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

Degradation-Kinetics-Controllable and Tissue-Regeneration-Matchable Photocross-linked Alginate Hydrogels for Bone Repair

“…The molecular weight of the macromer, the degree of cross-linking, and the chemical structure of the polymer affect its morphology. 15,18 Previous studies reported that a lower degree of alginate oxidation led to a lower density of hydrogel networks, 15,28 which is in accordance with the results of this study. In this study, the changes in the structure of alginate by the oxidation reaction may also have resulted in denser, interconnected network-like structures on POMA gels compared to PMA gels.…”

“…Compared with PMA gels, POMA hydrogels displayed obviously faster swelling kinetics. Many factors, such as the macromer molecular weight and cross-linking density, impact the swelling behavior. , Compared to PMA gels, the decrease in the SR of POMA hydrogels may be due to oxidation-induced changes in the chemical structure of alginate and rapid degradation of the gels.…”

“…However, due to the absence of related hydrolytic enzymes, photocross-linked alginate hydrogels (and ionic cross-linked alginate gels) degrade much more slowly in vivo in an unpredictable manner by releasing various molecular weight alginate strands and may not be completely degraded or removed from the body through physiological systems in terms of their high-molecular-weight alginate polymers, which seriously limits their applications in biomedicine. 11,15,16 According to previous research, it is known that the degradation rate of photocross-linked alginate hydrogels is related to many factors like the molecular weight of alginate, 17,18 macromer concentration, 9,18 photoinitiator concentration, 18 UV light intensity and exposure time, 18 and the degradation microenvironment. 19 Lueckgen et al 20 found that enzymatically degradable peptides grafted into photocrosslinked alginate hydrogels can accelerate hydrogel degradation.…”

“…According to previous research, it is known that the degradation rate of photocross-linked alginate hydrogels is related to many factors like the molecular weight of alginate, , macromer concentration, , photoinitiator concentration, UV light intensity and exposure time, and the degradation microenvironment . Lueckgen et al found that enzymatically degradable peptides grafted into photocross-linked alginate hydrogels can accelerate hydrogel degradation.…”

Click Chemistry Hydrogels for Extrusion Bioprinting: Progress, Challenges, and Opportunities

“…Photo-cross-linking is widely used for 3D bioprinting due to its cost effectiveness, its ability to be carried out at room or physiological temperature, and its comparative flexibility of precursor polymer types in that any material that can be functionalized with a free radical polymerizable group can be used . However, photo-cross-linking typically requires the use of cytotoxic photoinitiators or the introduction of cytotoxic photopolymerizable functional groups into bioinks as well as the use of low-wavelength light that can impact cell viability at certain wavelengths and intensities, while the free radicals produced by photoinitiators and UV light may have harmful effects on cells by damaging cell membranes, nucleic acids, and proteins . Only a few studies exist that systematically document these concerns, and the practical impact of any kind of photoinduced toxicity is found to be insignificant in many publications; however, concerns still do persist over the use of photo-cross-linking particularly for the bioprinting of more sensitive cell types or using higher-intensity/lower wavelength lights.…”