Effect of altering photocrosslinking conditions on the physical properties of alginate gels and the survival of photoencapsulated cells

Abstract

Research on biocompatible photocrosslinked organic chemical polymers for applications in biomedicine and tissue engineering has achieved satisfactory results, such as repairing or augmenting tissues. Photocrosslinked alginate gel is one of those polymers. However, there is little information in the literature regarding the preparation of photocrosslinked alginate hydrogels with high cell activity and appropriate mechanical properties by using suitable photoinitiator concentrations and reasonable ultraviolet (UV) exposure times. In this work, photocrosslinked alginate hydrogels formed with different concentrations of photoinitiator or UV exposure times were characterized by testing their mechanical properties and the viability of photoencapsulated osteoblast-like cells. To explore the degree of photocrosslinking of methacrylated alginate, the 1H NMR spectra of the gels were recorded with an NMR spectrometer, and the results showed that methacrylated alginate did not photocrosslink completely at low photoinitiator concentrations or for short UV exposure times. It was also revealed that the swelling behaviour, degradation profiles and elastic moduli of the hydrogel are tuneable by varying the photoinitiator concentration or UV exposure time. In addition, the viability and proliferation of the cells photoencapsulated in the gels gradually decreased with increasing photoinitiator concentration or UV exposure time. However, when the photoinitiator concentration and UV exposure time were controlled within a reasonable range, the cells in the gels maintained their high activity. In summary, the results indicated that the performance of the hydrogels could be tailored by adjusting the concentrations of photoinitiator or UV exposure time. This research may be used to further optimize cell photoencapsulation and photopolymerization strategies of photocrosslinked alginate gels or other biophotopolymers in tissue engineering and biomedicine and provides a theoretical basis for related research and future applications.