What does fibroin mean?
Fibroin is the tough, insoluble protein that forms the structural core of silk, secreted as liquid by silkworms and spiders and solidifying into the fine, remarkably strong filaments we know as silk thread. In the natural fibre, fibroin strands are coated with sericin, a gummy protein that binds them together; removing the sericin leaves pure fibroin, prized for its smoothness and tensile strength. Beyond textiles, fibroin has become an important material in modern science: because it is strong, biocompatible, and slowly biodegradable, it is processed into films, hydrogels, and scaffolds for tissue engineering, as well as surgical sutures. The word derives from Latin fibra, meaning fibre, joined to the chemical suffix -in, and belongs to the same family of terms as fibril and fibrin. Though uncommon in casual conversation, fibroin is a staple of biochemistry and materials-science writing about silk.
nounAn insoluble structural protein that forms the filaments of silk, produced chiefly by silkworms and spiders; together with sericin it makes up raw silk fibre.
- The insoluble fibrous protein forming the structural core of silk filaments produced by silkworms and spiders.
- A material derived from this protein, used in biomedical engineering such as sutures, films, and tissue scaffolds.
"The researchers spun a biodegradable suture from purified fibroin."
"Raw silk consists largely of fibroin filaments coated in a sticky layer of sericin."
"The team electrospun fibroin into a fine mesh that supported the growth of skin cells."
Rarely used; the plural appears mainly in scientific literature when comparing fibroin variants from different species or sources.
"Fibroins from different spider species show distinct mechanical properties."
The same protein that gives silk its legendary strength is now stitched into surgical sutures and engineered into lab-grown tissue scaffolds.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of fibroin
Fibroin was coined in the nineteenth century from Latin fibra, 'fibre', combined with the suffix -in commonly used for proteins and chemical substances. It thus shares its root with words such as fibre, fibril, and fibrin, all describing thread-like structures or substances. The term entered scientific English as chemists began analysing the composition of silk and sought a name for its principal structural protein.
Related word forms
How fibroin is actually used
Fibroin is a technical term used mainly in biochemistry, materials science, and textile chemistry rather than everyday speech; it is typically an uncountable mass noun referring to the substance, though a plural ('fibroins') appears when distinguishing variants from different species.
Easily confused with fibroin
Fibrin is a blood-clotting protein formed from fibrinogen, whereas fibroin is the structural protein of silk.
Sericin is the gummy protein that coats and binds fibroin filaments in raw silk; fibroin is the strong core fibre itself.