Lecture Notes: Surfactants, Soaps, and Quaternary Ammonium Compounds

Surfactants

• Definition: Substances that lower surface tension.
  • Example: Surfactants in lungs.
• Role: Major ingredient in soaps and detergents.

Soaps vs. Detergents

• Soaps:
  • Natural by-products of fats.
  • Can leave soap film, especially in hard water with minerals like calcium and magnesium.
  • Antimicrobial Properties:
    • Not effective antimicrobials on their own.
    • Act as a degerming agent by physically removing microbes.
• Detergents:
  • Synthetic, do not leave soap film.
  • Types: Anionic and cationic detergents.
  • Focus: Cationic detergents related to disinfectants.

Quaternary Ammonium Compounds (Quats)

• Definition: Cationic detergents widely used as disinfectants.
• Examples:
  • Cetylpyridinium chloride
  • Benzalkonium chloride
• Mechanism:
  • Insert into the plasma membrane and disrupt phospholipids lipid bilayer.
• Applications:
  • Found in Lysol products and other cleaning agents.
  • Increasingly used as triclosan is phased out.
  • Used in disinfectants, antiseptics, hand sanitizers, oral rinses, and mouthwashes.
  • Common in healthcare settings.

Summary

• Soap:
  • Acts as a surfactant and degerming agent.
  • Physically removes microbes.
• Quats:
  • Can act as disinfectants and antiseptics.
  • More effective than soap in microbial control.

• Note: Quats are replacing alcohol in some products due to their efficacy.

End of Lecture Notes