Colloidal Dispersions Quiz

<p>Invisibility to the immune system (C)</p> Signup and view all the answers

<p>Polyethylene glycol (PEG) and poloxamers (A)</p> Signup and view all the answers

<p>10 nm to 1 µm (A)</p> Signup and view all the answers

<p>They are significantly larger. (A)</p> Signup and view all the answers

<p>Lyophilic colloids (C)</p> Signup and view all the answers

<p>In aqueous and non-aqueous media (A)</p> Signup and view all the answers

<p>No, they can also form in organic liquids (A)</p> Signup and view all the answers

<p>They contain a large number of monomers. (B)</p> Signup and view all the answers

<p>Lyophobic colloids (B)</p> Signup and view all the answers

<p>They remain as aggregated particles. (B)</p> Signup and view all the answers

<p>To the air-water interface (D)</p> Signup and view all the answers

<p>It forms additional micelles (A)</p> Signup and view all the answers

<p>Above the CMC (B)</p> Signup and view all the answers

<p>Potential destabilization of the micelle system (C)</p> Signup and view all the answers

<p>Phospholipids and cholesterol (C)</p> Signup and view all the answers

<p>Both water-soluble and lipid-soluble drugs (C)</p> Signup and view all the answers

<p>One or two surfactants (B)</p> Signup and view all the answers

<p>Microemulsions exhibit higher stability (B)</p> Signup and view all the answers

The lowest concentration of an amphiphile at which micelles form in solution.

The concentration of an amphiphile in the system exceeds the CMC, further amphiphile molecules will preferentially join the existing micelles.

The process of dissolving a substance that is not normally soluble in a solvent, using a surfactant to assist in dissolving the substance.

Liposomes are vesicles consisting of an aqueous core surrounded by concentrically arranged bilayer membranes, composed primarily of phospholipids and often containing cholesterol.

Liposomes can accommodate both water-soluble and lipid-soluble drugs.

The chemical nature of the solubilizate determines where it resides within the micelle: nonpolar solubilizates in the core, slightly polar solubilizates in the palisade layer, and amphipathic solubilizates with both ends in different regions.

The presence of a high concentration of surfactants may lead to increased toxicity, decreased solubility, or changes in biological activity.

The formation of micelles depends on factors such as the concentration of the amphiphile, the temperature, and the presence of other molecules like electrolytes or polymers.

The balance between the hydrophilic (water-loving) and hydrophobic (water-fearing) nature of the lipids used to form the liposomes is crucial. If hydrophobic interactions dominate, micelles form. If hydrophilic interactions dominate, liposomes form.

Drug release from a liposome can occur through several mechanisms: diffusion through the membrane, fusion with the cell membrane, or enzymatic degradation of the liposome. A key factor is the liposome's stability and the drug's permeability.

Liposomes injected intravenously face rapid elimination from the bloodstream. Their half-life is typically short, usually measured in hours. The Mononuclear Phagocyte System (MPS) readily removes liposomes, which can be beneficial for targeting immune cells or detrimental for other applications.

Stealth liposomes have surface modifications which minimize uptake by the MPS. They typically use polyethylene glycol (PEG) or other water-soluble polymers. These stealth liposomes can have half-lives of days or weeks, allowing for prolonged circulation in the bloodstream.

Liposomes can encapsulate drugs, protecting them from degradation in the body. However, they are not perfect. One major disadvantage is their potential for immunogenicity, triggering an immune response. Drugs encapsulated within liposomes can be more resistant to degradation.

Dispersion systems are mixtures where one substance is dispersed uniformly throughout another. Colloidal systems are a type of dispersion system where the dispersed particles are between 1 nm and 1000 nm in size. This size range is unique because particles are large enough to scatter light but small enough to be suspended.

The shape and size of colloidal particles can significantly impact their properties. For instance, a spherical particle will have a smaller surface area compared to a long, thin particle of the same volume. This increased surface area in colloids contributes to their unique properties like stability and reactivity.

Lyophilic colloids have a strong affinity for the dispersion medium, forming spontaneously and interacting extensively. They are often covered with a solvent sheath, forming a protective layer. Examples include gelatin in water.

Lyophobic colloids have weak affinity for the dispersion medium, requiring specific conditions to form. They lack a solvent sheath and tend to be unstable. Examples include gold nanoparticles in water.

Association colloids are formed by the aggregation of molecules called amphiphiles, which have both hydrophobic and hydrophilic regions. These aggregates can range from micelles to larger structures, depending on the concentration of the amphiphiles.

Micelles are spherical aggregates formed by amphiphilic molecules in a solution. They typically contain 50 to 100 monomers and have a diameter of a few nanometers. Their cores are hydrophobic, attracting other nonpolar molecules while the exterior interacts with the surrounding water.

Hydrophilic colloids, also known as hydrocolloids, are lyophilic colloids dispersed in water. They are formed by materials that have a strong affinity for water, such as polymers like starch, gelatin, and gums.

Hydrophobic colloids are lyophobic colloids that are dispersed in water. They are formed by materials that have a weak affinity for water, such as oil droplets in water. These colloids typically require stabilizing agents to prevent them from aggregating.