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Three-dimensional (3D) printed calcium phosphate cement (CPC) scaffolds are increasingly being used for bone tissue repair. Traditional materials used for CPC scaffolds, such as bovine and porcine bone, generally contain low amounts of calcium phosphate compounds, resulting in reduced production rates of CPC scaffolds. On the other hand, cockle shells contain more than 99% CaCO3 in the form of amorphous aragonite with excellent biocompatibility, which is expected to increase the CPC production rate. In this study, 3D-printed cockle shell powder-based CPC (CSP-CPC) scaffolds were developed by the material extrusion method. Lactic acid and hyaluronic acid were used to promote the printability. The characterization of CSP-CPC scaffolds was performed using Fourier transform infrared spectra, X-ray diffraction patterns, and scanning electron microscopy. The biocompatibility of CSP-CPC scaffolds was evaluated using cell viability, Live/Dead, and alkaline phosphatase assays. In addition, CSP-CPC scaffolds were implanted into the mouse calvarial defect model to confirm bone regeneration. This study provides an opportunity to create high value added in fishing villages by recycling natural products from marine waste. [ABSTRACT FROM AUTHOR]

Though 2,5-dihydroxyterephthalic acid (DHT) is composed of a single benzene molecule, it is blue-emissive in common organic solvents and in the solid state. Like most organic fluorophores, DHT is not soluble in water, which limits its versatile use in metal ion detection in an aqueous medium. To improve the water solubility of DHT and its use as a molecular sensor in aqueous solutions, its deprotonated form, DHT-K, was synthesized through the simple one-pot reaction of DHT with KOH. Compared with DHT, DHT-K was highly soluble in water and emitted yellow fluorescence in the solution and the solid. In addition, DHT-K showed high selectivity for Al ions, exhibiting fluorescence wavelength changes from 540 to 495 nm depending on the Al ion concentration. A linear relationship between the fluorescence intensity of DHT-K and Al ion concentration was established ranging from 18.96 to 247 μM with a detection limit of 1.84 µM. The binding stoichiometry between DHT-K and Al ions was determined by Job's plot and found to be 1:2. Upon exposure to Al ions, DHT-K showed significant changes in fluorescence color and emission wavelength, whereas no fluorescence changes were observed by the addition of various metal ions such as Zn2+, Mg2+, Ca2+, Cu2+, Fe3+, and Co2+. Thus, DHT-K can be applied as a fluorescent sensor that can selectively detect Al ions in aqueous solutions. [ABSTRACT FROM AUTHOR]