Applications of Nanotechnology in Food and Agriculture – What is Nanotech and how can I use it?

Michael A. Meador Director, National Nanotechnology Coordination Office

mmeador@nnco.nano.gov www.nano.gov

Overview •  What is Nano? •  National Nanotechnology Initiative •  Nanotechnology is in Commercial Products •  Nanotechnology for Food and Agriculture

•  Food Safety •  Water Management •  Fertilizers and Pesticides •  Environmental, Health and Safety

•  Summary

What is Nanotechnology?

Control of matter and processes at the atomic and molecular level •  Typically 100 nanometers in

two dimensions »  Nanometer is one billionth

of a millimeter –  Single sheet of paper is

about 100,000 nm thick

Conventional physics often breaks down at the nano-level •  Affects electrical, optical,

thermal and mechanical properties

Source: National Nanotechnology Initiative (www.nano.gov)

How Nanotechnology Impacts Materials Properties Nanotechnology enables discrete control of desired materials properties : Mechanical

•  Dictated by particle size (Griffith criteria), morphology and strength of interfaces (chemistry and roughness)

•  High aspect ratios and surface areas radically changes nanocomposite properties relative to host material

•  Molecularly perfect, highly ordered, defect free structures, e.g. carbon nanotubes, leads to maximized properties (not just mechanical)

Thermal •  Emissivity influenced by particle size and enhanced surface area/

roughness •  Thermal conductivity controlled by particle size (phonon coupling and

quantum effects) and nanoscale voids Electrical

•  Nano structure and defects influence conductivity and bandgap energy (conductivity, current density, thermoelectric effects)

•  High aspect ratios enhance field emission and percolation threshold •  Nanoscale dimensions lead to inherent radiation resistance

Optical •  Transparency and color dominated by size effects •  Photonic bandgap controlled by size (λ/10) and nanostructure

Other •  Enhanced reactivity – high surface area •  Wettability – nanscale surface textures

NNI Vision A future in which the ability to understand and control matter at the nanoscale leads to a revolution in technology and industry that benefits society.

The National Nanotechnology Initiative (NNI)

Sustainable Nanomanufacturing

Nanoelectronics for 2020 and

Beyond

Nanotechnology Enhanced Solar Energy Capture and Conversion

Nanotechnology for Sensing

Nanotechnology Knowledge

Infrastructure

Signature Initiatives

•  Established in 2000 under an Executive Order from President Bill Clinton

•  Intent of the NNI is to provide a framework for member agencies to work together to: −  Advance world-class

nanotechnology research −  Foster the transfer of technologies

into products for commercial and public benefit

−  Develop and sustain educational resources, a skilled workforce and the supporting infrastructure and tools to advance nanotechnology

−  Support the responsible development of nanotechnology

President Clinton’s Vision

Just imagine, materials with 10 times the strength of steel and only a fraction of the weight; shrinking all the information at the Library of Congress into a device the size of a sugar cube; detecting cancerous tumors that are only a few cells in size. Some of these research goals will take 20 or more years to achieve. But that is why—precisely why there is such a critical role for the Federal Government. President Clinton, California Institute of Technology, January 21, 2000

NNI Funding Trends

Since 2001, NNI participating agencies have invested over $22B in nanotechnology R&D, unique user facilities, commercialization, education and outreach

NNI Planned Investments in FY2016

NNI Reporting

The NNI Supplement to the President’s Budget: §  Funding information by

agency/department and PCA for prior, current FY and requested amount for budget year

§  Accomplishments from prior FY

§  Plans for current FY and budget year

§  Available on www.nano.gov

Nanotechnology Products

Nanoscale Silver Antimicrobials Nanoscale Titanium

Dioxide UV Absorbers

Polymer Nanocomposites

QD Vision’s Color IQ Technology •  QD Vision developed CdSe

quantum dots for use in solid state lighting and displays (Color IQ)

•  Color IQ incorporated into Bravia LED televisions in 2013

•  “Best of 2013 CES” – Tech Radar

•  Reduces power consumption by 20% - less pollution

•  QD Vision received EPA’s Green Chemistry Challenge Award in 2014 for reducing use of hazardous materials in their manufacturing processes

Nanotechnology Has Made it into Space

CNT Nanocomposites for Charge Dissipation

CNT “Electronic Nose”

Silica Aerogels

Polyimide Aerogels

Nanotechnology Applications in Food and Agriculture

•  Food safety •  Improved packaging to reduce spoilage •  Sensors to detect pathogens and spoilage •  Disinfectants and antimicrobial surfaces

•  Water management •  Sensors for soil moisture content •  Water purification •  Coatings to reduce energy for water distribution

•  Fertilizers and Pesticides

Clay Nanocomposite Films for Food Packaging

•  Nanocomposites made by blending clay into a variety of polymers •  Synthetic – PET,

polystyrene •  Biopolymers – Zein,

chitosan, PLA •  Improvements in:

•  Film strength •  Barrier properties –

oxygen, carbon dioxide, water, contaminants

Tortuous Path Model for Diffusion Through Polymer/Clay

Nanocomposites

Nanocellulose •  Two forms crystals and fibrils •  Produced from both plants and animals,

typically by chemical digestion methods ü  Wood pulp ü  Grasses ü  Cotton ü  Algae ü  Tunicates

•  Characteristics depend upon source and production method ü  Aspect ratio (length/diameter) – important

for high strength and barrier properties ü  Biodegradability ü  Heat resistance

•  Films produced from nanofibrils and blends of nanofibrils and clay

•  US Forestry Service recently established two pilot plants for nanocellulose production

•  Significant investments in R&D and production by other countries (Canada, Sweden, Finland)

Transmission Electron Microscopy Images of Cellulose Nanocrystals (left)

and Fibrils (right) (Source: Xu et al ACS Applied Materials and

Interfaces 2013, 5, 2999-3009)

Antimicrobials Incorporated into Food Packaging

•  Nanoparticles have been used to impart antimicrobial actitivity to food packaging ü Nanosilver in commercial

products (right) ü  Titanium dioxide – uv

activated

Antibacterial performance of TiO2 nanocomposite films (Source: Duncan, Journal of Colloid and Interface Science 2011, 363, 1-24

Active Packaging – Poly(ethylene) Nancomposites with Clay and TiO2

Source: Bodaghi et al Journal of Applied Polymer Science 2014, 14, 41764

0

20000

40000

60000

Oxygen Carbon Dioxide

Tran

smis

ion,

cc-

mL

m-2

day

-1

PE

3% CL

5% CL

3% TIO2

3% CL+TIO2

5% CL+TIO2

Packaging film shows combination of: •  Low permeability to oxygen and

carbon dioxide (clay) •  Antimicrobial activity when

exposed to uv light (titanium dioxide)

•  TiO2 also catalyzes photo-decomposition of ethylene

Active Packaging •  Active packaging can be made

with nanoscale additives to inhibit oxygen infiltration and natural antimicrobial agents

•  Example at the right involves an essential oil model (carvacol) intercalated clay nanocomposite in poly(ethylene)

ü  Films containing clay are more effective at suppressing bacterial growth because they starve the bacteria for oxygen

ü  Essential oils may be more attractive for packaging since they don’t have potential EH&S issues

Source: Shemesh et al Polymer Advance Technologies 2014, 26, 110-116.

Smart Packaging •  Sensors incorporated into polymer

packaging can detect: ü  Pathogens ü  Spoilage ü  Presence of oxygen or

other gaseous species ü  Tampering

•  Example at the right is an optical sensor to detect presence of oxygen due to leaks in packaging

ü  Difficult to quantify the amount of oxygen in the package

ü  Easy way for consumers and vendors to see that oxygen has leaked into the product

Blue dot is sensor comprised of titanium dioxide and Methlyene Blue (indicator dye) which will turn blue in the presence of oxygen. Pictures show two dots top one is outside package, bottom is inside: (a) freshly sealed sample, (b) after activation of sensor with uv light, (c) after standing for a few minutes, (d) package is opened

Sensors for Detection of Food-borne Pathogens •  Functionalized metal

nanoparticles and nanostructures have been used in detection of pathogens

•  Functional groups designed to attach to specific pathogens

•  Optical or electrochemical properties of the nanoparticles change when they bind with the pathogen

•  Many groups are working on the development of handheld sensors, such as the one on the right, for pathogen detection

A.C. Alocoilja, Michigan State University

J. Inudayaraj, Purdue

D. Luo, Cornell

Nanoemulsions Can Help Reduce Bacteria on Produce

•  Essential oils such as those from thyme, oregano, and clove are known to have strong anitmicrobial activity

ü  Oregano oil shown to be effective against E coli, Salmonella and Lysteria

ü  Effectiveness limited by poor solubility in water

•  Nanoemulsions prepared by treatment of emulsions with ultrasound

ü  High shear forces bread down emulsions into smaller particle sizes

•  Lettuce innoculated with E coli, Salmonella and Lysteria, then treated with 0.05 and 0.1% oregano nanoemulsions and stored at 4°C

•  Nanoemulsions have also been used in flavor additives, antifungal agents for plants, and pharmaceuticals

(Source: Bhargava, Conti, da Rocha, Zhang Food Microbiology 2015, 47, 69-73)

Engineered Nanowater for Disinfecting Surfaces •  Electrospray process involves

building up a large electric charge on water drop

ü  Water droplets condense on the electrode (Petier cooling element), become charged

ü  Charged droplets break up into smaller droplets and accelerate away from the electrospray module

ü  High charge also breaks down water into reactive species (radicals) which attack and damage bacterial cell walls

ü  Studies reveal little or no damage to the product being decontaminated

Nanotechnology Applications in Food and Agriculture

•  Food safety •  Improved packaging to reduce spoilage •  Sensors to detect pathogens and spoilage •  Disinfectants and antimicrobial surfaces

•  Water management •  Sensors for soil moisture content •  Water purification •  Coatings to reduce energy for water distribution

•  Fertilizers and Pesticides

Controlled Wetting •  Mimic biological systems to design

surfaces that are highly water repellant (superhydrophobic) or oil repellant (superoleophobic) and self-cleaning

•  Wetting characteristics follow two models:

ü  Wenzel – liquid fills the spaces between pillars

ü  Cassie – air fills the spaces between pillars

•  Can change surface properties by changing both the material used and the type of nanotexturing

•  Potential use of controlled wetting coatings in agriculture and food:

ü  Coatings for pipes to reduce pumping energy

ü  Antimicrobial surfaces ü  Self-cleaning tools and machinery

Self-cleaning, superhydrophobic character of lotus leaf due to nanopillared surface

Tailored Wettability of Surfaces •  Surface prepared by coating arrays of

glass or polystyrene spheres on a silicon surface with fluoropolymer (hydrophobic) or silica (hydrophillic)

•  Contact angle measures wettability of surface

ü  0˚ - water completely wets surface ü  180˚ - water droplet completely

holds its shape •  Wetting behavior controlled by sphere

diameter (D) and distance between spheres (L):

ü  At L/D less than 1.5 (larger spheres) – surfaces follow Cassie-Baxter model

ü  A L/D greater than 1.5 (smaller spheres) – surfaces follow Wenzel model

Electron microscope image of arrays of 100nm (a) and 2700nm (b) spheres on

silicon wafer

Source: Dhinojwala Soft Matter 2013, 9, 3032 (U of Akron)

Nanotextured Surfaces for Antimicrobial Protection •  Nanotextured surfaces can

inhibit adhesion of bacteria onto surfaces

•  Application of a nanoporous alumina surface (anodized alumina) onto metals inhibits cell adhesion and growth of biofilms

ü  E coli O157:H7 ü  Listeria monocytogenes

•  Smaller pore sizes (15 and 25 nm) are the most effective

Source: Feng et al Biofouling 2014, 30, 1253-1268 Joint effort between Cornell and RPI

Confocal light microscopy images of attachment and biofilm formation by live E coli

SEM images of live E coli cells attached to a nanoporous alumina surface

Nanoporous Graphene for Water Desalination •  Single layer of graphene

treated with oxygen plasma ü  Produces nanoscale

pores within the graphene

ü  Pore size can be controlled by varying reaction time

•  Membranes show high water molecule selectivity over dissolved ions

ü  ~100% salt reject rate ü  Water fluxes as high as

high as 106 gm-2s-1 at 40°C

Source: Surwade et al Nature Nanotechnology 2015, 10, 459-464

Advanced Zeolite Membranes for Water Purification (Rive Technology) •  Zeolites, nanoporous

ceramics, are used extensively in:

ü  Catalysis ü  Water purification

(filtration) materials – removal of heavy metals, organics

ü  Air purification •  Pore structure within

conventional zeolites restricts movement of gasses and liquids resulting in low throughput

•  New hierarchical zeolites (small and large pores) have better diffusion and throughput

Comparison of SEM images of conventional zeolite (top) with “molecular highway” zeolite

(bottom)

Nanotechnology Applications in Food and Agriculture

•  Food safety •  Improved packaging to reduce spoilage •  Sensors to detect pathogens and spoilage •  Disinfectants and antimicrobial surfaces

•  Water management •  Sensors for soil moisture content •  Water purification •  Coatings to reduce energy for water distribution

•  Fertilizers and Pesticides

Titanium Dioxide Antifungal Agents •  Titanium dioxide phototocatalysts

are known to be effective antimicrobial agents

ü  Generates reactive oxygen species (free radicals) upon exposure to uv light

ü  Free radicals attack cell walls of bacteria

•  Shown at upper right: potato dextrose agar films treated with P. expansum: (a) No TiO2, (b and c) TiO2, no UV, (d) UV, no TiO2, (e and f) TiO2 and UV

•  Shown at bottom right: effect of TiO2 on suppressing Penicillum rot on apples

(Source: Maneerat and Hayati Int. J. Food Microbiology 2006, 107, 99-101)

Titanium Dioxide Can Aid Photosynthesis and Plant Growth •  Titanium dioxide has

been shown to improve photosynthetic activity and efficiency

•  Titanium dioxide also shown to enhance nitrogen fixation

•  Shown at the right: Spinach plants from aged seeds grown in a nitrogen deficient Hoagland solution: (a) untreated, (b) treated with nano- TiO2

Source: Yang et al Biol. Trace Elem. Res. 2007, 119, 77-88

Environmental, Health and Safety Aspects of Nanotechnology •  EH&S risks associated with nanomaterials are a function of

two factors ü Toxicological effects of nanomaterial ü Risk of exposure

•  Significant amount of toxicological studies have been done on a variety of nanomaterials ü Study conditions should closely mimic those that would likely

occur during exposure •  Not as much work has been done to understand exposure

ü Agencies funding work in EHS under the NNI are looking at assessing the knowledge gaps with respect to exposure

ü Joint workshop with the NNI and Consumer Product Safety Commission : Quantifying Exposure to Engineered Nanomaterials from Manufactured Products, July 7-8, Arlington, VA

Summary •  US Government Agencies have invested over $22B in nanotechnology

R&D •  Nanotechnology has become pervasive in commercial products

•  Automotive •  Health Care •  Cosmetics •  Sporting Goods •  Consumer Electronics

•  Significant amount of R&D in nanotechnology for food and agriculture ü  Food safety – packaging (passive, active and smart), sensors (food

spoilage, pathogens, contaminants), antimicrobials ü  Water management – purification (desalination, contaminants),

controlled wetting coatings, sensors ü  Fertilizers and Pesticides

•  NNI 2.0 ü  Grand Challenges RFI – coming out this month