Nanomedicine for protein drug delivery

Question 1

what are the main properties of protein?

Answer 1

high MW
highly water soluble
hydrolysable bonds
large SA 30-50

Question 2

barriers to oral administration?

Answer 2

enzymatic degradation
acidic environments
transport across the intestinal epithelium

Question 3

what are the instability problems associated with oral administration?

Answer 3

1. chemical instability - incompatibility with excipients. hydrolysis and oxidation
2. physical instability - proteins denature, heat/pH/organic solvents exposure

Question 4

how are proteins administered?

Answer 4

parenteral routes - IV/IM/SC
mucosal - oral/nasal/pulmonary

Question 5

name intranasal protein administration

Answer 5

flu vaccine
calcitonin

Question 6

name sublingual protein administration

Answer 6

desmopressin

Question 7

why is hydrolysable bonds important in proteins?

Answer 7

increase risk of enzymatic degradation and risk of hydrolysis

Question 8

how are large proteins cleared?

Answer 8

liver
spleen
lung

Question 9

how are small proteins cleared?

Answer 9

glomerular filtration

Question 10

what are the immunogenicity risk factors of protein administration?

Answer 10

SC, IM >IV (half-life is low)
large size
protein aggregation (Provokes immune response)

Question 11

what are the least immunogenic risk factors of protein administration?

Answer 11

neutral charged proteins

Question 12

how do you improve bioavailability of protein administration?

Answer 12

1. modify the chemical structure
2. co-administration of enzyme inhibitors - proteolytic enzyme inhibitors = prevent hydrolysis of peptide/proteins
3. polyethylene glycol PEG - mask surface charge properties

Question 13

what does polyethylene glycol PEG do?

Answer 13

1. increase molecular volume above glomerular filtration
2. extends biological half life
3. reduces immunogenicity effects (Stealth Effect)
4. prevent premature degradation

Question 14

whats the adv/disadv of nasal/pulmonary delivery of proteins?

Answer 14

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

Question 15

what proteins are administered via transdermal route?

Answer 15

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

Question 16

what are the adv/barriers of therapeutic protein drugs?

Answer 16

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

Question 17

how are nanoparticle technologies used to deliver protein?

Answer 17

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

Question 18

how does PEG have a longer half-life ?

Answer 18

increased systemic circulation due to evading mononuclear phagocytic system (MPS)

Question 19

how does PEG evade mononuclear phagocytic system (MPS)?

Answer 19

neutral surface charge = avoids opsonisation

reduces non-specific adsorption of opsonin-stealth properties

Question 20

what is active targeting used for in NPs?

Answer 20

facilitate drug transport

Question 21

name active targeting agents used in NPs

Answer 21

cell-penetrating peptides (CPP)
- argine-rich peptides
- amphiphilic peptide carriers - Pep-1 = cell permeable sequence

Question 22

how do cell-penetrating peptides work ? different methods

Answer 22

1. direct penetration
2. endocytosis-mediated uptake
3. translocation via transitory structure formation
   = improve intracellular protein delivery

Question 23

what are the barriers for creating NPs?

Answer 23

1. organic solvents to make = denatures proteins/harm biological activity
2. low loading efficiency -due to large lize and MW of these molecules
3. drug release - controlled release needed

Question 24

name the types of proteins delivered?

Answer 24

1. polymeric
2. inorganic
3. lipid-based

Question 25

name examples of polymeric proteins delivered?

Answer 25

polymersome dendrimer polymer micelle nanosphere

Question 26

name examples of inorganic proteins delivered?

Answer 26

silica NP quantum dot iron oxide NP gold NP

Question 27

name examples of lipid-based proteins delivered?

Answer 27

liposome lipid NP emulsion

Question 28

what must be added to inorganic proteins? and why?

Answer 28

a linker attached to the surface - mask properties of the protein/peptide - surface charge and linker must degrade at site of action

Question 29

name an example of polymeric NPs

Answer 29

poly(lactic-co-glycolic acid) PLGA

Question 30

why is poly(lactic-co-glycolic acid)/PLGA used?

Answer 30

biocompatible biodegradable with favourable degradation rates

Question 31

what are the advantages of polymeric NPs?

Answer 31

Biodegradable, water soluble, biocompatible, stable, and surfaces modification

Question 32

what are the disadvantages of polymeric NPs?

Answer 32

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

Question 33

name an example of inorganic NPs

Answer 33

mesoporous silica NP

Question 34

describe mesoporous silica NP

Answer 34

inert non-immunogenic modifiable therapeutic agents

Question 35

name an example of lipid-based NPs

Answer 35

liposome

Question 36

what are the disadvantages of using lipid-based NPs

Answer 36

stability issues encapsulation efficacy release profiles

Question 37

what are virosomes

Answer 37

lipid-based NPs drug delivery systems based on unilamellar phospholipid membrane which incorporate virus-derived proteins

Question 38

what are stimuli-responsive liposomes?

Answer 38

control drug release at site of action by lipid dissociation and simple diffusion Examples:PH responsive and Thermosensitive Liposomes

Question 39

what stimuli activate stimuli-responsive liposomes?

Answer 39

temperature pH enzyme redox light

Question 40

how do thermosensitive liposomes work (TSL)?

Answer 40

contain phospholipids with phase transition temperature (Tm) slightly above the physiological temperature

Question 41

what are alternative nanocarriers for protein delivery?

Answer 41

- polymer network - polymersomes - polymer micelles - nano/micro emulsions - solid lipid - exosomes - micelles - niosomes

Question 42

how do polymer network deliver proteins?

Answer 42

contains alot of H20 protein loading/release: swelling and degradability

Question 43

what are the adv/disadv of polymer networks?

Answer 43

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

Question 44

what are the adv/disadv of polymersomes?

Answer 44

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

Question 45

what are polymersomes made of?

Answer 45

block/graft of amphiphilic copolymers with low MW PEG = hydrophilic core

Question 46

name examples of polymer networks

Answer 46

insulin-loaded chitosan-based hydrogel nanoparticles

Question 47

name examples of polymersomes

Answer 47

poly ethylene glycol-poly propylene sulfide block copolymers and low MW PEG polymersomes (1)

Question 48

name examples of polymeric micelles

Answer 48

poly(ethylene glycol)-b-poly(l-glutamic acid) (PEG-PLE),

Question 49

what are polymeric micelles made of? and what does this mean?

Answer 49

amphiphilic block copolymers = hydrophobic core low micellar composition = low drug dissolution when injected into the blood = increase stability

Question 50

what are the adv/disadv of polymeric micelles as a protein carriers?

Answer 50

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)

Question 51

what are nanoemulsions made out of?

Answer 51

Colloidal dispersions composed of oil, water and surfactants (1, 2) * Oil-in-water or water-in-oil microemulsion and nanoemulsions

Question 52

what are the adv/disadv of using nanoemulsions as a protein carriers?

Answer 52

Advantages * high encapsulation efficiency * Cheap process, can easily be scaled up Disadvantages * organic solvents, and high mechanical forces: pressure and temperatures (3)

Question 53

what are exosomes made out of?

Answer 53

lipid bilayer neutral extracellular vesicles

Question 54

what are the adv/disadv of using exosomes as protein carriers?

Answer 54

Advantages * Safe- minimal toxicity * immunocompatibility * High biocompatibility Disadvantages * Complex preparative and purification methods needed

Question 55

what are the adv/disadv of using niosomes as protein carriers?

Answer 55

Advantages * ease preparation * Biocompatibility * low toxicity Disadvantages * physical instability- aggregate or fuse between themselves (3)

Question 56

what are niosomes made out of?

Answer 56

non-ionic surfactant vesicles with non-ionic surfactants and cholesterol

Question 57

what are the adv/disadv of using protein based NPs as a protein carrier?

Answer 57

Advantages * Optimally sized for endocytosis * Nontoxic * Biocompatible * Biodegradable Disadvantages * Lack of reproducibility