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A colloid is a mixture in which one substance consisting of microscopically dispersed insoluble particles is suspended throughout another substance. Some definitions specify that the particles must be dispersed in a liquid , [ 1 ] while others extend the definition to include substances like aerosols and gels .
Drugs administered through topical application can act locally or systemically. [1] [6] However, the drug molecules must first be retained in and penetrate the surface layer of the skin. [6] Absorption of the drug through the skin surface is a passive process of diffusion.
Parenteral drug delivery: Emulsions serve as carriers for intravenous or intramuscular administration of drugs, solubilizing lipophilic ones while protecting from degradation and decreasing injection site irritation. Examples include propofol as a widely used anesthetic and lipid-based solutions used for total parenteral nutrition delivery.
A sol is a colloidal suspension made out of tiny solid particles [1] in a continuous liquid medium. Sols are stable, so that they do not settle down when left undisturbed, and exhibit the Tyndall effect, which is the scattering of light by the particles in the colloid. The size of the particles can vary from 1 nm - 100 nm.
WB Hardy linked formation of biological colloids with phase separation in his study of globulins, stating that: "The globulin is dispersed in the solvent as particles which are the colloid particles and which are so large as to form an internal phase", [6] and further contributed to the basic physical description of oil-water phase separation.
Milk is an emulsified colloid of liquid butterfat globules of 0.1 to 10 micrometer dispersed within a water-based solution.. Interface and colloid science is an interdisciplinary intersection of branches of chemistry, physics, nanoscience and other fields dealing with colloids, heterogeneous systems consisting of a mechanical mixture of particles between 1 nm and 1000 nm dispersed in a ...
Monodisperse colloids provide this potential. [8] [9] [21] Monodisperse powders of colloidal silica, for example, may therefore be stabilized sufficiently to ensure a high degree of order in the colloidal crystal or polycrystalline colloidal solid which results from aggregation. The degree of order appears to be limited by the time and space ...
In their paper, they give many more examples of colloid systems that flocculate into an emulsoid state, either by varying the temperature, by adding salts, co-solvents or by mixing together two oppositely charged polymer colloids, and illustrate their observations with the first microscope pictures of coacervate droplets.