smart release technology for improving fertilizer … release technology for improving fertilizer...
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Emily Mastronardi, Dr. Carlos Monreal, Dr. Maria C. DeRosa
AAFC-ECORC and Carleton University
Smart release technology for improving fertilizer efficiency
• Canada has a large area of cultivated land • Leader in fertilizer production • By 2050 – Increased demand for fertilizer for
food, biomass, biofuels – Population to increase from 7 B to 9.8 B people – Close to 1 B people undernourished – Increase food production 70% for > 2 B more people
• Major economic and environmental implications – 30 to 50% efficiency – N losses to the environment
Why create nanofertilizers in Canada?
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Fertilizer runoff can cause algal blooms
• Algal blooms deplete oxygen and secrete a neurotoxin, affecting wildlife
• Targeted release problem – Need to increase
fertilizer efficiency
http://globalnews.ca/news/1492850/it-came-from-lake-erie-why-toxic-algaes-a-nightmare-for-canada-too/
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• Synchronize the application of nutrients with crop uptake
The challenge: increase NUE
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1. Use acquired knowledge to propose and test new hypothesis
2. Create new knowledge on soil-crop ecology 3. Develop new tools and devices using
nanotechnology (i.e. DNA aptamers) 4. Integrate knowledge and nano-tools into
novel Intelligent Nanofertilizers
How do we synchronize nutrient release with uptake?
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• Last century – the 1950s and 60’s – Crop roots emit organic materials (Rovira
et al. 1966) – Different crop root species emit different
types of organic compounds (Rovira, 1956)
– Root emissions consist of sugars, amino acids, vitamins, organic acids (Rovira, 1966)
– Root emissions from cereals are similar, but different from exudates from tomato and red peppers (Vancura and Hovadik, 1965)
Interactions and communication in plant-soil systems
http://www.lesco.com/?pageid=63 6
• Early this century – Root emissions control nutrient uptake and soil
microbial growth and function (Dakora and Phillips 2002)
– Increased root emissions occur in response to decreased nitrate (NO3) availability (Darwent et al. 2003)
– The rate of nitrogen uptake in Prairie crops is associated with growth stage (Malhi et al. 2006)
Root exudation and nutrient uptake
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• Plant pores are nano-sized • Use nanotechnology to increase NUE
DeRosa, et. al. “Nanotechnology in Fertilizers” Nature Nano. 2010, 5, 91.
Utilizing nanotechnology
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• Multi-disciplinary approach mixing soil-plant ecology and nanotechnology – New knowledge of soil-plant ecology: Identification
of root exudates associated with soil N mineralization and its uptake by crops
– Development of biosensors to detect root exudates (for on-demand release)
– Development of coating polymers and 3-D nano-coating tools
– Intelligent nano-fertilizer prototypes and products
Testing the central hypothesis
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Intelligent nanofertilizer – proposed technology
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Intelligent nanofertilizer – proposed technology
Biosensor with polymer layers
Urea
- 1 nanometer = 10-9 m or billionth of a meter
(10 to 100 nm)
Root exudates
• The biosensor will be incorporated into a very thin polymer film.
• Interaction of the biosensor with the desired root exudate changes the permeability of the polymer film:
release of urea-N according to crop demand.
• Immediate goals: 1. Identify important root
exudates 2. Develop biosensor to detect
them 12
- Crops: wheat and canola (each grown twice) - Soil: Manotick, uncropped for 15 years, 0-20 com depth - Treatments: 1) Soil alone 2) Soil + crop 3) Soils + crop (no crop) (0 N) (100 kg urea-N/ha) - Weekly characterizations: soil solution composition, enzyme activities, microbial biomass, crop N uptake and yield, C and N flows in rhizosphere using 13C and 15N - Soil solution - Four techniques of Mass Spectrometry: - Py-FIMS, GC-MS, ESI-MS, LC-ESI-MS/MS
Identifying exudates important for nitrogen uptake
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• Found increased N uptake during specific growth periods
• Used Mass Spectrometry
to identify exudates in the soil during this time
kg N
/ha/
d
3 leafs unfolded
1
2
0.1
0.2
50 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800 850 900
200 400 600Temperature in °C
Inten
sity
m / z
IF03157
71
8599126
178 222
278
294306
318
503 577651
4 leaves unfolded, September 30
Identifying exudates important for nitrogen uptake
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Canola Wheat
Identifying exudates important for nitrogen uptake
• Found exudates that track with nitrogen uptake
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Identifying exudates important for nitrogen uptake
• Identified 12 chemical signals closely associated with crop N uptake
• Some signals are specific to wheat and others to canola
• Potential for designing crop specific fertilizer
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Nano-biosensors – Aptamers
• Single-stranded oligonucleotides
• Synthesized chemically • Fold into 3D nanoscale
shapes capable of binding targets
• Can distinguish small structural differences
http://www.genelink.com/newsite/products/aptamers.asp 17
Aptamers selected through iterative process called SELEX
• Systematic Evolution of Ligands by EXponential enrichment
• In vitro technique beginning with 1012-1015 random DNA sequences
• Each round increases affinity of pool for the target
• Pool is cloned and sequenced
• Control over selection conditions
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• Alternating layers of positive/negative polyelectrolytes creates a film
• DNA aptamers can act as the negative layer, making the film responsive
Layer-by-layer deposition creates smart aptamer films
Sultan, DeRosa, Monreal Biomacromolecules 2009, 10, 1149–1154 19
• Aptamer films show higher target binding and higher permeability than control films
Mastronardi et.al. (2015) Methods
Embedded aptamers retain binding and increase permeability
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Mastronardi et.al. (2014) Sensors, 14:3156-3171
• A) Aptamer-target binding leads to change in permeability and release of payload
• B) Aptamers act as structural support for microcapsule, and target-binding leads to microcapsule rupture
Zhang et.al. (2013) ACS App. Mater. Interfaces, 3: 5500-5507 Sultan and DeRosa. (2011). Small, 7: 1219-1226.
Layer-by-layer deposition creates smart aptamer microcapsules
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• A and D: Fluorescein channel
(Aptamer)
• B and E: Rhodamine channel (Target)
• C and F: Overlaid signals - binding
Aptamer microcapsules maintain target binding
• Fluorescence co-localization study
Sultan and DeRosa. (2011). Small, 7: 1219-1226. 22
Aptamer capsules specific for a root exudate show increased dye permeability
Target molecule Diffusion coefficient (µm2/s)
Aptamer film with Exudate 0.0113± 0.0040 Aptamer film with Negative
control 0.0051± 0.0008
Zhang et.al. (2013) ACS App. Mater. Interfaces, 3: 5500-5507 Sultan and DeRosa. (2011). Small, 7: 1219-1226.
A
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• Microcapsules show target-triggered morphology changes – Morphology unaffected
without target
• Rupture controlled by target concentration and time
Aptamer capsules for exudate-triggered delivery
Zhang et.al. (2013) ACS App. Mater. Interfaces, 3: 5500-5507 24
• Developing nanofertilizers requires a multi-disciplinary approach
• Chemical signals (exudates) important for nitrogen uptake have been identified in wheat and canola
• Biosensors (Aptamers) have been developed for these exudates
• Early prototypes of smart-release nanobiosensors have been developed for use with intelligent fertilizers
Concluding remarks
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• Organizations – The Alberta Innovations Bio Solutions and AAFC for providing financial support – Grain Growers of Canada, Canola Council of Canada and Agrium Inc. – La Coop Fédérée
The DeRosa lab Carleton University
Department of Chemistry
The Monreal lab Agriculture and Agri-Food Canada
ECORC
Acknowledgements
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