Yan Bai

The effects of selenium species on Belousov-Zhabotinsky (B-Z) reaction were investigated by adding them to the system before and during the oscillation. When selenium species were added into the system before the oscillation, sodium selenite prolonged the induction period, whose effect was strong as sodium selenite could consume malonic acid to prohibit the accumulation of bromomalonic acid. For selenomethionine and selenocystine, their effects were derived from their reaction with ·CH2COOH and ·Br2- producing radical cation of selenoamino acids, which prohibited the accumulation of bromomalonic acid. Here, the selenium atoms in selenoamino acids, as reactive centers, took part in the redox reaction. As a result, the induction period was prolonged. However, as a diselenide, selenocystine can reduce bromate in acidic medium, which led to shortening the induction period. Therefore, the effect of selenocystine on the induction period was the result of two opposite effects. Nanoselenium shortened the induction period in a certain concentration range, because bromate was directly reduced by nanoselenium and the accumulation of bromomalonic acid was promoted. Furthermore, the dose perturbation effect was investigated by the injection of nanoselenium during the oscillation. It was found that the amplitude was increased or decreased in a dose-dependent fashion, when nanoselenium was injected at peak or trough of the time-dependent redox potential curve.

Photothermal therapy has attracted much interest for use in cancer treatment in recent years. In this study, Cu₂Se nanoparticles as a novel photothermal agent modified by chitosan (CS‐Cu₂SeNPs) were successfully synthesized through a facile route at room temperature. The as‐synthesized CS‐Cu₂SeNPs exhibited good water solubility and significant stability. CS‐Cu₂SeNPs can efficiently convert near‐infrared (NIR) light into heat and exhibit excellent thermostability. In vitro experiments showed that CS‐Cu₂SeNPs had selective cellular uptake between cancer and normal cells and expressed clear anticancer activity on A375 and HeLa human cancer cells. In addition, the anticancer activity was increased to about 400 % by combination with a laser at 808 nm, which acted through induction of apoptosis with the involvement of intrinsic and extrinsic pathways. CS‐Cu₂SeNPs irradiated with a laser effectively triggered the intracellular reactive oxygen species (ROS) overproduction that promoted cell apoptosis. Therefore, the developed CS‐Cu₂SeNPs could be used as a novel phototherapeutic agent for the photothermal therapy of human cancers.

This study investigated the effect of colloidal selenium nanoparticles modified with bovine serum albumin (nanoSe⁰–BSA) on the crystal phase and morphology of CaC₂O₄ and explained the cooperative inhibition mechanism of nanoSe⁰ and BSA on the crystallization of CaC₂O₄. The results were compared with those for nanoSe⁰ and BSA individually. NanoSe⁰ could induce the formation of oval or spherical calcium oxalate monohydrate (COM) crystals at high concentrations. BSA could induce the formation of hexagonal plate-shaped COM crystals at low concentrations and the formation of thin diamond-shaped COM crystals and mixed hydrates with cracks at high concentrations. NanoSe⁰–BSA showed additive effects on CaC₂O₄ crystal growth. NanoSe⁰–BSA could induce the formation of mixed hydrates with more surface cracks and obvious voids at relatively low BSA concentrations. These mixed hydrates were considered to be calcium oxalate trihydrate (COT) or calcium oxalate dihydrate (COD) crystals containing BSA or nanoSe⁰–BSA. These results were a consequence of the interaction of nanoSe⁰ with BSA. UV–vis, circular dichroism, and FT-IR spectra indicated that the binding of nanoSe⁰ to BSA induces a change in the secondary structure of BSA and forms the complex. The nanoSe⁰–BSA binding constant (2.257 × 10⁴ L mol^–1) and number of binding sites (1.13) were calculated from the data of fluorescence spectra.