Nanomedicine for protein drug delivery Flashcards
what are the main properties of protein?
high MW
highly water soluble
hydrolysable bonds
large SA 30-50
barriers to oral administration?
enzymatic degradation
acidic environments
transport across the intestinal epithelium
what are the instability problems associated with oral administration?
- chemical instability - incompatibility with excipients. hydrolysis and oxidation
- physical instability - proteins denature, heat/pH/organic solvents exposure
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
why is hydrolysable bonds important in proteins?
increase risk of enzymatic degradation and risk of hydrolysis
how are large proteins cleared?
liver
spleen
lung
how are small proteins cleared?
glomerular filtration
what are the immunogenicity risk factors of protein administration?
SC, IM >IV (half-life is low)
large size
protein aggregation (Provokes immune response)
what are the least immunogenic risk factors of protein administration?
neutral charged proteins
how do you improve bioavailability of protein administration?
- modify the chemical structure
- co-administration of enzyme inhibitors - proteolytic enzyme inhibitors = prevent hydrolysis of peptide/proteins
- polyethylene glycol PEG - mask surface charge properties
what does polyethylene glycol PEG do?
- increase molecular volume above glomerular filtration
- extends biological half life
- reduces immunogenicity effects (Stealth Effect)
- prevent premature degradation
whats the adv/disadv of nasal/pulmonary delivery of proteins?
adv-
1. low proteolytic activity compared to GI tract
2. strong immune responses
3. lower doses of drug required
4. nasal route - delivery to the brain
disadv-
1. epithelium is firmly closed by tight functions - transcellular
2. loose epithelium, no mucus barrier - paracellular only
what proteins are administered via transdermal route?
small hydrophobic drugs-due to low permeability through the stratum corneum
must
* 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/barriers 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
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
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 barriers for creating NPs?
- organic solvents to make = denatures proteins/harm biological activity
- low loading efficiency -due to large lize and MW of these molecules
- 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) PLGA
why is poly(lactic-co-glycolic acid)/PLGA used?
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
name an example of inorganic NPs
mesoporous silica NP
describe mesoporous silica NP
inert
non-immunogenic
modifiable therapeutic agents
name an example of lipid-based NPs
liposome
what are the disadvantages of using lipid-based NPs
stability issues
encapsulation efficacy
release profiles
what are virosomes
lipid-based NPs
drug delivery systems based on unilamellar phospholipid membrane which incorporate virus-derived proteins
what are stimuli-responsive liposomes?
control drug release at site of action by lipid dissociation and simple diffusion
Examples:PH responsive and Thermosensitive Liposomes
what stimuli activate stimuli-responsive liposomes?
temperature
pH
enzyme
redox
light
how do thermosensitive liposomes work (TSL)?
contain phospholipids with phase transition temperature (Tm) slightly above the physiological temperature
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 H20
protein loading/release: swelling and degradability
what are the adv/disadv of polymer networks?
Advantages
* stealth character- guarantee extended plasma half-life - due to hydrophilic polymers
* Enhanced targeting- control polymer composition Disadvantages
* the interference of the polymer with protein activity (4) - due to steric hinderance
what are the adv/disadv of polymersomes?
Advantages
* higher membrane stability than liposomes
* Controlled size, shape, membrane thickness, mechanical strength, permeability and surface chemistry (2)
Disadvantages
* poor encapsulation efficiency (<5% for BSA and Hb) (3)
* membrane thickness - thermodynamic/kinetic barrier
what are polymersomes made of?
block/graft of amphiphilic copolymers with low MW PEG = hydrophilic core
name examples of polymer networks
insulin-loaded chitosan-based hydrogel nanoparticles
name examples of polymersomes
poly ethylene glycol-poly propylene sulfide block copolymers and low MW PEG polymersomes (1)
name examples of polymeric micelles
poly(ethylene glycol)-b-poly(l-glutamic acid) (PEG-PLE),
what are polymeric micelles made of? and what does this mean?
amphiphilic block copolymers = hydrophobic core
low micellar composition = low drug dissolution when injected into the blood = increase stability
what are the adv/disadv of polymeric micelles as a protein carriers?
Advantages
* more stable than surfactant-based micelles
* slow kinetics of dissociation: intravenous administration do not cause immediate dissolution (1)
Disadvantages
* Limited encapsulation- hydrophobic core (2)
* Ionic-hydrophilic block copolymers - polyionic complex micelles for proteins via electrostatic interactions (3)
what are nanoemulsions made out of?
Colloidal dispersions composed of oil, water and surfactants (1, 2)
* Oil-in-water or water-in-oil microemulsion and nanoemulsions
what are the adv/disadv of using nanoemulsions as a protein carriers?
Advantages
* high encapsulation efficiency
* Cheap process, can easily be scaled up
Disadvantages
* organic solvents, and high mechanical forces: pressure and temperatures (3)
what are exosomes made out of?
lipid bilayer
neutral extracellular vesicles
what are the adv/disadv of using exosomes as protein carriers?
Advantages
* Safe- minimal toxicity
* immunocompatibility
* High biocompatibility
Disadvantages
* Complex preparative and purification methods needed
what are the adv/disadv of using niosomes as protein carriers?
Advantages
* ease preparation
* Biocompatibility
* low toxicity
Disadvantages
* physical instability- aggregate or fuse between themselves (3)
what are niosomes made out of?
non-ionic surfactant vesicles
with non-ionic surfactants and cholesterol
what are the adv/disadv of using protein based NPs as a protein carrier?
Advantages
* Optimally sized for endocytosis
* Nontoxic
* Biocompatible
* Biodegradable
Disadvantages
* Lack of reproducibility
