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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

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Organic Chemistry 101 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
Q

What happens to nanomaterials if a stabilising agent (i.e., stabilising steric) is added?

A

there will be no aggregation

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26
Q

How do nanoparticle surfaces acquire charge?

A

Ionisation of surface groups (attraction between positive NP and negative ions)
Specific adsorption of ions (ionic surfactants)

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27
Q

What is an example of an ionic surfactant which can be attributed to nanoparticles acquiring charge?

A

Anionic surfactant

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28
Q

What is zeta potential?

A

measure of the surface charge of particles in aqueous solution

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29
Q

What is the electrical double layer when considering nanoparticles?

A

Double layer- where some water and counter ions are pulled along with particle

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30
Q

What is the slipping plane when considering nanoparticles?

A

the plane defined by the distance at which the structure with its chemically bound water and ions moves in bulk through the solution

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31
Q

What process can be used to measure zeta potential?

A

electrophoresis

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32
Q

How does electrophoresis work?

A

2 electrodes one positive charge and one negative with opposite chare particles being pulled to each one

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33
Q

Cells and particles move with a velocity dependant on which properties?

A

Electrical field strength
Dielectric constant of the medium
Viscosity of the medium
Zeta potential

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34
Q

What occurs at the isoelectric point?

A

all charges are neutralised

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35
Q

What is the zeta potential dependant on?

A

pH

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36
Q

What is stability like around the isoelectric point?

A

Unstable until either +20 or -20 zeta potential

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37
Q

What does stabilisation of nanoparticles depend on?

A

strength of acid

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38
Q

What is a strong acid?

A

acid which is completely ionised in water

39
Q

What is a weak acid? (with example)

A

partially ionises in water
e.g., ethanoic acid

40
Q

What does a higher Ka (acidity dissociation constant) mean?

A

A stronger acid

41
Q

What is the difference acid strength and acidity?

A

Acid strength in water= molecule property
Acidity= qualitive measure of its pH

42
Q

What is the Lewis theory? (acids and bases)

A

Bases donate electron pairs
Acids accept electron pairs

43
Q

What are the advantages of the Lewis theory?

A

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
Q

What is the HSAB theory?

A

Pearson’s Hard and Soft Acid and Bases theory

45
Q

How does HSAB further the Lewis theory?

A

Lewis acids and bases can be further split into hard or soft or boder-line

46
Q

What are hard Lewis acids characterised by?

A

small ionic radii,
high positive charge,
strongly solvated,
empty orbitals in the
valence shell and with high energy LUMO

47
Q

What dies LUMO stand for?

A

Lowest Unoccupied Molecular Orbital

48
Q

What are soft Lewis acids characterised by?

A

large ionic radii,
low positive charge,
completely filled atomic orbitals and with low energy LUMO

49
Q

What is the principle of HSAB?

A

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
Q

How does the HSAB theory affect precipitation reactions?

A

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
Q

What can the photodegradation of nanoparticle coatings lead to?

A

aggregation

52
Q

What does oxidation of nanoparticles lead to?

A

dissolution and release to toxic Ag+ (aq)

53
Q

What can nanoparticle interaction with different ligands do?

A

Promote or inhibit oxidation and dissolution

54
Q

What can Thiol Ligands increase in nanoparticles?

A

dissolution

54
Q

What does sulfidation do to nanoparticles?

A

Inhibits dissolution

55
Q

What does sulfidation of Ag nanoparticles surface do?

A

Reduces their ecotoxicity

56
Q

What is the oxidative dissolution timescale of Ag0 nanoparticles?

A

Relatively short - days to weeks

57
Q

Why is oxysulphidation?

A

mechanism by which silver is oxidized and sulfidized at the metal without dissolution and release of Ag+ ions

58
Q

What might the result be of oxysulfidation at high sulfide to AgNP Molar ratios?

A

formation of a passivating layer of Ag2S around the Ag0 core of AgNPs, thus slowing or preventing further Ag+ release

59
Q

What is a passivating layer?

A

creation of an outer layer of shield material

60
Q

What is homoaggregation?

A

this is when just nanoparticles agglomerate together to form a larger molecule

61
Q

What does agglomeration do to nanoparticles?

A

Increases size but reduces surface area and reactivity

62
Q

What can happen to a molecule that has undergone homoaggregation?

A

the homoaggregated molecules can end up undergoing heteroaggregation

63
Q

What is heteroaggregation?

A

Can occur to nanoparticles individually or aggregated and is when they join a larger different particle

64
Q

What does heteroaggregation do to nanoparticles?

A

increases particle size and affects transport and reactivity

65
Q

What can biological oxidation result in?

A

Carboxylation of CNTs (carbon nano tube) or formaiton of an insoluble metal oxide shell

66
Q

What can biological degredation of polymer coatings on nanomaterial affect?

A

surface properties and lead to aggregation

67
Q

What does adsorption of biomacromolecule affect?

A

Aggregation
Uptake
Biodistribution
Dissolution

68
Q

What can adsorption of Natural Organic Matter (NOM) do when nanoparticles interact with bio-macromolecules?

A

Can displace smaller ligands and stabilise the nanomaterial against aggregation
or
Causes flocculation

69
Q

What can adsorption of natural organic matter do to layering in the molecule?

A

can lead to poorly characterised heterogeneous mixed polymer-NOM layers

70
Q

How can bacteria and toxicity be affected by adsorption of Natural Organic matter on nanoparticles?

A

Decrease nanoparticle-bacteria interactions
Decrease ion dissolution and thus toxicity

71
Q

What is the distribution of environmental corona in different resevoirs?

A

Atmospheric - air =1.5%
Industrial - land fill= 63-91%
Terrestrial- soils= 8-28%
Aquatic- surface water= 7%

72
Q

What are the atmospheric sources of environmental corona?

A

Humans- breath condensate
Atmo bacteria- Pseudomonas syringae
Pollen generating plants- grass

73
Q

What are the terrestrial sources of environmental corona?

A

Crops- rice, wheat, maize
Rhizosphere- Rhizobiaceae, nitrobacter, azotobacter

74
Q

What are the industrial sources of environmental corona?

A

Proteobacteria- Alphaproteobacteria, Delta” and Beta”

75
Q

What are the aquatic sources of environmental corona?

A

Biofilms- E.coli, cyanobacteria
Crustaceans- Daphnia
Fish- Dani rerio, Oncorhynchus mykiss

76
Q

What will nanomaterials bind to in the environment?

A

bio-molecules or co-pollutants

77
Q

What is the effect of nanomaterials binding to bio-molecules or co-pollutants?

A

Reduce surface reactivity
New particle identity (i.e., more like food)

78
Q

What are the environment factors for protein corona?

A

Composition
Exposure time
pH
Temperature
Shear stress

79
Q

What does the binding of nanoparticles depend on in the environment?

A

affinities of available molecules

80
Q

What do nanoparticle and environmental characteristics play a role in determining?

A

what proteins/ biomolecules bind

81
Q

What are some examples of protein characteristics?

A

Charge,
Hydrophobicity,
Molecular weight,
Abundance

82
Q

What are the Cooperativity effects?

A

the presence of one protein attracts another

83
Q

What are the main parts of the complex soup of secretions?

A

Bacterial gut secretions
Moulting
Moulting fluid
Signalling/ Kairomones
Undigested matter

84
Q

What are the parts of bacterial gut secretions?

A

Bacteria released by conspecific horizontal transmission
Release of Enzyme/ structural proteins from degraded bacteria
By-product- harmful algae

85
Q

What is the moulting part of the complex soup of secretions?

A

carbohydrate chitin-based exoskeleton

86
Q

What is the moulting fluid of the complex soup of secretions made up of?

A

Digestion enzymes (proteins) chitinase/ chitinobase

87
Q

What occurs in the signalling/ Kariomones part of the complex soup of secretions?

A

Overcrowding/ stress induced signalling to regulate population
Signalling to algae

88
Q

What is the undigested matter of the complex soup of secretions made up of?

A

Undigested algae
Organic detrius (dead organic matter)
Bacteria
Algae

89
Q

What are the different types of environmental corona?

A

simplified corona
Complex corona
Corona formed in vivo
Corona formed insitu

90
Q

What is simplified corona?

A

ex-vivo (outside organism)
One or few biomolecule

91
Q

What are the characteristics of complex corona?

A

ex-vivo
biomolecular diversity

92
Q

What are the characteristics in vivo corona?

A

in-vivo = in organism formed
biomolecular diversity in & near organisms

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

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