80
the presence of a swelling inhibiting salt. Hetastarch contains molecules of variable molecular weights and therefore can be divided into three classes by their
average molecular weights: low molecular weight (70–130 kD), medium
molecular weight (about 200 kD) and high molecular weight (450–480 kD).
Examples of commercially available starches are Pentaspan, Hespan, EloHAES,
Hextend, HAES-steril, and Voluven. An intravenous solution of hydroxyethyl
starch is used to prevent shock and is used as plasma expander following hypovolemia caused by traumatic injuries, surgery, or other problem like malperfusion, as well as for acute normovolaemic hemodilution and preoperative
autologous blood donation (Gallandat Huet et al. 2000).
(b) Cadexomer iodine (CI): It is a hydrophillic modified starch polymer produced
by the crosslinking of dextrin with epichlorohydrin. It contains 0.9% iodine
arranged in the form of small beads. The iodine is immobilized in the microsphere’s helical matrix. Cadexomer iodine has a high absorptive capacity and
about 7 g of fluid can be absorbed by 1 g of CI (Torres et al. 2013). It is widely
used as a biomaterial for dressing wounds. It acts as an effective debriding agent
and antiseptic for exudative wound (Moberg et al. 1983; Laudanska and
Gustavson 1988; Holloway et al. 1989). When formulated as a topical wound
dressing, the iodosorb aborbs the exudate and particulate matter from the wound
surface. As the dressing becomes moist, the size of micropores is increased and
iodine is slowly released into the wound bed.
(c) Oxidized starch (OS): OS production involves the introduction of carboxyl and
carbonyl groups by means of subsequent starch depolymerization. It is achieved
by reacting starch with an oxidizing agent under controlled temperature and pH
of 2–7. This results in the hydroxyl groups (primarily at C-2, C-3 and C-6 positions) being transformed to carbonyl and/or carboxyl groups (Wang and Wang
2003). Bromine, chromic acid, hydrogen peroxide, hypochlorite, nitrogen
dioxide, oxygen, ozone, and permanganate have been used as oxidants to prepare OS. The desired characteristics of OS include high stability, film forming
ability, binding properties and low viscosity (Lawal et al. 2005; Sangseethong
et al. 2009). Oxidized starch is used to produce nontoxic, soluble and biodegradable PVA-OS fibers that may be used as a potential biomaterial in wound
dressing, tissue engineering and drug delivery (Wang et al. 2011).
Compatibility of Starch and Starch Based Products
for Biomedical Applications
The potential of starch and starched based products as medical polymer materials
has been widely recognized during recent years due to some advantages biomaterials. These include biodegradability, nontoxicity, low prices, acceptable mechanical
properties and most importantly, biocompatibility. Biocompatibility may be defined
as the ability of a material to perform with an appropriate host response in a specific
M. Ahmad et al.
the presence of a swelling inhibiting salt. Hetastarch contains molecules of variable molecular weights and therefore can be divided into three classes by their
average molecular weights: low molecular weight (70–130 kD), medium
molecular weight (about 200 kD) and high molecular weight (450–480 kD).
Examples of commercially available starches are Pentaspan, Hespan, EloHAES,
Hextend, HAES-steril, and Voluven. An intravenous solution of hydroxyethyl
starch is used to prevent shock and is used as plasma expander following hypovolemia caused by traumatic injuries, surgery, or other problem like malperfusion, as well as for acute normovolaemic hemodilution and preoperative
autologous blood donation (Gallandat Huet et al. 2000).
(b) Cadexomer iodine (CI): It is a hydrophillic modified starch polymer produced
by the crosslinking of dextrin with epichlorohydrin. It contains 0.9% iodine
arranged in the form of small beads. The iodine is immobilized in the microsphere’s helical matrix. Cadexomer iodine has a high absorptive capacity and
about 7 g of fluid can be absorbed by 1 g of CI (Torres et al. 2013). It is widely
used as a biomaterial for dressing wounds. It acts as an effective debriding agent
and antiseptic for exudative wound (Moberg et al. 1983; Laudanska and
Gustavson 1988; Holloway et al. 1989). When formulated as a topical wound
dressing, the iodosorb aborbs the exudate and particulate matter from the wound
surface. As the dressing becomes moist, the size of micropores is increased and
iodine is slowly released into the wound bed.
(c) Oxidized starch (OS): OS production involves the introduction of carboxyl and
carbonyl groups by means of subsequent starch depolymerization. It is achieved
by reacting starch with an oxidizing agent under controlled temperature and pH
of 2–7. This results in the hydroxyl groups (primarily at C-2, C-3 and C-6 positions) being transformed to carbonyl and/or carboxyl groups (Wang and Wang
2003). Bromine, chromic acid, hydrogen peroxide, hypochlorite, nitrogen
dioxide, oxygen, ozone, and permanganate have been used as oxidants to prepare OS. The desired characteristics of OS include high stability, film forming
ability, binding properties and low viscosity (Lawal et al. 2005; Sangseethong
et al. 2009). Oxidized starch is used to produce nontoxic, soluble and biodegradable PVA-OS fibers that may be used as a potential biomaterial in wound
dressing, tissue engineering and drug delivery (Wang et al. 2011).
Compatibility of Starch and Starch Based Products
for Biomedical Applications
The potential of starch and starched based products as medical polymer materials
has been widely recognized during recent years due to some advantages biomaterials. These include biodegradability, nontoxicity, low prices, acceptable mechanical
properties and most importantly, biocompatibility. Biocompatibility may be defined
as the ability of a material to perform with an appropriate host response in a specific
M. Ahmad et al.