Controlling the microstructure of lyophilized porous biocomposites by the addition of ZnO‐doped bioglass

Abstract

The study presents the results of the study on porous composite biomaterials obtained using lyophilization method based on polymer solutions: chitosan solution, sodium alginate solution, or polylactide solution, and ZnO‐doped bioglass from CaO‐SiO2‐P2O5 system. The properties of zinc ions were used, which have bactericidal, immune‐stimulating, and tissue‐regenerating functions in the organism. The effects of the polymer type, granulation, and bioglass amount, as well as the amount of solvent on composite microstructure, were studied. SEM‐EDS technique was used to visualize and describe the surface results occurring after incubation of composite in the Simulated Body Fluid (SBF). The selected method of preparation, used substrates, and the process conditions resulted in porous composites of the open, connected pore structure. It was proved that composite microstructure may be controlled by the appropriately selected amount of bioglass in relation to the polymer and its appropriate grain sizes. The morphology of the obtained composites is also affected by the amount of the solvent in lyophilizated dispersions. It was proved that bioactivity in composite material is induced by bioglass because after SBF incubation the surface layer is enriched with Ca and P, what may lead to a gradual formation of apatite layer. The obtained results enabled selection of the composites for further in vitro studies concerning cytotoxicity and antibacterial activity.

The studies of cytotoxicity and antibacterial activity of composites with ZnO‐doped bioglass

“…Table presents the symbols of composites obtained in accordance with the methods described by Ciołek and the polymer‐to‐bioglass weight ratio for those composites. The composites were derived by means of lyophilization of stable dispersions formed by magnetic and ultrasound mixing of the polymer solutions with bioglass grains.…”

“…The lyophilization process involving freezing and sublimation of the solvent was performed using the Christ BETA 1‐16 lyophilizer. The composites were characterized by the microstructure of open connected pores, while, after incubation in SBF, their surface layer was enriched with Ca and P …”

“…Composite morphology depends on the type of polymer matrix and fillers used, as well as the mutual proportions of particular components. It has been shown that among the group of biomaterials based on chitosan, sodium alginate, and polylactide‐biocomponents with the polymer to ZnO‐doped bioglass ratio of 1:1 had the highest stability …”

Porous chitosan/ZnO‐doped bioglass composites as carriers of bioactive peptides

“…In the bioglass 1 wt% of CaO was replaced with ZnO (among which 50% of the grains were below 30 µm (P5Zn1g)) or in which 2 wt% of CaO was replaced with ZnO (among which grains were smaller than 1 mm (P5Zn2)). Procedure for obtaining the composites has been mentioned in our previous work 19 . The composites were derived by means of lyophilization of stable dispersions formed by mixing of 2% chitosan solution in acetic acid solution with bioglass grains in order to maintain 1:1, 1:3, and 1:5 bioglass and polymer weight ratios in the composites (Table 1).…”

“…The porous polymer scaffolds are often filled by hydroxyapatite particles that mimic the natural extracellular matrix of the bone 17,18 . There are also reports on the introduction of bioactive glasses into the structure of the scaffold, which increases the bioactivity of the scaffolds, thereby supporting bone regeneration 19‐21 . Bioglasses are often additionally doped with elements such as silver, gold, copper, zinc, and cerium, which adds to their antibacterial properties 20,22‐27 …”