Peptide Synthesis

• Peptides are synthesized using solid-phase peptide synthesis (SPPS) or liquid-phase synthesis, depending on the length and complexity of the peptide.

• After synthesis, peptides are purified to remove any synthesis-related impurities, typically through high-performance liquid chromatography (HPLC).

Preparation for Lyophilization

• The purified peptide is dissolved in a suitable solvent, often a mixture of water and acetic acid, to form a solution.

• The solution may be filtered to ensure purity, removing any particulate matter that could interfere with the drying process or the peptide’s activity.

Freezing

• The peptide solution is rapidly frozen to create a solid state, which is essential for lyophilization.

• Freezing can be done at very low temperatures (usually below -40°C) to ensure all water and solvents are solidified.

• Proper freezing creates a stable matrix for the peptide, preserving its structure and preventing degradation.

Primary Drying (Sublimation)

• In a vacuum, the frozen solvent is removed by sublimation, directly converting ice into vapor without passing through the liquid phase.

• Controlled low temperatures and pressures prevent the peptide from denaturing and maintaining its integrity.

• This step removes most of the water content, but the process is kept slow to prevent the peptide’s structure from collapsing.

Secondary Drying (Desorption)

• The temperature is gradually increased under continued vacuum to remove any residual, tightly bound water molecules.

• This step further reduces the moisture content, typically below 1-2%, which is ideal for storage stability.

Sealing and Storage

• The freeze-dried peptide, now in powder form, is sealed in an inert environment (often under nitrogen gas) to prevent moisture absorption.

• Peptides are usually stored at low temperatures to maintain their stability over extended periods.

This freeze-drying process results in a stable, powdered peptide product that can be reconstituted with a suitable solvent when ready for use, making it easier to handle, store, and transport while preserving efficacy.