Final Review - Chapter 12

Question 1

hydrogels are formed by

Answer 1

crosslinking of water-soluble/hydrophillic polymers resulting in insoluble network polymers with high affinity for water

Question 2

HEMA can be used to create a hydrogel using radical polymerization - true or false

Answer 2

FALSE - it needs a crosslinker to be able to form a hydrogel - EDGMA connects layers of HEMA

Question 3

methacrylated hylauronic acid crosslinker

Answer 3

PEG dimethylcrylate

Question 4

base materials of 1. naturally derived hydrogels and 2. synethically derived hydrogels

Answer 4

1. collagen/gellatin - decellularized ECM, Fibrin, hyaluronic acid
2. PEG, poly(vinyl alcohol, urethanes, acrylamides-NIPAaM)

Question 5

advantages of naturally derived hydrogels

Answer 5

intrinsic support of cell adhesion, inherent biodegradabilty into non-toxic compounds

Question 6

disadvantages of naturally derived hydrogels

Answer 6

batch-to-batch variability, immunogenicity/contamination issues, weak mechanical properties, little control over degradation

Question 7

advantages of synthetically derived hydrogels

Answer 7

reproductive manufacturing
affordable
non-immunogenic
controlled properties

Question 8

disadvantages of synthetically derived hydrogels

Answer 8

lack of bioactivity
lack of bio-responsiveness

Question 9

collagen gel

Answer 9

made from gly-x-y, commonly immunogenic, composition: acid-solubilized collagen NaOH, 10X phosphate buffered saline - triple helix and covalent crosslinks lost during acid solubilization

Question 10

Advantages of click chemistry

Answer 10

spontanous, rapid, highly selective (orthogonal), high yield/ high conversion, no by-products

Question 11

Gel-MA structure

Answer 11

gelatin modified with vinyl groups for covalent crosslinking

Question 12

Thoilated HA structure

Answer 12

Hyaluronic acid modified with thiol groups and crosslinked with acrylates by micheal addition step-growth polymerization

Question 13

guest-host crosslinking defintion

Answer 13

non-covalent crosslinking method for self-healing materials

Question 14

gel-ma advantages

Answer 14

increased crosslinking equals better mechanical properties and better degradation control because of covalent crosslinking

Question 15

Thoilated-HA advantages

Answer 15

Biocompatible, degradable, low MW fragments promote angiogenesis - this is most biomimetic approach - can combine with thiolated gelatin

Question 16

synthetic ECM

Answer 16

biomemetic, chemically reversible, easily degradeable, creates integrin mediated adhesion because of RGD sequence - contains thiolated HA, Gelatin with SH groups and PEGDA

Question 17

guest host hydrogels

Answer 17

host for hydrophobic “guest” molecules
-results in non-covalent crosslinking

Question 18

shear thinning

Answer 18

shear is present, covalent bonds are not present
foundational to self-healing materials

Question 19

PEGylated fibrinogen

Answer 19

contain RGD sequence, cleaved at certain recognized sequences - however, sourcing fibrinogen is hard since it is from humans and there it is a high regulatory burden

Question 20

Hubbell created _____

Answer 20

PEG peptides

Question 21

functional groups for micheal addition

Answer 21

esters and thiols

Question 22

PEG peptides structure

Answer 22

PEG acrylate chain with MMP sensitive/cleavable peptides with adhesive and growth factors

Question 23

how to promote cell adhesion

Answer 23

add RGD sequence

Question 24

good things about hydrogels

Answer 24

great for local/controlled delivery of growth factors, made from aqueous buffers, physiological tonicity, pH protects protein, crosslinking is benign

Question 25

bad things about hydrogels

Answer 25

most therapeutically useful peptides are smaller than 10 nm which makes release mainly controlled by diffusion and makes it last for a shorter period of time (hours)