Nanotechnology in Agriculture and Food Industry

Abstract

There is a growing demand for healthy and safe food, strategy against an increasing risk of biotic factors such as disease, and threats to agricultural and food production from changing global climate condition. Nanotechnology is a new discipline and developed innovative tools to revolutionize the agricultural and food industry through diagnosis and treatment of diseases, enhancing the ability of plants to absorb nutrients, combat microbial and pest infections, increase the efficiency of biocides, reduce pollution and clean-up existing pollutants. Controlled Environment Agriculture (CEA) can immensely benefit itself from nanotechnology by using nano-sensors and nano-devices, and improve the grower's ability for timely harvest of the crop, maintaining the vitality of the crop, and abatement of microbial or chemical hazards. With these technological development, societal issues associated with nanotechnology and to improve public awareness are emerging. [PUBLICATION ABSTRACT]

Headnote

Abstract: There is a growing demand for healthy and safe food, strategy against an increasing risk of biotic factors such as disease, and threats to agricultural and food production from changing global climate condition. Nanotechnology is a new discipline and developed innovative tools to revolutionize the agricultural and food industry through diagnosis and treatment of diseases, enhancing the ability of plants to absorb nutrients, combat microbial and pest infections, increase the efficiency of biocides, reduce pollution and clean-up existing pollutants. Controlled Environment Agriculture (CEA) can immensely benefit itself from nanotechnology by using nano-sensors and nano-devices, and improve the grower's ability for timely harvest of the crop, maintaining the vitality of the crop, and abatement of microbial or chemical hazards. With these technological development, societal issues associated with nanotechnology and to improve public awareness are emerging.

Keywords: Nanotechnology, Nanoparticles, Nano-carbon, Carbon Nanotubes, Nano silver, Nano Alumino-silicate, Nano-sensors, Nano-emulsion.

1. Introduction:

"Nanotechnology', is a brain child of late Richard Feynman, Nobel laureate in Physics in the year 1965. Nanotechnology - the frontier science of materials having unique properties than their macroscopic or bulk counter parts, has wider applications in material sciences and biology as well. The ability of nano-materials to work at the molecular level, atom by atom, to create large structures with fundamentally new molecular organization is the key to its applications. Nanotechnology will leave no field untouched by its ground breaking scientific innovations. The agriculture and food industry is no exception. Nanotechnology has provided new solutions to problems in plants, plant products and post-harvest technology in enhancing the quality of plant products. It has a significant effect in the food industry - development of new functional materials, product development, and design of methods and instrumentation for food safety and bio-security [1]. The effects of nanotechnology, as such on society is going to be immense.

Nanotechnology is based on the prefix of the Greek word "nano" which means 10"9. According to National Science Foundation (NSF, USA) and National Nanotechnology Initiative (NNI), nanotechnology is defined as the ability to understand, control, and manipulate matter at the level of individual atoms and molecules, as well as at the ""supramolccular" level involving clusters of molecules (in the range of about 0.1 to 100 nm), in order to create materials, devices, and systems with fundamentally new properties and functions because of their small structure. Nanotechnology is an interdisciplinary science encompassing areas like physics, chemistry, biology, material science and engineering [2], Nanotechnologists are capable of self assembling atoms into structures with highly controlled properties. These nanostructures may be zero dimensional (nanoparticles), one dimensional (nanowires), two dimensional (thin films) or three dimensional (arrays, hierarchical structures) [2], A comparative dimention of different nano and micro structures in biology are given in Fig. 1:

Nanoparticles show properties sharp contrast to their bulk in many respects which is utilised for its use in 'nanotechnology" e.g.

* Small size (1-1 OOnm)

Large surface to volume ratio

Chemically alterable physical properties

Change in the chemical and physical properties with respect to size and shape

Structural sturdiness in spite of atomic granularity

Enhanced or delayed particles aggregation depending on the type of the surface modification, enhanced photoemission, high electrical and heat conductivity and improved surface catalytic activity [2].

Nanostructures can be obtained through two different approaches which have been termed as top down process and bottom up process. The top down approach usually involves breaking down of big chunks of material (physically or chemically) into smaller objects of desired shapes and sizes through mechanical milling, ion implantation, etc. The bottom up approach uses self assembly to build up the nanostructures by bringing in individual atoms and molecules together.

2. Why Agriculture and Food Industry?

The increase in human population and demand for habitat, utilizes agriculture land and water resources. A large proportion of those living in developing countries are facing daily food shortages, while in the developed world there is a food surplus. For developing countries, the drive is to develop drought and pest resistant crops, which also maximize yield. In developed countries, the agro-food industry is driven by consumer demand for fresher and healthier foodstuffs. The food production in near future will not match the ever increasing world population. It is through innovative agriculture that we can envisage a self sustainable world. With limited land and water resources, demand-output ratio in agriculture can be met only by increasing productivity through the effective use of modern technology. Nanotechnology, focusing on special properties of materials emerging from nanometric size has the potential to revolutionize the agricultural and food sectors, biomedicine, environmental engineering, safety and security, water resources, energy conversion, and numerous other areas. In fact several products enabled by nanotechnology are already in the market, such as antibacterial dressings, transparent sunscreen lotions, stain-resistant fabrics, scratch free paints for cars, and self cleaning windows. The application of nanotechnology to the agriculture and food industry was first addressed by a United States Department of Agriculture in 2003. The prediction is that nanotechnology will transform the entire food industry, changing the way food is produced, processed, packaged, transported, and consumed. An estimate by market research and industry analysis shows that, the market for the nanotechnology was 7.6 billion US$ in 2003 and was expected to be US$1 trillion in 2011.

The application of nano-technology in disease control, slow release of pesticides and developing diagnostic tools, and development of functional food systems, to produce interactive, edible nano wrappers to keep the pathogens away, targeted release of chemicals, packaging, extensive nano surveillance, interactive agrochemicals as herbicides and pesticides are discussed in this review.

3. Control of Plant Diseases

Some of the nano particles are used for controlling plant diseases are nano forms of carbon, silver, silica and alumino-silicates. Carbon nano-fibers to strengthen natural fibers for example those from coconuts (Cocus nucífera) and sisal (Agave sisalana) and making nanoparticles that contain pesticides and control their release. Carbon nanotubes (CNT) are allotropes of carbon with cylindrical shape. CNT have applications in the fields of nanotechnology, electronics, and architecture. Khodakovsky et al. [3] reported that tomato seedlings growing in a CNT-enriched soil showed enhanced growth due to increased water uptake caused by penetration of CNT. This principle can be utilized to use CNT as vehicle to deliver desired molecules either nutrient or biocides into the seeds during germination.

Silver is now an accepted agrochemical replacement. It controls pathogenic microorganisms in the soil and hydroponics systems. Moreover, silver is an excellent plant-growth stimulator. Nano Silver is known to have strong bactericidal and broad spectrum antimicrobial activities [4], Silicon (Si) is known to be absorbed into plants to increase disease resistance and stress resistance [5], Silica itself has no direct effect on pathogenic microorganisms and has no effect on diseases. So a new composition of nano-sized Silica- Silver for control of various plant diseases has been developed [6], Alumino-Silicate nanotubes sprayed on plant surfaces are also developed and are easily picked up in insect hairs. Insects actively groom and consume pesticide-filled nanotubes. These are biologically more active and relatively more environmentally-safe pesticides. Wang et al. [7] have shown that mesoporous Silica nano particles can deliver DNA and chemicals into Plants thus, creating a powerful new tool for targeted delivery into plant cells. It has been successfully used to introduce DNA and chemicals into Arabidopsis, tobacco and corn plants. The other advantage is that with the mesoporous nanoparticles, one can deliver two biogenic species at the same time.

4. Early Detection and Diagnosis of Plant Diseases

Early detection of plant diseases has prompted Nanotechnologists to look for a nano solution for protecting the food and agriculture from bacteria, fungi and viral agents through autonomous nano-sensors linked into a GPS system for real-time monitoring throughout the field to monitor soil conditions and crop. The union of biotechnology and nanotechnology in sensors will create equipment of increased sensitivity, allowing an earlier response to environmental changes and diseases.

There is an urgent need of ultrasensitive diagnostic tool which can detect the molecular defects, be it at genomic or biochemical level, rapidly. Bio-systems are endowed with functional nanometric devices such as enzymes, proteins, and Nucleic acids, which detectable vital processes in plants. Disease diagnosis is difficult mainly because of the extremely low concentrations of biochemicals and also due to the presence of very low amount of detectable virus and many fungal or bacterial infections.

5. Nanoscale "Smart" Biosensors

Nanosensors can provide security in food manufacturing, processing, and shipping of products through the detection of pathogens and contaminants. These sensory systems detect biological molecules such as sugars or proteins in foods [8] to detect pathogens and other contaminants. Nanosensors are small, portable, sensitive with real-time monitoring, specific, quantitative, reliable, accurate, reproducible, robust and stable which can overcome the deficits of present sensors.

Controlled Environmental Agriculture (CEA) can be improved by the use of 'nano-sensors' enhancing the ability to determine the time of crop harvest, detect crop health and determine microbial or chemical contamination of the crop. Nano-devices are envisioned that could detect and treat an infection, nutrient deficiency, or other health problem, much earlier than the visual symptoms are detected. This type of treatment is location and time specific. Nanosensors has made real time monitoring of crop husbandry possible by planting autonomous biosensors linked to GPS system and are called "smart sensors". These sensors have already been employed in US and Australia. Smart delivery systems assist in regulated delivery of nutrients, pesticides, and neutraceuticals. Nano sensors are being used by the food stores to identify expired products and by vine growers to control and monitor production of finer wine grapes.

Soil temperature and moisture is of prime importance in agriculture, irrigation management systems should get accurate updates about the soil moisture at the root level of plants. Sensors based on wireless nanotechnology composed of micromachined MEMS (Micro Electro Mechanical Systems) cantilever beams coated with a water sensitive nanopolymer for moisture detection and a on chip piezo resistive temperature sensor detects temperature variations [9], These sensors are capable of sensing and monitoring temperature and moisture through microelectronic circuits [10],

6. Smart Delivery Systems

Syngenta (world-leading agri-company), is using nanoemulsions in its growth regulator Primo MAXX®, 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 [11], Another encapsulated product Karate® ZEON from Syngenta delivers a broad control spectrum on insecticide which breaks open on contact with leaves [12], However, 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 (Syngenta's US Patent No. 6,544,540). The ultimate aim is to tailor these products is a controlled release 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 eco-friendly.

7. Packaging of Plant Products

A major problem in food science is determining and developing an effective packaging material. Antimicrobial packaging of edible food films made with cinnamon or orégano oil, or nanoparticles of zinc, calcium other materials that kill bacteria is being tried. Green packaging using nano-fibers made from lobster shells or organic corn (both are antimicrobial and biodegradable) is also a food safety effort. Improved food packaging needs packaging materials having strength, barrier properties and stability to heat and cold. These are being achieved using nanocomposite materials. Bayer Polymers have produced a nanocomposite "hybrid system" film 'Durethan', enriched with silicate nanoparticles which reduces the entrance of oxygen and other gases, and preserves moisture, thus preventing food from spoiling [13], When this plastic is processed into a thin film and wrapped over food, it does a better job than previous plastics of preventing food from going bad on the shelf and it helps prevent odors from one food mixing with another.

8. Functional Food

New concepts and engineering approaches involved in functional foods and nutraceuticals using nanomaterials to target the delivery of bioactive compounds and micronutrients is developing [14], Nanomaterials allow better encapsulation in liposomes, micelles, nanoemulsions and cubosomes, and release efficiency of the active food ingredients as compared to traditional encapsulating agents [15], Nanomaterials are also quite stable and can be processed cost effectively [16], The major disadvantage of colloids is that they can spontaneously dissociate if diluted. Nano-emulsions can encapsulate functional ingredients within their droplets, which can facilitate a reduction in chemical degradation [17], Nanolamination is a technique for protecting the food from moisture, lipids and gases. Moreover, they can improve the texture and preserve colour and odour of the food. Nanolaminates consist of two or more layers of nano-sized (1 - 100 nm) thin foodgrade films which are present on a wide variety of foods: fruits, vegetables, meats, etc. [18], These are prepared from edible polysaccharides, proteins, and lipids. Coating foods with nanolaminates is done simply by spraying it on the food surface.

9. Environmental Safety

Nanotechnology can be applied simultaneously to remove the harmful effects of highly toxic organic pesticides and increasing the fertility of the soil through photocatalysis. Nanostructures like titanium dioxide (Ti02) and zinc oxide (ZnO) nanoparticles and nanowires offer large surface to volume ratio attract higher probability of the organic molecules to come in contact with the metal oxide molecules residing on the surface of the nanoparticles [19], It has also been observed that the rate of photocatalysis can be improved by creating intentional defects in the crystal of ZnO nanoparticles during crystallization [20], Owing to high aspect ratios, nanowires possess large surface to volume ratio and are capable of degrading organic molecules faster than similar amount of nanoparticles. There are reports on the photocatalysis of herbicides like 2,4-D (dichloro-phenoxy-acetic acid) [21] and pesticides like (tetrachlorvinphos, fenitrothion, pirimiphos-methyl and fenamiphos) [21], (dichlorvos and phosphamidon) [22] and cyproconazole [23], Bandala et al. [24] have reported the use of solar photocatalysis for degradation of aldrin. An attractive part of photocatalysis is that the end products are carbon dioxide which escape into the atmosphere, water and mineral salts which add to the fertility of the soil. Photocatalysis degradation process has also gained popularity in the area of wastewater treatment. Peral et al. [25] has explained the use of photocatalysis for purification, decontamination and deodorization of air. Mills et al. [26] also explained semiconductor sensitized photosynthetic and photocatalytic processes for the removal of organics, destruction of cancer cells, bacteria and viruses.

10. Particle Farming and Water Purification

Nanotechnology can improve crops yield and nutritional values, and can offer added value to crops or environmental remediation. Particle farming is one such fields, which yields nanoparticles for industrial use by growing plants in gold rich soil. The gold nanoparticles can be mechanically separated from the plant tissue following harvest [27].

Nanotechnology can also be used to clean ground water e.g. the use of aluminium oxide nanofibres (NanoCeram) can remove viruses, bacteria and protozoan cysts from water [28], Nanocheck - a commerical lanthanum nano-particles that absorb phosphates from aqueous environments, is utilized for cleaning fish ponds and swimming pools effectively [29], The iron nanoparticles catalyse the oxidation and breakdown of organic contaminants such as trichloroethene, carbon tetrachloride, dioxins, and PCBs (Polychlorinated biphenyl) to simpler carbon compounds which are much less toxic [30], This developed a nano-aquaculture system. Nanoscale iron oxide particles can effectively bind and removing arsenic from groundwater [32] and can help to develop potable water problems in the developing world.

11. Societal Effects

Coming nanotechnologies in the agricultural field seem quiet promising. However, the potential risks in using nanoparticles in agriculture are no different than those in any other industry. Through the rapid distribution of nanoparticles to food products - whether it be in the food itself or part of the packaging - nanoparticles will come in direct contact with virtually everyone. The environmental group ETC (Action Group on Erosion, Technology and Concentration) is deeply concerned with the implications and regulation of nanotechnology used in food. Currently, there are none. Their main concern is that of the unknown. In a publication in November 2004, the ETC stated that "the merger of nanotech and biotech has unknown consequences for health, biodiversity and the environment" [32], Since there is no standardization for the use and testing of nanotechnology, products incorporating the nanomaterials are being produced without check. The ability for these materials to infiltrate the human body is well known, but there is really no information on the effects that they may have. While there is no evidence of harm to people or the environment at this stage, nanotechnology is a new and evolving area of study that could cause a great deal of harm due to its still ambiguous chemical properties.

The applications of nanotechnology in the fields of agriculture and food technology are summarized in Table 1.

12. Conclusion and Future Perspective

New tools with nanodevices capable of replacing many cellular types of machinery efficiently are underway. Nanorobotics devices roaming inside the body can give a plethora of information for detecting and mitigating biological hazards. Nano particles for delivery of drugs or nutrients etc. in near future for therapy of all pathological sufferings of plants are underway. Use of nanotechnology could permit rapid advances in agricultural research, such as reproductive science and technology, early detection of stresses and alleviating stress effects, conversion of agricultural and food wastes to energy and other useful byproducts through enzymatic nano bioprocessing, disease prevention and treatment in plants and animals.

Still, the full potential of nanotechnology in the agricultural and food industry is yet to be realised. It is gradually moving from theoretical knowledge towards the application regime. Smart sensors and smart delivery systems will help the agricultural industry combat viruses and other crop pathogens. Nanostructured catalysts will be available which will increase the efficiency of pesticides and herbicides, allowing 'on demand' doses to be used. Nanotechnology will also protect the environment indirectly through the use of alternative (renewable) energy supplies, and filters or catalysts to reduce pollution and clean-up existing pollutants. In the future, nanoscale devices could be used to make agricultural systems "smart".

At present there is no evidence of harmful effect of nano-technology to human health or the environment. But nanotechnology is a new and evolving area of study that could cause a great deal of hazardous effects due to the chemical properties of nano-particles. Globally, many countries have identified the potential of nanotechnology in the agri-food sector and are investing a significant amount in it. Equal importance has been given to the societal issues associated with nanotechnology and to improve public awareness.

References

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