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Colloidal dispersions: Classification of dispersed systems & their general characteristics, size & shapes of colloidal particles

The term "colloid" is derived from the Greek word "kolla," which means "glue." Colloid is an abbreviation for colloidal system.

Colloidal Dispersions

The term "colloid" is derived from the Greek word "kolla," which means "glue."
  • Colloid is an abbreviation for colloidal system.
  • The system is diverse and biphasic.
  • Colloidal particle sizes range from 1nm to 100nm.
They are divided into two stages:
  • Phase dispersion
  • Continuous phase (solution medium/dispersion medium).
Suspensions and emulsions, for example.

Classification

Particulate matter (dispersed phase) is scattered across a continuous phase in dispersed systems (dispersion medium).

They are categorized based on the particle diameter of the scattered material:

Molecular dispersions (less than 1nm)

  • These particles are not visible with an electron microscope.
  • Pass semipermeable membranes and filter paper through
  • Particles do not settle when they are upright.
  • Experiencing fast diffusion
  • Ordinary ions, for example, glucose

Colloidal dispersions (1nm – 0.5nm)

  • Particles that are not visible under a standard microscope can be found in this sample.
  • Pass through filter paper but not a semipermeable membrane
  • Particles that have been centrifuged to settle
  • Diffuse at a gradual rate.
  • Colloidal silver sols, natural and manufactured polymers, for example.

Colloidal dispersions (>0.5nm)

  • Under a normal microscope, these particles are visible.
  • Neither filter paper nor a semipermeable membrane should be used.
  • Gravity causes particles to settle.
  • Do not disperse
  • For example, emulsions, suspensions, and red blood cells



General characteristics of colloidal dispersions

Particle size has an impact on the color of dispersion. 1/ Radius 1/ Wavelength of light absorbed (small wavelength) VIBGYOR (large wavelength)

Particle form is determined by the technique of production and the affinity of the dispersion medium.

This has an effect on the color of dispersion. Spherical, rods, flakes, threads, and ellipsoidal are some of the shapes available. The gold particles are spherical (red) and disc-shaped (blue).

Surface area: Particle size ranges from tiny to huge. Enhance solubility using an effective catalyst.

Positive (+) surface charge = gelatin, metal.

Acacia, tragacanth = negative (-).

The inside of the particle is neutral, while the surface is charged. Because of repulsions, surface charge causes colloids to remain stable.

Size and shapes of colloids

When compared to the surface area of an equal volume of larger particles, colloidal particles have a large surface area.
  • Area of the surface of a material per unit weight or volume of the material.
  • The presence of a large specific surface leads in: Platinium is only useful as a catalyst when present in colloidal form because of the huge surface area that adsorbs reactant on their surface.
  • Due to the vast surface area that adsorbs reactants on their surface, platinum is only useful as a catalyst when present in colloidal form.
  • Colloidal dispersion's color is determined by the particle size.
When the particle size of the red gold solution increases, the color changes to blue.

It is critical to consider the form of colloidal particles in the dispersion. Particles of the dispersed phase and the dispersion medium attract more strongly when their specific surfaces are greater.

A colloidal system's dynamics are affected by the morphology of its particles, including osmotic pressure, sedimentation, and flow. The form of the particle may also have an effect on its pharmacologic function.

Pharmaceutical applications

Treatment: Small size – good absorption – better action

Silver-germicidal

Copper-anticancer Mercury has anti-syphilis properties.

Toxicity and absorption

Treatment for sulfur deficiency. Colloidal sulfur is made up of tiny particles that absorb quickly. Toxicity is caused by an excess of sulfur in the blood.

Colloidal systems are employed as medicinal excipients, vehicles, transporters, and product components due to their stability.

Drugs can be targeted to a specific organ.

Liposomes, niosomes, nanoparticles, and microemulsions with drug-entrapped liposomes, niosomes, nanoparticles, and microemulsions aimed towards the liver and spleen.
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Ankur Choudhary is India's first professional pharmaceutical blogger, author and founder of pharmaguideline.com, a widely-read pharmaceutical blog since 2008. Sign-up for the free email updates for your daily dose of pharmaceutical tips.
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