DODAB
Encyclopedia
Dioctadecyldimethylammonium bromide (DODAB) is a doublechained quaternary ammonium surfactant
that forms unilamellar vesicles (ULVs) in water. Among various preparation methods, the ‘‘hot-water” method offers a simple procedure to prepare DODAB cationic vesicles by simply dissolving the DODAB in hot water above 50 °C, i.e., chain melting (main) transition
, Tm.
In general, the DSC
thermograms of the unsonicated DODAB dispersions
are dominated by two endotherms; the pre- (35–36 °C) and main transition (42.7–45 °C) peaks. Moreover, in literature reported the presence of a third
endotherm (post transition) at 52.2 °C.
The main transition (Tm) is ascribed to gel
to liquid-crystalline phase transition in which the alkyl chains transform from solidlike to liquid-like state.
The 10 mM DODAB is a critical concentration
, below which the dispersions consist of large polydispersed unilamellar vesicles (ULVs) that exhibit a local (chain melting) transition at 43 °C, beyond which a structural transition occurs: ULVs --> MLVs (multilamellar vesicles) as indicated by the sudden increase in the dynamic moduli. However, above 10 mM DODAB, the dispersions are mostly formed by ULVs in coexistence with lamellar fragments resulting in a network that shows a rheogram similar to that of hexagonal liquid-crystalline phase.
Surfactant
Surfactants are compounds that lower the surface tension of a liquid, the interfacial tension between two liquids, or that between a liquid and a solid...
that forms unilamellar vesicles (ULVs) in water. Among various preparation methods, the ‘‘hot-water” method offers a simple procedure to prepare DODAB cationic vesicles by simply dissolving the DODAB in hot water above 50 °C, i.e., chain melting (main) transition
Transition state
The transition state of a chemical reaction is a particular configuration along the reaction coordinate. It is defined as the state corresponding to the highest energy along this reaction coordinate. At this point, assuming a perfectly irreversible reaction, colliding reactant molecules will always...
, Tm.
In general, the DSC
DSC
-in academia:* D.Sc., Doctor of Science* Doctor of Surgical Chiropody, superseded in the 1960s by Doctor of Podiatric Medicine* Dalton State College, Georgia* Daytona State College, Florida* Deep Springs College, California* Dixie State College of Utah...
thermograms of the unsonicated DODAB dispersions
Dispersion (chemistry)
A dispersion is a system in which particles are dispersed in a continuous phase of a different composition . See also emulsion. A dispersion is classified in a number of different ways, including how large the particles are in relation to the particles of the continuous phase, whether or not...
are dominated by two endotherms; the pre- (35–36 °C) and main transition (42.7–45 °C) peaks. Moreover, in literature reported the presence of a third
endotherm (post transition) at 52.2 °C.
The main transition (Tm) is ascribed to gel
Gel
A gel is a solid, jelly-like material that can have properties ranging from soft and weak to hard and tough. Gels are defined as a substantially dilute cross-linked system, which exhibits no flow when in the steady-state...
to liquid-crystalline phase transition in which the alkyl chains transform from solidlike to liquid-like state.
The 10 mM DODAB is a critical concentration
Concentration
In chemistry, concentration is defined as the abundance of a constituent divided by the total volume of a mixture. Four types can be distinguished: mass concentration, molar concentration, number concentration, and volume concentration...
, below which the dispersions consist of large polydispersed unilamellar vesicles (ULVs) that exhibit a local (chain melting) transition at 43 °C, beyond which a structural transition occurs: ULVs --> MLVs (multilamellar vesicles) as indicated by the sudden increase in the dynamic moduli. However, above 10 mM DODAB, the dispersions are mostly formed by ULVs in coexistence with lamellar fragments resulting in a network that shows a rheogram similar to that of hexagonal liquid-crystalline phase.
See also
- Alkyltrimethylammonium salts: cetyl trimethylammonium bromide (CTAB) a.k.a. hexadecyl trimethyl ammonium bromide, cetyl trimethylammonium chlorideCetrimonium chlorideCetrimonium chloride is a topical antiseptic. It is also commonly used in hair conditioners and shampoos, as a conditioning agent.- References:...
(CTAC); - Cetylpyridinium chlorideCetylpyridinium chlorideCetylpyridinium chloride is a cationic quaternary ammonium compound in some types of mouthwashes, toothpastes, lozenges, throat sprays, breath sprays, and nasal sprays. It is an antiseptic that kills bacteria and other microorganisms. It has been shown to be effective in preventing dental plaque...
(CPC); - Polyethoxylated tallow aminePolyethoxylated tallow aminePolyethoxylated tallow amine is a surfactant that enhances the activity of herbicides. It improves the solubility of many common herbicides in organic solvents, increasing their penetration of the waxy surfaces of plants. It may also interfere with the function of tadpole gills...
(POEA); - Benzalkonium chlorideBenzalkonium chlorideBenzalkonium chloride, also known as alkyldimethylbenzylammonium chloride and ADBAC, is a mixture of alkylbenzyldimethylammonium chlorides of various even-numbered alkyl chain lengths. This product is a nitrogenous cationic surface-acting agent belonging to the quaternary ammonium group...
(BAC); - Benzethonium chlorideBenzethonium chlorideBenzethonium chloride is a synthetic quaternary ammonium salt. This compound is an odorless white solid; soluble in water. It has surfactant, antiseptic, and anti-infective properties, and it is used as a topical antimicrobial agent in first aid antiseptics. It is also found in cosmetics and...
(BZT); - 5-Bromo-5-nitro-1,3-dioxaneBronidoxBronidox, or 5-bromo-5-nitro-1,3-dioxane, is an antimicrobial chemical compound.Bronidox causes inhibition of enzyme activity in bacteria.Bronidox is corrosive to metals.- Uses :* Stabilizer* Surfactant...
; - Dimethyldioctadecylammonium chloride