Unraveling the structural complexity of and the effect of calcination temperature on calcium phosphates derived from Oreochromis niloticus bones.

In this study, the interplay between the structural complexity, microstructure, and mechanical properties of calcium phosphates (CaPs) derived from fish bones, prepared at various calcination temperatures, and their corresponding sintered ceramics was explored. Fourier-transform infrared analysis revealed that the calcined powders primarily consisted of hydroxyapatite (HAp) and carbonated calcium hydroxyapatite, with an increasing concentration of Mg-substituted ß-tricalcium phosphate (ß-TCP) as the calcination temperature was increased. X-ray diffraction patterns showed enhanced sharpness of the peaks at higher temperatures, indicating a larger crystallite size and improved crystallinity. The ceramics exhibited a significantly larger crystallite size and an increased concentration of the ß-TCP phase. Rietveld analysis revealed a larger volume of the ß-TCP phase in the ceramics than in their calcined powders; this could be attributed to a newly formed ß-TCP phase due to the decomposition of HAp. Extended X-ray absorption fine structure analysis revealed the incorporation of Mg in the Ca2 site of HAp, Ca2 site of ß-TCP, and Ca5 site of ß-TCP, with a higher substitution of Mg in the Ca5 site of ß-TCP at elevated temperatures. The mechanical properties of HAp ceramics can be improved by increasing the calcination temperature because of their improved relative density and dense porous structure at elevated temperatures. This comprehensive investigation sheds light on the phase evolution, microstructural changes, and consequential impact on the mechanical properties of CaPs derived from fish bones, thereby facilitating the development of tailored CaP ceramics for biomedical applications.

Influence of low-cost Thai leucoxene minerals on the growth, bioactive compounds, and antibacterial activities of Chrysanthemum indium L. cuttings in in vitro culture.

The effects of low-cost Thai leucoxene mineral (LM) at different concentrations (10, 20, 30, 40, 50, and 60 mg/L) on the growth and antibacterial properties of Chrysanthemum indium L. cuttings under in vitro were evaluated. The primary chemical composition of LM was approximately 86% titanium dioxide (TiO2), as determined by dispersive X-ray spectroscopy. The crystalline structure, shape, and size were investigated by X-ray diffraction and scanning electron microscopy. LM at 40 and 50 mg/L significantly increased plant height, leaf number, node number, and fresh and dry weight. These growth-promoting properties were accompanied by improved chlorophyll and carotenoid contents and antioxidant enzyme activities and reduced malondialdehyde levels. Additionally, LM treatment at 40 and 50 mg/L had positive effects on antibacterial activity, as indicated by the lowest minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values. The high levels of phenolic compounds in the plants contributed to the MIC and MBC values. In conclusion, these findings provide evidence for the effectiveness of LM in enhancing the growth of Chrysanthemum plants in in vitro culture and improving their antibacterial abilities.

Impacts of pre-treatment methods on the morphology, crystal structure, and defects formation of hydroxyapatite extracted from Nile tilapia scales.

The comprehensive control of hydroxyapatite (HAp), involving morphological and structural variations, particle sizes, and defect formations, has garnered considerable attention for its versatile functionalities, rendering it applicable in diverse contexts. This work examined the shape, structure and optical characteristics, and defect formation in hydroxyapatite (HAp) extracted from Nile tilapia (Oreochromis niloticus) scales with various pre-treatments through experiments and density functional theory (DFT) calculations. Utilizing scanning electron microscopy, our findings revealed that dried fish scales (FS-D) exhibited a layered pattern of collagen fibers, while boiled fish scales (FS-B) had smoother surfaces and significantly reduced collagen content. After calcination, the FS-D sample produced nanorods with an average length of 150 ± 44 nm, whereas the FS-B samples yielded agglomerated spherical particles whose size increased with the rising calcining temperature. In-depth analysis through X-ray diffraction and Fourier-transform infrared spectroscopy confirmed the presence of biphasic calcium phosphates in the FS-B samples, while the FS-D sample presented a pure HAp phase. The boiled fish scale calcined at 800 °C (FS-B800) exhibited an optical band gap (Eg) of 5.50 eV, whereas the dried fish scale calcined at 800 °C (FS-D800) showed two Eg values of 2.87 and 3.97 eV, as determined by UV-visible spectroscopy. DFT calculations revealed that the band gap of 3.97 eV correlated with OH- vacancies, while that of 2.87 eV indicated Mn-substituted HAp, explaining the blue powder. The Eg value for the white powder resembled pure HAp, S- and Cl- substituted OH- vacancies, and various cations substituting Ca sites of HAp. Different pre-treatment procedures influence the characteristics of HAp, offering opportunities for applications in bone replacement and scaffolds for bone tissue engineering.

Impact of pretreatment with dielectric barrier discharge plasma on the drying characteristics and bioactive compounds of jackfruit slices.

BACKGROUND: Hot-air drying is a popular method for preserving the production of jackfruit, but heat treatment damages its nutritional qualities. Cold plasma is one of the pretreatment methods used to preserve quality attributes of fruits before drying. In the present work, we studied the effect of dielectric barrier discharge (DBD) plasma on the drying characteristics, microstructure, and bioactive compounds of jackfruit slices with different pretreatment times (15, 30, 45, and 60 s), followed by hot-air drying at 50, 60, and 70 °C. A homemade DBD device was operated via three neon transformers. RESULTS: Optical emission spectrophotometry revealed the emitted spectra of the reactive species in DBD plasma, including the N2 second positive system, N2 first negative system, nitrogen ion, and hydroxyl radical. The results showed that the DBD plasma promoted moisture transfer and enhanced the drying rate, related to the changes in the surface microstructure of samples damaged by DBD plasma. The modified Overhults model was recommended for describing the drying characteristics of jackfruit slices. The contents of ascorbic acid, total phenolics, total flavonoids, total polysaccharides, and antioxidant activity in pretreated jackfruit slices were improved by 9.64%, 42.59%, 25.77%, 27.00%, and 23.13%, respectively. However, the levels of color and carotenoids were reduced. CONCLUSION: Thus, the bioactive compounds in dried jackfruit slices can be improved using the DBD plasma technique as a potential pretreatment method for the drying process. © 2023 Society of Chemical Industry.

Investigation on the physical properties and biocompatibility of zirconia-alumina-silicate@diopside composite materials and its in vivo toxicity study in embryonic zebrafish.

Bioceramic materials have a wide range of applications in the biomedical field, such as in the repair of bone defects and dental surgery. Silicate-based bioceramics have attracted biomedical researchers' interest due to their bioactivity and biodegradability. In this study, extended the scope of ZAS utilization in bone tissue engineering by introducing calcium-magnesium-silicate (diopside, CMS) as an interface material aim to develop a machinable bioceramic composite (ZASCMS) by the sol-gel method. The physicochemical characterization, in vitro biological properties and in vivo zebrafish cytotoxicity study of ZAS-based composites as a function of CMS contents, 0, 25, 50, 75 and 100 wt%, were performed. Results showed that the as-prepared ZASCMS possessed porous architecture with well-interconnected pore structure. Results also revealed that the mechanical properties of ZASCMS composite materials were gradually improved with increasing CMS contents. The ZASCMS composites with more than 50 wt% CMS had the highest compressive strength and modulus of 6.78 ± 0.62 MPa and 340.10 ± 16.81 MPa, respectively. Regarding in vitro bioactivities, the composite scaffolds were found to stimulate osteoblast-like UMR-106 cell adhesion, growth, and proliferation. The antibacterial activity of the ZASCMS composite scaffolds was tested against Staphylococcus epidermidis (S. epidermidis) and Escherichia coli (E. coli) also exhibited an antibacterial property. Furthermore, the in vivo studies using embryonic zebrafish were exposed to as-prepared particles (0-500 µg mL-1) and showed that the synthesized ZAS, CMS and ZASCMS composite particles were non-toxic based on the evaluation of survivability, hatching rate and embryonic morphology. In conclusions, our results indicated that the synthesized composite exhibited their biological properties and antibacterial activity, which could well be a promising material with high potential to be applied in orthopaedic and dental tissue engineering.