Solubility of structurally complicated materials: 3. Hair

Area of Science:

• Biochemistry
• Materials Science

Background:

• Hair is primarily composed of protein keratin, organized into filaments.
• Keratin is a highly resilient protein, making hair difficult to digest or dissolve.
• Analysis of hair requires solubilizing solid samples into a liquid phase.

Purpose of the Study:

• To understand the chemical properties of hair relevant to its dissolution.
• To identify characteristics of effective solvents for hair solubilization.

Main Methods:

• Review of common hair dissolving procedures, including acidic, alkaline, and enzymatic hydrolysis.
• Discussion of solvent properties, such as molecular size and hydrophobicity, in relation to hair affinity.

Main Results:

• Hair's protein structure, particularly disulfide bonds in cystine, presents a challenge for dissolution.
• Solvents with small molecular size and hydrophobic groups show higher affinity for hair.
• Effective solvents attack disulfide bonds and hydrate the hair shaft, leading to a jelly-like consistency.

Conclusions:

• Solubilization of hair for analysis relies on chemical methods that break down its protein structure.
• Understanding solvent-hair interactions is key to developing efficient hair digestion protocols.