Construction of Chitin/PVA Composite Hydrogels with
Jellyfish Gel-Like Structure and Their Biocompatibility
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Abstract
High
strength chitin/poly(vinyl alcohol) (PVA) composite hydrogels
(RCP) were constructed by adding PVA into chitin dissolved in a NaOH/urea
aqueous solution, and then by cross-linking with epichlorohydrin (ECH)
and freezing–thawing process. The RCP hydrogels were characterized
by field emission scanning electron microscopy, FTIR, differential
scanning calorimetry, solid-state <sup>13</sup>C NMR, wide-angle X-ray
diffraction, and compressive test. The results revealed that the repeated
freezing/thawing cycles induced the bicrosslinked networks consisted
of chitin and PVA crystals in the composite gels. Interestingly, a
jellyfish gel-like structure occurred in the RCP75 gel with 25 wt
% PVA content in which the amorphous and crystalline PVA were immobilized
tightly in the chitin matrix through hydrogen bonding interaction.
The freezing/thawing cycles played an important role in the formation
of the layered porous PVA networks and the tight combining of PVA
with the pore wall of chitin. The mechanical properties of RCP75 were
much higher than the other RCP gels, and the compressive strength
was 20× higher than that of pure chitin gels, as a result of
broadly dispersing stress caused by the orderly multilayered networks.
Furthermore, the cell culture tests indicated that the chitin/PVA
composite hydrogels exhibited excellent biocompatibility and safety,
showing potential applications in the field of tissue engineering