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  Review Nanotechnologiesin agriculture:New toolsfor sustainabledevelopment Hongda Chen a, * ,1 andRickey Yada b a National Institute of Food and Agriculture,U.S. Department of Agriculture, 1400 IndependenceAvenue, MS 2220, SW Washington, DC 20250-2220,USA (Tel.:  D 1 202 401 6497; fax:  D 1 202 401 5179;e-mail: b Department of Food Science, University of Guelph,Guelph, ON N1G 2W1, Canada Nanoscale science and nanotechnology have been demon-strated to have great potential in providing novel and improvedsolutions to many grand challenges facing agriculture and soci-ety today and in the future. This review highlights some of themost promising and important nanotechnology applications inagriculture; and recommends several strategies for advancingthe best scientific and technological knowledge presently beingexamined. In addition, implications for human and environ-mental health, and technical, financial and capacity-relatedchallenges as they relate to developing countries are identified.Finally, some suggested mechanisms for partnerships and col-laborations are also identified and suggested. Science and technology in agriculture: opportunitiesand challenges for the developing world Presently, the agricultural sector is facing various globalchallenges: climate change, urbanization, sustainable use of resources, and environmental issues such as run-off and ac-cumulation of pesticides and fertilizers. These situationsare further exacerbated by the growing food demand thatwill be needed to sustain an estimated population growthfrom the current level of about 6 billion to 9 billion by2050. In addition, considering the world’s diminishing pe-troleum resources, agricultural products and materials willsoon be viewed again as the foundation of commerce andmanufacturing, hence additional demands on agriculturalproduction. At the same time there are new opportunitiesemerging. For example, the use of agricultural waste forthe generation of energy and electricity could be a viablesolution pending workable economics and encouraging pol-icy. This aforementioned scenario of rapidly evolving andyet complex agriculture system is, and will pose evengreater challenges to developing countries. The agriculturalsector and commodity production in developing regions arethe backbone of the national economy where multitude crit-ical issues such as lack of new arable soil, reduction of thecurrent agricultural land due to competing economic devel-opment activities, commodity dependence, poverty andmalnutrition are closely intertwined.Over the last several decades, the rapid growth in techno-logical innovations have led to profound structural changesin the agricultural sector, including a transition from small-holder mixed farms toward large-scale specialized industrialproductionsystems,a shift inthegeographic locusofdemandandsupplytothedevelopingworld,andanincreasingempha-sis on global sourcing and marketing. The latter presentchallenges to the agricultural sector to provide possible im-provements to its production sustainability in ways that pro-mote food security, poverty reduction and public healthimprovement.Advances in science and technology could offer potentialsolutions for developing countries to innovate and add valueto their current commodities production systems. Many tech-nologies being developed have the potential not only toincreasefarmproductivitybutalsotoreducethe environmen-tal and resource costs often associated with agricultural pro-duction. These include technologies that conserve land andwater by increasing yields with the same or fewer inputsand technologies that protect environmental quality. It willbecrucial,however,tosupporttheseapplicationseventhoughthey may not be commercially lucrative while avoiding therisk that some advances in science and technology may in-crease the disparity between developed and developing * Corresponding author. 1 Theviewsexpressedinthisreviewarticlearethoseoftheauthors.TheyarenotnecessarilythoseoftheUnitedStatesGovernmentortheNationalInstituteof Food and Agriculture (NIFA) of U.S. Department of Agriculture (USDA). 0924-2244/$ - see front matter Published by Elsevier Ltd.doi:10.1016/j.tifs.2011.09.004 Trends in Food Science & Technology 22 (2011) 585 e 594  countries. Therefore, serious consideration of the social andethical implications on new agriculture technologies will benecessary. It should also be recognized that while new agri-food technologies may deliver efficiencies in some areas,they may not necessarily solve existing problems of globalfood production and distribution. In this regard it is essentialfor developing countries to actively participate in researchand development while respecting their needs and capacityto utilize these new technologies. Therefore, critical to the in-novation, capacity building is the establishment of relevant,complementary and synergistic partnerships between devel-oping countries and more advanced countries. Nanotechnologies in future agriculture Nanoscale science, engineering and technology embracean exciting and broad scientific frontier which will havesignificant impacts on nearly all aspects of the global econ-omy, industry, and people’s life in the 21st century (Gru  ere,Narrod, & Abbott, 2011; Scott & Chen, 2003). Nanoscalesciences reveal the properties, processes, and phenomenaof matters at the nanometer (1 to approximately 100 nm)range. Nanoscale engineering renders precise capability tocontrol and/or fabricate matters at this scale to render noveland useful properties thus leading to many new applicationsof nanoscale science and nanomaterials that can be used toaddress numerous technical and societal issues.In this section, some potential applications of nanoscalescience, engineering and nanotechnology for agricultureand food production and related issues are discussed. De-spite a wide-range of industrial interest in this area, exam-ples of available commercial products are few. Mostapplications are either in research and development(R&D) pipeline or at bench-top exploration stage; however,it is likely that the agriculture and food sector will see somelarge-scale applications of nanotechnologies in the near fu-ture. Some current industrial examples are indicated in thesections below. Nanotechnologies in plant-based agriculturalproduction and products Plant-based agricultural production is the basis of broadagriculture systems providing food, feed, fiber, fire (thermalenergy), and fuels through advancements in materials sci-ences, and biomass conversion technologies. While the de-mand for crop yield will rapidly increase in the future, theagriculture and natural resources such as land, water andsoil fertility are finite. Other production inputs including syn-thetic fertilizers and pesticides are predicted to be much moreexpensive due to the constraints of known petroleum reserve.Precision farming is hence an important area of study to min-imizeproductioninputsandmaximizeagriculturalproductionoutputs for meeting the increasing needs of theworld sustain-ability. Given that nanotechnology may allow for the precisecontrol of manufacturing at the nanometer scale, a numberof novel possibilities in elevating the precision farming prac-tices are possible.   Nanotechnology enabled delivery of agriculture chemicals(fertilizers, pesticides, herbicides, plant growth regulators,etc.) : Many nanoscale carriers, including encapsulationand entrapment, polymers and dendrimers, surface ionicand weak bond attachments and other mechanisms maybe used to store, protect, deliver, and release by controlof intended payloads in crop production processes. Oneof the advantages of nanoscale delivery vehicles in agro-nomic applications is its improved stability of the pay-loads against degradation in the environment, therebyincreasing its effectiveness while reducing the amountapplied. This reduction helps address agricultural chem-icals run-off and alleviate the environmental conse-quence. The nanoscale delivery vehicles may bedesigned to “anchor” to plant roots or the surroundingsoil structures and organic matter if molecular or confor-mational affinity between the delivery nanoscale struc-ture and targeted structures and matters in soil couldbe utilized (Johnston, 2010). Controlled release mecha-nisms allow the active ingredients to be slowly takenup, hence, avoiding temporal overdose, reducing theamount of agricultural chemicals used, and minimizingthe input and waste. Environmental considerationincluding precision farming can reduce pollution toa minimum.   Field sensing systems to monitor the environmental stresses and crop condition : Nanotechnology may be de-velopedanddeployedforrealtimemonitoringofthecropgrowth and field conditions including moisture level, soilfertility, temperature, crop nutrient status, insects, plantdiseases, weeds, etc. Networks of wireless nanosensorspositioned across cultivated fields provide essential dataleading to best agronomic intelligence processes withthe aim to minimize resource inputs and maximizing out-putandyield(Scott&Chen,2003).Suchinformationandsignalsincludetheoptimaltimesforplantingandharvest-ing crops and the time and level of water, fertilizers, pes-ticides, herbicides, and other treatments that need to beadministered given specific plant physiology, pathology,and environmental conditions.   Nanotechnology enables the study of plant disease mech-anisms . The advancement in nanofabrication and charac-terization tools have enabled studies of physical,chemical and biological interactions between plant cellorganelles and various disease causing pathogens, i.e.,plant pathology. A better understanding of plant patho-genic mechanisms such as flagella motility and biofilmformation will lead to improved treatment strategies tocontrol the diseases and protect production (Cursino et al  ., 2009). For example, spatial and temporal studiesof plant pathogenic xylem inhabiting bacteria have tradi-tionally been conducted by monitoring changes in bacte-rial populations through destructive sampling techniquesof tissues at various distances from inoculation sites. Thisapproach seriously limits the information that can be ob-tained regarding colonization, biofilm development, and 586  H. Chen, R. Yada / Trends in Food Science & Technology 22 (2011) 585  e 594  subsequent movement and re-colonization at new areas,primarily because the same region or sample site cannotbe followed temporally. Micro-fabricated xylem vesselswith nano-size features have been shown very useful ingaining an appreciation of the mechanisms and kineticsof bacterial colonization in xylem vessels such that noveldiseasecontrolstrategiesmaybedeveloped(Zaini,DeLaFuente, Hoch & Burr, 2009).   Improving plant traits against environmental stresses and diseases:  Biotechnological research has been focusing onimproving plant resilience against various environmentalstresses such as drought, salinity, diseases, and others.Genomesofcropcultivarsarecurrentlybeingextensivelystudied. The advancement in nanotechnology-enabledgene sequencing is expected to introduce rapid and costeffective capability within a decade (Branton  et al. ,2008), hence leading to more effective identificationand utilization of plant gene trait resources.   Lignocellulosic nanomaterials : Recent studies haveshown that nanoscale cellulosic nanomaterials can be ob-tained from crops and trees. It opens up awhole new mar-ket for novel and value-added nano biomaterials andproducts of crops and forest. For example, cellulosicnano crystals can be used as light weight reinforcementin polymeric matrix as nanocomposite (Laborie, 2009;Mathew, Laborie, & Oksman, 2009). Such applicationsmay include food and other packaging, construction,and transportation vehicle body structures. A consortiumledbyNorthDakotaStateUniversity(NDSU)iscurrentlyengaged in a project to commercialize a cellulosic nanowhisker production technology, developed by MichiganBiotechnology Incorporate (MBI) International, fromwheat straw. The cellulosic nano whiskers (CNW) wouldthen be used to make biocomposites that could substitutefor fiberglass and plastics in manyapplications, includingautomotive parts (Leistritz  et al  ., 2007).As indicated earlier, nanosized agricultural chemicals aremainly still at the research and developmental stage. NaturalNano, a start-up company in Rochester, N.Y., has founda way to use Halloysite, a naturally found clay nanotube,as a low cost delivery for pesticides to achieve an extendedrelease and better contact with plants. It is estimated that us-ingthistechnologycouldreducetheamountofpesticidesap-plied by 70 or 80 percent, a significant reduction in quantityand cost ofpesticides aswell asless impact on water streams(Murphy, 2008).Developing countries like China have been aggressivelydeveloping nanotechnology based delivery of agriculturalchemicals. These technologies are expected to be deployedfor field applications in next 5 e 10 years. The success of broad applications of nanoscale agricultural chemicals incrop production will largely depend on market demands,profit margin, environmental benefits, risk assessment andmanagement policy in the background of other competitivetechnologies. Nanotechnologies in animal production andanimal health Agriculturallyrelevantanimalproduction(livestock,poul-try, and aquaculture) provides society with highly nutritiousfoods (meat, fish, egg, milk and their processed products)whichhavebeen,andwillcontinuetobe,animportantandin-tegral part of human diets. There are a number of significantchallenges in animal agricultural production, including pro-duction efficiency, animal health, feed nutritional efficiency,diseases including zoonoses, product quality and value, by-products and waste, and environmental footprints. Nanotech-nologies may offer effective, sometimes novel, solutions tothese challenges (Kuzma, 2010).   Improving feeding efficiency and nutrition of agricultural animals : A critical element of sustainable agriculturalproduction is the minimization of production input whilemaximizing output. One of the most significant inputs inanimal production is feedstock. Low feeding efficiencyresults in high demand of feed, high discharges of waste,heavy environmental burden, high production cost, andcompeting with other uses of the grains, biomass, andother feed materials. Nanotechnology may significantlyimprove the nutrient profiles and efficacy of minor nutri-ent delivery of feeds. Most animal feeds are not nutrition-ally optimal, especially in developing countries. Addingsupplemental nutrients is an effective approach to im-prove the efficiency of protein synthesis and the utiliza-tion of minor nutrients. Other digestive aids such ascellulosic enzymes can facilitate better utilization of theenergy in plant-based materials. Furthermore, minor nu-trients and bioactives can help improve overall health of animals so that an optimal physiological state can beachieved and maintained. A variety of nanoscale deliverysystems have been investigated for food applications.They include micelles, liposomes, nano-emulsions, bio-polymeric nanoparticles, protein-carbohydrate nanoscalecomplexes, solid nano lipid particles, dendrimers, andothers. These systems collectively have shown numerousadvantages including better stability against environmen-tal stresses and processing impacts, high absorption andbioavailability, better solubility and disperse-ability inaqueous based systems (food and feed), and controlled re-lease kinetics (Chen, Weiss, & Shahidi, 2006). Self as-sembled and thermodynamically stable structuresrequire little energy in processing thereby helping to ad-dress issues related to sustainability. Nanoscale deliverycan be used to improve the nutritional profiles of feedand feeding efficiency. In addition, the nanoscale deliverysystems can also be designed for veterinary drug deliverywhich protects the drug in GI tract, and allows for releaseat the desired location and rate for optimal effect. Theseadvantages help improve the efficiency by which animalsutilize nutrient resources, reduce material and financialburden of the producers, and improve product qualityand production yield. Similar to food applications, the 587 H. Chen, R. Yada / Trends in Food Science & Technology 22 (2011) 585  e 594  design of an appropriate nanoscale delivery system willrequire a full consideration of the effectiveness of its in-tended uses while preventing any adverse effects or unin-tended consequences. The nanoscale particles should besubject to a rigorous risk assessment to ensure responsibleand safe development and deployment in the products.   Minimizing losses from animal diseases, including Zoono-ses : Many animal diseases cause substantial losses in agri-cultural animal production. Some of the more significantdiseases include bovine mastitis, tuberculosis, respiratorydiseasecomplex,Johne’sdisease,avianinfluenza,andpor-cine reproductive and respiratory syndrome (PRRS). TheWorld Health Organization (WHO) estimates that animaldiseasesrepresentasmuchas17percentofanimalproduc-tioncosts inthe developedworld,andmorethantwice thisfigure in developing nations. On average, one newly iden-tified animal infectious disease has emerged each year forthe past 30 years of which approximately 75 percent havebeen zoonotic (e.g., mad cow disease; Avian influenza;H1N1 Influenza; Ebola virus; Nipah virus) (WHO,2005). Zoonotic diseases not only cause devastating eco-nomic losses to animal producers, but also impose seriousthreats to human health, e.g., Variant Creutzfeldt-JakobDisease(vCJD).Detectionandinterventionaretwoimpor-tant tools of an integrated animal disease managementstrategy that is critical to significantly reducing losses/ threatsfromthe disease,and/oreradicatingdisease,orpre-venting disease introduction into the animal production.Nanotechnology has the potential to enable revolutionarychanges in this area, and some specific technologies maybefeasibleinnearfuturegiventhecurrentstateofresearchand development (Emerich & Thanos, 2006; Scott, 2007).Nanotechnology offers numerous advantages in detectionand diagnostics including high specificity and sensitivity,simultaneous detection of multiple targets, rapid, robust,on-board signal processing, communication, automation,convenient to use, and low cost. The uses of portable, im-plantable or wearable devices are particularly welcome inagricultural field applications. Early detection is impera-tive so that quick, simple and inexpensive treatmentstrategies can be taken to remedy the situation. Nanotech-nology based drugs and vaccines can be more effective intreating/preventing the diseases than current technologies,thus reducing cost. Precise delivery and controlled releaseof nanotechnology enabled drugs leave little footprint inthe animal waste and the environment, which alleviatethe increasing concern of antibiotic resistance, and de-crease health and environmental risks associated with theuse of antibiotics. The targeted delivery and active nano-particles may enable new drug administrations that areconvenient, fast, non-intrusive to animals, and cost effec-tive. Theragnostics e a new generation of smart treatmentcombining diagnostics and therapy in a single step viananotechnology e will further improve disease treatmentefficiency and cost, and eliminate the diseases at earlystage,evenpre-clinically(Morris,2009).Theeffectivenessofnewdrugdeliverytechnologyplatformsmustfirstbees-tablished using pharmacokinetic and pharmacodynamicstudies  in vivo  to investigate the relationship betweendose, drug concentration at the site of action, and drug re-sponse. Only then can a new drug delivery system be de-ployed. Research and development for dealing withzoonotic diseases should collaborate with expertise fromthe human and veterinary medical communities fora more effective advancement.   Animalreproductionand fertility : Animalreproduction re-mains a challenge not only in developing countries, butalso in developed nations. Low fertility results in low pro-duction rate, increases in financial input, and reduced effi-ciency of livestock operations (Narducci, 2007). Severaltechnological fronts have been explored in order to im-prove animal reproduction. Microfluidic technology hasmatured overthe lasttwo decades,and has beenintegratedinto many nanoscale processing and monitoring technolo-gies including food and water quality, animal health, andenvironmental contaminations. The development of effi-cient microfluidic technology has enabled the automatedproduction of large numbers of embryos  in vitro , whichhas led to the rapid development of genetic improvementand selection of superior livestock for human food and fi-ber production (Raty  et al. , 2004). Brazilian animal scien-tists have used Fixed-Time Artificial Insemination (FTAI)technology to effectively increase the cattle reproductionrate for many years. However, the technology dependson the regulation of progesterone administered throughasiliconematrix.Theprocedurehassubstantialdrawbacksincluding inefficient and irregular dispersion of hormone,disposal issues, being labor intensive, and requiring multi-ple animal handlings for each attempt. Nanoscale deliveryvehiclesaresoughttosubstantiallyimprovebioavailabilityand better control of release kinetics, reduce labor inten-sity, and minimizewaste and discharge to the environment(Emerich&Thanos,2006;Narducci,2007).Anotherstrat-egy that may be explored is to monitor animal hormonelevelusingimplantednanotechnology-enabledsensingde-vice with wireless transmission capability, thus the infor-mation of optimal fertility period can become availablein real time to assist the livestock operators for reproduc-tion decision making (Afrasiabi, 2010).   Animal product quality, value and safety : Modification of animal feeds has been effectively used to improve animalproduction as well as product quality and value. The regu-lation of nutrient utilization can be used to enhance theefficiency of animal production, and to design animal-derived foods consistent with health recommendationsand consumer perceptions. For example, the concepts of nutrient regulation have been used to redesign foods,suchasmilkfattyacids, cis- 9, trans- 11conjugatedlinoleicacid(CLA)andvaccenicacid(VA),thatmayhaveapoten-tial role in the prevention of chronic human diseases suchas cancer and atherogenesis (Bauman, Perfield, Harvatine,& Baumgard, 2008). The biosynthesis and concentration 588  H. Chen, R. Yada / Trends in Food Science & Technology 22 (2011) 585  e 594
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