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CHEM426 > Synthesis of Nanomedicines > Flashcards

Synthesis of Nanomedicines Flashcards

(80 cards)

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1
Q

what are the 2 categories of nanomedicines that will be focused on

A

solid drug nanoparticles

nanocarriers

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2
Q

what are polymers made up of

A

a chain of multiple monomers

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3
Q

what are the 2 ways of making polymers

A

chain growth

step growth

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4
Q

describe the process of chain growth

A

adding monomers to the end of the polymer chain

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5
Q

describe the process of step growth

A

using a monomer with 2 functional ends growth can occur in both directions

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6
Q

what type of monomers are used in chain growth

A

molecules with alkenes form the carbon backbone

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7
Q

what monomers are used for step growth of polymers

A

bifunctional molecules like amino acids

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8
Q

what is the degree of polymerisation

A

chain length (number of monomers in chain)

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9
Q

what is a polymer therapeutic

A

polymers where an active drug makes up more than 50% of the polymer

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10
Q

give an example of a therapeutic polymer and describe how the drug is released in the body

A

aspirin or morphine polymer

polymer is hydrolysed to yield drug

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11
Q

what is a dendrimer and how can it bind to pathogens

A

highly branched polymer

has many binding sites for pathogen to bind

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12
Q

how do polymer drug conjugates work

A

drug is bound to polymer backbone by spacer (PEG)

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13
Q

what advantages are there of using polymer drug conjugates and give an example

A

may reduce toxicity via enhanced permeation and retention

doxorubicin is an example

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14
Q

how are polymer micelles formed

A

PEGylation of drug to make drug surfactants

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15
Q

what can be added to aid amine conjugation

A

N-succinimidyl carbonate

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16
Q

how do polymers act as surfactants when bound to a drug

A

if drug is hydrophobic the polymer acts as the hydrophilic section and forms micelles above the CMC

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17
Q

how does the length of a polymer chain effect the activity of the chain ends

A

in longer chains the concentration of chain ends is lower

heavy polymers coil so the chain ends can be harder to find

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18
Q

how can gold nanoparticles be used as nanocarriers

A

can be stabilised by surface adsorbed molecules (PEG)
these can undergo exchange with drugs
exchange can be tuned

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19
Q

give an example of how gold nanoparticles as nanocarriers can be tuned

A

ligands can chelate with radioactive materials as part of radiotherapy

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20
Q

describe multifunctional AuNPs as radiotherapy

A

thioterminated antibodies target breast tumours
177Lu isotope on thiolated PEG
stabilised by thio-PEGs

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21
Q

how gold nanoshells be made

A

NH2 functionality given to Si NPs
AuNPs added
treated with AuCl4 and H2O2 to grow gold surface

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22
Q

how can goldnanoshell be used as an anticancer drug

A

if they accumulate in tumours they can be selectively heated and killed with rear-IR laser

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23
Q

what can be achieved by ring opening polymerisation

A

from cyclic ester when acted by PEG form long chain carbonyls can be generated
PEG group can then be modified as part of a surfactant

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24
Q

how can nonfunctionalized polymer surfactant be used

A

can form micelles that can contain hydrophobic drugs - doxorubicin

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25
what can be achieved by mixing functionalised and nonfunctionalized polymers
mixed micelle is formed - properties can be tuned depending on polymer ratio
26
how can dialysis be used to assemble micelles
put polymer in good solvent within membrane place membrane in water solvent will exchange fresh water is added and final organic solvent is removed
27
what property must a dialysis membrane have to form micelles
pores must be smaller than the molecular weight cut off (MWCO)
28
how can dendrimers be used as unimolecular micelles
has cavities within structure | can encapsulate hydrophobic drugs
29
what size are the droplets in nanoemulsions
10-100nm
30
describe the properties of a macroemulsion
>1 micrometre opaque unstable
31
describe the stability of nanoemulsions
unstable
32
what are the droplet sizes in microemulsions
10-50nm
33
describe micro emulsions
stable emulsion | clear
34
how can emulsions be stabilised
by surfactants
35
what are solid lipid nanoparticles
similar to emulsion but with solid fat rather than droplets
36
how can solid lipid nanoparticles be made
mix lipid with drug and a solvent emulsify into water evaporate off organic solvent forms homogenised emulsion as solvent evaporation reduces droplet size
37
what are some advantages of solid lipid nanoparticles
improved drug stability control over drug release lipids are biodegradable relatively easy to scale
38
what is the main issue with solid lipid nanoparticles
lipid can crystallise without encapsulating drug - poor loading
39
what are 2 lab techniques that can be used to make solid lipid nanoparticles
homogenisation | ultrasonication
40
what is homogenation
process of making nanoparticles by pushing macroemulsion through small gap at high pressure
41
how can polymer nanoprecipitates be formed
amphiphilic polymers in organic solvent are quickly added to water poorer solvent displacement leads to worsening environment small structures assemble structures aggregate aggregation stops when colloidal stability is reaches
42
what factors effect the size of nanoprecipitates made
``` organic solvent and its conc miscibility of the polymer viscosity temperature rate of addition to antisolvent (water) ```
43
what are liposomes made up of
unimers with 1 hydrophilic head and 2 hydrophobic tails
44
how does the liposome bilayer form
interdigitation of hydrophobic tails
45
how can both hydrophilic and hydrophobic molecules be encapsulated in liposomes
hydrophilic molecules can reside in the core | hydrophobic molecules can be stored in the bilayer
46
what are some advantages of using liposomes
made of easily modifiable lipids biodegradible low immunoresponce low toxicity
47
what are the disadvantages of liposomes
hydrophobic layer is thin | can be hard to encapsulate hydrophilic molecules
48
what are SUVs
small unilamellar vesicles <100nm
49
what are LUVs
large unilamellar vesicles 100-1000nm
50
what is a GUV
giant unilamellar vesicle | 1-50 micrometres
51
what is a MLV
``` multilamellar vesicle (1-50 micrometres) double bilayer ```
52
what is MVV
multivesicular vesicles liposomes in liposomes 1-50 micrometres
53
how are liposomes produced
``` phospholipid dissolved in organic solvent dried rehydrated with water gentle stirring produces MLVs processing gives LUV/SUV ```
54
give the properties of neat doxorubicin
highly toxic administered as Cl salt has 3 different pKa values self assembles in water via pi stacking
55
what are the advantages of using doxil
avoids non-specific tumour toxicity extends circulation life targeting of tumour can be enhanced by EPR
56
what is EPR
enhanced permeation and retention poor quality ethelial lining of tumours allows liposomes to selectively enter tumours, lack of lymphatic system leads to retention
57
what are the issues with using doxorubicin in a liposome
nanoparticles can be detected as foreign bodies by MPS
58
what is MPS
mononuclear phagocyte system - removes foreign objects from blood stream
59
what are the maximum allowed doses of doxorubicin and doxil
rubicin - 60 mg/m2 | doxil - 50 mg/m2
60
what conditions must ideally be met for dox-liposome manufacture
simple method with cheap materials uniform liposome formation 100% trapping of drug good release rate
61
how do lipids effect drug release and elimination
choice of lipid effects bilayer permeability | longer chain phospholipids release drug more slowly
62
what can be added to doxil to modify membrane permeablity
chloesterol
63
what are the 2 two approaches to adding doxorubicin into a liposome
active and passive
64
how does passive encapsulation work and what is a problem with this
hydrate lipid layers with aqueous doxorubicin about 80% ends in liposome some ends in bilayer
65
how does active encapsulation work
dried liposome is hydrated with an acid buffer (citrate) external pH is increased doxorubicin is deprotonated and enters liposome it is then reprotonated
66
what is an alternative active encapsulation method
make liposomes with ammonium sulfate replace exterior with same pH NaOH ammonia in liposome leaves dox-NH2 moves in and protonates
67
what is the main problem that is addressed by solid drug nanoparticles
oral drugs are preferred but many have poor: solubility bioavailability permeation across key barriers
68
what are the 2 key barriers that are typically difficult to cross
blood brain barrier | gut blood barrier
69
what is bioavailablity
percentage of drug that enters the blood stream
70
what decides what can enter the blood from the gut
epithelial cells in the villi (small intestine)
71
describe drug uptake from gut to blood
active or passive
72
describe drug uptake from blood to gut and what is it called
reflux | active
73
why do nanoparticles strongly adhere to surfaces
have very high surface to volume ratio
74
what are the 2 approaches for making solid drug nanoparticles
bottom up and top down
75
what is the top down approach to making SDNs
homogenisation or nanomilling of large particles into smaller ones
76
what is the bottom up approach for making SDNs
nanoprecipitation or emulsion manipulation
77
what is nanomilling and what must be present in the process
grinding of large particles with solid beads | needs stabiliser present
78
what are the issues with attrition methods for making SDNs
breaking large particles makes new surfaces | if these are not stabilised the particles will aggregate
79
what can be used to stabilise newly broken SDNs
surfactants and polymers
80
what does the suitability of a stabiliser depend on
surface interactions conc of polymer balance of entropy loss and enthalpy gain

CHEM426 (4 decks)

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