Nanoparts & cancer drug delivery Flashcards
Lec: intro to cancer and drug dleivery + characterisation of nanomedicines
unlike healthy cells, cancer cells do not …
carry on maturing (differentiation) or become so specialised
thus cells dont carry out their function in body
name of process of tumour creating its own blood vessels for blood supply and get rid of waste products etc?
angiogenesis
meaning of metastasis?
cancerous cells invade and destory surrounding healthy tissues and or organs
cancer spreading
term given where the cancer starts?
primary tumour
term given to tumour that has spread/ metastasized to another part from where it has originated?
secondary tumour
difference between benign and malignant tumour?
benign: cancer that doesnt metastasize
malignnat: cancer that invade/metastasize
cancer is a genetic disease, give some reasons for it?
inherited,
virus exposure,
toxic agent exposure,
unhealthy diet
examples of toxic agents thtat may cause cancer?
chemicals
radiation
UV rays form sun
…
what is cancer caused by specifically?
changes to genes (mutations) that control how cells function, especially grow and divide
type of tumour that is shielded by normal cells, grow slowly, do not spread?
benign
in what conditions/ cases may benign tumours cause problems?
if:
- become v large
- become uncomfortable/ painful
- are visible
- press on other organs
- take up space in skull
- release hormones, affecting how body works
malignant tumours can spread via what mechanisms to form secondary tumours?
bloodstream or lymph system
..they account for majority of cancer deaths
type of cancer treatment depends on what 2 things?
type of cancer
how advanced
all cancer treatment plans have SEs which are…
dose dependent
name the different treatment options for cancers?
hyperthermia
chemo
immunotherapy
hormone therapy
radiation
surgery
photodynamic therapy PDT
DDS
chemo uses drugs to kill cancer cells, slow growth, or prevent spread.
is treatment targeted for chemotherapeutic agents?
no
when are chemo drugs used?
when targeted/localised treatments not suitable
how are chemo drugs admin?
systemically.
have a NTW!
why may chemo be used after surgery/ radiation therapy?
to destroy any cancer cells remaining or spread to otherparts of body
3 examples of chemo drugs?
docetaxel
5FU
docorubicin
3 serious side effects of chemo such as docetaxel, 5 fluorouracil and doxorubicin?
fatigue, nausea and hair loss
name of treatment where body tissue is heated as high as 113F to help damage and kill cancer cells via probes that make energy from microwaves, radiowaves, ultrasound etc?
hyperthermia
some cons of hyperthermia treatment?
requires special treatment and expertise and can cause:
burns. blisters, pain, diarrhoea, nausea and vomiting
name of treatment used to slow/stop growth of breast and prostate cancers that use hormones to grow?
hormone therapy
- blocks bodys ability to make hormones/ interfered with how they behave in body
based on the MoA, list some SEs of hormone therapy?
hot flashes
diarrhea
nausea
fatigue
what does immunotherapy do?
helps bodys natural defence system in fighting cancer
name given to immune cells found near tumours?
TILs
tumour infiltrating lymphocytes
what may cause tumour to be undetected by immune system?
due to genetic changes of cancer cells or as result of having some surface proteins that shield tumour
name some cells immunotherapy includes
immune checkpoint inhibitors
Tcell transfer energy
MABs
immune system modulators- eg cytokines: INFs and ILs
name of therapy that is targeted and admin systemically?
immuno
MoA that allows T cell killing of tumour cell?
using checkpoint inhibitors
PD-L1 binds PD-1 and inhibits Tcell killing of tumour cell
by blocking PD-L1/ PD-1, then T cell can kill tumour cell
radiation treatment is localised and not targeted meaning it may cause damage to surrounding tissue, how does it work?
high doses of radiation damage DNA of exposed cancer cells to kill them and shrink tumours
surgery is the first line for most solid tumours - remove whole/part of it.
side effects?
pain and possible infections
name of treatment that uses drugs activated by light, called photosensitisers?
PDT
why is PDT associated with reduced damage to healthy tissues?
targeted and localised
how does PDT induce DNA damage and kill cancer cells?
upon exposure to light, the drugs (photosensitisers) make free radicals that do the job.
benefit of using DDSs in treating cancer? inc and dec what
inc conc of drug to tumour cells
dec conc of drug to healthy cells
2 types of targeting you can do w DDS to treat?
passive
active: e.g. antibody targeting
tumours share set of characteristics= ‘hallmarks of cancer’ such as…
inc cell proliferation
resistance to cell death
inc cell motility+ invasiveness
induction of angiogenesis
name of area around a tumour, including surrounding BV, immune cells, fibroblasts, signalling mols, and ECM?
TME
tumour microenvironment
what effect does fibrosis have on tumours ?
makes them stiff
ECM makes up >50% of total tissues and is acidic.
whats the range of pH (pHi) of intracellular?
7.0 - 7.2
why is intersistial pressure in solid tumours characteristically high?
high vessel permeability, low lymphatic drainage, poor perfusion and high cell density around blood vessels
effect of the high interstitial pressure within tumour?
may hamper adequate uptake of therapeutics in tumour tissue
what is pH of tumours?
outside acidic but inside is normal around 7
what causes the EPR effect?
increased permeability and decreased clearance of the tumor blood vessels.
This effect is primarily caused by the abnormal structure and function of the blood vessels within tumors, which tend to be leaky and disorganized compared to normal vessels.
what does the EPR effect allow for?
accumulation of larger molecules within the tumor, such as nanoparticles or macromolecular drugs, while also preventing their efficient clearance from the tumor tissue.
3 requirements of EPR effect?
small part size (>600nm)
apparent MW >50kDa
long circ time in bloodstream
why can very small particles not take advantage of EPR?
filtered out by kidneys :(
to do EPR effect, drug must have large MW above renal clearance threshold why?
to circulate for longtime. (as takes at least 6h to obtain EPR effect)
most small drugs have t1/2 of around 20min
2 potential benefits of loading drugs into NPs include primary and secondary targeting.
whats the difference?
primary targets drugs to disease site and secondary targets particular subcellular compartments such as nucleus -> more damage to cancer cells
use of nanomedicines means you can potentially reduce off target effects and lower amount of drug need to admin, why?
specific targeting and can control drug release (delay to specific location upon stimuli eg pH,light,heat,enz) and can alter PK of drugs (eg disperse hydrophobic drugs in aq conditions)
what 4 things can we modify/ select about a nanoparticle to improve drug delivery?
size
surface
shape
material
4 things to alter surface of NPs for better drug delivery?
PEGylation/ other coating
surface func group
surface charge
targeting ligand (antibody, peptide, aptamer)
different materials for a NP?
carbon NT or metal particle
- dendrimer
-PDC
-liposome
-polymer particle
….
different biological ligands eg proteins, polysaccharides, peptides, aptamers, small mols may be added to NPs –> ligand-modified NPs. what may this allow?
injected into body + active targeting! by specific binding of biological ligands
to receptor on target disease cells
BLs can facilitate uptake of modified NPs
how may biological ligands be incorporated/ introduced to NPs?
chemically conjugates/ physically adsorbed on NPs after formed
or linked with NP components eg polymers before formation
most common biological ligand and features of it?
proteins
antibodies = large and have high specificity
limits hm can attach on NP surface
antibodies (AB) can interrupt signals that cancer cells need to grow.
give an example AB and its use?
trastuzumab - cancer that is HER2 receptor +ve (breast cancer)
antibodies (AB) can help immune system destroy cancer cells
give an example AB and its use?
rituximab binds to cell surface protein CD20
antibodies (AB) can stop signals that help form blood vessels (angiogenesis inhibitors)
give an example AB and its use?
bevacizumab blocks angiogenesis by inhibiting VEGF-A
antibodies (AB) can deliver cell-killing substances to cancer cells including chemo agents, toxins, radioactive materials.
give an example AB and its use?
brentuximab vedotin (chemo agent) conjugate to treat lymphoma
advantages of peptides as an active targeting strategy?
well studies,
small,
low cost,
good stability,
ease of conjugation to NP surface,
can be conjugated to NPs at high density
aptamers can be used as biological ligands as active targeting.
what are they?
class of short nucleic acid (DNA/RNA) comprising several nucleotides
-ve charged
small
v sensitive
biodegradable
have immunogenecity
aptamers can be used as biological ligands as active targeting.
what can they recognise?
proteins
lipids
nucleic acids
sugars
intra and extracellularly
need special care to avoid nucleases
small molecules eg folic acid/ folate may be used as a biological ligand for active targeting. why?
folate receptors known to be overexpressed in solid tumour cells and macrophages
= attractive targets for many NPs via receptor mediated endocytosis
advantages and disadvantages of using proteins like antibodies and transferrins for active targeting?
+ high specificity
- large size
- low stability
advantages and disadvantages of using peptides such as RGD, IL4RPep-1 for active targeting?
+ easy fabrication
+small size
- cleavable by peptidase
advantages and disadvantages of using aptamers for active targeting?
+ high specificity
+ small size
- cleavable by nuclease
- high cost
advantages and disadvantages of using small molecules such as folate, anisamide and phenylboronic acid for active targeting?
+ small size and low cost
- targets also expressed in normal tissues
what is the difference between passive and active targeting?
passive relies on leaky vasculature and poor lymphatic drainage to improve pharmacodynamic of drug and does not provide sufficient delivery and has high systemic adverse effects.
active has high efficiency, reduces systemic effects, targets primary and secondary tumours and benefits from passive targeting properties
give one exmaple of a nanomedicine used in clincic and one way a systemic effect has been avoided?
liposome encapsulated doxorubicin for ovarian cancer: doxil protects patents from cardiotox of unencapsulated drug
characterisation of nanomedicines……
what can we check about NMs?
all physicochem props: size, surface charge, shape
stability
loading efficiency and controlling release mechanism
toxicity to diff cell lines
why may particle size + size distribution always be checked with NPs?
they affect PK
size also affects cellular uptake, tissue distribution, clearance…
name diff techniques that can be used to determine the size and surface morphology of nanoparticles?
DLS dynamic light scattering
NTA nanoparticle tracking analysis
briefly outline how dynamic light scattering (DLS) works?
particles in suspensions and emulsions, exposed to laser beam, particles move, laser scattered at different intensities, analysis of fluctuations using stokes einstein gives particle size
smaller parts move faster than larger in liquid,
based on Brownian motion (diffusion coefficient)
DLS estimates the size and size distribution of particles by giving what 2 parameters?
hydrodynamic diameter and PDI
why might DLS not work accurately if samples are too dilute or too concentrated?
dilute: not enough scattering events and concentrated causes multiple scattering, particles may not be freely mobile in suspension
DLS: whats calculated from the electrophophoretic mobility measured using laser soppler velocimetry. scattered light
surface charge/ zeta potential
name one technique that is based on light scattering and brownian motion that provides information about particle size, size distribution and count based concentration of particles?
nanoparticle tracking analysis
camera gets video of particles
give 3 microscopy techniques that are useful for size and surface morphology characterization?
TEM
SEM
AFM
name one technique that used an electron beam that interacts with an ultra thin specimen as it passes through, forming an image, which gives direct observation of the sample and tells us about the size, size distrubution, shape and aggregation?
TEM
electron microscopes have lower resolving power and magnification compared to light microscopes, true or false?
false
how is SEM different to TEM?
helps visualise surface morphology by adding 3d viewing
cons of sem?
expensive, time consuming, stability issues and lead to artefacts
which technique is helpful for visualising SLNs and can be obtained in an aq medium, which then provides analysis in 3D?
AFM
what information can we get from XRD?
atomic arrangements in amorphous materials
crystallinity
DSC (differential scanning calorimetry- diff to DLS) can give us what information about a sample ?
polymorphism, degree of crystallinity, purity, decomposition behaviour and melting behaviour
what does DSC measure?
diff in amount of heat req to increase temp of sample and reference measured as function of temp
ref sample should have well-defined heat capacity over range of temps to be scanned
what can be determined by measuring particle velocity in an electric field?
surface charge
what can laser doppler velocimetry be used to measure?
= laser light scattering technique.
velocity
what can be used to check the zeta potential?
malvern zetasizer
2 electrodes used and surface charge detected
what technique separates molecules based on their hydrophobicity in order to determine surface hydrophobicity?
hydrophobic interaction chromatography HIC
biphasic partitioning and measure contact angle
drug encapsulation
encapsulated drug = X - Y
total amount drug - free drug in supernatant solution
% of encapsulated drug = ?
amount of trapped drug/ total amount drug x 100
drug-excipient compatibility done using?
FT-IR spectrophotometer
results for drug, polymer, DDS are analysed sep then correlated for incompatibilities
