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30019- Molecules to Materials: deconstructing the environment > Environmental transformations of nanomaterials & Environmental corona > Flashcards

Environmental transformations of nanomaterials & Environmental corona Flashcards

1
Q

What is nanotechnology?

A

creation and utilization of materials, devices, and systems through the control of matter on the nanometer-length scale

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2
Q

How can nanoparticles be thought of as enabling technologies

A

they allow other technologies/ products to function better

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3
Q

What are the main application areas of nanoparticles?

A

Textiles
Biomedical
Healthcare
Food agriculture
Industrial
Electronics
Environment
Renewable energy

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4
Q

What forms can nanomaterials be found in?

A

Nanoparticles
Nanorods/ nanowires
Arrays of nanoparticles
Nanostructure surfaces

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5
Q

What are the dimensions of nanoparticles?

A

less then 100nm in all 3 dimensions

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6
Q

What are the dimensions of nanowires?

A

2 dimensions less then 100nm with “length” being larger then 100nm

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7
Q

What can nanostructures develop materials to be?

A

anti-fouling= prevent attachment of unwanted organisms

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8
Q

What happens as you make an object smaller?

A

more exposed to surface

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9
Q

What is the equation for the surface area of a sphere?

A

4πr*2

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10
Q

What is the equation for volume of a sphere?

A

4/3πr*3

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11
Q

What is the equation for volume of a cube?

A

s*3

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12
Q

What is the equation for volume of a rectangular solid?

A

lwh
(length, width, height)

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13
Q

What is the equation for volume of a right circular cylinder?

A

πr*2h

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14
Q

What is the equation for the surface area of a cube?

A

6s*2

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15
Q

What is the equation for the surface area of a rectangular solid?

A

2wl+2lh+2wh

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16
Q

What is the equation for the surface area of a right circular cylinder?

A

2πr*2+2πrh

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17
Q

What nanoparticles properties can affect environmental fate?

A

Concentration
Shape
Size
Size distribution
Structure/ crystallinity
Composition
Porosity/ surface area
Surface functionality
Surface change
Surface speciation
Agglomeration state

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18
Q

What 2 forces are there in colloids/ nanomaterials?

A

Electrostatic stabilisation
Steric stabilisation

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19
Q

What is electrostatic stabilisation?

A

Wander Vaals attraction counterbalanced by electrostatic repulsion of atoms with same charge

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20
Q

What is more stable between electrostatic stabilisation and steric stabilisation?

A

Steric as less environmentally sensitive

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21
Q

What theory describes electrostatic stabilisation?

A

DLVO

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22
Q

What happens if the charge of electrostatic stabilisation is neutralised?

A

particles will become unstable and agglomerate

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23
Q

What is an acid? (in relation to water)

A

a substance which produces H+ (aq) ions when dissolved in water

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24
Q

What is the word formula for the neutralisation reaction?

A

Acid + base ↔ salt + water

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25
What happens to nanomaterials if a stabilising agent (i.e., stabilising steric) is added?
there will be no aggregation
26
How do nanoparticle surfaces acquire charge?
Ionisation of surface groups (attraction between positive NP and negative ions) Specific adsorption of ions (ionic surfactants)
27
What is an example of an ionic surfactant which can be attributed to nanoparticles acquiring charge?
Anionic surfactant
28
What is zeta potential?
measure of the surface charge of particles in aqueous solution
29
What is the electrical double layer when considering nanoparticles?
Double layer- where some water and counter ions are pulled along with particle
30
What is the slipping plane when considering nanoparticles?
the plane defined by the distance at which the structure with its chemically bound water and ions moves in bulk through the solution
31
What process can be used to measure zeta potential?
electrophoresis
32
How does electrophoresis work?
2 electrodes one positive charge and one negative with opposite chare particles being pulled to each one
33
Cells and particles move with a velocity dependant on which properties?
Electrical field strength Dielectric constant of the medium Viscosity of the medium Zeta potential
34
What occurs at the isoelectric point?
all charges are neutralised
35
What is the zeta potential dependant on?
pH
36
What is stability like around the isoelectric point?
Unstable until either +20 or -20 zeta potential
37
What does stabilisation of nanoparticles depend on?
strength of acid
38
What is a strong acid?
acid which is completely ionised in water
39
What is a weak acid? (with example)
partially ionises in water e.g., ethanoic acid
40
What does a higher Ka (acidity dissociation constant) mean?
A stronger acid
41
What is the difference acid strength and acidity?
Acid strength in water= molecule property Acidity= qualitive measure of its pH
42
What is the Lewis theory? (acids and bases)
Bases donate electron pairs Acids accept electron pairs
43
What are the advantages of the Lewis theory?
Compliments redox Suggest acid react with bases to share electron with no REDOX number change Expands number of acid and bases and their reactions
44
What is the HSAB theory?
Pearson's Hard and Soft Acid and Bases theory
45
How does HSAB further the Lewis theory?
Lewis acids and bases can be further split into hard or soft or boder-line
46
What are hard Lewis acids characterised by?
small ionic radii, high positive charge, strongly solvated, empty orbitals in the valence shell and with high energy LUMO
47
What dies LUMO stand for?
Lowest Unoccupied Molecular Orbital
48
What are soft Lewis acids characterised by?
large ionic radii, low positive charge, completely filled atomic orbitals and with low energy LUMO
49
What is the principle of HSAB?
hard acids prefer binding to the hard bases to give ionic complexes, whereas the soft acids prefer binding to soft bases to give covalent complexes
50
How does the HSAB theory affect precipitation reactions?
The softer acids like Ag+, Hg+, Hg2+ etc., and border line acids like Fe2+, Ni2+, Cu2+, Zn2+, Pb2+ etc., can be precipitated as sulphides from aqueous solutions since S2- ion is a softer base
51
What can the photodegradation of nanoparticle coatings lead to?
aggregation
52
What does oxidation of nanoparticles lead to?
dissolution and release to toxic Ag+ (aq)
53
What can nanoparticle interaction with different ligands do?
Promote or inhibit oxidation and dissolution
54
What can Thiol Ligands increase in nanoparticles?
dissolution
54
What does sulfidation do to nanoparticles?
Inhibits dissolution
55
What does sulfidation of Ag nanoparticles surface do?
Reduces their ecotoxicity
56
What is the oxidative dissolution timescale of Ag0 nanoparticles?
Relatively short - days to weeks
57
Why is oxysulphidation?
mechanism by which silver is oxidized and sulfidized at the metal without dissolution and release of Ag+ ions
58
What might the result be of oxysulfidation at high sulfide to AgNP Molar ratios?
formation of a passivating layer of Ag2S around the Ag0 core of AgNPs, thus slowing or preventing further Ag+ release
59
What is a passivating layer?
creation of an outer layer of shield material
60
What is homoaggregation?
this is when just nanoparticles agglomerate together to form a larger molecule
61
What does agglomeration do to nanoparticles?
Increases size but reduces surface area and reactivity
62
What can happen to a molecule that has undergone homoaggregation?
the homoaggregated molecules can end up undergoing heteroaggregation
63
What is heteroaggregation?
Can occur to nanoparticles individually or aggregated and is when they join a larger different particle
64
What does heteroaggregation do to nanoparticles?
increases particle size and affects transport and reactivity
65
What can biological oxidation result in?
Carboxylation of CNTs (carbon nano tube) or formaiton of an insoluble metal oxide shell
66
What can biological degredation of polymer coatings on nanomaterial affect?
surface properties and lead to aggregation
67
What does adsorption of biomacromolecule affect?
Aggregation Uptake Biodistribution Dissolution
68
What can adsorption of Natural Organic Matter (NOM) do when nanoparticles interact with bio-macromolecules?
Can displace smaller ligands and stabilise the nanomaterial against aggregation or Causes flocculation
69
What can adsorption of natural organic matter do to layering in the molecule?
can lead to poorly characterised heterogeneous mixed polymer-NOM layers
70
How can bacteria and toxicity be affected by adsorption of Natural Organic matter on nanoparticles?
Decrease nanoparticle-bacteria interactions Decrease ion dissolution and thus toxicity
71
What is the distribution of environmental corona in different resevoirs?
Atmospheric - air =1.5% Industrial - land fill= 63-91% Terrestrial- soils= 8-28% Aquatic- surface water= 7%
72
What are the atmospheric sources of environmental corona?
Humans- breath condensate Atmo bacteria- Pseudomonas syringae Pollen generating plants- grass
73
What are the terrestrial sources of environmental corona?
Crops- rice, wheat, maize Rhizosphere- Rhizobiaceae, nitrobacter, azotobacter
74
What are the industrial sources of environmental corona?
Proteobacteria- Alphaproteobacteria, Delta" and Beta"
75
What are the aquatic sources of environmental corona?
Biofilms- E.coli, cyanobacteria Crustaceans- Daphnia Fish- Dani rerio, Oncorhynchus mykiss
76
What will nanomaterials bind to in the environment?
bio-molecules or co-pollutants
77
What is the effect of nanomaterials binding to bio-molecules or co-pollutants?
Reduce surface reactivity New particle identity (i.e., more like food)
78
What are the environment factors for protein corona?
Composition Exposure time pH Temperature Shear stress
79
What does the binding of nanoparticles depend on in the environment?
affinities of available molecules
80
What do nanoparticle and environmental characteristics play a role in determining?
what proteins/ biomolecules bind
81
What are some examples of protein characteristics?
Charge, Hydrophobicity, Molecular weight, Abundance
82
What are the Cooperativity effects?
the presence of one protein attracts another
83
What are the main parts of the complex soup of secretions?
Bacterial gut secretions Moulting Moulting fluid Signalling/ Kairomones Undigested matter
84
What are the parts of bacterial gut secretions?
Bacteria released by conspecific horizontal transmission Release of Enzyme/ structural proteins from degraded bacteria By-product- harmful algae
85
What is the moulting part of the complex soup of secretions?
carbohydrate chitin-based exoskeleton
86
What is the moulting fluid of the complex soup of secretions made up of?
Digestion enzymes (proteins) chitinase/ chitinobase
87
What occurs in the signalling/ Kariomones part of the complex soup of secretions?
Overcrowding/ stress induced signalling to regulate population Signalling to algae
88
What is the undigested matter of the complex soup of secretions made up of?
Undigested algae Organic detrius (dead organic matter) Bacteria Algae
89
What are the different types of environmental corona?
simplified corona Complex corona Corona formed in vivo Corona formed insitu
90
What is simplified corona?
ex-vivo (outside organism) One or few biomolecule
91
What are the characteristics of complex corona?
ex-vivo biomolecular diversity
92
What are the characteristics in vivo corona?
in-vivo = in organism formed biomolecular diversity in & near organisms

30019- Molecules to Materials: deconstructing the environment (29 decks)

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