I believe that is one reason why they used clay encapsulation

Even abstract from actual study confirms that:

"We demonstrate that dsRNA can be loaded on designer, non-toxic, degradable, layered double hydroxide (LDH) clay nanosheets. Once loaded on LDH, the dsRNA does not wash off, shows sustained release and can be detected on sprayed leaves even 30 days after application."

Thank you.

Hi Sudipta,

That is a good question.

According to the authors, one of the main purpose of using clay nanosheets is because it can stick to the leaves very well. The clay nanosheets definitely provide some protection to the RNA. However, I think, after nanosheet/RNA lands on plant leaves and slowly break down to release RNA, the released RNA (from this point to their entry of plant cell nucleus) will be risking the attack of RNase.

I have a comment on the site of this paper (on RG):

https://www.researchgate.net/publication/312181808_Clay_nanosheets_for_topical_delivery_of_RNAi_for_sustained_protection_against_plant_viruses

This is my comment to the paper:

" When the RNA enclosed in the nanosheet releases onto the leaves after the nanosheet slowly degrades, will the RNase on/inside the leaves posts a serious threat to the RNA-- by attacking them? Obviously, since the paper has reported that it works, indicating that at least a portion of the RNA survive RNase attacking. The question I have is that how much of the RNA spread on the leaves has degraded/or survive due to RNase attack? And how much of the RNA is needed for farmers to spread to ensure that at least some of the RNA survive RNAse attack and reach inside the plant cells (and trigger a RNAi response). And is that amount of RNA reagent needed affordable for farmers economically?"

Article Clay nanosheets for topical delivery of RNAi for sustained p...

Similar technology is under development by other companies:

The method used in this paper is: dsRNA/nanosheet spread onto leaves, nanosheets degrade, RNA released and up taken by plant, RNA get into plant cells and trigger RNAi response against the virus in the plant.

Monsanto company is also developing another kind of dsRNA spray to against insect. The dsRNA is sprayed on plant leaves. When the pest insect eats the leaves, the dsRNA can be taken in and triggers RNAi response to an essential gene of the insect and kill the insect. See this link below.

http://www.farmindustrynews.com/crop-protection/new-approach-pest-control

I got one of the co-authors (Elizabeth Worrall) of the paper answered my comment (mentioned above):

"Elizabeth A. Worrall (University of Queensland)

When the dsRNA is encapsulated in LDH, the dsRNA is protected from RNase. Even when the dsRNA was without LDH and sprayed onto the leaf, it was detected longer than expected. Several companies are working on the mass production of RNAs. “Our technology for RNA production should be ready in 2—3 years. We are targeting US$2 per gram,” APSE’s John Killmer."

Thank you very much for your reply Yuan-Yeu Yau. Nanosheet made with clay particle would have help escaping genetic recombination. A great revolution is knocking at door. So wonderful.

It is indeed a great invention. Besides, most importantly, I think, is that the nanosheet is bio-degradable, meaning no or little impact on the environment or probably on human health. It is necessary to make sure that all the nanosheet reagent is completely gone before farmers can harvest the crops for human or animal consumption.

One more thing: It might prevent genetic recombination in those plants they intend to use on. What about if these material drifted away onto other plant species by blowing wind? Will this dsRNA causes some effect on other crops at nearby farms?

Hi Sudipta,

There are more comments given on the paper from the authors.

Please see at link:

https://www.researchgate.net/publication/312181808_Clay_nanosheets_for_topical_delivery_of_RNAi_for_sustained_protection_against_plant_viruses

Article Clay nanosheets for topical delivery of RNAi for sustained p...