Smart Delivery Systems

The use of pesticides increased in the second half of the 20th century with DDT becoming one of the most effective and widespread throughout the world. However, many of these pesticides, including DDT were later found to be highly toxic, affecting human and animal health and as a result whole ecosystems. As a consequence they were banned. To maintain crop yields, Integrated Pest Management systems, which mix traditional methods of crop rotation with biological pest control methods, are becoming popular and implemented in many countries, such as Tunisia and India.

In the future, nanoscale devices with novel properties could be used to make agricultural systems “smart”. For example, devices could be used to identify plant health issues before these become visible to the farmer. Such devices may be capable of responding to different situations by taking appropriate remedial action. If not, they will alert the farmer to the problem. In this way, smart devices will act as both a preventive and an early warning

system. Such devices could be used to deliver chemicals in a controlled and targeted manner in the same way as nanomedicine has implications for drug delivery in humans. Nanomedicine developments are now beginning to allow us to treat different diseases such as cancer in animals with high precision, and targeted delivery (to specific tissues and organs) has become highly successful.

Technologies such as encapsulation and controlled release methods, have revolutionised the use of pesticides and herbicides. Many companies make formulations which contain nanoparticles within the 100-250 nm size range that are able to dissolve in water more effectively than existing ones (thus increasing their activity). Other companies employ suspensions of nanoscale particles (nanoemulsions), which can be either water or oil-based and contain uniform suspensions of pesticidal or herbicidal nanoparticles in the range of 200- 400 nm. These can be easily incorporated in various media such as gels, creams, liquids etc, and have multiple applications for preventative measures, treatment or preservation of the harvested product.

One of the world’s largest agrochemical corporations, Syngenta, is using nanoemulsions in its pesticide products. One of its successful growth regulating products is the Primo MAXX plant growth regulator, which if applied prior to the onset of stress such as heat, drought, disease or traffic can strengthen the physical structure of turfgrass, and allow it to withstand ongoing stresses throughout the growing season. Another encapsulated product from Syngenta delivers a broad control spectrum on primary and secondary insect pests of cotton, rice, peanuts and soybeans. Marketed under the name Karate® ZEON this is a quick release microencapsulated product containing the active compound lambda-cyhalothrin (a synthetic insecticide based on the structure of natural pyrethrins) which breaks open on contact with leaves. In contrast, the encapsulated product “gutbuster” only breaks open to release its contents when it comes into contact with alkaline environments, such as the stomach of certain insects.

In other areas, scientists are working on various technologies to make fertiliser and pesticide delivery systems which can respond to environmental changes. The ultimate aim is to tailor these products in such a way that they will release their cargo in a controlled manner (slowly or quickly) in response to different signals e.g. magnetic fields, heat, ultrasound, moisture, etc.

New research also aims to make plants use water, pesticides and fertilizers more efficiently, to reduce pollution and to make agriculture more environmentally friendly. Smaller companies are forming alliances with major players such as LG, BASF, Honeywell, Bayer, Mitsubishi, and DuPont to make complete plant health monitoring systems in the next 10 years using nanotechnologies.

Other Developments in the Agricultural Sector due to Nanotechnology

Agriculture is the backbone of most developing countries, with more than 60% of the population reliant on it for their livelihood. As well as developing improved systems for monitoring environmental conditions and delivering nutrients or pesticides as appropriate, nanotechnology can improve our understanding of the biology of different crops and thus potentially enhance yields or nutritional values. In addition, it can offer routes to added value crops or environmental remediation.

Particle farming is one such example, which yields nanoparticles for industrial use by growing plants in defined soils. For example, research has shown that alfalfa plants grown in gold rich soil, absorb gold nanoparticles through their roots and accumulate these in their tissues. The gold nanoparticles can be mechanically separated from the plant tissue following harvest.

Nanotechnology can also be used to clean ground water. The US company Argonide is using 2 nm diameter aluminium oxide nanofibres (NanoCeram) as a water purifier. Filters made from these fibres can remove viruses, bacteria and protozoan cysts from water. Similar projects are taking place elsewhere, particularly in developing countries such as India and South Africa. The German chemical group BASF’s future business fund has devoted a significant proportion of its 105 million USD nanotechnology research fund to water purification techniques. The French utility company Generale des Eaux has also developed its own Nanofiltration technology in collaboration with the Dow Chemical subsidiary Filmtec. Ondeo, the water unit of French conglomerate Suez, has meanwhile installed what it calls an ultrafiltration system, with holes of 0.1 microns in size, in one of its plants outside Paris.

While some companies are working on water filtration, others such as Altairnano are following a purification approach. Altairnano’s Nanocheck contains lanthanum nanoparticles that absorb phosphates from aqueous environments. Applying these in ponds and swimming pools effectively removes available phosphates and as a result prevents the growth of algae. The company expects this product to benefit commercial fish ponds which

spend huge amounts of money to remove algae.

Research at Lehigh University in the US shows that an ultrafine, nanoscale powder made from iron can be used as an effective tool for cleaning up contaminated soil and groundwater- a trillion-dollar problem that encompasses more than 1000 still-untreated Superfund sites (uncontrolled or abandoned places where hazardous waste is located) in the United States, some 150,000 underground storage tank releases, and a huge number of landfills, abandoned mines, and industrial sites.

The iron nanoparticles catalyse the oxidation and breakdown of organic contaminants such as trichloroethene, carbon tetrachloride, dioxins, and PCBs to simpler carbon compounds which are much less toxic. This could pave the way for a nano-aquaculture, which would be beneficial for a large number of farmers across the world. Other research at the Centre for Biological and Environmental Nanotechnology (CBEN) has shown that nanoscale iron oxide particles are extremely effective at binding and removing arsenic from groundwater (something which affects the water supply of millions of people in the developing world, and for which there is

no effective existing solution).