Physicochemical Characterization of Biomineralized Structures of Sea Pen Pteroeides spinosum (Ellis & Solander, 1786)(Octocorallia: Pennatulidae)

Abstract

In this study, biomineralized polyp leaf spicules and the endoskeletal axis of the coral Pteroeides spinosum were physicochemically characterized by FTIR, SEM, EDX, TGA, and XRD analyses. The mineralized inner axis of P. spinosum was also pulverized and incorporated into the polyacrylamide (PAAm) hydrogel structure. In vitro bioactivity of coral polyp leaf spicules was evaluated by using simulated body fluid. Characterization analyses identified the major crystalline phase of coral polyp leaves spicules and the inner axis as calcite. The coral's inner axis exhibits a looser structure due to its organic content, and also it has a notched and perforated surface morphology. Calcite sclerites obtained from polyp leaves exhibit a harder and crystalline structure and smooth surface morphology. TGA results revealed the organic matter in the coral individual is higher than that of the polyp leaf spicules. It resulted the coral's inner axis was compatible with the PAAm hydrogel. Coral polyp leaf spicules did not form apatit on their surface in simulated body fluid (SBF). The calcite content of the coral P. spinosum can be evaluated as an additive to improve mechanical properties and thermal stability in hydrogels and tissue engineering scaffolds.