{
  "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.\n",
  "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",
    "designations": [],
    "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,
      "bound": "exact",
      "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",
      "source_detail": {
        "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)"
      }
    },
    {
      "benchmark": "ultimate_tensile_strength",
      "label": "Tensile strength of dragline silk, single figure",
      "value": 1.3,
      "bound": "exact",
      "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",
      "source_detail": {
        "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)"
      }
    },
    {
      "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",
      "source_detail": {
        "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)"
      }
    },
    {
      "benchmark": "toughness",
      "label": "Energy density of dragline silk (toughness, printed as energy density)",
      "value": 120,
      "bound": "exact",
      "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",
      "source_detail": {
        "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)"
      }
    },
    {
      "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",
      "source_detail": {
        "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)"
      }
    },
    {
      "benchmark": "elastic_modulus",
      "label": "Young's modulus of the silk named on the page with the highest value",
      "value": 37,
      "bound": "exact",
      "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",
      "source_detail": {
        "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)"
      }
    },
    {
      "benchmark": "elongation",
      "label": "Elongation at break, highest strain named on the page",
      "value": 65,
      "bound": "exact",
      "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",
      "source_detail": {
        "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)"
      }
    },
    {
      "benchmark": "min_service_temp",
      "label": "Lower temperature limit for dragline silk strength",
      "value": -40,
      "bound": "exact",
      "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",
      "source_detail": {
        "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)"
      }
    },
    {
      "benchmark": "max_service_temp",
      "label": "Upper temperature limit for dragline silk strength",
      "value": 220,
      "bound": "exact",
      "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",
      "source_detail": {
        "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)"
      }
    },
    {
      "benchmark": "ultimate_tensile_strength",
      "label": "Wild-type silkworm silk, control line",
      "value": 202.027,
      "bound": "exact",
      "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",
      "source_detail": {
        "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)"
      }
    },
    {
      "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",
      "source_detail": {
        "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)"
      }
    },
    {
      "benchmark": "elastic_modulus",
      "label": "Young's modulus, wild-type silkworm silk, control line",
      "value": 3681.163,
      "bound": "exact",
      "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",
      "source_detail": {
        "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)"
      }
    },
    {
      "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",
      "source_detail": {
        "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)"
      }
    },
    {
      "benchmark": "toughness",
      "label": "Toughness, wild-type silkworm silk, control line",
      "value": 30.573,
      "bound": "exact",
      "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",
      "source_detail": {
        "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)"
      }
    },
    {
      "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",
      "source_detail": {
        "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)"
      }
    },
    {
      "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",
      "source_detail": {
        "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)"
      }
    },
    {
      "benchmark": "ultimate_tensile_strength",
      "label": "Tenacity of 96-mer recombinant MaSp1 fibre",
      "value": 508,
      "bound": "exact",
      "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",
      "source_detail": {
        "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)"
      }
    },
    {
      "benchmark": "elongation",
      "label": "Elongation of 96-mer recombinant MaSp1 fibre",
      "value": 15,
      "bound": "exact",
      "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",
      "source_detail": {
        "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)"
      }
    },
    {
      "benchmark": "elastic_modulus",
      "label": "Young's modulus of 96-mer recombinant MaSp1 fibre",
      "value": 21,
      "bound": "exact",
      "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",
      "source_detail": {
        "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)"
      }
    },
    {
      "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)",
      "source_detail": {
        "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)"
      }
    },
    {
      "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)",
      "source_detail": {
        "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)"
      }
    },
    {
      "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)",
      "source_detail": {
        "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)"
      }
    },
    {
      "benchmark": "ultimate_tensile_strength",
      "label": "Ultimate strength (true breaking stress), forcibly silked C. darwini major ampullate silk",
      "value": 1652,
      "bound": "exact",
      "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",
      "source_detail": {
        "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)"
      }
    },
    {
      "benchmark": "elastic_modulus",
      "label": "Young's modulus (initial stiffness), forcibly silked C. darwini major ampullate silk",
      "value": 11.5,
      "bound": "exact",
      "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",
      "source_detail": {
        "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)"
      }
    },
    {
      "benchmark": "toughness",
      "label": "Toughness, forcibly silked C. darwini major ampullate silk (mean)",
      "value": 354,
      "bound": "exact",
      "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",
      "source_detail": {
        "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)"
      }
    },
    {
      "benchmark": "ultimate_tensile_strength",
      "label": "Ultimate strength (true breaking stress), web-collected C. darwini major ampullate silk",
      "value": 1850,
      "bound": "exact",
      "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)",
      "source_detail": {
        "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)"
      }
    },
    {
      "benchmark": "elastic_modulus",
      "label": "Young's modulus (initial stiffness), web-collected C. darwini major ampullate silk",
      "value": 11.5,
      "bound": "exact",
      "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)",
      "source_detail": {
        "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)"
      }
    }
  ],
  "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."
  ],
  "story": {
    "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",
        "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.",
        "benchmark": "ultimate_tensile_strength",
        "scope": "material",
        "value": "roughly 1.3 GPa"
      },
      {
        "label": "Toughness",
        "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.",
        "benchmark": "toughness",
        "scope": "material",
        "value": "350 to 520 MJ/m3 for C. darwini"
      },
      {
        "label": "Stretch",
        "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).",
        "benchmark": "elongation",
        "scope": "material",
        "value": "65% at break for C. darwini"
      },
      {
        "label": "Temperature",
        "line": "Dragline silks hold their strength below -40 °C and up to 220 °C (Wikipedia).",
        "benchmark": "max_service_temp",
        "scope": "material",
        "value": "-40 °C to 220 °C"
      },
      {
        "label": "Transgenic silkworm composite",
        "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).",
        "benchmark": "ultimate_tensile_strength",
        "scope": "material",
        "value": "241.043 to 325.951 MPa"
      }
    ],
    "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",
        "benchmark": "ultimate_tensile_strength",
        "scope": "material"
      },
      {
        "label": "Toughness (energy density)",
        "benchmark": "toughness",
        "scope": "material"
      },
      {
        "label": "Young's modulus",
        "benchmark": "elastic_modulus",
        "scope": "material"
      }
    ],
    "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.",
    "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",
          "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",
        "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."
          }
        ],
        "level": 0,
        "verdict": "No hazard data found"
      },
      {
        "title": "If the fibre gets wet",
        "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."
          }
        ],
        "level": 1
      },
      {
        "title": "If the fibre is heated",
        "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."
          }
        ],
        "level": 1
      }
    ]
  },
  "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."
  },
  "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": {
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  "url": "https://spacemushroom.com/profiles/spider-silk/"
}