UV-Crosslinked Collagen and Gelatin Sheets as Cell Scaffold Materials: Nanoscale Surface Properties and Cell...

Collagen and gelatin are promising cell scaffold materials, but their structural instability under physiological conditions necessitates crosslinking treatment. This study evaluated UV crosslinking (254 nm, 0-180 min) as a non-toxic alternative to chemical crosslinking for collagen sheets (CS) and gelatin sheets (GS). Physicochemical properties were characterized by gel fraction analysis, atomic force microscopy (AFM) in PBS, and Fourier transform infrared spectroscopy (FT-IR), while NIH-3T3 fibroblast proliferation was evaluated by CCK-8 assay. UV crosslinking dramatically improved GS water resistance (gel fraction increased from 22% to 80% at 60 min) while maintaining smooth nanoscale surfaces (R_q: 1-4 nm), whereas CS exhibited inherent high stability (90% gel fraction without UV treatment, reaching 95-98% after irradiation). Both materials achieved maximum elastic modulus at 60 min (CS: 2.0 MPa; GS: 1.5 MPa). UV irradiation significantly enhanced cell proliferation on both substrates compared to untreated controls (p < 0.05). CS showed consistently high proliferation across all UV-treated conditions (day 3 absorbance: ~2.5-2.7), while GS exhibited progressive increases reaching a maximum at 180 min (absorbance: ~2.9). The continued GS enhancement despite slightly decreased elastic modulus suggests that chemical factors, possibly related to RGD motif accessibility, contribute beyond mechanical optimization. UV crosslinking effectively establishes structural stability essential for cell scaffold function, with both materials representing effective, biocompatible scaffolds for tissue engineering applications.