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SOM 3 > Nanomedicines > Flashcards

Nanomedicines Flashcards

1
Q

what is angiogenesis?

A

creating of new blood vessels to cancerous tumour to provide nutrition/oxygen

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2
Q

what causes mutations to the DNA?

A
  • errors when dividing
  • inherited cancer genes
  • exposure to a virus e.g. HIV/HEPB
  • exposure to toxic substances e.g. chemicals/radiation
  • other e.g. parasites
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3
Q

what are characteristics of benign tumours

A

grow slowly
don’t spread
usually covered by normal cells

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4
Q

what are characteristics of malignant tumours

A

grow faster than benign tumour
spread; form secondary tumours

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5
Q

when are benign tumours a problem?

A

if large
uncomfortable/painful
visible/unpleasant to look at
press onto other organs
take up space
release hormones

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6
Q

what do treatment plans depend on?

A

location
severity
number of metastasis
age/condition on the pt
type of cancer

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7
Q

characteristics of chemotherapy

A

drugs kill cancerous cells, slowing the growth/prevent the spread

have a NTW
administered systemically; not targeted
reduce risk of recurrence
destroys cells after surgery

side effects - fatigue/nausea/hair loss

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8
Q

what is hyperthermia used for?

A

a treatment where body tissue is heated to 113 degrees F. to kill cancerous cells.
targeted to not reach healthy tissue
energy emitted from microwaves/radiowaves/laser/ultrasound

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9
Q

side effects of hyperthermia treatment

A

diarrhoea/vomiting/nausea

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10
Q

what are treatment plans for cancer

A

-chemotherapy
-hyperthermia
-immunotherapy
-hormone therapy

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11
Q

when is hormone therapy used?

A

slow/stop growth of breast/prostate cancer

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12
Q

side effects of hormone therapy

A

male - prostate cancer - nausea/fatigue/hot flashes/ enlarged breasts/diarrhoea

female - breast cancer - mood changes/nausea/fatigue/hot flashes/vaginal dryness/mood changes

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13
Q

what is immunotherapy treatment?

A

using the immune cells around the body defence system to target tumours

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14
Q

what are immune cells found around the tumour?

A

tumour-infiltrating lymphocytes (TIL)

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15
Q

what are some examples of immunotherapy?

A

-immune checkpoints inhibitors
-T cell transfer therapy
-monoclonal antibodies
-immune system modulators
-radiation
-surgery
-photodynamic therapy (PDT)
-drug delivery systems (DDS)

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16
Q

what are immune checkpoint inhibitors?

A

prevent an immune response from being so strong that it kills healthy cells

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17
Q

what are t-cell transfer therapy?

A

collecting T cells from patients, culturing them and reinfecting it

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18
Q

what are monoclonal antibodies?

A

bind to over-expressed receptors on the surface of cancer cells, helping the immune system to recognise and destroy cancer cells

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19
Q

what are immune system modulators?

A

boost the body’s immune system by producing cytokines

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20
Q

which cytokines treat cancer?

A

interferon alpha (INFs) and interleukin (ILs)

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21
Q

how does photodynamic therapy (PDT) work?

A

activated by light using a laser or other types
drugs are known as photosensitisers
targeted/localised treatment
useful for superficial tumours as light cannot penetrate the body

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22
Q

how does DDS work?

A

increasing the amount/concentration of drug delivery to tumour cells
decreasing the amount/concentration of drug delivery to tumour cells normal tissue

passively or actively (antibody targeting)

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23
Q

what is tumour microenvironment (TME)?

A

environment surrounding the tumour, including blood vessels/immune cells/fibroblasts/ signalling molecules and the extracellular matrix (ECM)

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24
Q

what are the characteristics for tumour targeting?

A

tumour stiffness due to fibrosis
-extracellular matrix
-intracellular pH (pH7-7.2)
-extracellular pH (acidic)
-uneven blood vessel distribution
- increase blood viscosity
-high interstitial pressure within the tumour
-high vessel permeability, low lymphatic drainage, poor perfusion, high cell density = interactions in tumour uptake

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25
Q

what are normal endothelium characteristics?

A

tight junctions
low permeability to large or hydrophilic molecules

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26
Q

how do conventional drugs (small, lipophilic molecules) pass through the capillary?

A

partition/diffusion processes

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27
Q

true or false is the endothelium leaky?

A

true

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28
Q

what helps retention of drug delivery systems in the tumour? what does this mean?

A

poor lymphatic drainage

increase accumulation due to the EPR effect

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29
Q

why is the EPR effect important for nanoparticles?

A

nanoparticles can deliver to cancer tissues

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30
Q

what is a problem for EPR?

A

rapid uptake by the RES, especially the liver&spleen

rapid clearance by the kidney

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31
Q

what is the characteristics of RES?

A

part of the immune system
formed from phagocytic cells
removes immune complexes from circulation

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32
Q

how can we avoid nanoparticles from being removed by RES?

A

change the
size
shape
charge
composition
tumour targeting moiety
using PEG coating

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33
Q

how does PEG coating avoid nanoparticles from being detected by RES?

A

shield the surface from phagocytosis, therefore, prolonging the retention time/circulation time

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34
Q

requirements for EPR (Enhanced Permeation Retention)?

for capillaries:

for kidney clearance

A

capillaries:
Small size (<600nm)
MW (>50kDA)
long circulation time in blood stream

kidneys:
5-10nm - KIDNEY PORE SIZE FOR GF
<50kDa MW

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35
Q

whats the difference between primary/secondary targeting of nano-medicines?

A

primary targeting - drug release to the disease state

secondary targeting - drug release to particular sub cellular compartments

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36
Q

how are ligands used for active targeting of nanoparticles?

A

ligands - protein/polysaccharide/aptamers/ peptides/small molecules

biological ligands used to…
-bind specific receptors on the surface of target cells
-facilitate uptake of modified NPs

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37
Q

how can proteins been used as active targeting strategies for biological ligands?

A

antibodies interrupt signals for cancer cells to grow

help immune system to destroy cancer cells
stop signals to form any blood vessels
delivery cell-killing substances to cancer cells (incl. chemotherapy/toxins/radiation)

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38
Q

how can peptides be used as active targeting strategies for biological ligands?

A

small in size
low costs
good stability
easy conjugation to the surface of NPs

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39
Q

how can aptamers be used as active targeting strategies for biological ligands?

A

class of short DNA/RNA several nucleotides
negatively charged
small, highly sensitive, biodegradable, immunogenicity
used to recognise proteins/lipids/nucleic acids/ sugars

special care needed to avoid nucleases

40
Q

advantages & disadvantages of active targeting strategies using biological ligands? and examples

A
41
Q

whats the difference between active vs passive targeting

A
42
Q

how can NPs size and surface morphology be assessed and why?

A

dynamic light scattering (DLS)/nanoparticle tracking analysis (NTA)/Transmission electron microscopy (TEM)/ scanning electron microscopy (SEM)/ atomic force microscopy (AFM) to check particle size distribution

43
Q

DLS characterisation (1/2)

A
44
Q

DLS characterisation (2/2)

A
45
Q

NTA characterisation

A
46
Q

TEM characterisation (1/2)

A
47
Q

TEM characterisation (2/2)

A
48
Q

SEM characterisation

A
49
Q

AFM characterisation

A
50
Q

how can NPs crystallinity be assessed?

A

x-ray diffraction (XRD)
differential scanning calorimetry (DSC)
brunauner emmet teller (BET)

51
Q

XRD characterisation

A
52
Q

DSC characterisation

A
53
Q

BET characterisation

A
54
Q

how can NPs surface charge be assessed?

A

measure the particles velocity in an electric field, electrophoretic mobility

using a laser light scattering technique to check the zeta potential of the surface

55
Q

how can the NPs surface hydrophobicity be determined?

A

hydrophobic interaction chromatography (HIC)
biphasic partitioning
contact angle measurements
x-ray photon correlation

55
Q

how can the NPs drug encapsulation be determined?

A
56
Q

how can the NPs drug stability studies be determined?

A

checked at different temperatures and maintaining their characteristics

57
Q

how can the NPs drug-excipient compatibility be determined?

A

FT-IR spectrophotometrey

58
Q

what are some therapeutic macromolecules?

A

1.amino acid based therapeutics
-peptides (<50 A.A.)
- insulin/cyclosporin
-proteins
- erythropoietin/vaccines/antibodies
2. polysaccharide therapeutics
-heparin
3. nucleic acid-based therapeutics
-siRNA
-plasmid DNA
-oligonucleotides

59
Q

what are the objectives of genetic material?

A
  1. restore/replace defective genes
  2. silence a defective gene
60
Q

how can you restore/replace defective genes using genetic material?

A

increase protein expression

using
- plasmid DNA
- mRNA

61
Q

how can you silence a defective genes using genetic material?

A

decrease protein expression (mainly RNA therapeutics)
* Antisence oligonucleotides (asODN)
* miRNA repressors
* RNA aptamers
* Small-interfering RNA (siRNA)
* Short-hairpin RNA (shRNA)

62
Q

how do Small-interfering RNA (siRNA) silence genes?

A

blocking translation of the gene

63
Q

how do Short-hairpin RNA (shRNA) silence genes?

A

blocking translation of the gene

64
Q

what are the types of gene carriers?

A

viral gene carriers
non viral gene carriers

65
Q

what is the risk of viral gene carriers?

A

natural ability to target the nucleus

66
Q

what are non-viral gene carriers?

A
  1. organic- peptide
  2. inorganic - CNT/Metals
    - cationic - bind to genetic material which is negatively charged
67
Q

what prevents absorption of gene carriers?

A
  1. degradation
  2. size - large
  3. charge - unionic
  4. hydropholicity - hydrophilic/water-soluble
68
Q

how are gene carriers administered?

A

parentreal
intrathecal
intravitreal
intradermal
intratumoural - not used much

69
Q

what gene carrier undergoes the most enzymatic degradation?

A

RNA

70
Q

how do gene carriers deliver through a membrane?

A

transcellular
paracellular - limited by tight junctions
carrier mediated

71
Q

how can large hydrophilic molecules cross the membrane?

A

rarely cross
if they do - carrier mediated

72
Q

how to increase gene carriers transport through the membrane?

A
  1. inc. hydrophobicity = incr. interaction w/ cell membrane = inc. permeation
  2. add permeation enhancers
  3. encapsulate nanomedicines
73
Q

how can you increase hydrophobicity of gene carriers? what does this allow?

A

increase cell penetration
e.g. lipidisation of peptides or oligonucleotides

increase transport across the cell membrane

74
Q

what are some examples of permeation enhancers?

A

surfactants
cationic polymers
calcium chelators - EDTA

75
Q

how do permeation enhancers increase gene transport across the cell membrane ?

A

disrupt tight junctions

76
Q

what are the types of enzymatic degradation ?

A

endonucleases - cuts in the middle of the DNA/RNA

exonucleases - cuts the end of the DNA/RNA

77
Q

what route of administration has a lot of proteolytic activity?

A

mainly oral, some rectal, buccal n nasal

78
Q

how do we protect from degradation?

A
  1. chemical modifications
    - phosphorothioate for oligonucleotides
    - pegylation - buffers the environment
  2. co-administration of inhibitors
    - risk of long term toxicity
  3. encapsulation of nanomedicines
79
Q

what is the nomenclature of complexes for polymers, dendrimers, CNT and lipid/liposomes?

A

polyplex
dendriplex
carboplex
lipoplex

80
Q

what happens when protein complexes interact with large salt conc. in the blood?

A

nucleic acid release too early = no effect

81
Q

what are extracellular non-viral gene therapy barriers?

A
  1. haemolysis (competition with -‘ve albumin and +’vely charged genetic material)
  2. nuclease attack
  3. tightly packed endothelial cells = prevent diffusion
  4. embolisation of capillaries
  5. RES entrapment
  6. extravasation to the extracellular space
  7. Large salt conc. in the blood = nucleic acid release
82
Q

what are intracellular non-viral gene therapy barriers?

A

lowered pH in cancerous cells compared to healthy cells = acidic conditions = increased lysosomes activity = degradation

83
Q

How do PEI work for gene delivery ? and deliver what?

A

PEI - Poly(ethyleneImine) - siRNA delivery
1. adsorptive endocytosis - condense -‘ve DNA
2. endosomal escape - increase osmotic swelling
3. endosomal rupture
4. siRNA break away from fragments of the carrier

84
Q

what polyamines are used for gene delivery?

A

PEI - Poly(ethyleneImine)

85
Q

what is the proton sponge effect?

A
  1. protonation and osmotic gradient established
    - increased protons = increase alkylation
    - increased protons = increase Cl conc. entering the cell
  2. swelling and osmotic pressure
    - H20 enters the cell to balance the osmotic pressure and follow the conc. gradient
  3. rupture of the cell
    - releases components
86
Q

what are theories of endosomal membrane rupture?

A
  1. proton sponge effect
    2.
    - 1. membrane disintegration
    - 2. local hole formation
      1. free polymer membrane intercalation and membrane disintegration
      1. polymer assisted hole formation
87
Q

name an example of a lipoplex?

A

lipofectamine 3000

88
Q

describe lipoplex gene transport

A
  1. -‘ve DNA and +’ve liposome = lipoplex
  2. lipoplex undergoes endocytosis to enter the cell
  3. lipoplex within an endosome
  4. endosome lipid mixing
  5. lipid disruption = genetic material release

OR
4. endosomal maturation
5. DNA fragmentation
6. lysosome

89
Q

describe lipoplex endosomal release?

A
  1. cationic lipid - interacts with -‘ve membrane
  2. re-arrangement of phospholipids within the membrane
  3. formation of neutral phospholipid pairs
  4. pore formed
  5. displacement and release of DNA inside the cell
90
Q

how can we aid lipoplex endosomal release?

A
  1. take advantage of the pH
    - pH sensitive liposome
    - helper-lipid (DOPE) = conformational change in acidic environments = membrane disruption
  2. liposome membrane fusion
    - cell-penetrating peptides - fusogenic peptides
91
Q

describe mRNA gene transport into a cell?

A
92
Q

why is PEG used in lipoplexes?

A

mask the positive charge of the surface area = increase transport into the cell

93
Q

what is a disadvantage to using PEG in lipoplexes?

A

allergic reaction - activation of caspase

administer GC prior to administration to minimise allergy

94
Q

what can you do to allergic pt’s when using PEGylated material?

A

administer GC prior to administration to minimise allergy

SOM 3 (26 decks)

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