Layered double hydroxides [Mn ₂ Al(OH) ₆ ](A ⁿ⁻ ) _x/n · y H ₂ O (A ⁿ⁻ = Cl ⁻ or NO ₃ ⁻ ) were exchanged with Na ₂ SO ₄ and cationic/anionic exchangers [Mn ₆ Al ₃ (OH) ₁₈ ](SO ₄ ,NaSO ₄ ) were obtained.

Bone tissue substitutes are increasing in importance. Hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP) act as a cell matrix and improve its mechanical properties. One of their raw materials is marine-origin by-products. Objectives: To synthesize, characterize, and evaluate the cellular cytotoxicity of a 3D biomaterial based on HA and β-TCP from mussel shells. Methods: We prepared pellets with 150, 200, and 250 mg and evaluated them through sintering, XRD, FTIR, ICP-OES, Scanning Electron Microscopic (SEM), and immunocytochemical tests. The Alamar Blue method was applied to the Balb-T3T cell line within 72 h to evaluate cytotoxicity. Results: Our biomaterials presented a smooth surface with slight irregularity and porosities presenting different diameters and morphologies and showed chemical, morphological, and ultrastructural similarity to bone hydroxyapatite, mainly the 150 and 200 mg pellets. Significance: We produced promising HA/β-TCP bioceramics with characteristics that allowed cell culture, promoting adhesion, spreading, and proliferation.

Here, a carbon paste modified electrode (CPME) with Zn/Al-layered double hydroxide (Zn/Al-LDH) was developed for the simultaneous electrochemical detection of dopamine (DA) and uric acid (UA). The surface morphology and structural features of the synthesized Zn/Al-LDH were analyzed using scanning electron microscopy and X-ray diffraction analysis. The LDH-modified sensor exhibited enhanced adsorptive properties, significantly improving the preconcentration and detection of the targets. Electrochemical characterization using square wave voltammetry demonstrated that the Zn/Al-LDH structure plays a crucial role in increasing sensitivity due to its high surface area and favorable electrostatic interactions by adsorptive preconcentration separate from the electrochemical cell. Under optimized conditions (preconcentration pH of 6.0 and an electrochemical cell pH of 7.0), the sensor demonstrated excellent linearity across biologically relevant concentrations, ranging from 0.2 to 20 μM, in phosphate-buffered saline (PBS), synthetic urine, and synthetic cerebrospinal fluid, with limits of detection of 68 nM for UA and 71 nM for DA. Recovery studies confirmed the sensor’s reliability in complex biological matrices, with recoveries ranging from 90% to 120%. Compared to existing electrochemical sensors, the Zn/Al LDH-modified CPE offers a promising, selective, and efficient platform for neurotransmitter and metabolite analysis in biological samples.

Cobalt Complexes: Introduction and Spectra Analysis

This study aimed to synthesize magnesium oxide (MgO) using a colloidal starch method for two primary purposes: the removal of chromium (III) ions from synthetic wastewater and the subsequent use of the chromium-containing material as synthetic inorganic pigments (SIPs) in commercial paints. The synthesis used to obtain the oxide (St-MgO) is a promising method for using plants, such as cassava, as green fuels due to their abundance, low cost, and non-toxicity. With this, the oxide showed greater porosity and alkalinity, compared to commercial magnesium oxide (Cm-MgO). The MgO samples were subjected to structural characterization using XRD and FTIR, surface area and pore volume study by B.E.T. and SEM, and chemical composition by ICP-OES and thermogravimetric analysis (TGA). The crystalline periclase phase was identified for both samples, but the brucite phase was shown to be a secondary phase for the commercial sample. After the removal of chromium ions, the brucite crystalline phase became the majority phase for the samples, regardless of the concentration of ions removed. The pigments were characterized by color measurements and discussed in terms of colorimetric parameters using the CIELab method and electron spectroscopy (VIS-NIR). This study also evaluated the colorimetric stability of green pigments in aggressive environments (acidic and alkaline) over a 240 h exposure period, demonstrating minimal color difference. This study aims to develop materials for the decontamination of wastewater containing chromium and its reuse as a synthetic inorganic pigment, using an innovative and sustainable synthesis method.