This study tested the degradation properties of polyelectrolyte complex (PEC) films made of chitosan and polygalacturonic acid at different compositions and thicknesses. The films were tested for degradation in solutions with and without lysozymes over 17 days. Thinner films at 40% chitosan degraded more than thicker or 60% chitosan films. In vivo studies in rats found that 195 and 260 micron films were stable for at least 2 weeks and prevented adhesions without foreign body reactions. Ongoing research is further testing the films in rats to determine optimal anti-adhesion properties.

1. Design of PEC Films to Control Degradation
Karishma Desai, Shiv A. Mistry, Jordan R. Tutnauer*, Rene Schloss, Noshir A. Langrana
Department of Biomedical Engineering, Rutgers University, Piscataway, New Jersey 08854
*School of Arts and Sciences, Rutgers University, Piscataway, New Jersey, 08854
Background
A vast number of abdominal surgeries result in post-surgical adhesions that must later be
removed though a second procedure called adhesiolysis. These adhesions are often
associated with high medical expense as well as immense pain for the patient. These
adhesions are a result of two tissues that would normally move past each other, binding
via a fibrous bridge at a wound site with an inflammatory response which also consists
of the formation of a fibrous mass [1]. In normal conditions this mass resolves after some
period of time, however when an adhesion forms, fibroblast and macrophage cells
migrate towards it, strengthening the fibrous band. Polyelectrolyte Complex (PEC) films
are composed of two complementary charged polymers, in this case, Chitosan (Chi) and
Polygalacturonic Acid (PgA). The research in this lab focuses on Chi based PEC to
combat the problem of adhesions and produce an anti-inflammatory response at the site
of injury [2]. Lysozymes, which are secreted by macrophages that are found near wound
sites, were used to simulate a state of inflammatory response. Furthermore, based on
findings from in-vitro and early and animal studies [3], 40% and 60% composition and
thickness of the PEC were analyzed as design parameters. We present the results of the
testing done on this film for characterization of its degradation properties.
Conclusions
Materials and Methods
Results (cont.)
References
Acknowledgments
Results
Making of the PEC
• 300 mg of Chitosan dissolved in 30 mL of deionized water and 1 mL of 1.0 M HCL
and then centrifuged.
• 300 mg of Polygalacturonic Acid dissolved in 30 mL of deionized water and 1 mL of
1.0 M NaOH and then centrifuged.
• Certain volumes of Chitosan added into PgA to make the various concentrations
from 30%-70% to make 20 mL of total solution of each concentration.
• The 20 mL solutions are sonicated and and air dried to produce large films.
• For different thicknesses, layers of solution are added on top of already dried layers.
Degradation Testing
• 6 mm diameter sterilized samples of 40% and 60% Chitosan with thicknesses of 130
microns, 195 microns, and 260 microns were placed in solutions at 37C.
• Solutions of either pure PBS or PBS with lysozymes used to test whether the
inflammatory response simulated by lysozymes have an effect on degradation.
• Initial weights recorded, and then weights periodically taken between 3 and 17 days
to check for signs of degradation.
Degradation of In-Vivo Sized Samples
• 35 by 45 micron sized samples of 40% Chitosan at a thickness of 130, 195 and 260
microns were placed in solutions at 37C.
• Solutions of pure PBS were used to test whether there was any effects on degradation
in parallel with the In-Vivo study.
• Initial weights were recorded, and then weights were taken periodically at the one
week and two weeks marks to check for signs of degradation.
In-Vivo Studies
• 195 micron and 260 micron thickness films of 40% Chitosan were created.
• Vertical midline incision made in a single animal for each time point (1 week and 2
weeks).
• 3 intra-abdominal peritoneal ”buttons’’ made on each side.
• On one side, 1 button was a control while two were experimental and covered with a
195 micron thickness sample of film.
• On the other side, 1 button was a control while two were experimental and covered
with a 260 micron thickness sample of film.
• Surgical outcomes on the Control and Experimental buttons were examined after one
and two weeks.
• All films degraded between 3 and 17 days under environmental conditions of
37oC, regardless of whether the film samples were in contact with lysozymes or
not.
• The level of degradation varied based on the thickness of the material and for
130 and 260 micron films the 40% film degrades more in comparison to the
60% film.
• This shows that stability of three different film thicknesses were sustained up
until 17 days, beyond which the integrity of the films was such that they were
difficult to handle.
• The data suggests that the materials do not degrade for a minimum of two
weeks.
• The films implanted into the abdomen of a rat did not cause a foreign body
reaction, and were stable for at least two weeks.
• On going research includes further In-Vivo tests of the film in peritoneal
cavities of rats to determine the optimal anti-adhesion design.
1. Ward B. C. and Panitch A. ‘Abdominal Adhesions: Current and Novel Therapies.”
Journal of Surgical Research, 2011;91-111
2. Verma D, Previtera M, Schloss R, Langrana N. Polyelectrolyte complex membranes
for prevention of post-surgical adhesions in neurosurgery. Annals of Biomedical
Engineering, 2012;40(9)
3. D. Verma, , Previtera M, Schloss R, Langrana N. ,” Anti-Adhesions Properties of
Polyelectrolyte Complex Based Films”, 2013 Proc. ASME Summer Bioengineering
Conference, SBC-14481.
This work was performed towards partial fulfillment of the Honors Academy
program of the first author.
We would like to thank Dr. Hilton Kaplan for his help in performing the animal
surgeries.
Degradation Testing
• The above graphs show the degradation of the 40% and 60% Chitosan films
for 130, 195, and 260 micron thicknesses.
• The graphs indicate the percent change in weight for all concentrations and
thicknesses both with and without lysozymes.
• The lysozymes were found to have no significant effect on the degradation
of the films.
• The above graphs show the degradation of the three different film
thicknesses regardless of contact with lysozymes.
• All films began to degrade after incubation and by 17 days they degraded
on average 17-20% from their initial mass.
• Beyond 17 days all films became visibly weaker and more difficult to
handle when wet as well as when dry.
In-Vivo Studies
Degradation of In-Vivo Sized Samples
• The graph above shows the degradation of the 40% Chitosan films at 130, 195
and 260 micron thicknesses at the same size as the film used in the In-Vivo
studies.
• The 130 micron thickness film was more stable than the 195 or 260 micron
films between the 1 week and 2 week time points.
• All films began to degrade after incubation and by two weeks the 260 micron
thick film degraded an average of 14% of initial mass while the 195 micron
thick film degraded an average of 1.16%.
• Films provided a physical barrier at the potential sites of adhesion.
• 13 of 14 corner suture holdings had adhesions.
Buttons in rat PEC film placed over
two buttons
Film sample post In-Vivo study
-30
-20
-10
0
10
20
30
40
50
60
0 7 14
%ChangeinWeight
Day
Degradation of 40c Film
130 microns
-40
-30
-20
-10
0
10
20
0 5 10 15
Weight%Change
Day
130 microns
40c
40ly
60c
60ly
-40
-30
-20
-10
0
10
20
3 7 10 14 17
Weight%Change
Day
195 microns
40c
40ly
60c
60ly
-40
-30
-20
-10
0
10
20
3 7 10 14 17
Weight%Chang
Day
260 microns
40c
40ly
60c
60ly
-35
-25
-15
-5
5
0 5 10 15 20
%WeightChange
Day
130 Microns
40
60
-35
-25
-15
-5
5
0 5 10 15 20
%WeightChange
Day
195 microns
40
60
-35
-25
-15
-5
5
0 5 10 15 20
%WeightChange
Day
260 microns
40
60
-30
-20
-10
0
10
20
30
40
50
60
0 7 14
%ChangeinWeight
Day
Degradation of 40c Film
195 microns
260 microns
Films tested were circular and 0.5’’ in diameter Films tested were 35 by 45 micron sized