Nanotechnology

Question 1

Name 3 advantages of micro needles

Answer 1

1) Painless and easy to use
2) Safe needle disposal
3) Eliminate spread of pathogens

Question 2

Name 2 reasons why drugs can’t always be oral

Answer 2

1) Poor absorption

2) Drug degradation in GI tract and Liver

Question 3

Where do micro needles penetrate the skin

Answer 3

Stratum corner into viable epidermis avoiding contact with nerve fibres and blood belles that reside in german layer

Question 4

Describe the process of photolithography

Answer 4

1) Silicon Wafer
2) Layer of oxide and nitrate
3) Layer of photo resist
4) UV shine
5) Photoresist developed to remove area exposed to UV
6) Reactive ion etching with KOH removes oxide and nitrate

Question 5

Describe the process of sacrificial micromolding and selective electrodeposition

Answer 5

1) Fabrication of master structure with laser ablated cavity
2) Micromold created featuring protruding pillow that will become lumen exit hole
3) Creation of replica
4) Sputting a gold seed layer onto replica
5) Electrodeposition of metal everywhere except cavity - dissolving sacrificial base material to release metal hollow microneedle

Question 6

Describe how solid micro needles work

Answer 6

Skin pretreatment
Insert and remove micro needles to form micro scale pores in surface
Drug formulation applied to skin for slow diffusion of drug through pores into body

Question 7

Drug coated micro needles - expectations

Answer 7

Dipping or spray
Controlled wetting/spreading
Should be water soluble for coating and dissolution
Adhesion between dried drug coating and micro needle
Coating excipient and solvent safe and compatible

Question 8

Explain and describe Drug Encapsulated microneedles

Answer 8

Rapid dissolving - water soluble sugars and polymers, photopolymerisable liquid monomers. - PLGA
Thermo -sensitive - moderate conditions
Speed of dissolution decides time of insertion

Question 9

Hollow Microneedles
What are they
Advantages
Requirements

Answer 9

Infusion of liquid formulations or diffusion through needle
Great control over amount/timing
Separation of micro needles during manufacturing
Already existing drug liquid formulations
Requires drug reservoir, pump, microfluidic networks

Question 10

A small molecule is how big

Answer 10

~1nm

Question 11

Basic structure of insulin

Answer 11

Six insulin molecules assembled in a hexameter ~6kda

Question 12

Size of trastuzumab

Answer 12

Herceptin (breast cancer) ~160kda with 10nm radius

Question 13

Advantage and disadvantage of proteins

Answer 13

Highly specific and potent, low permeability across biological barriers so injection route

Question 14

Structure of nucleic acids

Answer 14

Negatively charged due to phosphate group in backbone and hydrophilic due to sugar-phosphate backbone

Question 15

Disadvantages of antibodies

Answer 15

Low cell uptake, short blood circulation time, rapid degradation and lack of cell specificity

Question 16

What are the four viral vector types

Answer 16

1 - Adenovirus (non-enveloped, without outer layer)
2 - Adeno-associated virus
3 - Retrovirus
4 - Lentivirus

Question 17

Advantages and disadvantages of viral vectors

Answer 17

Efficient cell uptake, endosomal escape

Immunogenicity, low cell specificity, limited packaging ability and difficult to produce

Question 18

Advantages of non-viral vectors

Answer 18

Lower immunogenicity, no pre-existing immunity, larger pay load and easier to synthesise

Question 19

Advantages of degradable (PGLA)

Answer 19

Long term delivery, can affect pharmacokinetics by enabling sustained release

Question 20

Nanoparticles role in cancer

Answer 20

Usually larger than 10nm impedes diffusion through small vascular pores, leaky in tumours so up to 700nm can penetrate through endothelium

Question 21

How can we increase serum 1/2 life

Answer 21

Fc fusion proteins fuse with drug.
DNA recombinant technologies can endow proteins with IG like property by utilising neonatal Fc receptor recycling pathway

Question 22

Major Components of liposome

DOTMA

Answer 22

Phosphatidylcholine and phosphatidylserine

Ampiphillic molecule for making liposome

Question 23

Define ampiphillic

Answer 23

Both hydrophilic and lipophilic

Hydrophobic tails face inwards away from aqueous solution while hydrophilic heads are in contact with solution

Question 24

How do polymerosomes work

Answer 24

Polymeric versions of liposome (nitrogen = hydrophilic) self assemble into vesicle

Question 25

How do cationic polymers work

Answer 25

PE1 (Polyethyenimine) for delivering nucleic acids, positively charged so can condense negatively charged nucleic acids to form polyplexes.
Also helps binding to negative cell membrane

Question 26

Describe cell-penetrating peptides

Answer 26

Transactivator of transcription (TAT) protein from HIV virus could directly enter cells

Question 27

Describe pegylation

Answer 27

1) Highly hydrated which increase hydrodynamic radius of conjugate, reduce renal filtration
2) Prevents uptake and clearance by mononuclear phagocyte system
3) Decreases formation of neutralising antibodies against a protein drug by masking antigenic sites
4) Protection from proteolytic enzymes and proteases

Question 28

Three types of endocytosis

Answer 28

1) Phagocytosis
2) Pinocytosis
3) Receptor-mediated endocytosis

Question 29

Drug loading efficiency =

Loading capacity =

Answer 29

DLE = (drug added-free)/drug added
LC = (encapsulated drug/ nanoparticle mass) X 100

Question 30

Principle of 3D printing

Answer 30

Complex structures difficult to make using subtractive, additive can make within limited timeframe

Question 31

Problems with bioprinting

Answer 31

1) High temp - fuse deposition and selective laser sintering
2) Long UV exposure time - stereolithography
3) 3D printing - toxic binders

Question 32

Describe process of selective laser sintering

Answer 32

1) Lay an even layer of powders using roller
2) Laser beam scanned at pre-decided positions to fuse/melt powders together
3) Stage lowered and second layer laid
METAL, POLYMER, CERAMIC

Question 33

Describe process of 3D printing

Answer 33

1) Lay even layer of powder using roller
2) Binder jetted onto positions to fuse powders - adhesive
3) repeated then put in oven to make mechanically strong
METAL, POLYMER, CERAMIC

Question 34

Describe Inkjet printing

Answer 34

1) Piezoelectric actuator generates picoliter drop
2) Drop ejects and reaches substrate
3) Solidification - UV
PHOTOPOLYMERISABLE MONOMERS or cell suspension

Question 35

Describe the process of Stereolithography

Answer 35

1) UV laser scanned across layer of photopolymerisable monomers (reservoir of liquid monomers)
2) monomers polymerise and solidify
PHOTOPOLYMERISABLE MONOMERS

Question 36

Describe process of Fused Deposition Modelling

Answer 36

1) feed polymer into heater
2) Melt polymer
3) Extrude polymer through nozzle whilst stage moved in x,y,z direction
4) Cools and solidified
THERMOPLASTIC MONOMERS - Polyetherether ketone

Question 37

Describe Laser assisted printing

Answer 37

1) Laser beam shines upon energy absorbing layer
2) Shockwave generated resulting in ejection of drop which reaches substrate
3) Energy absorbing layer expands when UB light shone, expelling drop

Question 38

Describe Microextrusion bioprinting

Answer 38

1) Hydrogel with suitable viscosity range loaded into cartridge
2) Material extruded through nozzle by pressure
3) Hydrogel strand forms 3D structure

Question 39

What is a hydrogel

Answer 39

Non-fluidic colloidal network/polymer networks that ar physically or chemically cross-linked and contain a large amount of water. (shear thinning)