Visible-Light-Driven Mitigation of Rhodamine B and Disinfection of E. coli Using Magnetic Recyclable Copper–Nitrogen Co-doped Titania/Strontium Ferrite/Diatomite Heterojunction Composite

The Art of Exploring Diatom Biosilica Biomaterials: From Biofabrication Perspective

Diatom is a common single-cell microalgae with large species and huge biomass. Diatom biosilica (DB), the shell of diatom, is a natural inorganic material with a micro-nanoporous structure. Its unique hierarchical porous structure gives it great application potential in drug delivery, hemostat materials, and biosensors, etc. However, the structural diversity of DB determines its different biological functions. Screening hundreds of thousands of diatom species for structural features of DB that meet application requirements is like looking for a needle in a seaway. And the chemical modification methods lack effective means to control the micro-nanoporous structure of DB. The formation of DB is a typical biomineralization process, and its structural characteristics are affected by external environmental conditions, genes, and other factors. This allows to manipulate the micro-nanostructure of DB through biological regulation method, thereby transforming the screening mode of the structure function of DB from a needle in a seaway to biofabrication mode. This review focuses on the formation, biological modification, functional activity of DB structure, and its application in biomaterials field, providing regulatory strategies and research idea of DB from the perspective of biofabrication. It will also maximize the possibility of using DB as biological materials.

Tuning the Structural and Magnetic Properties of the Stuffed Framework Structures MeFe2O4 (Me = Ni, Ca, and Sr)

Spinel ferrite nanoparticles (NPs), have received a lot of attention in medical applications. Therefore, facile synthesis of ferrite NPs of numerous shapes and sizes using the citrate autocombustion technique was utilized in this article. A series of ferrite with the general formula MeFe2O4 [Me = nickle (Ni), calcium (Ca), and strontium (Sr)] are synthesized with varying average ionic radii and cation disorder on the A-site. The structural and morphological characterization of the prepared samples was performed using XRD, HRTEM, FESEM, EDAX, XPS, and Raman analyses. The phase transformation from cubic (Ni) to orthorhombic (Ca) to monoclinic (Sr) was also revealed by XRD. Accordingly, HRTEM images demonstrated nanoparticles in orthorhombic and monoclinic shapes, which are inconsistent with XRD analyses. The coercive field HC for monoclinic SrFe2O4 is ≈ 42 times larger than the Hc for NiFe2O4 with a cubic structure. This deviation in HC compared to the cubic shape particles can be coupled to the shape anisotropy present in SrFe2O4 and refers to the presence of a preferred magnetization direction within the material. The use of monoclinic SrFe2O4 NPs as antifungal activity agents is noteworthy due to their advantages in terms of surface area, efficacy, and biodegradability.