BIOMATERIALS LAB
NETWORK DEGRADATION
Monday, February 6th and Tuesday, February 7th
PRE-LAB
 Sign-in
 Quiz (Metters. 2000)
Rectangular Approximation
"Approximating the Area Under a Curve for AP Calculus | Education.com." Education.com | An Education & Child Development Site
for Parents | Parenting & Educational Resource. Web. 06 Feb. 2012. <http://www.education.com/study-help/article/rectangularapproximations/>.
Procedural Notes
 Teamwork
 Take turns pipetting, massing, ect. but make sure you
remember what has been added to the solution
 Pipetting




Check the volume, change by twisting dial
When filling, go to first stop
When ejecting precursors, go to second stop
When ejecting into syringe mold, go to first stop (to
avoid bubbles)
LINEAR MOLECULES
 PEG-PLA-MA
 MSA
MAA
(CH2)4
METHACRYLATE POLYMERIZATION
Step-growth
Polymerization
1 “Arm”
……
PEG
PLA
MA
Unlike last lab, each double bond can hook up with TWO
other molecules.
(Lin, C.C., Pharmaceutical Research. 26(3): 631-643. 2009)
SECTION 1
PEG-PLA-MA Network Synthesis
 Can surmise from Metters.2000 this will be bulk degrading
 Monitor change in network over time…




Size (diameter / height)
Weight
Young’s Modulus
Stereo-microscopy Imaging
Polyanhydrides. Wikipedia. 2011
PEG NETWORK SYNTHESIS
1. 10wt% PEG-PLA-MA in PBS
2. 10% photo-initiator by volume (LAP)
3. 40μL placed in 1mL syringe (tip cut off)
 to create cylindrical hydrogel sample geometry
4. exposed to UV-lamp for 10min
5. Remove and place in PBS
6. 3 PEG samples
SECTION 2
MSA/MAA Network Synthesis
 Glassy polymer
 Monitor change in network over time…




Size (diameter / height)
Weight
Young’s Modulus
Stereo-microscopy Imaging
Polyanhydrides. Wikipedia. 2011
(CH2)4
MSA/MAA NETWORK SYNTHESIS
Unlike PEG-PLA-MA, the MSA/MAA is a bulk reaction that
is not polymerized in a liquid phase.
1.
2.
3.
4.
5.
≈0.25g of MSA/MAA
0.1wt% DMAP photo-initiator added to PA-MA
Fill mold “sandwich” (glass slide / Teflon / glass slide)
exposed to UV-lamp for 10min
Remove and place in PBS
6. 1 MSA/MAA sample
TESTING
 Young’s modulus in Materials Testing Lab – 5N load cell
 Mass – after patting networks dry
 Size – use calipers for height and diameter. Don’t squish
hydrogel
 All three will be assembled and posted on blackboard.
 Stereo-microscopy Imaging – collect images with digital
camera
 Each group is responsible for collecting their own images
 All performed on D0, D1, D3, D8, D10
Big Picture
 Control of mechanical properties & degradation behavior allows
tuning to your application
 Ex: Control degradation rate  Control drug release rate
 Bulk
 Typically hydrophilic  Biologically inert
 Large number of available chemistries
 Surface
 Typically hydrophobic  Protein adsorption, cell interaction
 Constant turnover at surface  difficult to integrate with tissue
 Applications




Prevent postsurgical adhesion formation
In vivo drug and protein delivery
Temporary scaffold for tissue repair
Degradable sutures
SECTION 3
Degradation time-course
 Look at how networks degrade over time
 1 team member per data collection day
DAY
Monday’s Lab
Tuesday’s Lab
0
Monday, February 6th (in lab)
Tuesday, February 7th (in lab)
1
Tuesday, February 7th
Wednesday, February 8th
3
Thursday, February 9th
Friday, February 10th
8
Tuesday, February 14nd
Wednesday, February 15th
10
Thursday, February 16th
Friday, February 17th