Photocrosslinkable chitosan as a scaffold for tissue engineering

Abstract

UV-crosslinked chitosan was fabricated into porous scaffolds by freeze-dry method. In the first part, parameters including type of chitosan, concentration of chitosan solution, and freezing temperature to prepare uncrosslinked scaffolds were studied by scanning electron microscope (SEM). Freezing temperature was an important parameter affecting the pore morphology of the scaffolds. At the freezing temperature of -10℃, interconnecting round pores of 30-50 µm in diameter formed within the scaffold. In the second part, l,3-diazido-2-propanol (DAZ), a UV-labile compound, was added to chitosan acidic solution. The mixture was exposed to UV light in order to initiate crosslinking, and further fabricated by optimum freeze-dry condition obtained from the first part. The influences of type of chitosan, mole ratios between chitosan and DAZ, and irradiation time on the degree of crosslinking were studied. FT-IR was used to monitor the crosslinking reaction from the decrease of azide signal at 2100 cm⁻¹. The degree of crosslinking increased with the amount of DAZ and the irradiation time. The photo-crosslinked scaffold could retain their shape in acidic pH, unlike the non-crosslinked one. Compressive modulus of the crosslinked scaffold, however, decreased when the amount of DAZ increased. This is possibly resulted from photo-degradation of chitosan chain and/or the DAZ acting as a plasticizer. For cytotoxicity testing, the photo-crosslinked scaffold was proven to be non-toxic with L929 cells.