Scientifically reviewed by Dr Stephan Hansberg
How to store research peptides
Why lyophilised and in-solution peptides have very different stability profiles, and how that shapes correct storage, light exposure and handling practice.
Key takeaways
- •Lyophilised (freeze-dried) peptide powder is generally more stable than the same peptide once it is in solution.
- •Once in solution, peptides are more exposed to hydrolysis, oxidation and microbial growth, so storage conditions matter more, not less.
- •Pre-filled, pre-mixed pens like Celyfe's are already in solution, which is why they are shipped and stored refrigerated rather than frozen.
- •Freezing an in-solution peptide product can damage it through freeze-thaw stress and is not the same thing as safe cold storage.
- •Light exposure and non-aseptic handling both accelerate degradation and contamination risk in solution.
Lyophilised versus in-solution stability
Lyophilisation (freeze-drying) removes water from a peptide preparation, leaving a stable powder or cake with very little chemical activity because the reactions that degrade peptides (hydrolysis, oxidation, aggregation) generally require water to proceed at a meaningful rate. This is why lyophilised peptide is typically the most stable long-term storage form and why suppliers who ship powder often quote long stability windows when kept correctly.
Once a peptide is reconstituted into solution, water is reintroduced and those degradation pathways become active again. From that point on, stability is measured in weeks rather than months or years, and storage conditions have a much larger effect on how much intact peptide remains over time.
Why pre-filled pens are refrigerated, not frozen
A Celyfe pen contains a pre-filled, pre-mixed 3ml cartridge, meaning the compound is already in solution rather than a powder waiting to be reconstituted. That is precisely why the correct storage condition is refrigeration at 2 to 8 degrees Celsius, never freezing: refrigeration slows the chemical degradation pathways that affect any peptide in solution, while freezing and thawing a liquid formulation can introduce its own damage through ice crystal formation and physical stress on the dissolved compound.
This is a different situation to storing dry powder, where freezing is sometimes used specifically because there is no water present to form damaging ice crystals in the first place.
Light exposure
Many peptides and coenzymes are sensitive to light, particularly ultraviolet and strong visible light, which can drive oxidative degradation of susceptible amino acid side chains. This is why research compounds are typically supplied in opaque or amber packaging and shipped inside a sealed foil pouch, and why keeping cartridges away from direct light during storage is good general practice.
Aseptic handling
Any point at which a sterile solution is accessed, whether through a septum, a cap, or an open vial, is a potential entry point for microbial contamination. Aseptic technique (clean hands or gloves, disinfected surfaces and access points, minimal exposure to open air) reduces this risk. A pre-filled cartridge system that is only accessed through a single needle port at the point of dispensing reduces the number of times the solution is exposed compared with repeatedly opening a vial.
Cold-chain shipping
Because in-solution stability depends on temperature from the moment of manufacture, Celyfe ships every pen cold-chain: sealed in a foil pouch with ice packs inside a plain, unbranded box. This is intended to keep the cartridge within the correct temperature range for the whole transit period, so it should go straight into refrigeration at 2 to 8 degrees Celsius on arrival.
Research use only
These storage principles are provided to support correct laboratory handling of research compounds. Nothing here describes or implies administration to a human or animal body.
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