Figure 5.

Effects of warming on genipin structure and genipin-induced crosslinking activities.

Notes: (A) ¹³C NMR spectra of genipin in pure water. (B) ¹³C NMR spectra of genipin in 5 × NPB at 37°C for 6 h. (C) UV spectra of genipin in pure water (solid line) and in 5 × NPB at 37°C for 6 h (broken line). (D) Effects of warming times on genipin-induced crosslinking activities at 23°C. Genipin solution (5 mM) in 5 × NPB was incubated at 37°C for 0–17 h and was then mixed with 1% collagen solution to prepare collagen sols. Gelation times at 23°C were determined using rheological tests. (E) Gelation curves of collagen sols at 37°C after reaching gel points (G′ = G″) at 23°C. Numbers in the figure indicate warming times of genipin solutions.

Abbreviations: NMR, nuclear magnetic resonance; NPB, neutral phosphate buffer; UV, ultraviolet; min, minutes.