Nanoparticle biofabrication using English ivy (Hedera helix)

Abstract

Background: English ivy (Hedera helix) is well known for its adhesive properties and climbing ability. Essential to its ability to adhere to vertical surfaces is the secretion of a nanocomposite adhesive containing spherical nanoparticles, 60-85 nm in diameter, produced exclusively by root hairs present on adventitious roots. These organic nanoparticles have shown promise in biomedical and cosmetic applications, and represent a safer alternative to metal oxide nanoparticles currently available.

Results: It was discovered that the maximum adventitious root production was achieved by a 4 h application of 1 mg/ml indole-3 butyric acid (IBA) to juvenile English ivy shoot segments cultured in custom vessels. After incubation of the shoots under continuous light at 83 μmol/m2 s at 20°C for 2 weeks, the adventitious roots were harvested from the culture system and it was possible to isolate 90 mg of dry weight nanoparticles per 12 g of roots. The nanoparticle morphology was characterized by atomic force microscopy, and found to be similar to previous studies.

Conclusions: An enhanced system for the production of English ivy adventitious roots and their nanoparticles by modifying GA7 Magenta boxes and identifying the optimal concentration of IBA for adventitious root growth was developed. This system is the first such platform for growing and harvesting organic nanoparticles from plants, and represents an important step in the development of plant-based nanomanufacturing. It is a significant improvement on the exploitation of plant systems for the formation of metallic nanoparticles, and represents a pathway for the generation of bulk ivy nanoparticles for translation into biomedical applications.

Figure 1

H. helix adventitious root production after 2 weeks.A. Initial 50 cm stems were cut into 12.5 cm pieces and treated with either B. low levels of IBA overnight or C. high levels of IBA for 4 h.

Figure 2

H. helix adventitious root production by weight (g) treated with either A. high levels of IBA ([0–6 mg/ml]) for 4 h or B. low levels of IBA ([0–0.6 mg/ml]) for 16 h. Error bars represent 95% confidence intervals using least significant differences (P<0.05).

Figure 3

Adventitious roots produced from H. helix A. after 2 weeks treated with 100 mg IBA for 4 h, B. adventitious roots releasing adhesive, and C. root primordial after 1 week.

Figure 4

Two root types produced by H. helix.A. adventitious and B. subterranean roots as viewed under a light microscope. C. High levels of IBA shoots and D. subterranean roots.

Figure 5

AFM and DLS of isolated ivy nanoparticles.A. AFM micrograph of ivy nanoparticles. B. DLS of ivy nanoparticles, with a mean diameter of 109.8 ± 5.6 nm.