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Two types of alginates, AlgLF and AlgP, were used in this study to produce alginate beads by electro-vibratory extrusion. AlgLF and AlgP exhibited different Mannuronate/Guluronate (M/G) ratios and molecular weights as measured by NMR and SEC-MALS. The calcium chloride concentration was found to have the greatest effect on bead size. Higher concentrations resulted in smaller beads. AlgLF with a higher molecular weight and a lower proportion of G blocks showed smaller beads. For both alginates, the bead size was also influenced by the flow rate and vibration frequency. Alginate solution aging showed a minimal effect. Alginate reticulation was modeled using a mathematical equation. The study provides insights for the optimization of alginate-based materials in different applications by shedding light on the main factors influencing bead size. The importance of the molecular weight, M/G ratio and calcium ion concentration in the gelling process is highlighted, providing opportunities for the tailoring of alginate materials through a phenomenological model. [ABSTRACT FROM AUTHOR]

Two types of alginates, AlgLF and AlgP, were used in this study to produce alginate beads by electro-vibratory extrusion. AlgLF and AlgP exhibited different Mannuronate/Guluronate (M/G) ratios and molecular weights as measured by NMR and SEC-MALS. The calcium chloride concentration was found to have the greatest effect on bead size. Higher concentrations resulted in smaller beads. AlgLF with a higher molecular weight and a lower proportion of G blocks showed smaller beads. For both alginates, the bead size was also influenced by the flow rate and vibration frequency. Alginate solution aging showed a minimal effect. Alginate reticulation was modeled using a mathematical equation. The study provides insights for the optimization of alginate-based materials in different applications by shedding light on the main factors influencing bead size. The importance of the molecular weight, M/G ratio and calcium ion concentration in the gelling process is highlighted, providing opportunities for the tailoring of alginate materials through a phenomenological model.

Ceratopteris thalictroides is a water fern very sensitive to both dehydration and low temperature. This study focuses on the cryopreservation of this species by encapsulation-dehydration technique, in particular on the effects of pre-culture step, alginate bead size and the physical conditions of culture on the cryopreservation efficiency. Encapsulated and non-pre-cultured gametophytes did not survive cooling with liquid nitrogen. When cryopreservation was preceded by a 2-week period of pre-culture, regrowth reached 42.1%. Reduction in the size of the alginate bead, and culture in total darkness resulted in improved gametophyte regrowth capacity (75.5% or 81.7%, respectively). The best results (91.3%) were obtained when all factors tested occurred simultaneously. The gametophytes recovered very quickly and sporophytes were formed within 4 weeks after rewarming. These simple improvements can be used, not only for the cryopreservation of gametophytes in cryptogams but also for some recalcitrant species of seed plants.

Ceratopteris thalictroides is a water fern very sensitive to both dehydration and low temperature. This study focuses on the cryopreservation of this species by encapsulation-dehydration technique, in particular on the effects of pre-culture step, alginate bead size and the physical conditions of culture on the cryopreservation efficiency. Encapsulated and non-precultured gametophytes did not survive cooling with liquid nitrogen. When cryopreservation was preceded by a 2-week period of pre-culture, regrowth reached 42.1%. Reduction in the size of the alginate bead, and culture in total darkness resulted in improved gametophyte regrowth capacity (75.5% or 81.7%, respectively). The best results (91.3%) were obtained when all factors tested occurred simultaneously. The gametophytes recovered very quickly and sporophytes were formed within 4 weeks after rewarming. These simple improvements can be used, not only for the cryopreservation of gametophytes in cryptogams but also for some recalcitrant species of seed plants. [ABSTRACT FROM AUTHOR]