Biomedical Engineering Reference
In-Depth Information
Chapter 15
Cross-linking Chemistry of type i and type iii
Collagen with anionic Polysaccharides
A. Gnanamani, Tapas Mitra, G. Sailakshmi, and A. B. Mandal
iNtroduCtioN
The present study describes cross-linking chemistry of Type I and Type III collagen
with anionic polysaccharides (alginic acid), followed by characterization of the resul-
tant cross-linked material for, degree of cross-linking, thermal, and mechanical stabil-
ity. Required concentration of alginic acid (AA) and collagen (Type I and Type III)
was optimized. Results reveal, irrespective of the nature of collagen, 75% degree of
cross-linking was observed with AA at 1.5% concentration (w/v). Cross-linking with
AA increases the mechanical strength and thermal stability of both Type I and Type III
collagen. About 5-6-fold increase in tensile strength compared to plain collagen was
observed upon cross-linking with AA. The nature of bonding pattern and the reason
for thermal stability of AA cross-linked collagen biopolymer was discussed in detail
with the help of bioinformatics.
Collagen, the most abundant body protein and a biopolymer, till date, identified
as 28 different types and grouped under collagen super family. Fibrillar collagen, one
of the subfamily comprises, Type I, II, III, V, and XI as members. About 40% of
skin, 10-20% of bone and teeth and 7-8% of blood vessel shared by fibrillar collagen
(Kadler et al., 2007). Fibril-forming collagen, Type I, II, and III (Van der Rest and
Garrone, 1991) constitute the majority of the internal structure of the body. Type I col-
lagen comprises two α 1 chains and one α 2 chain whereas, Type III collagen comprises
of three α 1 chains. Collagen is an important biomaterial finding several applications
as prosthesis, artificial tissue, drug carrier, cosmetics, and in wound healing and in all
these applications stable collagen is required.
However, the low denaturation temperature of collagen restricts the applica-
tion as suitable biopolymers for clinical applications (Ru et al., 2005). As a re-
sult, most of the research is focused on to increases the thermal stability of the
biopolymer materials. Recently, use of cross-linking agent to increase and also
to improve the mechanical properties and thermal stability is reported by num-
ber of researchers (Sung et al., 1997).Collagen cross-linked with glutaraldehyde
introduced by Carpentier in the year 1960 showed high stability and after him,
almost all the biopolymer materials prepared from collagen is cross-linked with
glutaraldehyde. Nevertheless, realization on various demerits such as; calcifica-
tion, induction of local cytotoxicity due to depolymerization; release of unreacted
glutaraldehyde monomer; incomplete suppression of immunological recognition
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