Hybrid Composite Ni(OH)₂@NiCo₂O₄ Grown on Carbon Fiber Paper for High-Performance Supercapacitors

We have successfully fabricated and tested the electrochemical performance of supercapacitor electrodes consisting of Ni­(OH)₂ nanosheets coated on NiCo₂O₄ nanosheets grown on carbon fiber paper (CFP) current collectors. When the NiCo₂O₄ nanosheets are replaced by Co₃O₄ nanosheets, however, the energy and power density as well as the rate capability of the electrodes are significantly reduced, most likely due to the lower conductivity of Co₃O₄ than that of NiCo₂O_4. The 3D hybrid composite Ni­(OH)₂/NiCo₂O₄/CFP electrodes demonstrate a high areal capacitance of 5.2 F/cm² at a cycling current density of 2 mA/cm², with a capacitance retention of 79% as the cycling current density was increased from 2 to 50 mA/cm². The remarkable performance of these hybrid composite electrodes implies that supercapacitors based on them have potential for many practical applications

Biomimetic and Cell-Mediated Mineralization of Hydroxyapatite by Carrageenan Functionalized Graphene Oxide

In bone tissue engineering, it is imperative to design multifunctional biomaterials that can induce and assemble bonelike apatite that is close to natural bone. In this study, graphene oxide (GO) was functionalized by carrageenan. The resulting GO-carrageenan (GO-Car) composite was further used as a substrate for biomimetic and cell-mediated mineralization of hydroxyapatite (HA). It was confirmed that carrageenan on the GO surface facilitated the nucleation of HA. The observation of the effect of the GO-Car on the adhesion, morphology, and proliferation of MC3T3-E1 cells was investigated. In vitro studies clearly show the effectiveness of GO-Car in promoting HA mineralization and cell differentiation. The results of this study suggested that the GO-Car hybrid will be a promising material for bone regeneration and implantation

A Retrievable and Highly Selective Fluorescent Probe for Monitoring Sulfide and Imaging in Living Cells

A novel selective fluorescent chemosensor based on an 8-hydroxyquinoline-appended fluorescein derivative (<b>L1</b>) was synthesized and characterized. Once combined with Cu²⁺, it displayed high specificity for sulfide anion. Among the various anions, only sulfide anion induced the revival of fluoresecence of <b>L1</b>, which was quenched by Cu²⁺, resulting in “off–on”-type sensing of sulfide anion. What’s more, the sensor was retrievable to indicate sulfide anions with Cu²⁺, and S^2–, in turn, increased. With the addition of Cu²⁺, compound <b>L1</b> could give rise to a visible pink-to-yellow color change and green fluorescence quenching. The resulting yellow solution could change to pink and regenerate to green fluorescence immediately upon the addition of sulfide anion; however, no changes were observed in the presence of other anions, including CN^–, P₂O₇^4–, and other forms of sulfate, making compound <b>L1</b> an extremely selective and efficient sulfide chemosensor. The signal transduction occurs via reversible formation–separation of complex <b>L1</b>Cu and CuS. What’s more, the biological imaging study has demonstrated that the chemosensor can detect sulfur anions in biological systems at a relatively low concentration