Nanomaterials Flashcards
T/F: all nanostructures are manmade
False; nanostructures occur naturally in many foods
Many food proteins are ____ structures between _____ nm in size
globular structures
10-100nm
What are some naturally occuring nanostructure molecule types in food: (3)
food proteins
polysaccharides/lipids (thickness)
stabilized foam/emulsions (interface)
Describe the nanostructure features of a stabilized foam:
2D nanostructure: 1 molecule thick at the interface (between the air/water or oil/water)
Give some examples of foods with nanoparticles (natural) (2)
starch nanocrystals (custard) casein particles in milk
How do starch nanocrystals change in the process of custard making
heated starch -> nanocrystals melt
recrystallization/hydration during coolin -> forms paste
Casein particles are about ____ nm in milk.
100nm
How is milk converted to a gel in yogurt production?
microbe action -> lactic acid -> cleave kappa chains ends in casein particles grow (agglomerate) -> gel structure
What interesting phenomena can materials display at the nano-scale? (7)
New properties:
high mobility new optical properties molecular recognition (bind/disrupt) in endocrine/DNA supermagnetism superconductivity increased reactivity very attractive/repulsive surface charge
What is nanotechnology?
understanding/control of matter at the nanoscale (0.1-100nm) & the unique phenomena (property changes)
What is the scale (dimensions) for nanotechnology?
0.1-100nm
What technology is used to observe nanoparticles? (5)
zetasizer mastersizer SEM (scanning electron microscopy) AFM (atomic force microscopy) TEM (transmission electron microscopy)
The zetasizer measures nanoparticles based on _______, reporting it as _____
dynamics light scattering
hydrodynamic diameter
Smaller particles will show (faster/slower) dynamics in a zetasizer
faster
A Mastersizer works based on the principle of _____. How does it differentiate between particle sizes?
laser diffraction
small particle -> more scattering
big particle -> less scatteriing
What is the principle of SEM?
electron beam directed at sample
electrons interact with sample -> produce signals
gives information on topography & composition
How does AFM work, and what does it provide information on?
gives topographical information (surface scan)
rigid cantilever with tip (Si) -> brought close to sample surface
forces will cause tip deflection (van der waals, chem bonds, magnetic, etc)
measure with beam-deflection (laser aimed down, reflects into photodiode; angle changes if cantilever moved)
General mechanism of TEM:
electron beam directed through thin sample (<100nm thick)
interacts with sample -> beam transmitted
magnify/focus onto imaging device (SED: selected electron diffraction)
nanotechnology is applied in what food-related products? (7)
dietary supplements nutritional additives color additives food procesing aids long-life packaging antibacterial kitchenware fertilizers/pesticides
What are possible future nano food and agriculture technology? (8)
interactive personalized food edible nano wrapper chem release packaging extensive nano surveillance interactive agrochemicals nano-manipulation of seeds synthetic biology
nanotechnology is involved in what sectors of food science and technology?
processing
product (Health/nutrition)
food safety/biosecurity
Materials
What is nanotech used for in materials? (4)
nanoparticles
nanoemulsions
nanocomposites
nano-structured materials
How is nanotech used in health and nutrition? (2)
nanoencapsulation (flavor/nutrient control, protect nutraceuticals)
engineered nanoparticulate addditives (nanosized ingredients)
how is nanotech involved in novel materials? (2)
antibacterial packaging
controlled gas permeability
How is nanotech involved in food safety?
small environmental sensors (humidity, frost, temp, light…)
self-evident shelf life labels (shows when food spoils/contaminated)
What is nanoencapsulation?
coating + entrapment of pure material or mixture inside another material (emulsion droplets < 100nm)
Can the core material in nanoencapsulation can be in forms other than liquid?
Yes: usually liquid, but can be solid or gas
How is the emulsion method of nanoencapsulation done?
disperse material in carrier solution -> coat with surfactant -> form emulsion droplets <100nm
Benefits of encapsulation: (4)
stability (heat, pH, oxidation)
taste/color (no unpleasant taste/color)
safety (mild on stomach; insoluble in gastric juice)
bioavailability (sustained release -> high absorption/bioavailability)
The 3 emulsion methods for nanoencapsulation:
extreme emulsification (high flow -> produce small particles)
phase inversion composition (add/disperse nonsolvent into material ; eventually add enough and phases change -> material dispersed in nonsolvent)
phase inversion temperature (lower temperature of emulsion -> cause phase inversion -> further dilute)
T/F: there is no temperature change in the extreme emulsification and phase inversion (composition) methods
true
Can nanoemulsions be used directly after forming?
yes - liquid form
What is done to convert nanoencapsulated materials into a powder form?
spray drying
How does a spray dryer work?
sprays fine particles (atomized) into heated dryig chamber -> dry particles collected by ELECTRODE
NSSL technology was innovated by _____. What is it?
nanosized self-assembled liquid structures (emulsions <30nm)
NutraLease ltd.
intended for nutrient/supplement delivery (coenzyme Q10, lutein, lycopene, phytosterols, vit D)
What are nutritional concerns about coenzyme Q10 (2), and what are the benefits of being encapsulated (2)?
- not soluble in water;
- bioavailability is reduced by high fibre diet (-40 to 74%)
nanoencapsulation:
1. can fortify/incorporate into any water or oil-based food
2. better bioavailability (can get known % from the food)
Nutritional significance of phytosterols
competes with cholesterol; high solubility and replacement of cholesterol in bile salt micelles
REDUCES CHOLESTEROL
What is the advantage of phytosterol nanomicelles (vs normal phytosterol)
INCREASES CHOLESTEROL REDUCING EFFECT:
- improved solubility
- allows transport without breaking up
- identify large micelle membrane (bile salt) -> compete for transport (with cholesterol)
Why would omega 3 be nanoencapsulated?
allows incorporation into food for health benefit, without altering the taste (fishiness), or break down of the fragile oil
(only released in stomach)
nanoparticles can be ____ or ____ crosslinked
chemically
physically
What is the most common chemical cross-linker for NP?
What are some some novel ones? (2)
common: glutaraldehyde novel: genipin natural di/tri carboxylic acids
What is the issue with glutaraldehyde
toxic
physical cross-linked NPs are linked by _____
electrostatic interaction
types of physical crosslinkers for NPs: (2)
anion crosslinker: TPP (tripolyphosphate)
cation crosslinker: bivalent Ca ion
chemical crosslinked NPs are linked by _____
chemical bonds
glutaraldehyde links NP using ____. Does TPP use the same mechanism?
chemical bonds.
No: TPP uses electrostatic interaction
How are bioactive compounds loaded onto nanoparticles (2)
incorporation (during preparation)
incubation (after preparation)
wood cellulose based polyelectrolyte NP are made of ____ and ____
CMC (carboxymethyl cellulose)
QC (quaternized cellulose)
how does the proportions of CMC and QC in wood cellulose NPs affect the final NP properties?
more CMC -> form complex with QC in core, CMC outer = negative charged NP
more QC -> CMC in core, QC outer = positive charge NP
More CMC in a wood cellulose NP will lead to a (positive/negative) NP
negative
Which crosslinking method is better for bioactive agents?
physical crosslinking
Advantages of physical crosslinking: (4)
no chemical crosslink reagents
mild aqueous conditions
simple procedure
suitable for bioactive agents
What is the benefits of nano-sized ingredients and additives? (4)
improved texture/flavor/taste
reduce amounts of salt/fat/sugar/additives
better bioavailability/health benefit
antimicrobial (minerals)
advantage of nano-sizing minerals:
better bioavailability (nutrition) antimicrobial
How is nanotechnology used in chicken feed? (2)
nano selenium - may stop bird flu
PS nanoparticles bind bacteria (antibiotic alternative)
real life examples of technology for food processing involving nanotech:
- nano powered catalytic device
2. nanofilters
What is a nano-powered catalytic device, and what is the advantage? (3)
coated with 20nm zeolite NP (frying oil enhancing device)
better taste/consistency/crispness
lower cost
approved (FDA)
what are nano-filters, and what are the advantages? (3)
filtration (extraction) method for food colors and flavors
gentle process (no phase change, heating, chemicals)
fresher flavors
cheaper (less energy needed)
What is a nanomaterial?
film with incorporated nanoparticles (usually inorganic particles - silver, TiO2, nanoclay)
Why are nanoparticles added to films? (2)
change functionalities:
antibacterial
improve barrier properties
What are common NP added to films? (3)
silver, TiO2, nanoclay
beer bottles can incorporate ____ NPs, which has the benefit of: (2)
nanoclay
lighter/stronger
minimize CO2 loss (better barrier)
the possible distribution patterns when adding NP into a polymer:
- microcomposites: NP clump up
- nanocomposite: NP regularly arranged
- nanocomposite: NP disorderly arranged
The greater the interatomic spacing (d-spacing), the (greater/less) the gas permeability
less
an increased number of bilayers (applied layers of polymer + NP) on the substrate leads to (higher/lower) permeability
lower
“Smart dust” - nanosensors have what potential applications?
- monitor humidity/temp (environment)
- detect food spoilage/freshness
- monitor soil conditions (precision farming)
What is a ‘lab on a chip’
tiny device integrating many lab functions (sample collection/concentration/separation/detection)
NPs used as tags/labels -> better sensitivity
What can a nano-electric tongue be used for?
QC for beverages
What are self-evident shelf life labels and what can they indicate?
change color (signal) to indicate change in product
temp, pathogens, freshness, integrity, humidity, etc
gas indicators examples: (2)
TiO2 NPs (with methylene blue indicator) - O2 sensor
C-coated Cu NPs: change colors according to gas or moisture (ethanol, H2O)
Why is sensing CO2 increase relevant?
CO2 made by microbial respiration/fermentation
CO2 made by produce respiration
What is a self-evident label that is a poultry freshness indicator, and how does it work?
Metmyoglobin based
detects H2S produced by bacteria (pseudomonas)
H2S react w/ metmyoglobin (brown) -> sulfmyoglobin (green)
green color = spoiled
How does a ripeness indicator work?
detects CO2 (more ripe = more CO2) -> changes color from red to yellow
What is an example of antibody-based freshness indicator? How does it work?
Toxin Guard
polyer with detector Ab (against specific pathogen toxins/spoilage metabolites)
Ab bind toxin -> complex binds to capture area on label
cause color change/fluorescence = product not safe
what is the mechanism of a temperature dependent color changing plastic mug?
thermo-chromic dye incorporated into plastic - changes color according to temp
ex: coffee lid turning red when hot, back to brown when cool
How does a 1 time usage temperature indicator work, and what is it used for?
bringing product to specific temp -> wax melts & mixes with dye
(irreversible)
color change indicates product has reached endpoint temperature
What are some areas of safety concern for NP technology? (3)
Worker safety
Product safety
Environmental safety
What are some concerns with product safety for NPs? (4)
dermal/inhalation/ingestion?
crossing biological membranes, cells, etc
bio-concentration
higher reactivity (larger surface area)
examples of potential harm caused by exposure to NP:
neuron degeneration inflammation organ injury oxidative damage necrosis carcinogenic
concerns with environmental safety of NPs:
multiple pathways to environment (manufacture, transport, use, disposal)
risks not fully assessed - mobility, reactivity, durability, bioaccumulation?
nano silver has enhanced germ killing properties, but can also cause harm - how?
antimicrobial properties can also harm aquatic organisms/microbes and ecosystems
What are the environmental and human health impacts of fullerenes (carbon 60)?
environment: brain damage in fish, kill water fleas, bacteriocidal
human: low levels toxic to hepatocytes
How could TiO2 and ZnO be harmful to human health? What are they usually found in?
possibly photoactive - made free radicals and cause DNA damage in epithelial cells in UV light
in sunscreens
For NP consumer safety, what needs to be ensured? (4)
- ensure they are solubilized/digested in gut
- ensure greater bioavailability doesnt increase health risks
- tissue distribution not different from conventional forms
- evaluate toxicological properties!
What needs to be kept in mind in the future of NP development? (3)
weight risks vs benefits (risks acceptable?)
ensure regulatory compliance
consumer information
