DESIGN OF SUPERMACROPOROUS BIOMATERIALS VIA GELATION AT SUBZERO TEMPERATURES —CRYOGELATION - Advanced Biomaterials: Fundamentals, Processing, and Applications - page 505

TABLE 14.2. The MG s Prepared Through Cryogelation Technique

Cryogels Mechanism of gelation Reference

Pore size, μ m

Physically cross-linked
PVA (DH > 97%) Up to 1 Through hydrogen

bond formation

[Bajpai and Saini
2005a,b ; Kokabi
et al., 2007;
Lozinsky, 1998 ;
Lozinsky et al.,
1998; Nho et al.,
2001]

Agarose cryogel Up to 500 Through hydrogen

bond formation

[Plieva et al., 2007b ]

Chemically cross-linked
Through cross-linking reaction using cross-linking agents
PVA (DH

Up to 80 Through chemical

reaction at acidic
pH using the
glutaraldehyde (GA)
as cross - linker

[Plieva et al., 2006b ]

< 90%)

Chitosan Up to 100 Through chemical

reaction at pH 5- 5.5
using the GA as
cross - linker

[Noir et al., 2007 ]

Agarose Up to 200 Through chemical

reaction at pH
13 using the
epichlorohydrin
(ECH) as cross-
linker

[Plieva et al., 2007b ]

Alginate Up to 100 Through reaction with

metal ions

Through free-radical polymerization reaction using APS/TEMED initiating system
pAAm, pDMAAm,
pHEMA, PEG, allyl-
agarose, dextran -
methacrylate

Up to 200 [Plieva et al.,

2006a,c ; Plieva
et al., 2007a,b,c ]

Through free-radical polymerization reaction using UV-vis light irradiation
Gelatin -
methacrylamide

[Dubruel et al.,
2007 ; Vlierberghe
et al., 2007 ]

Cellulose [Petrov et al., 2006 ]

resulting in entanglement of macromolecular coils [Lozinsky, 1998; Lozinsky and
Plieva, 1998]. Thus by simply controlling the thawing rate it is possible to prepare
mechanically stable and highly-porous PVA cryogel during one cycle of freezing-
thawing.