Recently I chatted with several brand owners and was repeatedly asked: "After your recombinant collagen dressing is sterilized at 121°C, does it still have activity?"
This question hits the point. There are many medical dressings claiming "recombinant collagen" on the market, but few can truly maintain activity after high-temperature moist heat sterilization at 121°C.
This article will thoroughly explain the sterilization process of recombinant collagen medical dressings and tell you why "no deactivation at 121°C" is the real technical barrier.
First, let's be clear: why do medical dressings need sterilization
This is not optional; it is mandatory.
According to the appendix of the "Good Manufacturing Practice for Medical Devices", Class II medical devices that directly contact wounds or wound surfaces must be sterilized. Common sterilization methods include:
- Ethylene oxide sterilization (EO sterilization): low-temperature sterilization, suitable for materials not resistant to high temperature
- Irradiation sterilization (cobalt-60, electron beam): room-temperature sterilization, but some materials degrade
- Moist heat sterilization: 121°C high temperature and high pressure, 15-30 minutes
- Filtration sterilization: only suitable for liquid products, not applicable to solid dressings
121°C moist heat sterilization is the gold standard for medical device sterilization, because it is thorough, has no chemical residues, and is highly reliable. But the problem is—most bioactive ingredients lose activity at 121°C.
Ordinary collagen (animal-derived) directly denatures and solidifies at 121°C, turning into a lump of protein residue. Whether recombinant collagen can withstand 121°C has become a watershed for judging the technical content of a product.
Recombinant collagen vs animal collagen: essential differences
Before discussing 121°C sterilization, we need to understand the essential differences between recombinant collagen and animal collagen.
Animal collagen (mainly type I): Extracted from pig skin, cowhide, fish skin and other animal tissues, obtained through acid dissolution, enzymatic digestion, purification and other processes. The triple helix structure is intact, but it retains the telopeptide structure of animal-derived proteins, with molecular weights ranging from tens of thousands to hundreds of thousands of Daltons. The problem is: at 121°C, the triple helix structure unwinds and undergoes irreversible denaturation, basically losing activity.
Recombinant collagen (recombinant humanized collagen): Through genetic engineering technology, the gene sequence of specific functional fragments of human collagen is recombined, fermented in the laboratory (commonly using E. coli or yeast expression systems), and then purified. According to the National Medical Products Administration's "Guidelines for Naming Recombinant Collagen Biomaterials" (issued in 2023), recombinant collagen is divided into three categories:
- Recombinant human collagen (full-length sequence, closest to the human body's own structure)
- Recombinant humanized collagen (partial functional fragments)
- Recombinant collagen-like protein (modified non-natural sequence)
The molecular weight of recombinant collagen is controllable, the sequence is clear, it contains no telopeptides, and has low immunogenicity. However, the thermal stability of products obtained from different manufacturers, different expression systems, and different purification processes varies greatly.
121°C sterilization: real deactivation or fake deactivation?
Back to the core question: after 121°C moist heat sterilization, does recombinant collagen remain active or not?
The answer depends on two situations.
Situation 1: Deactivation (most products)
Most recombinant collagen products use a conventional fermentation-purification-lyophilization process. The resulting protein powder at 121°C for 15 minutes will show:
- Molecular weight degradation (SDS-PAGE detection, bands shift downward)
- Destruction of tertiary structure (circular dichroism detection, characteristic peaks disappear)
- Decreased activity (cell proliferation assay, activity drops below 30%)
- Appearance
