Nanomedicines Flashcards
what is angiogenesis?
creating of new blood vessels to cancerous tumour to provide nutrition/oxygen
what causes mutations to the DNA?
- 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
what are characteristics of benign tumours
grow slowly
don’t spread
usually covered by normal cells
what are characteristics of malignant tumours
grow faster than benign tumour
spread; form secondary tumours
when are benign tumours a problem?
if large
uncomfortable/painful
visible/unpleasant to look at
press onto other organs
take up space
release hormones
what do treatment plans depend on?
location
severity
number of metastasis
age/condition on the pt
type of cancer
characteristics of chemotherapy
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
what is hyperthermia used for?
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
side effects of hyperthermia treatment
diarrhoea/vomiting/nausea
what are treatment plans for cancer
-chemotherapy
-hyperthermia
-immunotherapy
-hormone therapy
when is hormone therapy used?
slow/stop growth of breast/prostate cancer
side effects of hormone therapy
male - prostate cancer - nausea/fatigue/hot flashes/ enlarged breasts/diarrhoea
female - breast cancer - mood changes/nausea/fatigue/hot flashes/vaginal dryness/mood changes
what is immunotherapy treatment?
using the immune cells around the body defence system to target tumours
what are immune cells found around the tumour?
tumour-infiltrating lymphocytes (TIL)
what are some examples of immunotherapy?
-immune checkpoints inhibitors
-T cell transfer therapy
-monoclonal antibodies
-immune system modulators
-radiation
-surgery
-photodynamic therapy (PDT)
-drug delivery systems (DDS)
what are immune checkpoint inhibitors?
prevent an immune response from being so strong that it kills healthy cells
what are t-cell transfer therapy?
collecting T cells from patients, culturing them and reinfecting it
what are monoclonal antibodies?
bind to over-expressed receptors on the surface of cancer cells, helping the immune system to recognise and destroy cancer cells
what are immune system modulators?
boost the body’s immune system by producing cytokines
which cytokines treat cancer?
interferon alpha (INFs) and interleukin (ILs)
how does photodynamic therapy (PDT) work?
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
how does DDS work?
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)
what is tumour microenvironment (TME)?
environment surrounding the tumour, including blood vessels/immune cells/fibroblasts/ signalling molecules and the extracellular matrix (ECM)
what are the characteristics for tumour targeting?
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
what are normal endothelium characteristics?
tight junctions
low permeability to large or hydrophilic molecules
how do conventional drugs (small, lipophilic molecules) pass through the capillary?
partition/diffusion processes
true or false is the endothelium leaky?
true
what helps retention of drug delivery systems in the tumour? what does this mean?
poor lymphatic drainage
increase accumulation due to the EPR effect
why is the EPR effect important for nanoparticles?
nanoparticles can deliver to cancer tissues
what is a problem for EPR?
rapid uptake by the RES, especially the liver&spleen
rapid clearance by the kidney
what is the characteristics of RES?
part of the immune system
formed from phagocytic cells
removes immune complexes from circulation
how can we avoid nanoparticles from being removed by RES?
change the
size
shape
charge
composition
tumour targeting moiety
using PEG coating
how does PEG coating avoid nanoparticles from being detected by RES?
shield the surface from phagocytosis, therefore, prolonging the retention time/circulation time
requirements for EPR (Enhanced Permeation Retention)?
for capillaries:
for kidney clearance
capillaries:
Small size (<600nm)
MW (>50kDA)
long circulation time in blood stream
kidneys:
5-10nm - KIDNEY PORE SIZE FOR GF
<50kDa MW
whats the difference between primary/secondary targeting of nano-medicines?
primary targeting - drug release to the disease state
secondary targeting - drug release to particular sub cellular compartments
how are ligands used for active targeting of nanoparticles?
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
how can proteins been used as active targeting strategies for biological ligands?
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)
how can peptides be used as active targeting strategies for biological ligands?
small in size
low costs
good stability
easy conjugation to the surface of NPs
how can aptamers be used as active targeting strategies for biological ligands?
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
advantages & disadvantages of active targeting strategies using biological ligands? and examples
whats the difference between active vs passive targeting
how can NPs size and surface morphology be assessed and why?
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
DLS characterisation (1/2)
DLS characterisation (2/2)
NTA characterisation
TEM characterisation (1/2)
TEM characterisation (2/2)
SEM characterisation
AFM characterisation
how can NPs crystallinity be assessed?
x-ray diffraction (XRD)
differential scanning calorimetry (DSC)
brunauner emmet teller (BET)
XRD characterisation
DSC characterisation
BET characterisation
how can NPs surface charge be assessed?
measure the particles velocity in an electric field, electrophoretic mobility
using a laser light scattering technique to check the zeta potential of the surface
how can the NPs surface hydrophobicity be determined?
hydrophobic interaction chromatography (HIC)
biphasic partitioning
contact angle measurements
x-ray photon correlation
how can the NPs drug encapsulation be determined?
how can the NPs drug stability studies be determined?
checked at different temperatures and maintaining their characteristics
how can the NPs drug-excipient compatibility be determined?
FT-IR spectrophotometrey
what are some therapeutic macromolecules?
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
what are the objectives of genetic material?
- restore/replace defective genes
- silence a defective gene
how can you restore/replace defective genes using genetic material?
increase protein expression
using
- plasmid DNA
- mRNA
how can you silence a defective genes using genetic material?
decrease protein expression (mainly RNA therapeutics)
* Antisence oligonucleotides (asODN)
* miRNA repressors
* RNA aptamers
* Small-interfering RNA (siRNA)
* Short-hairpin RNA (shRNA)
how do Small-interfering RNA (siRNA) silence genes?
blocking translation of the gene
how do Short-hairpin RNA (shRNA) silence genes?
blocking translation of the gene
what are the types of gene carriers?
viral gene carriers
non viral gene carriers
what is the risk of viral gene carriers?
natural ability to target the nucleus
what are non-viral gene carriers?
- organic- peptide
- inorganic - CNT/Metals
- cationic - bind to genetic material which is negatively charged
what prevents absorption of gene carriers?
- degradation
- size - large
- charge - unionic
- hydropholicity - hydrophilic/water-soluble
how are gene carriers administered?
parentreal
intrathecal
intravitreal
intradermal
intratumoural - not used much
what gene carrier undergoes the most enzymatic degradation?
RNA
how do gene carriers deliver through a membrane?
transcellular
paracellular - limited by tight junctions
carrier mediated
how can large hydrophilic molecules cross the membrane?
rarely cross
if they do - carrier mediated
how to increase gene carriers transport through the membrane?
- inc. hydrophobicity = incr. interaction w/ cell membrane = inc. permeation
- add permeation enhancers
- encapsulate nanomedicines
how can you increase hydrophobicity of gene carriers? what does this allow?
increase cell penetration
e.g. lipidisation of peptides or oligonucleotides
increase transport across the cell membrane
what are some examples of permeation enhancers?
surfactants
cationic polymers
calcium chelators - EDTA
how do permeation enhancers increase gene transport across the cell membrane ?
disrupt tight junctions
what are the types of enzymatic degradation ?
endonucleases - cuts in the middle of the DNA/RNA
exonucleases - cuts the end of the DNA/RNA
what route of administration has a lot of proteolytic activity?
mainly oral, some rectal, buccal n nasal
how do we protect from degradation?
- chemical modifications
- phosphorothioate for oligonucleotides
- pegylation - buffers the environment - co-administration of inhibitors
- risk of long term toxicity - encapsulation of nanomedicines
what is the nomenclature of complexes for polymers, dendrimers, CNT and lipid/liposomes?
polyplex
dendriplex
carboplex
lipoplex
what happens when protein complexes interact with large salt conc. in the blood?
nucleic acid release too early = no effect
what are extracellular non-viral gene therapy barriers?
- haemolysis (competition with -‘ve albumin and +’vely charged genetic material)
- nuclease attack
- tightly packed endothelial cells = prevent diffusion
- embolisation of capillaries
- RES entrapment
- extravasation to the extracellular space
- Large salt conc. in the blood = nucleic acid release
what are intracellular non-viral gene therapy barriers?
lowered pH in cancerous cells compared to healthy cells = acidic conditions = increased lysosomes activity = degradation
How do PEI work for gene delivery ? and deliver what?
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
what polyamines are used for gene delivery?
PEI - Poly(ethyleneImine)
what is the proton sponge effect?
- protonation and osmotic gradient established
- increased protons = increase alkylation
- increased protons = increase Cl conc. entering the cell - swelling and osmotic pressure
- H20 enters the cell to balance the osmotic pressure and follow the conc. gradient - rupture of the cell
- releases components
what are theories of endosomal membrane rupture?
- proton sponge effect
2.
- 1. membrane disintegration
- 2. local hole formation - free polymer membrane intercalation and membrane disintegration
- polymer assisted hole formation
name an example of a lipoplex?
lipofectamine 3000
describe lipoplex gene transport
- -‘ve DNA and +’ve liposome = lipoplex
- lipoplex undergoes endocytosis to enter the cell
- lipoplex within an endosome
- endosome lipid mixing
- lipid disruption = genetic material release
OR
4. endosomal maturation
5. DNA fragmentation
6. lysosome
describe lipoplex endosomal release?
- cationic lipid - interacts with -‘ve membrane
- re-arrangement of phospholipids within the membrane
- formation of neutral phospholipid pairs
- pore formed
- displacement and release of DNA inside the cell
how can we aid lipoplex endosomal release?
- take advantage of the pH
- pH sensitive liposome
- helper-lipid (DOPE) = conformational change in acidic environments = membrane disruption - liposome membrane fusion
- cell-penetrating peptides - fusogenic peptides
describe mRNA gene transport into a cell?
why is PEG used in lipoplexes?
mask the positive charge of the surface area = increase transport into the cell
what is a disadvantage to using PEG in lipoplexes?
allergic reaction - activation of caspase
administer GC prior to administration to minimise allergy
what can you do to allergic pt’s when using PEGylated material?
administer GC prior to administration to minimise allergy
