules, such as cholesterol and glycolipids, which are also included in these structures and give them different physical and biological properties. Two schematic representations of a phospholipid. ... Cholesterol is a sterol (a combination steroid and alcohol) and a lipid found in the cell membranes of all body tissues, and transported in the blood plasma of all animals. ... Glycolipids are carbohydrate-attached lipids. ...


Many other amphiphilic compounds strongly interact with biological membranes by insertion of hydrophobic part into the lipid membrane, while exposing the hydrophilic part to the aqueous medium, altering their physical behaviour and sometimes disrupting them.


Examples of Amphiphiles

There are several examples of molecules that present amphiphilic properties:


Surfactants are an example group of amphiphilic compounds. Their polar region can be either ionic, or non-ionic. Some typical members of this group are: sodium dodecyl sulphate (anionic), Benzalkonium chloride (cationic), Cocamidopropyl betaine (zwitterionic) and octanol (long chain alcohol, non-ionic). Surfactants, also known as wetting agents, lower the surface tension of a liquid, allowing easier spreading. ... “Multivalent” redirects here. ... “Multivalent” redirects here. ... Sodium dodecyl sulfate (SDS or NaDS) (CH3(CH2)11OSO3Na) (FW 288. ... An anion is an ion with negative charge. ... R-phrases , , S-phrases , , RTECS number BO3150000 Except where noted otherwise, data are given for materials in their standard state (at 25 Â°C, 100 kPa) Infobox disclaimer and references Benzalkonium chloride (alkyl dimethyl benzyl ammonium chloride) is a mixture of alkylbenzyl dimethylammonium chlorides of various alkyl chain lengths. ... A cation is an ion with positive charge. ... Cocamidopropyl betaine (CAPB) is a zwitterionic surfactant with a quaternary ammonium cation in its molecule. ... A zwitterion (from German Zwitter — hybrid, hermaphrodite) is a compound with acidic and basic groups in the same molecule. ... Octanol is a straight chain fatty alcohol with eight carbon atoms and the formula C8H17OH and its molecular weight is 130. ...


Many biological compounds are amphiphilic: phospholipids, cholesterol, glycolipids, fatty acids, bile acids, saponins, etc. Two schematic representations of a phospholipid. ... Cholesterol is a sterol (a combination steroid and alcohol) and a lipid found in the cell membranes of all body tissues, and transported in the blood plasma of all animals. ... Glycolipids are carbohydrate-attached lipids. ... In chemistry, especially biochemistry, a fatty acid is a carboxylic acid (or organic acid), often with a long aliphatic tail (long chains), either saturated or unsaturated. ... Bile acids are steroid acids found predominantly in bile of mammals. ... Saponins are a class of glucosides found in plants. ...


See also


  Results from FactBites:
 
United States Patent Application: 0040091546 (15321 words)
Amphiphilic copolymers and the additive target molecules can be mixed in a ratio between about 1:20 to about 20:1 by weight and result in nanoparticles of amphiphilic copolymers with additive target molecule.
The amphiphilic copolymers used in this invention are comprised of blocks of at least two sub-units or with a minimum contour length the equivalent of at least 5 ethylene units and of a given character and a molecular weight of at least 300 g/mole.
In the present case, nanoparticle compositions in which amphiphilic copolymers contain PEO as the water soluble component are used for steric stabilization of a target molecule are desirable to obtain the properties for a pharmaceutical formulation.
Patent 6,814,971 (3671 words)
The invention relates to adjuvants that contain a lecithin, an oil and an amphiphilic surfactant and that are capable of forming a stable oil-in-water emulsion vaccine so as to minimize local reactions to the vaccine in the injected animal.
In another preferred embodiment, two amphiphilic surfactants are used in an adjuvant of the invention, for example a Tween and a Span surfactant.
Amphiphilic surfactants useful in the adjuvant of the invention have HLB values from about 2 to about 20, preferably from about 3 to about 17.
  More results at FactBites »

 
 

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