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Magnetite (Fe3O4) nanoparticle (MNP)-substituted glass-ceramic (MSGC) powders with compositions of (45 − x)SiO2–24.5CaO–24.5Na2O–6P2O5–xFe3O4 (x = 5, 8, and 10 wt%) have been prepared by a sol–gel route by introducing Fe3O4 nanoparticles during the synthesis. The X-ray diffraction patterns of the as-prepared MSGC nanopowders revealed the presence of combeite (Na2Ca2Si3O9), magnetite, and sodium nitrate (NaNO3) crystalline phases. Heat-treatment up to 700 °C for 1 h resulted in the complete dissolution of NaNO3 along with partial conversion of magnetite into hematite (α-Fe2O3). Optimal heat-treatment of the MSGC powders at 550 °C for 1 h yielded the highest relative percentage of magnetite (without hematite) with some residual NaNO3. The saturation magnetization and heat generation capacity of the MSGC fluids increased with an increase in the MNP content. The in vitro bioactivity of the MSGC pellets was evaluated by monitoring the pH and the formation of a hydroxyapatite surface layer upon immersion in modified simulated body fluid. Proliferation of MG-63 osteoblast cells indicated that all of the MSGC compositions were non-toxic and MSGC with 10 wt% MNPs exhibited extraordinarily high cell viability. The MSGC with 10 wt% MNPs demonstrated optimal characteristics in terms of cell viability, magnetic properties, and induction heating capacity, which surpass those of the commercial magnetic fluid FluidMag-CT employed in hyperthermia treatment. [ABSTRACT FROM AUTHOR]

• Various enzyme immobilization strategies on porous silicon were discussed in detail. • Effect of different parameters of enzyme immobilization on porous silicon was outlined. • Porous silicon as a substrate material for enzyme immobilization. • Challenges and opportunities of porous silicon for biosensing applications were highlighted. The use of porous silicon (PS) for biosensing applications is now emerging as it offers desired properties such as better surface-volume ratio, tunable pore size, ease of fabrication, and compatibility with the current silicon-based technology. These superior properties make PS as a promising candidate for the immobilization of biomolecules with higher retention, stability, storage, and operational ease. High specificity and catalytic activity of the enzyme for the substrate are advantageous for the detection of a particular analyte with higher accuracy in less time. Immobilization of enzyme on the PS surface alters the surface electrical and optical properties, and can conveniently be used for the sample analysis. In the present review, the strategies of enzyme immobilization on PS and various influencing factors are discussed in detail. The scope of PS for enzyme immobilization and prerequisite surface modifications has been assessed in brief. The review discusses the various methods of enzyme immobilization on PS with their benefits and bottlenecks with special emphasis on the approaches to overcome the difficulties during the immobilization process. Further, various properties of PS influencing the process of immobilization have been outlined in brief. An overall analysis of enzyme immobilization on PS surface has been given for the successful development of PS based enzymatic biosensors. [ABSTRACT FROM AUTHOR]

Magnetite (Fe 3 O 4 ) nanoparticle (MNP)-substituted glass-ceramic (MSGC) powders with compositions of (45 - x )SiO 2 -24.5CaO-24.5Na 2 O-6P 2 O 5 - x Fe 3 O 4 ( x = 5, 8, and 10 wt%) have been prepared by a sol-gel route by introducing Fe 3 O 4 nanoparticles during the synthesis. The X-ray diffraction patterns of the as-prepared MSGC nanopowders revealed the presence of combeite (Na 2 Ca 2 Si 3 O 9 ), magnetite, and sodium nitrate (NaNO 3 ) crystalline phases. Heat-treatment up to 700 °C for 1 h resulted in the complete dissolution of NaNO 3 along with partial conversion of magnetite into hematite (α-Fe 2 O 3 ). Optimal heat-treatment of the MSGC powders at 550 °C for 1 h yielded the highest relative percentage of magnetite (without hematite) with some residual NaNO 3 . The saturation magnetization and heat generation capacity of the MSGC fluids increased with an increase in the MNP content. The in vitro bioactivity of the MSGC pellets was evaluated by monitoring the pH and the formation of a hydroxyapatite surface layer upon immersion in modified simulated body fluid. Proliferation of MG-63 osteoblast cells indicated that all of the MSGC compositions were non-toxic and MSGC with 10 wt% MNPs exhibited extraordinarily high cell viability. The MSGC with 10 wt% MNPs demonstrated optimal characteristics in terms of cell viability, magnetic properties, and induction heating capacity, which surpass those of the commercial magnetic fluid FluidMag-CT employed in hyperthermia treatment.