2. ENVIRONMENTAL ChEMISTRy & TEChNOLOGy 2.1. Lectures
2. ENVIRONMENTAL ChEMISTRy & TEChNOLOGy 2.1. Lectures
2. ENVIRONMENTAL ChEMISTRy & TEChNOLOGy 2.1. Lectures
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Chem. Listy, 102, s265–s1311 (2008) Environmental Chemistry & Technology<br />
P88 SuRGICAL POLyESTER FAbRIC<br />
IMPREGNATED by CROSS-LINKED<br />
COLLAGEN<br />
PAVeL FILKA, LUCY VOJTOVá and JOSEF JAnČář<br />
Brno University of Technology, Faculty of Chemistry,<br />
Institute of Materials Chemistry, Purkyňova 464/118, 612 00<br />
Brno, Czech Republic,<br />
xcfilka@fch.vutbr.cz<br />
Introduction<br />
Collagen is a widely applicable protein in medical applications.<br />
The main advantage of this biomaterial is its ability<br />
to create fibers with a high strength and stability by using different<br />
cross-linking agents or physical methods. Collagen’s<br />
significant properties are biocompatibility and resorbability in<br />
organism, which might be particularly used at surface modification<br />
of surgical fabrics based on polyester silk (PES). The<br />
collagen modified PES nets used in surgery for longtime fixation<br />
or reinforcing different organs may accelerate healing<br />
injury as well as reduce inflammation of a tissue surrounding<br />
the implanted fabrics 1 .<br />
natural crosslinking gives collagen special properties,<br />
namely higher rigidity and endurance against proteolytical<br />
cleavage. However, during processing and utilization the<br />
collagen loses those particular properties. That is why the<br />
collagenous material is additionally cross-linked by chemical<br />
or physical methods in order to regenerate original net<br />
behaviours.<br />
Chemical methods employ bifunctional compounds<br />
(e.g. aldehydes, epoxides, isocyanides, carbodimides, acrylic<br />
acid etc.) which can react with amino groups of collagen<br />
in two different places resulting in generation of a new<br />
strengthing bond. Their main disadvantage is toxicity of<br />
used chemicals 2 . Instead of toxic aldehydes it might be used<br />
nontoxic 1-ethyl-3-(-dimethylaminopropyl) carbodiimide<br />
(EDC), which is soluble in water. For reaction acceleration<br />
the n-hydroxysuccinimide (nHS) as catalyst can be added to<br />
the system with EDC 3 .<br />
In this work cross-linking agents based on melaminformaldehyde<br />
resin (named as LYOFIX and MH – 83) as<br />
well as carbodiimide (system EDC/nHS) were used for<br />
crosss-linking collagen impregnated on the polyester surgical<br />
net CHS 100. Swelling behaviours in the water and degradation<br />
at 37 °C in physiological solution with the purpose of<br />
increasing biocompatibility of commercial surgical net were<br />
examined.<br />
Experimental<br />
Modified derivative of alkylmelamineformaldehyde in<br />
aqueous solution (LYOFIX, Ciba, Hungary), hexamethylolmelamineformaldehyde<br />
resin (MH-83, Draslovka a.s. Kolin,<br />
CZ), 1-ethyl-3-3-dimethylaminopropyl)-carbodiimide hydrochloride<br />
(EDC, Sigma-Aldrich s.r.o.), n- hydroxysukcinimide<br />
(nHS 98 %, Sigma-Aldrich s.r.o.), na 2 HPO 4 . 12H2 O<br />
(Lach-ner a.s. CZ), collagen type I (8 %, VUP a.s., Brno),<br />
net for surgical purposes (CHS 100 – knitwork made from<br />
s516<br />
polyester silk, VUP a.s., Brno), ultra - clean demineralize and<br />
deionize MILIQ water (prepared in arrangement of Millipore<br />
S.A. at FCH BUT, CZ).<br />
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<br />
Polyester fabric CHS 100 was cut into same size square<br />
pieces of about 1 cm 2 which were diped layed on the 5 ml<br />
of 1% collagen solution (prepared from 100% freeze – dried<br />
collagen) embedded with extra 5 ml of 1% collagen solution.<br />
This sample was air-dried for approximately 48 h to the constant<br />
weight.<br />
C r o s s - L i n k i n g<br />
Collagenous films were cross-linked by 2% solution<br />
of LYOFIX and Mn-83 resins for a period of 12 mins.<br />
Subsequently the samples were five times washed by the<br />
distilled water for 5 mins and dryied by air to the constant<br />
weight.<br />
Collagenous films were cross-linked by the ethanol solution<br />
containing 50 mmol dm –3 of EDC and 25 mmol dm –3 of<br />
nHS. After 4 h of cross-linking the samples were washed out<br />
for 2 h in 0.1M solution of na 2 HPO 4 . 12H2 O and finally four<br />
times for half an hour in the distilled water followed by airdrying<br />
to the constant weight.<br />
S w e l l i n g<br />
Swelling characteristics were evaluated to compare the<br />
cross-linking effectivity by each agent. Swelling proceeded<br />
for a period of 40 min to 1 h in MILIQ water at a laboratory<br />
temperature. Quantity of absorbed water was weighted in five<br />
minute intervals. Both water content (OV) and swelling ratio<br />
(SB) of each sample were calculated according to equation<br />
(1) and (2), where mc is weight of swollen sample in a given<br />
time and ms is weight of dry sample prior the swelling 4 .<br />
m<br />
OV [%] =<br />
c −ms<br />
⋅ 100<br />
(1)<br />
mc SB [–] = m c<br />
m s<br />
D e g r a d a t i o n<br />
Each sample was placed in the physiological solution<br />
with addition of sodium azide (0.1% naCl + 0.02% na 3 n)<br />
and placed into the incubator set to 37 °C to determine the<br />
hydrolytic degradation. Prepared samples were every day<br />
taken out from the incubator, dried by the filtration paper,<br />
consequently weighted and immediately placed back with<br />
fresh physiological solution. Degradation was expressed as<br />
percentual decrease of collagen weight in certain time having<br />
the zero point at the maximum of swelling according to equations<br />
(3) and additionaly (4)–(6).<br />
(2)