Effect of Gd3+-,Pr3+-or Sm3+-substituted cobalt-zinc ferrite on photodegradation of methyl orange and cytotoxicity tests

Gd3+-,Pr3+-or Sm3+-doped Co-Zn(Co0.5Zn0.5Fe2 O4)magnetic ferrites(i.e.,Co0.5Zn0.5Gd0.1Fe1.9O4,Co0.5Zn0.5Pr0.1Fe1.9O4 and Co0.5Zn0.5Sm0.1Fe1.9O4)were prepared using a facile sol-gel approach,and the structure,surface morphology and chemical composition of the products were studied by means of scanning electron microscopy(SEM),energy dispersive X-ray analysis(EDX),X-ray diffraction(XRD),UVvisible diffuse reflectance spectroscopy(DRS),photoluminescence(PL)spectroscopy,Fourier transform infrared spectroscopy(FT-IR)and vibrating sample magnetometer(VSM)spectroscopy.XRD patterns show the Co-Zn product is composed of cubic spinel phases with few impurities or secondary phases,and the average crystallite sizes of the samples are determined to be approximately^51—80,~99—181,~68—103 and^83—133 nm.Also the coercivity and remnant and saturation magnetizations,evaluated by vibrating sample magnetometer(VSM),are found to increase linearly with the incorporation of Gd3+,Pr3+and Sm3+in the product formulation.The CO1-xZnxFe2-yRyO4 photocatalyst sample is found to display a red shift in its absorption,and exhibits outstanding photocatalytic effects in the degradation of MO under ultraviolet(UV)light.This is attributed to the reduction of the band gap of cobalt-zinc ferrite due to the presence of rare earth ions.Further in vitro evaluations of the cytotoxic effects of the synthesized nanoparticles were performed on a HeLa cell line.

Poriferan chitin as a template for hydrothermal zirconia deposition

Chitin is a thermostable biopolymer found in various inorganic-organic skeletal structures of numerous invertebrates including sponges （Porifera）. The occurrence of chitin within calcium- and silica-based biominerals in organisms living in extreme natural conditions has inspired development of new （extreme biomimetic） synthesis route of chitin-based hybrid materials in vitro. Here, we show for the first time that 3D-a-chitin scaffolds isolated from skeletons of the marine sponge Aplysina aerophoba can be effectively mineralized under hydrothermal conditions （150℃） using ammonium zirconium（IV） carbonate as a precursor of zirconia. Obtained chitin-ZrO2 hybrid materials were characterized by FT-IR, SEM, HRTEM, as well as light and confocal laser microscopy. We suggest that formation of chitin-ZrO2 hybrids occurs due to hydrogen bonds between chitin and ZrO2.

Extreme biomimetic approach for developing novel chitin-GeO2 nanocomposites with photoluminescent properties

This work presents an extreme biomimetics route for the creation of nano- structured biocomposites utilizing a chitinous template of poriferan origin. The specific thermal stability of the nanostructured chitinous template allowed for the formation under hydrothermal conditions of a novel germanium oxide- chitin composite with a defined nanoscale structure. Using a variety of analytical techniques （FTIR, Raman, energy dispersive X-ray （EDX）, near-edge X-ray absorption fine structure （NEXAFS）, and photoluminescence （PL） spectroscopy, EDS-mapping, selected area for the electron diffraction pattern （SAEDP）, and transmission electron microscopy （TEM））, we showed that this bioorganic scaffold induces the growth of GeO2 nanocrystals with a narrow （150-300 nm） size distri- bution and predominantly hexagonal phase, demonstrating the chitin template＇s control over the crystal morphology. The formed GeO2-chitin composite showed several specific physical properties, such as a striking enhancement in photo- luminescence exceeding values previously reported in GeOR-based biomaterials. These data demonstrate the potential of extreme biomimetics for developing new-generation nanostructured materials.

Extreme biomimetics： A carbonized 3D spongin scaffold as a novel support for nanostructured manganese oxide（IV） and its electrochemical applications

Composites containing biological materials with nanostructured architecture have become of great interest in modem materials science, yielding both interesting chemical properties and inspiration for biomimetic research. Herein, we describe the preparation of a novel three-dimensional （3D） nanostructured MnO2-based com- posite developed using a carbonized proteinaceous spongin template by an extreme biomimetics approach. The thermal stability of the spongin-based scaffold fadlitated the formation of both carbonized material （at 650 ℃ with exclusion of oxygen） and manganese oxide with a defined nanoscale structure under 150 ℃. Remarkably, the unique network of spongin fibers was maintained after pyrolysis and hydro^ermal processing, yielding a novel porous support. The MnO2-spongin composite shows a bimodal pore distribution, with macropores originating from the spongin network and mesopores from the nanostructured oxidic coating. Interestingl3~ the composites also showed improved electrochemical properties compared to those of Mno2. Voltammetry cycling demonstrated the good stability of the material over more than 3,000 charging/discharging cydes. Additionally, electrochemical impedance spectroscopy revealed lower charge transfer resistance in the prepared materials. We demonstrate the potential of extreme biomimetics for developing a new generation of nanostructred materials with 3D centimeter-scale architecture for the storage and conversion of energy generated from renewable natural sources.