Transcript Document

BIOMATERIALS LAB
Drug Delivery & Controlled Release
Monday, March 19th and Tuesday, March 20th
BME 245/445 – Lab 4
PRE-LAB
 Sign-in
 Quiz (Lin. 2009)
BME 245/445 – Lab 4
Big Picture: Drug Delivery
 Control drug delivery rate, dose & location
Toxic Level
Drug Concentration
Therapeutic Range
With Delivery
Device
Period of
Efficacy
Traditional
Delivery
Time
BME 245/445 – Lab 4
Big Picture: Drug Delivery
 Monolithic Device
 Drug is released by diffusion out of polymer matrix
 Release rate depends on:




Drug loading
Drug size
Mesh size
Shape of device
http://www.sigmaaldrich.com/materials-science/biomaterials/tutorial.html
 Applied in Norplant – implantable contraceptive device
 Release hormone over 5 years
 Discontinued – unpopular, not cost-effective
BME 245/445 – Lab 4
LINEAR MOLECULES
 PEGMA (2, 10, 20kD)
 Increase number of repeat units (n)
 Alter mesh size and thus rate of BSA release
Small Mesh Size
Large Mesh Size
BME 245/445 – Lab 4
METHACRYLATE POLYMERIZATION
Step-growth
Polymerization
1 “Arm”
PEG
MA
(Lin, C.C., Pharmaceutical Research. 26(3): 631-643. 2009)
BME 245/445 – Lab 4
SECTION 1
PEGMA Network Synthesis
1. 10wt% PEGDA in PBS+BSA (10 mg/mL)
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
PEG (mg)
28.3
PBS solution (μl)
225
Initiator (μl)
25
SECTION 2
Protein Collection Time Course (done by TA)
 BSA in hydrogel will release into surrounding PBS
 PBS will be routinely changed (stored in -80°C freezer)
 BSA concentration will be assessed for total release
BME 245/445 – Lab 4
SECTION 3
Protein Detection Assay – Coomassie
 Compared unknowns to known [BSA] standards
 Measure Absorbance at 590nm
BME 245/445 – Lab 4
From plate reader….
BSA Standards
Calibration Curve
1400
Absorbance at 590 nm
y = Ax +B
R² = 0.98
1200
PEG MW
[BSA] (ug/mL)
1000
800
Sample
#
600
1
400
2
200
…
2 kDa
10 kDa
20 kDa
n
0
0.2
0.4
0.6
0.8
1
1.2
Absorbance
BME 245/445 – Lab 4
% BSA released
What we are interested in….
Time
BME 245/445 – Lab 4
Theoretical Governing Eqns
Drug diffuses out
z=L
z=L/2
z=0
Drug diffuses out
BME 245/445 – Lab 4
Drug Concentration CA
C0
0
Governing Eqns
z=0
time
z=L
BME 245/445 – Lab 4
Simplifying Governing Eqns
BME 245/445 – Lab 4
Mesh Size Calculations
BME 245/445 – Lab 4
Safety
 General
 PEG/PBS/BSA are relatively benign
 Lab glasses, gloves, closed toed shoes
 No food, no drinks, no applying makeup
LAB TEAMS- Monday
TEAM A
2k
TEAM B
2k
TEAM C
10k
TEAM D
10k
TEAM E
20k
Ripa
Chowdhury
Chris Farrar
Matt Hazelett
Caressa Chen
Ruth Davis
Eric Comeau
Christine Mclin
Rachel Rakvica
Tonima Quabili
Corinne Lampe
Margaret Fettis
Kristen
Harding
Yi Rao
Ka Lai Tsang
Mitchell Long
Andrea Wong
Stephen Zhang
Chris Schmitt
Bingqing Wang
BME 245/445 – Lab 4
LAB TEAMS- Tuesday
TEAM F
2k
TEAM G
10k
TEAM H
20k
Team I
20k
Ibrahima Bah
Raymond
Goo
Seung Hoon Lee
Alex Kotelsky
Joseph
Mozingo
Sara Nowacki
David Narrow
Jennifer
Williams
Carly
Sombric
Spencer
Putnam
Erin
Schnellinger
Yoon-Suk Yi
Nicole Varble
Shijie Zhong
Sean Rodriguges
Sijia Zhang
Douglas Clift
Robert
Mcwhorter
Shijie Zhong
BME 245/445 – Lab 4