Nanomedicines for Protein Delivery Flashcards
What are biopharmaceuticals?
drugs made by living cells or organisms to treat diseases, such as monoclonal antibodies and recombinant proteins.
what are the main properties of biopharm/ proteins?
high MW >5000 Da
highly water soluble
hydrolysable bonds
large SA 30-50
diff types?
proteins
enz
peptides
nucleic acids
carbs
cell based therapies
vaccines
barriers to oral administration?
enzymatic degradation
acidic environments
transport across the intestinal epithelium
Is oral administration possible for proteins? Why?
no:
- need to overcome 3 barriers that limits their bioavailabulity
What are the instability problems for biopharmaceutical proteins? 2 types
chemical instability: Incompatibility with excipients: hydrolysis, Oxidation
physical instability: proteins are prone to denature, alter their native structure on exposure to heat, extremes of pH or organic solvents
difference between transcellular and paracellular transport?
T: though memb (lipophilic mols)
P: mols pass through tight junctions between cells (hydrophilic)
how are proteins administered?
parenteral routes - IV/IM/SC
mucosal - oral/nasal/pulmonary
name intranasal protein administration
flu vaccine
calcitonin
name sublingual protein administration
desmopressin
how are small proteins cleared?
glom filtration
how are large proteins cleared? >200nm
liver
spleen
lung
what are the immunogenicity risk factors of protein administration?
SC, IM >IV
large size
protein aggregation
what are the least immunogenic risk factors of protein administration?
neutral charged proteins
protein aggregates provoke what, compromising efficacy of drug?
immune response
How can you improve the bioavailability of protein drugs?
modify chemical structure
co-administer enzyme inhibitors
PEGylation
How does PEG affect the characteristics of protein drugs?
- increases proteins M volume abive glom filtration threshold
- Extends half-life
- Reduces immunogenicity- stealth effect!!
- Prevents premature degradation.
Advantanges of using protein nanodrugs for nasal and pulmonary delivery?
- low proteolytic activity compared to GI tract
- strong immune responses
- lower doses of drug required
- nasal route - delivery to the brain
Disadvantanges of using protein nanodrugs for nasal and pulmonary delivery?
- epithelium is firmly closed by tight functions - transcellular
- loose epithelium, no mucus barrier - paracellular only
What is the main barrier to nasal and pulmonary delivery?
airway epithelium is firmly closes by tight junctions.
What drugs are suitable for transdermal route?
Small hydrophobic drugs
what must proteins administered via transdermal route do?
i) penetrate through corneocytes and intervening lipids (intracellular transport) or
ii) pass between corneocytes (intercellular transport) or
iii) be transported across skin appendages such as hair follicles and sebaceous glands (skin appendageal transport) to reach target sites
what are the adv/disadv of therapeutic protein drugs?
Advantages:
- high specificity, great activity, and low toxicity
Barriers:
- vulnerable structure, susceptibility to enzymatic degradation, short circulation half-lives, and poor membrane permeability, stability issues, immunogenicity, inefficient membrane permeability and endosomal escape issues
- Development of effective protein delivery strategies is therefore essential to further enhance therapeutic outcomes to enable widespread medical applications
2 types of targeting w NPs?
passive: EPR effect
active: receptor-ligand ints
how are nanoparticle technologies used to deliver protein?
i) protect proteins from premature degradation or denaturation in biological environment
ii) enhance systemic circulation half-life of proteins with poor pharmacokinetic properties
iii) control sustained and/or tunable release which can maintain drug concentration in the therapeutic range
iv) target diseased tissues, cells, and subcellular organelles/ intracellular compartments, thus improving drug efficacy, mitigate adverse off-target effects and potentially lower the required dose for desired effect of biologic therapeutics
main issue w NPs: aggregates, why?
minimise surface charge + energy
triger opsonisation
MPS clears them after recognising :(
why do you get increase NP aggregation in blood?
complex, highly ionic nature
T/F: smaller liposomes <200nm are clared more slowly that larger?
true
what surface charge allows slower clearance/ better ability to avoid opsonisation and MPS?
neutral!
how does PEG have a longer half-life ?
increased systemic circulation due to evading mononuclear phagocytic system (MPS)
how does PEG evade mononuclear phagocytic system (MPS)?
neutral surface charge = avoids opsonisation
reduces non-specific adsorption of opsonin-stealth properties
what is active targeting used for in NPs?
facilitate drug transport
name active targeting agents used in NPs
cell-penetrating peptides (CPP)
- argine-rich peptides
- amphiphilic peptide carriers - Pep-1 = cell permeable sequence
how do cell-penetrating peptides work ? different methods
direct penetration
endocytosis-mediated uptake
translocation via transitory structure formation
= improve intracellular protein delivery
what are the 3 barriers for creating NPs?
organic solvents to make = denatures proteins/harm biological activity
low loading efficiency
drug release - controlled release needed
name the types of proteins delivered?
polymeric
inorganic
lipid-based
name examples of polymeric proteins delivered?
polymersome
dendrimer
polymer micelle
nanosphere
name examples of inorganic proteins delivered?
silica NP
quantum dot
iron oxide NP
gold NP
name examples of lipid-based proteins delivered?
liposome
lipid NP
emulsion
what must be added to inorganic proteins? and why?
a linker
attached to the surface - mask properties of the protein/peptide - surface charge
and linker must degrade at site of action
name an example of polymeric NPs
poly(lactic-co-glycolic acid) P
why is poly(lactic-co-glycolic acid)/PLGA used? polymeric NPs
biocompatible
biodegradable with favourable degradation rates
what are the advantages of polymeric NPs?
Biodegradable, water soluble, biocompatible, stable, and surfaces modification
what are the disadvantages of polymeric NPs?
particle aggregation, toxicity
Only a small number of polymeric nanomedicines are currently FDA approved and used in the clinic
Proteins release by both diffusion from the polymer matrix and the degradation/erosion of the polymer
how are polymeric NPs released?
by both diffusion from the polymer matrix and the degradation/erosion of the polymer
name an example of inorganic NPs
mesoporous silica NP
describe mesoporous silica NP (inorganic NPs)
inert
non-immunogenic
modifiable therapeutic agents
what are the disadvantages of using lipid-based NPs
stability issues
encapsulation efficacy
release profiles
classical eg of lipid based NPs?
liposomes
what are virosomes
lipid-based NPs
drug delivery systems based on unilamellar phospholipid membrane which incorporate virus-derived proteins
eg Epaxel
disadvantages of lipid based NPs?
have to use organic solvents in prep = not ideal for proteins
low loading efficacy esp smaller liposomes
how does drug release for lipid based NPs occur?
through diffusion - membrane
or by dissociation of lipid
what are stimuli-responsive liposomes?
smart liposomes
control drug release at site of action by lipid dissociation and simple diffusion
what stimuli activate stimuli-responsive liposomes?
temperature
pH
enzyme
redox
light
2 types of stimuli responsive liposomes?
pH responsive
thermosensitive TSL
how do thermosensitive liposomes work (TSL)?
contain phospholipids with phase transition temperature (Tm) slightly above the physiological temperature
eg DPPC - Tm 41degrees
what are alternative nanocarriers for protein delivery?
polymer network
polymersomes
polymer micelles
nano/micro emulsions
solid lipid
exosomes
micelles
niosomes
how do polymer network deliver proteins?
contains alot of H2O
protein loading/release: swelling and degradability
example of polymer network?
insulin loaded chitosan-based hydrogel NPs
Advantages of polymer networks as protein DDS?
- stealth character- guarantee extended plasma half-life - due to hydrophilic polymers
- Enhanced targeting- control polymer composition
Disadvantages of polymer networks as protein DDS?
the interference of the polymer with protein activity - due to steric hinderance
how are polymersomes made?
block/graft of amphiphilic copolymers with low MW PEG = hydrophilic core
have similar properties to those of liposomes
Advantages of polymersomes?
higher membrane stability than liposomes.
controlled size, shape and membrane thickness, mechanical strength, surface chemistry
Disadvantages of polymersomes?
- poor encapsulation efficiency (<5% for BSA and Hb) (3)
- membrane thickness - thermodynamic/kinetic barrier
name examples of polymersomes
poly ethylene glycol-poly propylene sulfide block copolymers and low MW PEG polymersomes
how are polymeric micelles made?
amphiphilic block copolymers = hydrophobic core
low micellar composition = low drug dissolution when injected into the blood = increase stability
low CMCs
Advantages of polymeric micelles ?
- more stable than surfactant-based micelles
- slow kinetics of dissociation: IV administration do not cause immediate dissolution
Disadvantages of polymeric micelles ?
- Limited encapsulation due to hydrophobic core
- Ionic-hydrophilic block copolymers - polyionic complex micelles for proteins via electrostatic interactions
what are nanoemulsions made out of?
Colloidal dispersions composed of oil, water and surfactants (1, 2)
o/w OR w/o microemulsion and nanoemulsions
Advantages of protein delivery by nanoemulsion?
- high encapsulation efficiency
- Cheap process, can easily be scaled up
Disadvantages of protein delivery by nanoemulsion?
use organic solvents, and high mechanical forces: pressure and temperatures
SLNs (term 1)
what are exosomes made out of?
lipid bilayer
neutral extracellular vesicles w native membrane composition
Advantages of using exosomes for protein drug delivery?
- Safe- minimal toxicity
- immunocompatibility
- High biocompatibility
disadvantages of using exosomes for protein drug delivery?
- Complex preparative and purification methods needed
what are niosomes made out of?
non-ionic surfactant vesicles (10-20um)
with non-ionic surfactants and cholesterol
Advantages of niosomes for protein drug delivery?
Biocompatibility
Low toxicity
Ease of preparation
Disdvantages of niosomes for protein drug delivery?
Physical instability as they can aggregate or fuse between themselves.
what are protein-based nanomaterials made of?
hollow protein NPs comprised of virus capsids, virus-like particles, ferritin, heat shock proteins, chaperonins….
formed by self assembly of protein subunits
carrier and drug in protein based nanomaterial made of..
same aa building blocks
advantages of protein based NPs as protein carrier?
Optimally sized for endocytosis
Nontoxic
Biocompatible
Biodegradable
disadvantages of protein based NPs as protein carrier?
Lack of reproducibility
