2. ENVIRONMENTAL ChEMISTRy & TEChNOLOGy 2.1. Lectures

Chem. Listy, 102, s265–s1311 (2008) Environmental Chemistry & Technology
P88 SuRGICAL POLyESTER FAbRIC
IMPREGNATED by CROSS-LINKED
COLLAGEN
PAVeL FILKA, LUCY VOJTOVá and JOSEF JAnČář
Brno University of Technology, Faculty of Chemistry,
Institute of Materials Chemistry, Purkyňova 464/118, 612 00
Brno, Czech Republic,
xcfilka@fch.vutbr.cz
Introduction
Collagen is a widely applicable protein in medical applications.
The main advantage of this biomaterial is its ability
to create fibers with a high strength and stability by using different
cross-linking agents or physical methods. Collagen’s
significant properties are biocompatibility and resorbability in
organism, which might be particularly used at surface modification
of surgical fabrics based on polyester silk (PES). The
collagen modified PES nets used in surgery for longtime fixation
or reinforcing different organs may accelerate healing
injury as well as reduce inflammation of a tissue surrounding
the implanted fabrics 1 .
natural crosslinking gives collagen special properties,
namely higher rigidity and endurance against proteolytical
cleavage. However, during processing and utilization the
collagen loses those particular properties. That is why the
collagenous material is additionally cross-linked by chemical
or physical methods in order to regenerate original net
behaviours.
Chemical methods employ bifunctional compounds
(e.g. aldehydes, epoxides, isocyanides, carbodimides, acrylic
acid etc.) which can react with amino groups of collagen
in two different places resulting in generation of a new
strengthing bond. Their main disadvantage is toxicity of
used chemicals 2 . Instead of toxic aldehydes it might be used
nontoxic 1-ethyl-3-(-dimethylaminopropyl) carbodiimide
(EDC), which is soluble in water. For reaction acceleration
the n-hydroxysuccinimide (nHS) as catalyst can be added to
the system with EDC 3 .
In this work cross-linking agents based on melaminformaldehyde
resin (named as LYOFIX and MH – 83) as
well as carbodiimide (system EDC/nHS) were used for
crosss-linking collagen impregnated on the polyester surgical
net CHS 100. Swelling behaviours in the water and degradation
at 37 °C in physiological solution with the purpose of
increasing biocompatibility of commercial surgical net were
examined.
Experimental
Modified derivative of alkylmelamineformaldehyde in
aqueous solution (LYOFIX, Ciba, Hungary), hexamethylolmelamineformaldehyde
resin (MH-83, Draslovka a.s. Kolin,
CZ), 1-ethyl-3-3-dimethylaminopropyl)-carbodiimide hydrochloride
(EDC, Sigma-Aldrich s.r.o.), n- hydroxysukcinimide
(nHS 98 %, Sigma-Aldrich s.r.o.), na 2 HPO 4 . 12H2 O
(Lach-ner a.s. CZ), collagen type I (8 %, VUP a.s., Brno),
net for surgical purposes (CHS 100 – knitwork made from
s516
polyester silk, VUP a.s., Brno), ultra - clean demineralize and
deionize MILIQ water (prepared in arrangement of Millipore
S.A. at FCH BUT, CZ).
P r e p a r a t i o n o f a C o l l a g e n F i l m s
Polyester fabric CHS 100 was cut into same size square
pieces of about 1 cm 2 which were diped layed on the 5 ml
of 1% collagen solution (prepared from 100% freeze – dried
collagen) embedded with extra 5 ml of 1% collagen solution.
This sample was air-dried for approximately 48 h to the constant
weight.
C r o s s - L i n k i n g
Collagenous films were cross-linked by 2% solution
of LYOFIX and Mn-83 resins for a period of 12 mins.
Subsequently the samples were five times washed by the
distilled water for 5 mins and dryied by air to the constant
weight.
Collagenous films were cross-linked by the ethanol solution
containing 50 mmol dm –3 of EDC and 25 mmol dm –3 of
nHS. After 4 h of cross-linking the samples were washed out
for 2 h in 0.1M solution of na 2 HPO 4 . 12H2 O and finally four
times for half an hour in the distilled water followed by airdrying
to the constant weight.
S w e l l i n g
Swelling characteristics were evaluated to compare the
cross-linking effectivity by each agent. Swelling proceeded
for a period of 40 min to 1 h in MILIQ water at a laboratory
temperature. Quantity of absorbed water was weighted in five
minute intervals. Both water content (OV) and swelling ratio
(SB) of each sample were calculated according to equation
(1) and (2), where mc is weight of swollen sample in a given
time and ms is weight of dry sample prior the swelling 4 .
m
OV [%] =
c −ms
⋅ 100
(1)
mc SB [–] = m c
m s
D e g r a d a t i o n
Each sample was placed in the physiological solution
with addition of sodium azide (0.1% naCl + 0.02% na 3 n)
and placed into the incubator set to 37 °C to determine the
hydrolytic degradation. Prepared samples were every day
taken out from the incubator, dried by the filtration paper,
consequently weighted and immediately placed back with
fresh physiological solution. Degradation was expressed as
percentual decrease of collagen weight in certain time having
the zero point at the maximum of swelling according to equations
(3) and additionaly (4)–(6).
(2)