A novel method for facile preparation of recoverable Fe3O4@TiO2 core-shell nanospheres and their advanced photocatalytic application

Facile synthesis of low toxicity iron oxide/TiO2 nanocomposites with hyperthermic and photo-oxidation properties

The present study aimed to assess the feasibility of developing low-cost multipurpose iron oxide/TiO2 nanocomposites (NCs) for use in combined antitumor therapies and water treatment applications. Larger size (≈ 100 nm) iron oxide nanoparticles (IONPs) formed magnetic core-TiO2 shell structures at high Fe/Ti ratios and solid dispersions of IONPs embedded in TiO2 matrices when the Fe/Ti ratio was low. When the size of the iron phase was comparable to the size of the crystallized TiO2 nanoparticles (≈ 10 nm), the obtained nanocomposites consisted of randomly mixed aggregates of TiO2 and IONPs. The best inductive heating and ROS photogeneration properties were shown by the NCs synthesized at 400 °C which contained the minimum amount of α-Fe2O3 and sufficiently crystallized anatase TiO2. Their cytocompatibility was assessed on cultured human and murine fibroblast cells and analyzed in relation to the adsorption of bovine serum albumin from the culture medium onto their surface. The tested nanocomposites showed excellent cytocompatibility to human fibroblast cells. The results also indicated that the environment (i.e. phosphate buffer or culture medium) used to disperse the nanomaterials prior to performing the viability tests can have a significant impact on their cytotoxicity.

Study on Photocatalytic Degradation of Acid Red 73 by Fe3O4@TiO2 Exposed (001) Facets

Water pollution can be treated through the photocatalytic reaction of TiO2 or TiO2 compounds. A solvothermal method was used to prepare Fe3O4 and Fe3O4@TiO2 composite photocatalyst with (001) high-energy facets exposed in the anatase phase. TiO2 and Fe3O4@TiO2 were characterized by field emission scanning electron microscopy, ultraviolet–visible diffuse reflectance spectroscopy, X-ray diffraction spectroscopy and Raman spectroscopy. It was found that the composite Fe3O4@TiO2 can reduce the band gap and maintain a certain proportion of (001) high-energy facet exposure. The band gaps of Fe3O4@TiO2 and TiO2 are 2.5 eV and 2.9 eV, respectively. The exposure percentages of (001) facets of Fe3O4@TiO2 and TiO2 are about 25.2% and 12.1%, respectively. Fe3O4@TiO2 was used for photocatalytic degradation of Acid Red 73, and it was found that Fe3O4@TiO2 could improve the efficiency of photocatalytic degradation of Acid Red 73. The photocatalytic degradation rates of Fe3O4@TiO2 and TiO2 at 24 min were 93.56% and 74.47%, respectively. The cycle experiment of photocatalytic degradation of Acid Red 73 by Fe3O4@TiO2 showed that at the fifth cycle, the rate of dye degradation decreased to 77.05%, but the rate of dye degradation can reach more than 90% after self-cleaning treatment. The photocatalytic degradation mechanism is explained by the energy band theory and the first-order kinetic equation model.

Electrochemiluminescent determination of CYFRA21-1 serum levels using Ti-Fe-O nanotubes immunoassay

Prominent electrochemiluminescence (ECL) in Ti-Fe-O nanotube arrays (Ti-Fe-O NTs) with K₂S₂O₈ as the cathode coreactant is reported for the first time. Compared with pure titanium dioxide nanotubes (TiO₂ NTs), this heterojunction could effectively reduce the band gap, facilitate electronic transitions, and move the ECL potential to a positive direction. The ECL performance motivated the development of an ultrasensitive ECL immunosensor for detecting cytokeratin fragment 21-1 (CYFRA21-1). Magnetic beads loaded with conductive carbon black (CCB/MNTs) were used to efficiently quench the ECL signal of a Ti-Fe-O NTs electrode and were combined with an ECL immunoassay to realize sensitive detection of CYFRA21-1. Over a CYFRA21-1 concentration range of 1.0 pg·mL^-1 ~ 100 ng·mL^-1, the change in the ECL signal was highly linear with the logarithm of the CYFRA21-1 concentration, and the limit of detection (LOD) was 0.114 pg·mL^-1. This ECL immunosensor was used to successfully determine the CYFRA21-1 content in serum. The recovery of CYFRA21-1 in actual serum was 88.6 - 104.4%, and the RSD was 1.4 - 3.0%. The coreaction solution used in this work was PBS (0.1 M, pH = 7.4) containing 0.05 M K₂S₂O₈, the scanning range was -1.0 - 0 V, the photomultiplier tube (PMT) was set to 750 V, and the scanning rate was 100 mV·s^-1.