Spider silk and recombinant spidroin fibres

spore: profile
id: spider-silk
spore_version: 0.2
family: spidroin
name: Spider silk and recombinant spidroin fibres
role: structural fibre
category: living
type: bio-grown-building-materials
summary: |
  Spider silk is a protein fibre spun by spiders. Dragline silk is cited for both high tensile strength and high extensibility (Yu et al. 2018). Wikipedia gives a dragline tensile strength of roughly 1.3 GPa and an energy density of roughly 1.2×108 J/m3, about 120 MJ/m3. The recombinant fibres read here are weaker so far: a 96-mer MaSp1 protein spun from E. coli gave a tenacity of 508 ± 108 MPa, and transgenic silkworm composite silks gave 241.043 to 325.951 MPa.
best_for: High-toughness, high-strain fibre applications (dragline silk toughness and strain values)
weakest_at: Recombinant fibres read here are weaker than natural dragline silk, and wet dragline silk shrinks up to 50% in length
identity:
  formula: Fibre of mainly protein (spidroin); for example major ampullate spidroin MaSp1 from Nephila clavipes
  source: wikipedia-spider-silk
  where: Lead section ('mainly protein'); Xia et al. 2010, Results (MaSp1 from Nephila clavipes)
tags:
  environments: []
  stresses:
    - extreme-cold
  applications:
    - structures
    - optics-and-cameras
properties:
  - benchmark: density
    label: Density of silk, printed as a sixth of the density of steel
    value: 1.3
    unit: g/cm3
    scope: material
    conditions:
      material: spider silk protein fibre
      species: not named on the page
    method: Figure printed in parentheses in an encyclopedia sentence that compares silk with steel; the page does not name the material of the figure explicitly
    status: ground
    note: 'Printed sentence: silks are about a sixth of the density of steel (1.3 g/cm3).'
    source: wikipedia-spider-silk
    where: Properties > Mechanical > Density
  - benchmark: ultimate_tensile_strength
    label: Tensile strength of dragline silk, single figure
    value: 1.3
    unit: GPa
    scope: material
    conditions:
      material: spider dragline silk
      species: not named on the page
    method: Printed as roughly 1.3 GPa in an encyclopedia article; secondary value, not a primary test
    status: ground
    source: wikipedia-spider-silk
    where: Properties > Mechanical > Tensile strength
  - benchmark: ultimate_tensile_strength
    label: Tensile strength of dragline silk, wider range on the same page
    value: 450
    value_high: 2000
    bound: range
    unit: MPa
    scope: material
    conditions:
      material: dragline silk
      comparison: compared with high-grade alloy steel
    method: Range printed in an encyclopedia article; secondary value
    status: ground
    note: The same article gives 1.3 GPa as a single figure. Both are kept side by side because the page does not reconcile them.
    source: wikipedia-spider-silk
    where: Properties > Mechanical > Tensile strength
  - benchmark: toughness
    label: Energy density of dragline silk (toughness, printed as energy density)
    value: 120
    unit: MJ/m3
    scope: material
    conditions:
      material: dragline spider silk
      unit_in_source: roughly 1.2×108 J/m3 as printed
    method: Converted by Space Mushroom from roughly 1.2×108 J/m3 printed on the page (1.2×108 J/m3 = 120 MJ/m3)
    status: ground
    source: wikipedia-spider-silk
    where: Properties > Mechanical > Energy density
  - benchmark: toughness
    label: Toughness of forcibly silked C. darwini fibres
    value: 350
    value_high: 520
    bound: range
    unit: MJ/m3
    scope: material
    conditions:
      process: forcibly silked fibres
      species: Caerostris darwini (Darwin's bark spider)
      basis: 350 is the average; 520 is for some samples
    method: Values printed in an encyclopedia article; no test method given on the page
    status: ground
    source: wikipedia-spider-silk
    where: Properties > Mechanical > Highest-performance
  - benchmark: elastic_modulus
    label: Young's modulus of the silk named on the page with the highest value
    value: 37
    unit: GPa
    scope: material
    conditions:
      species: Ariadna lateralis
      basis: highest value per the Spider Silkome Database, as cited on the page
    method: Value printed in an encyclopedia article; secondary value
    status: ground
    source: wikipedia-spider-silk
    where: Properties > Mechanical > Young's modulus
  - benchmark: elongation
    label: Elongation at break, highest strain named on the page
    value: 65
    unit: '%'
    scope: material
    conditions:
      species: Caerostris darwini
      basis: highest strain at break, as printed
    method: Value printed in an encyclopedia article; secondary value
    status: ground
    source: wikipedia-spider-silk
    where: Properties > Mechanical > Elongation at break
  - benchmark: min_service_temp
    label: Lower temperature limit for dragline silk strength
    value: -40
    unit: °C
    scope: material
    conditions:
      material: dragline silks
      basis: page says they hold their strength below this temperature
    method: Value printed in an encyclopedia article; secondary value
    status: ground
    source: wikipedia-spider-silk
    where: Properties > Mechanical > Temperature
  - benchmark: max_service_temp
    label: Upper temperature limit for dragline silk strength
    value: 220
    unit: °C
    scope: material
    conditions:
      material: dragline silks
      basis: page says they hold their strength up to this temperature
    method: Value printed in an encyclopedia article; secondary value
    status: ground
    source: wikipedia-spider-silk
    where: Properties > Mechanical > Temperature
  - benchmark: ultimate_tensile_strength
    label: Wild-type silkworm silk, control line
    value: 202.027
    unit: MPa
    scope: material
    conditions:
      material: wild-type silkworm (Bombyx mori) silk, Lan10-G5 line, homozygous G5
      replicates: 15
      form: fibre
      sd: 52.470 MPa as printed
    method: Average printed in Table 1 of Yu et al. 2018 (average ± SD; SD not carried here)
    status: ground
    source: yu2018
    where: Table 1, row Lan10-G5 (G5 hom.), Max stress column
  - benchmark: ultimate_tensile_strength
    label: Chimeric silkworm/spider silk, 2 to 16 re-MaSp1 repeat units
    value: 241.043
    value_high: 325.951
    bound: range
    unit: MPa
    scope: material
    conditions:
      material: chimeric silkworm/spider silk fibre, homozygous G5 transgenic silkworm
      repeats: 2 to 16 re-MaSp1 repeat units
      lower: MASP1-2-G5 (2 repeat units)
      upper: MASP1-16-G5 (16 repeat units)
    method: Averages of the two end lineages in Table 1 (SDs printed in the table, not carried here)
    status: ground
    source: yu2018
    where: Table 1, rows MASP1-2-G5 and MASP1-16-G5, Max stress column
  - benchmark: elastic_modulus
    label: Young's modulus, wild-type silkworm silk, control line
    value: 3681.163
    unit: MPa
    scope: material
    conditions:
      material: wild-type silkworm silk, Lan10-G5, homozygous G5
      replicates: 15
      form: fibre
    method: Average printed in Table 1 of Yu et al. 2018 (SD not carried here)
    status: ground
    source: yu2018
    where: Table 1, row Lan10-G5 (G5 hom.), Young's modulus column
  - benchmark: elastic_modulus
    label: Young's modulus, chimeric silkworm/spider silk, 2 to 16 re-MaSp1 repeat units
    value: 4178.42
    value_high: 5275.978
    bound: range
    unit: MPa
    scope: material
    conditions:
      material: chimeric silkworm/spider silk fibre, homozygous G5 transgenic silkworm
      repeats: 2 to 16 re-MaSp1 repeat units
    method: Averages of the two end lineages in Table 1 (SDs not carried here)
    status: ground
    source: yu2018
    where: Table 1, rows MASP1-2-G5 and MASP1-16-G5, Young's modulus column
  - benchmark: toughness
    label: Toughness, wild-type silkworm silk, control line
    value: 30.573
    unit: MJ/m3
    scope: material
    conditions:
      material: wild-type silkworm silk, Lan10-G5, homozygous G5
      replicates: 15
      form: fibre
    method: Average printed in Table 1 of Yu et al. 2018 (SD not carried here)
    status: ground
    source: yu2018
    where: Table 1, row Lan10-G5 (G5 hom.), Toughness column
  - benchmark: toughness
    label: Toughness, chimeric silkworm/spider silk, 2 to 16 re-MaSp1 repeat units
    value: 41.217
    value_high: 60.199
    bound: range
    unit: MJ/m3
    scope: material
    conditions:
      material: chimeric silkworm/spider silk fibre, homozygous G5 transgenic silkworm
      repeats: 2 to 16 re-MaSp1 repeat units
    method: Averages of the two end lineages in Table 1 (SDs not carried here)
    status: ground
    source: yu2018
    where: Table 1, rows MASP1-2-G5 and MASP1-16-G5, Toughness column
  - benchmark: elongation
    label: Max strain, chimeric silkworm/spider silk, 2 to 16 re-MaSp1 repeat units
    value: 23.203
    value_high: 27.318
    bound: range
    unit: '%'
    scope: material
    conditions:
      material: chimeric silkworm/spider silk fibre, homozygous G5 transgenic silkworm
      repeats: 2 to 16 re-MaSp1 repeat units
    method: Averages of the two end lineages in Table 1 (SDs not carried here)
    status: ground
    source: yu2018
    where: Table 1, rows MASP1-2-G5 and MASP1-16-G5, Max strain column
  - benchmark: ultimate_tensile_strength
    label: Tenacity of 96-mer recombinant MaSp1 fibre
    value: 508
    unit: MPa
    scope: material
    conditions:
      material: 96-mer recombinant MaSp1 from Nephila clavipes, 284.9 kDa, expressed in E. coli BL21(DE3)
      spinning: spun from 20% w/v solution
      stretch: hand-drawn to 5 times original length
      test: gauge length 20 mm, cross-head speed 10 mm/min, n = 10
    method: Printed as tenacity 508 ± 108 MPa in the Results; the ± 108 MPa SD is not carried here
    status: ground
    source: xia2010
    where: Results, Relationship Between Protein Size and Fiber Mechanical Properties
  - benchmark: elongation
    label: Elongation of 96-mer recombinant MaSp1 fibre
    value: 15
    unit: '%'
    scope: material
    conditions:
      material: 96-mer recombinant MaSp1 from Nephila clavipes, 284.9 kDa, expressed in E. coli BL21(DE3)
      spinning: spun from 20% w/v solution
      stretch: hand-drawn to 5 times original length
      test: gauge length 20 mm, cross-head speed 10 mm/min, n = 10
    method: Printed as elongation 15 ± 5% in the Results; the SD is not carried here
    status: ground
    source: xia2010
    where: Results, Relationship Between Protein Size and Fiber Mechanical Properties
  - benchmark: elastic_modulus
    label: Young's modulus of 96-mer recombinant MaSp1 fibre
    value: 21
    unit: GPa
    scope: material
    conditions:
      material: 96-mer recombinant MaSp1 from Nephila clavipes, 284.9 kDa, expressed in E. coli BL21(DE3)
      spinning: spun from 20% w/v solution
      stretch: hand-drawn to 5 times original length
      test: gauge length 20 mm, cross-head speed 10 mm/min, n = 10
    method: Printed as 21 ± 4 GPa in the Results; the SD is not carried here
    status: ground
    source: xia2010
    where: Results, Relationship Between Protein Size and Fiber Mechanical Properties
  - benchmark: ultimate_tensile_strength
    label: Native dragline silk tenacity, as quoted by Xia et al. 2010
    value: 740
    value_high: 1200
    bound: range
    unit: MPa
    scope: material
    conditions:
      material: native spider dragline silk (refs 23 to 25 of Xia et al. 2010)
      basis: range quoted from earlier work, not measured in that paper
    method: Range printed in the Results of Xia et al. 2010; the same paper uses 1,100 MPa as the native value for its 60 kDa comparison
    status: ground
    source: xia2010
    where: Results, native silk comparison (refs 23 to 25)
  - benchmark: elongation
    label: Native dragline silk elongation, as quoted by Xia et al. 2010
    value: 18
    value_high: 27
    bound: range
    unit: '%'
    scope: material
    conditions:
      material: native spider dragline silk (refs 23 to 25 of Xia et al. 2010)
      basis: range quoted from earlier work
    method: Range printed in the Results of Xia et al. 2010
    status: ground
    source: xia2010
    where: Results, native silk comparison (refs 23 to 25)
  - benchmark: elastic_modulus
    label: Native dragline silk Young's modulus, as quoted by Xia et al. 2010
    value: 11
    value_high: 14
    bound: range
    unit: GPa
    scope: material
    conditions:
      material: native spider dragline silk (refs 24 and 25 of Xia et al. 2010)
      basis: range quoted from earlier work
    method: Range printed in the Results of Xia et al. 2010
    status: ground
    source: xia2010
    where: Results, native silk comparison (refs 24 and 25)
  - benchmark: ultimate_tensile_strength
    label: Ultimate strength (true breaking stress), forcibly silked C. darwini major ampullate silk
    value: 1652
    unit: MPa
    scope: material
    conditions:
      material: forcibly silked major ampullate silk from Caerostris darwini (Darwin's bark spider)
      stress_basis: true breaking stress
      form: fibre
      summary_printed: 1652 ± 208 MPa as mean ± SD (SD not carried here)
    method: Mean printed in the Silk biomechanics section of Agnarsson et al. 2010, which gives true breaking stress
    status: ground
    source: agnarsson2010
    where: Results, Silk biomechanics (forcibly silked major ampullate silk); Table 1, row Caerostris darwini
  - benchmark: elastic_modulus
    label: Young's modulus (initial stiffness), forcibly silked C. darwini major ampullate silk
    value: 11.5
    unit: GPa
    scope: material
    conditions:
      material: forcibly silked major ampullate silk from Caerostris darwini
      summary_printed: 11.5 ± 2.6 GPa as mean ± SD (SD not carried here)
    method: Mean printed in the Silk biomechanics section of Agnarsson et al. 2010
    status: ground
    source: agnarsson2010
    where: Results, Silk biomechanics (forcibly silked major ampullate silk); Table 1, row Caerostris darwini
  - benchmark: toughness
    label: Toughness, forcibly silked C. darwini major ampullate silk (mean)
    value: 354
    unit: MJ/m3
    scope: material
    conditions:
      material: forcibly silked major ampullate silk from Caerostris darwini
      unit_in_text: J/cm3 in the running text (354 ± 93 J/cm3, range 233 to 520 J/cm3); MJ/m3 in Table 1
      maximum_printed: 520 MJ/m3 (Table 1, max)
    method: Mean printed in the text and Table 1 of Agnarsson et al. 2010; the text uses J/cm3, and 1 J/cm3 equals 1 MJ/m3
    status: ground
    note: Wikipedia gives an average of 350 MJ/m3 for the same forcibly silked fibres; the two averages are kept side by side, not merged.
    source: agnarsson2010
    where: Results, Silk biomechanics; Table 1, row Caerostris darwini, toughness column
  - benchmark: ultimate_tensile_strength
    label: Ultimate strength (true breaking stress), web-collected C. darwini major ampullate silk
    value: 1850
    unit: MPa
    scope: material
    conditions:
      material: web-collected major ampullate (radial) dragline silk from Caerostris darwini
      stress_basis: true breaking stress
      summary_printed: 1850 ± 340 MPa as mean ± SD (SD not carried here)
    method: Mean printed in the Silk biomechanics section of Agnarsson et al. 2010
    status: ground
    source: agnarsson2010
    where: Results, Silk biomechanics (web-collected major ampullate silk)
  - benchmark: elastic_modulus
    label: Young's modulus (initial stiffness), web-collected C. darwini major ampullate silk
    value: 11.5
    unit: GPa
    scope: material
    conditions:
      material: web-collected major ampullate (radial) dragline silk from Caerostris darwini
      summary_printed: 11.5 ± 5.1 GPa as mean ± SD (SD not carried here)
    method: Mean printed in the Silk biomechanics section of Agnarsson et al. 2010
    status: ground
    source: agnarsson2010
    where: Results, Silk biomechanics (web-collected major ampullate silk)
corrosion:
  - environment: Water (wet dragline silk)
    headline: Wet dragline silk shrinks by up to 50% in length.
    effect: When exposed to water, dragline silks undergo supercontraction and shrink up to 50% in length, then behave like a weak rubber under tension (Wikipedia). The page gives no time or temperature for this effect.
    rating: moderate
    conditions:
      exposure: water; wetting or immersion not specified on the page
      material: dragline silk
    source: wikipedia-spider-silk
    where: Properties > Mechanical > Supercontraction
risks:
  hazards:
    - text: No hazard record for spider silk fibre was found. As a proxy, PubChem's GHS record for glycine (CID 750, an amino acid) lists no hazard statements and says the chemical does not meet GHS hazard criteria for 96.7% (582 of 602) of all reports. The record is for glycine, not for the fibre.
      ghs: []
      source: pubchem-glycine
      where: Safety and Hazards, GHS Classification (CID 750)
  failure_risks:
    - mode: Loss of strength above the upper temperature limit
      trigger: Exposure above 220 °C
      consequence: The page says dragline silks hold their strength only up to 220 °C. It does not describe failure above that point or any decomposition temperature.
      severity: moderate
      source: wikipedia-spider-silk
      where: Properties > Mechanical > Temperature
    - mode: Shrinkage when wet
      trigger: Exposure to water
      consequence: Supercontraction shrinks dragline silk up to 50% in length and changes its tension behaviour to that of a weak rubber.
      severity: moderate
      source: wikipedia-spider-silk
      where: Properties > Mechanical > Supercontraction
  side_effects: []
  handling:
    - text: Keep the fibre below 220 °C. The page gives 220 °C as the upper limit of the range in which dragline silk holds its strength.
      source: wikipedia-spider-silk
      where: Properties > Mechanical > Temperature
    - text: Keep dragline silk dry if its length must stay fixed, because wet dragline silk shrinks up to 50% in length.
      source: wikipedia-spider-silk
      where: Properties > Mechanical > Supercontraction
  mitigations: []
uses:
  - application: structures
    device: Ballistic armour
    example: Wikipedia lists ballistic armour among the human uses of spider silk. The page gives no performance figures for armour.
    source: wikipedia-spider-silk
    where: Key uses, human uses list
  - application: optics-and-cameras
    device: Telescope and microscope crosshairs
    example: Wikipedia lists telescope and microscope crosshairs among the human uses of spider silk. The page gives no numbers for them.
    source: wikipedia-spider-silk
    where: Key uses, human uses list
supply:
  - subject: Spider silk (natural dragline silk)
    abundance: Not a mined commodity. Natural silk comes from spiders, and no abundance or production figure for spider silk was found in the sources read here.
    producers: []
    critical_lists: []
    recycling: Not found in any source read here.
    substitutes: []
    source: wikipedia-spider-silk
    where: Spider silk article, Uses and production sections
  - subject: Recombinant spidroin, other producers named on the page
    abundance: 'No production volume or country share was found. The article names these routes: KAIST (E. coli, 2010), Bolt Threads (yeast), Kraig Biocraft Laboratories (genetically altered silkworms), Nexia (goat milk, now defunct), RIKEN (artificial gland) and Spiber (synthetic silk).'
    producers: []
    critical_lists: []
    recycling: Not found in any source read here.
    substitutes: []
    source: wikipedia-spider-silk
    where: Spider silk article, Synthesis and production sections (company and institute names as printed)
  - subject: Recombinant spidroin, AMSilk
    abundance: AMSilk gives its address as Neuried / Munich, Germany, in its website footer. No production volume or country share was found.
    producers: []
    critical_lists: []
    recycling: Not found in any source read here.
    substitutes: []
    source: amsilk-home
    where: Website footer, company address
  - subject: Recombinant spider silk protein analog, grown in tobacco leaves (research pilot scale)
    abundance: Up to 400 mg of highly pure spider silk protein derivatives can be isolated from six kilograms of tobacco leaves (Heppner et al. 2016, abstract). Section 2.5 gives 273 mg of K-MaSp1-100x ELP and 413 mg of Q-MaSp1-100x ELP from 5.2 and 6.0 kg of Nicotiana tabacum leaves. Section 2.3 and the Discussion give gram amounts that conflict with these milligram figures, so only the milligram yields are used here.
    producers: []
    critical_lists: []
    recycling: Not found in any source read here.
    substitutes: []
    source: heppner2016
    where: Abstract; Section 2.5; Figure 7 caption; Discussion (yield per kg)
media: []
documents:
  - title: Extraordinary Mechanical Properties of Composite Silk Through Hereditable Transgenic Silkworm Expressing Recombinant Major Ampullate Spidroin (Scientific Reports, 2018)
    type: paper
    url: https://pmc.ncbi.nlm.nih.gov/articles/PMC6206087/
    year: 2018
  - title: Native-sized recombinant spider silk protein produced in metabolically engineered Escherichia coli results in a strong fiber (PNAS, 2010)
    type: paper
    url: https://pmc.ncbi.nlm.nih.gov/articles/PMC2922564/
    year: 2010
  - title: Liquid crystals and flow elongation in a spider's silk production line (Proceedings of the Royal Society B, 1999)
    type: paper
    url: https://pmc.ncbi.nlm.nih.gov/articles/PMC1689793/
    year: 1999
  - title: 'Bioprospecting Finds the Toughest Biological Material: Extraordinary Silk from a Giant Riverine Orb Spider (PLoS ONE, 2010)'
    type: paper
    url: https://pmc.ncbi.nlm.nih.gov/articles/PMC2939878/
    year: 2010
  - title: Low-Tech, Pilot Scale Purification of a Recombinant Spider Silk Protein Analog from Tobacco Leaves (Int J Mol Sci, 2016)
    type: paper
    url: https://pmc.ncbi.nlm.nih.gov/articles/PMC5085719/
    year: 2016
  - title: 'PubChem: Glycine (CID 750), GHS classification'
    type: database
    url: https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/750/JSON?heading=GHS+Classification
    year: 2026
gaps:
  - No space flight, vacuum, radiation or thermal-vacuum result for spider silk was found in the sources read for this profile, so no space environment is tagged.
  - The per-turn web search limit was reached, so the search for space uses and further open papers was not completed. Only the pages listed in sources were read.
  - Eight sources are cited. Knight and Vollrath (1999) gives no numbers and is cited for a qualitative statement only. Agnarsson et al. (2010) and Heppner et al. (2016) are cited for their own printed values only.
  - Agnarsson et al. (2010) print 27 ± 68.6 J/cm3 for web-collected silk. The standard deviation is larger than the mean, so this value was not carried. The paper also gives inconsistent sample counts (30 fibres, six spiders and 10 spiders), so no sample count is stated here.
  - Heppner et al. (2016) give gram amounts (37 g and 67 g) in Section 2.3 that conflict with the milligram yields in Section 2.5 and Figure 7. Only the milligram yields are used. No percentage of total soluble protein is given.
  - 'Density: the only figure is 1.3 g/cm3 in one Wikipedia sentence that does not name the material. Yu et al. 2018 gives no density values, and no primary density measurement was read.'
  - Bowen et al. 2018 (recombinant spidroin) was seen only as a search snippet and was not opened, so it is not listed as a property.
  - Toughness is not a canonical name in spores/property-canon.yaml. It is stored as toughness with the printed unit.
  - The Wikipedia dragline values do not give the species or test method, except where the page names Caerostris darwini or Ariadna lateralis.
  - 'Recipe: no amino-acid composition, atom count or molecular formula for spidroin was found in the sources read. The recipe lists the protein class only.'
  - 'Hazards: no safety data sheet or PubChem GHS record for spider silk itself was found. The one hazard entry uses the PubChem GHS record for glycine (CID 750) as a proxy, which says nothing about the fibre.'
  - 'Supply: no producer country shares, critical-mineral listings or production volumes were found.'
  - 'Ageing: no UV, humidity or long-term heat-ageing data were read. Only the wet-state supercontraction effect is recorded.'
  - Failure-risk severity ratings are the assistant's judgement and are not taken from a source.
  - Xia et al. 2010 gives no numerical toughness for the 96-mer fibre. Its comparisons are tenacity and elongation.
  - Only means are carried as values for the Yu et al. 2018 table rows. The standard deviations are printed in that table and are not carried here.
  - No images were sourced, so the media block is empty.
  - No space-related use of recombinant spider silk was found in the sources read. The uses list covers ballistic armour and crosshairs only.
sources:
  wikipedia-spider-silk:
    title: Spider silk (Wikipedia article)
    id: Wikipedia, en.wikipedia.org/wiki/Spider_silk
    url: https://en.wikipedia.org/wiki/Spider_silk
    year: 2026
    kind: web
    license: CC BY-SA 4.0 (Wikipedia)
  yu2018:
    title: Extraordinary Mechanical Properties of Composite Silk Through Hereditable Transgenic Silkworm Expressing Recombinant Major Ampullate Spidroin
    id: doi:10.1038/s41598-018-34150-y (Scientific Reports 8, 15956, PMC6206087)
    url: https://pmc.ncbi.nlm.nih.gov/articles/PMC6206087/
    year: 2018
    kind: paper
    license: open access (licence not checked)
  xia2010:
    title: Native-sized recombinant spider silk protein produced in metabolically engineered Escherichia coli results in a strong fiber
    id: doi:10.1073/pnas.1003366107 (PNAS 107(32):14059-14063, PMC2922564)
    url: https://pmc.ncbi.nlm.nih.gov/articles/PMC2922564/
    year: 2010
    kind: paper
    license: open access (licence not checked)
  knight1999:
    title: Liquid crystals and flow elongation in a spider's silk production line
    id: doi:10.1098/rspb.1999.0667 (Proc. R. Soc. B 266, 519, PMC1689793)
    url: https://pmc.ncbi.nlm.nih.gov/articles/PMC1689793/
    year: 1999
    kind: paper
    license: open access (licence not checked)
  amsilk-home:
    title: AMSilk GmbH website (company address in footer)
    id: amsilk.com
    url: https://www.amsilk.com/
    year: 2026
    kind: web
    license: company website
  agnarsson2010:
    title: 'Bioprospecting Finds the Toughest Biological Material: Extraordinary Silk from a Giant Riverine Orb Spider'
    id: 'doi:10.1371/journal.pone.0011234 (PLoS ONE 5(9): e11234, PMC2939878)'
    url: https://pmc.ncbi.nlm.nih.gov/articles/PMC2939878/
    year: 2010
    kind: paper
    license: open access (licence not checked)
  heppner2016:
    title: Low-Tech, Pilot Scale Purification of a Recombinant Spider Silk Protein Analog from Tobacco Leaves
    id: PMC5085719 (Int J Mol Sci, 2016)
    url: https://pmc.ncbi.nlm.nih.gov/articles/PMC5085719/
    year: 2016
    kind: paper
    license: open access (licence not checked)
  pubchem-glycine:
    title: 'PubChem: Glycine (CID 750), Safety and Hazards, GHS Classification'
    id: PubChem CID 750
    url: https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/750/JSON?heading=GHS+Classification
    year: 2026
    kind: database
    license: PubChem record (NCBI)
license: CC-BY-4.0
updated: '2026-11-01'
review:
  status: draft
  method: assistant
  checked_values: 27
  unreachable: 0
  caveats: 4
  note: Written by an AI assistant on 2026-11-01 from one encyclopedia article, two open papers and one open paper with no numbers, plus a company footer. The 22 original values were copied from those pages. On 2026-11-02 a deepen pass added five values from Agnarsson et al. 2010 (PMC2939878), a hazard entry from the PubChem GHS record for glycine (a proxy, not spider silk), and a supply entry from Heppner et al. 2016 (PMC5085719). No value was checked against a second source.
story:
  recipe:
    line: Spider silk is a fibre of mainly protein (Wikipedia). Its structural protein is spidroin. The recombinant route in Xia et al. (2010) uses MaSp1, the major ampullate spidroin 1 of Nephila clavipes, made in E. coli as a 284.9 kDa 96-mer protein. The protein was spun from a 20% w/v solution and the fibres were hand-drawn to 5 times their original length.
    parts:
      - name: Spidroin protein
        share: mainly protein (Wikipedia)
        role: The structural protein of the fibre. Yu et al. (2018) found that transgenic silkworm fibre strength rose with the number of re-MaSp1 repeat units, from 202.027 MPa for wild type to 325.951 MPa at 16 repeat units.
  risk_groups:
    - title: For people
      level: 0
      verdict: No hazard data found
      lead: No safety data sheet or PubChem hazard record for spider silk was found in the sources read for this profile.
      points:
        - label: Dust and fibre
          line: Not assessed. None of the sources read here covers airborne fibre or dust hazards.
    - title: If the fibre gets wet
      level: 1
      lead: Wet dragline silk changes length and behaviour.
      points:
        - label: Length change
          line: Dragline silks shrink up to 50% in length when exposed to water (supercontraction), according to Wikipedia. The page also says they then behave like a weak rubber under tension.
    - title: If the fibre is heated
      level: 1
      lead: The temperature limit comes from the encyclopedia article, not from a test of heating failure.
      points:
        - label: Upper limit
          line: Dragline silks hold their strength up to 220 °C, according to Wikipedia. The page does not describe failure above that point.
  why: Spider silk is a protein fibre. Wikipedia describes silks as consisting mainly of protein. Yu et al. (2018) note that dragline silk is of interest primarily because it displays both high tensile strength and extensibility. Knight and Vollrath (1999) refer to the exceptional mechanical properties of spider dragline silk but give no numbers. The numbers in this profile come from the encyclopedia article, from a transgenic silkworm study, and from a recombinant E. coli study. Wikipedia records a 2010 KAIST result that made spider silk directly in E. coli, avoiding the need to milk spiders.
  uses:
    - where: Human uses listed on the encyclopedia page
      line: Wikipedia lists ballistic armour, athletic footwear, fashion clothing and outerwear, and telescope and microscope crosshairs among the human uses of spider silk. The page gives no performance figures for these products.
    - where: Space use
      line: No use of spider silk in space, on a satellite or in aerospace was found in the sources read for this profile.
  can_do:
    - label: Strength
      benchmark: ultimate_tensile_strength
      value: roughly 1.3 GPa
      line: Dragline silk has a tensile strength of roughly 1.3 GPa (Wikipedia). The same page gives 450 to 2000 MPa for the same fibre, so the range is wide. The 96-mer recombinant fibre of Xia et al. (2010) reached a tenacity of 508 ± 108 MPa.
    - label: Toughness
      benchmark: toughness
      value: 350 to 520 MJ/m3 for C. darwini
      line: Forcibly silked Caerostris darwini fibres average 350 MJ/m3, with some samples reaching 520 MJ/m3 (Wikipedia). Dragline silk energy density is roughly 1.2×108 J/m3, which is about 120 MJ/m3.
    - label: Stretch
      benchmark: elongation
      value: 65% at break for C. darwini
      line: Caerostris darwini has the highest strain at break named on the page, 65% (Wikipedia). The recombinant 96-mer fibre stretched 15 ± 5% (Xia et al. 2010).
    - label: Temperature
      benchmark: max_service_temp
      value: '-40 °C to 220 °C'
      line: Dragline silks hold their strength below -40 °C and up to 220 °C (Wikipedia).
    - label: Transgenic silkworm composite
      benchmark: ultimate_tensile_strength
      value: 241.043 to 325.951 MPa
      line: Chimeric silkworm/spider silk with 2 to 16 re-MaSp1 repeat units reached 241.043 to 325.951 MPa, against 202.027 MPa for wild-type silkworm silk (Yu et al. 2018, Table 1).
  compare: 'Spider silk has a dragline tensile strength of roughly 1.3 GPa and a toughness of up to 520 MJ/m3 in the sources read here, but those top figures come from different species and test methods. Recombinant fibres read in this profile are weaker so far: the 96-mer MaSp1 fibre has a tenacity of 508 ± 108 MPa, which Xia et al. (2010) set against 740 to 1200 MPa for native dragline silk. Transgenic silkworm composites reached 241.043 to 325.951 MPa against 202.027 MPa for wild-type silkworm silk. For stiffness, Wikipedia gives 37 GPa for the highest-modulus silk it names (Ariadna lateralis), so the stiffness of spider silk in general is not fixed by these sources. The three compare rows set the strength, toughness and modulus figures side by side. Agnarsson et al. (2010) print 1652 MPa for forcibly silked Caerostris darwini major ampullate silk and 1850 MPa for web-collected silk, both as true breaking stress.'
  compare_rows:
    - label: Tensile strength (dragline
      roughly): null
      benchmark: ultimate_tensile_strength
    - label: Toughness (energy density)
      benchmark: toughness
    - label: Young's modulus
      benchmark: elastic_modulus
  handling:
    - Keep the fibre below 220 °C. Wikipedia gives 220 °C as the upper limit of the range in which dragline silk holds its strength.
    - Keep dragline silk dry if its length must stay fixed. Wet dragline silk shrinks up to 50% in length.
    - No safety data sheet for spider silk was read in this run, so treat its hazards as unknown.
  good_for:
    - High toughness in fibre form. Wikipedia gives 350 MJ/m3 on average for forcibly silked Caerostris darwini fibres, with 520 MJ/m3 for some samples.
    - A wide temperature range for dragline silk. The page says dragline silks hold their strength below -40 °C and up to 220 °C.
  watch_out:
    - Wet dragline silk shrinks by up to 50% in length (supercontraction, Wikipedia).
    - 'Recombinant fibres read here are weaker than natural dragline silk: 508 ± 108 MPa for the 96-mer fibre, against 740 to 1200 MPa for native silk as quoted by Xia et al. (2010).'
    - Species and test methods differ between sources. The 350 to 520 MJ/m3 toughness is for Caerostris darwini, not for dragline silk in general.
  verdict: Spider silk combines high toughness with a wide temperature range for dragline silk. The recombinant fibres read here are weaker than natural dragline silk, and no space flight or hazard data were found.