Unique Silk Fibers from Weaver Ants

Natural Protein Fibers

Keywords

Weaver ant • Nanofiber web • Hollow fiber • Protein fiber • Biocompatibility • Electrospun fiber

Weaver ants (Fig. 39.1) belonging to the Oecophylla smaragdina family produce natural silks in the form of nanofibers that are connected together to form webs that resemble a piece of fabric as seen in Fig. 39.2. Fibers in the webs were hollow and had average diameters of 450 nm and had a unique architecture. As seen in Fig. 39.3, ants stick the fibers to form a web, and the connecting places were considerably stronger and resist alkali treatment even at boiling temperature. Although properties of individual fibers produced by the ant were not tested, webs produced by the ants were considerably stronger than electrospun protein nanofiber webs with substantially higher elongation (32 %) as seen in Table 39.1. It would be considerably challenging to produce nanofiber webs, especially with hollow nanofibers in the laboratory. Since ants are social insects unlike spiders, it would be possible to produce unique nanofibers webs by rearing the ants. It was found that the webs could be used as substrates for tissue engineering and could also load high amounts of drugs due to the presence of hollow fibers [11Red]. Other researchers have also reported that fibers in the weaver ant webs have diameters between 266 nm and 3 pm and that the proteins are mostly in the form of random coils and p-sheets [10Sir].

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Fig. 39.1 Digital image of a weaver ant. Photo credit Ajata Reddy

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Fig. 39.2 Digital image of the weaver ant nest (left) between leaves and the fabric-like nest (right) harvested from the leaves. Photo credit Ajata Reddy

Table 39.1 Tensile properties of the ant nanofiber web compared with electrospun webs pro­duced from different proteins and with tensile properties of skin

Type of nanoweb

Fiber diameter (nm)

Strength

(MPa)

Elongation

(%)

Modulus

(MPa)

Weaver ant

200-2,500

4.0 ± 1.3

32 ± 9

59 ± 27

Collagen

250

0.7-1.5

26-53

Gelatin

1.3

32.4

46.5

Silk fibroin

112-275

0.9 ± 0.3

7.5 ± 2.1

Silk fibroin

2.4 ± 0.5

2.5 ± 0.5

Skin

5-10

35-115

15-150

Reproduced from Reddy et al. [11Red]

Подпись: Fig. 39.3 SEM image of a weaver ant web showing the attachment and gluing of threads at the edges
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References

[10Sir] Siri, S., Maensiri, S.: Int. J. Biol. Macromol. 46, 529 (2010)

[11Red] Reddy, N., Xu, H., Yang, Y.: Biotechnol. Bioeng. 108(7), 1726 (2011)