Influence of lyophilization factors and gelatin concentration on pore structures of atelocollagen/gelatin sponge biomaterial

Abstract

This study aimed to investigate influences of lyophilization factors and gelatin concentration on pore structures of ACG sponge. ACG sponges of different freezing temperatures (−30, −80 and −196 o C), freezing times (1, 2 and 24 h), gelatin concentrations (0.6%AC+0.15%G, 0.6%AC+0.6%G and 0.6%AC+2.4%G), and with 500 μM fluvastatin were fabricated. Pore structures including porosity and pore size were analyzed by scanning electron microscopy and ImageJ. The cytotoxic effects of ACG sponges were evaluated in vitro. Freezing temperature did not affect porosity while high freezing temperature (−30 o C) increased pore size. The high gelatin concentration group (0.6%AC+2.4%G) had decreased porosity and pore size. Freezing time and 500 μM fluvastatin did not affect pore structures. The cytotoxicity and cell proliferation assays revealed that ACG sponges had no cytotoxic effects on human mesenchymal stromal cell growth and proliferation. These results indicate that ACG sponge may be a good biomaterial scaffold for bone regeneration.

Anatase Incorporation to Bioactive Scaffolds Based on Salmon Gelatin and Its Effects on Muscle Cell Growth

“…The pore changed from a round-like geometry to a flatter shape, which could be explained by a dentification effect of the added anatase since its higher relative density can increase the overall material weight, showing an ellipsoidal-like geometry parallel to the surface [29]. This modulation of the pore size and shape is fundamental in order to provide a favorable environment for cell survival and growth [30], which in the case of muscle cells is essential for interconnectivity and three-dimensional proliferation [31].…”

Gas Permeability of Mold during Freezing Process Alters the Pore Distribution of Gelatin Sponge and Its Bone-Forming Ability

“…Three-dimensional porous materials have been widely used in various fields, such as regenerative medicine, as scaffolds [ 1 ], cell-seeding materials [ 2 , 3 ], or drug carriers [ 4 ]. Suitable porous structures of such materials contribute to the efficient supply of oxygen and nutrients [ 5 ], which significantly influence cell activity, such as vascular and cell ingrowth [ 6 ], and cellular differentiation [ 7 , 8 ], resulting in sufficient tissue regeneration [ 6 ].…”

“…Freeze-drying, which is also known as lyophilization, has been used for a long time in the food, cosmetic, and pharmaceutical industries as well as in biotechnology, chemical synthesis, and regenerative medicine [ 2 , 4 , 11 , 12 , 13 ]. Freeze-drying is a process that involves removing water from a sample without destroying its three-dimensional structure.…”

“…At the prefreezing step, water in the samples is transformed into ice through water solidification [ 2 , 14 ]. Thus far, it has been the consensus that a porous structure can be modified by altering the cooling rate [ 4 , 12 ], freezing temperature [ 4 , 8 , 12 , 15 ], freezing process [ 10 , 16 ], annealing process [ 15 ], porogenic template [ 17 ], and/or concentration of samples [ 4 ]. The freezing temperature is thought to regulate pore size [ 15 ].…”

“…Therefore, it is used in various biomedical applications, including bone regenerative medicine [ 13 , 25 ]. The porous gelatin sponge is used alone [ 1 ] or in combination with other polymers [ 26 ], polyphenols [ 13 , 25 ], small molecules [ 4 ], or calcium phosphates [ 9 ] as a bone substitute material [ 9 , 13 , 25 ] or cell-seeding scaffold [ 3 ] in bone regenerative medicine. Thus far, various researchers have reported valuable findings for regulating the pore structure of gelatin sponges by altering the freezing temperature, freezing time, or sample concentration [ 4 , 10 ].…”