Cross-linking Chemistry of Type I and Type III Collagen with Anionic Polysaccharides - Natural Polymers, Biopolymers, Biomaterials, and Their Composites, Blends, and IPNs - page 162

and their negative effect on osteoblast attachment and proliferation, necessaciates
the requirement of suitable cross-linking agent for the preparation of biopolymer
with required thermal stability. As an alternative, attempt was made on to exploit
the cationic and anionic polymers of both synthetic and natural polymers for cross-
linking with collagen. Though, reports on interaction of cationic polysaccharides
with collagen are available, however, the available reports on anionic polysaccha-
rides involve additional chemical agents to enhance the cross-linking ability of AA
with collagen. Furthermore, in the said study, sodium alginate was used as a source
material. Nevertheless, in order to avoid the use of external agent for induction, in
the present study, we made the attempt on to use plain AA for cross-linking with
collagen. The results of our study demonstrate, cross-linked biopolymer has high
thermal and mechanical properties. Thus, the detailed description of the study has
been summarized below;
The AA, a linear anionic copolymer of 1, 4 linked β- D- mannuronic acid (M) 1,4
linked α- guluronic acid (G) arranged as homopolymeric or heteropolymeric block
(GG, MM and GM), constitutes major structural polysaccharide of brown seaweeds
( Phaeopyta ), found non-toxic, non-carcinogenic, biocompatible, sterilizable, and of-
fers cheap processing technique. The AA and its sodium/calcium salts have long been
used in food, cosmetics, drugs, drug delivery, tissue engineering, and so on. Alginate
wound dressing has recently been introduced for heavy exudation wounds as occlu-
sive dressing by Pharmacy industries. It is reported that exchange of ions by calcium
salts of AA and wound exudates accelerates the healing process (Albarghouthi et al.,
2000). Further, retaining the moist condition during wound healing and increases the
reepithelization process and healing rate by the use of salts of AA is also in reports
(Gombotz and We, 1998). Salts of AA also found application as dewatering agent for
the collagen films used for food casings. The mixture of collagen, sodium alginate
and konjac glucommnnan increases the thermal stability of the mixture appreciably
according to Wang et al. (2007).
eXtraCtioN aNd reCoNstitutioN oF tyPe i CollaGeN
Type I collagen from bovine skin was extracted as per the method of Mitra et al (in
press) and reconstituted according to Nomura et al. (1997). Since collagen was ex-
tracted using acetic acid, the resultant collagen was designated as acid soluble collagen
(ASC) and all the cross-linking studies were carried out only with reconstituted ASC
(RASC).
eXtraCtioN oF reCoNstitutioN oF tyPe iii CollaGeN
Type III Collagen from avian intestine was extracted as per the steps followed in the
flow chart given below;