Facile Synthesis of Molecularly Imprinted Graphene Quantum Dots for the Determination of Dopamine with Affinity-Adjustable

A facilely prepared fluorescence sensor was developed for dopamine (DA) determination based on polyindole/graphene quantum dots molecularly imprinted polymers (PIn/GQDs@MIPs). The proposed sensor exhibits a high sensitivity with a linear range of 5 × 10^–10 to 1.2 × 10^–6 M and the limit of detection as low as 1 × 10^–10 M in the determination of DA, which is probably due to the tailor-made imprinted cavities for binding DA thought hydrogen bonds between amine groups of DA and oxygen-containing groups of the novel composite. Furthermore, the prepared sensor can rebind DA in dual-type: a low affinity type (noncovalent interaction is off) and a high affinity type (noncovalent interaction is on), and the rebinding interaction can be adjusted by tuning the pH, which shows a unique potential for adjusting the binding interaction while keeping the specificity, allowing for wider applications

Bamboo-like Composites of V₂O₅/Polyindole and Activated Carbon Cloth as Electrodes for All-Solid-State Flexible Asymmetric Supercapacitors

A bamboo-like nanomaterial composed of V₂O₅/polyindole (V₂O₅/PIn) decorated onto the activated carbon cloth was fabricated for supercapacitors. The PIn could effectively enhance the electronic conductivity and prevent the dissolution of vanadium. And the activation of carbon cloth with functional groups is conducive to anchoring the V₂O₅ and improving surface area, which results in an enhancement of electrochemical performance and leads to a high specific capacitance of 535.5 F/g. Moreover, an asymmetric flexible supercapacitor based on V₂O₅/PIn@activate carbon cloth and reduced graphene oxide (rGO)@activate carbon cloth exhibits a high energy density (38.7 W h/kg) at a power density of 900 W/kg and good cyclic stability (capacitance retention of 91.1% after 5000 cycles). And the prepared device is shown to power the light-emitting diode bulbs efficiently

All-Solid-State Flexible Supercapacitors Based on Highly Dispersed Polypyrrole Nanowire and Reduced Graphene Oxide Composites

Highly dispersed polypyrrole nanowires are decorated on reduced graphene oxide sheets using a facile in situ synthesis route. The prepared composites exhibit high dispersibility, large effective surface area, and high electric conductivity. All-solid-state flexible supercapacitors are assembled based on the prepared composites, which show excellent electrochemical performances with a specific capacitance of 434.7 F g^–1 at a current density of 1 A g^–1. The as-fabricated supercapacitor also exhibits excellent cycling stability (88.1% capacitance retention after 5000 cycles) and exceptional mechanical flexibility. In addition, outstanding power and energy densities were obtained, demonstrating the significant potential of prepared material for flexible and portable energy storage devices

Facile Synthesis of Highly Active Three-Dimensional Urchin-like Pd@PtNi Nanostructures for Improved Methanol and Ethanol Electrochemical Oxidation

Exploitation of highly active catalysts for alcohol electrooxidation is urgent for direct alcohol fuel cells (DAFCs). In this research, a facile and mild synthetic approach is utilized to control and tailor the morphology of the three-dimensional (3D) urchin-like Pd@PtNi nanostructures (NSs), and the formation mechanism of the as-prepared nanostructures is expounded in detail. The Pd@PtNi NSs exhibit outstanding electrochemical properties and remarkable durability toward both methanol and ethanol oxidation reaction (MOR and EOR) in alkaline solution. The electrochemically active surface area (ECSA) of the Pd@PtNi NSs is 59.5 m² g^–1, and their mass activities for MOR and EOR are 1614.3 and 1502.3 mA mg^–1, respectively, which are much higher than those of their ternary or binary alloy counterparts as well as commercial Pt black catalysts. Moreover, it still retains high current densities after catalyzing 10 000 s, while the current densities of other nanocatalysts reduce to nearly zero. The outstanding electrochemical activities and durability are owing to the specific 3D urchin-like nanostructures providing enormous active sites for catalytic reaction and the synergy effects between Pt, Pd, and Ni atoms. The 3D urchin-like Pd@PtNi NSs will enrich the electrocatalysts for DAFCs

Polypeptide-Functionalized NaYF₄:Yb³⁺,Er³⁺ Nanoparticles: Red-Emission Biomarkers for High Quality Bioimaging Using a 915 nm Laser

We prepared poly-l-aspartic acid (PASP) functionalized NaYF₄:Yb³⁺,Er³⁺ upconversion nanoparticles (UCNP-PASP). These nanoparticles can give red upconversion emission under excitation at 915 nm, whose wavelength of emission and excitation is located in the optical window of biological tissue. Dynamic laser scatting and zeta potentials of UCNP-PASP were used to study their stabilities in different aqueous solution. To understand the mechanism of the red emission of UCNP-PASP, photoluminescence spectra of samples were recorded before and after modification with PASP, poly acrylic acid (PAA), and poly­(ether imide) (PEI) ligands under excitation at 915 and 980 nm, respectively. The cytotoxicity of the UCNP-PASP was also examined on a A549 cell and KB cell by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide (MTT) assay. Moreover, the PASP-functionalized UCNP was employed as a potential biomarker for in vitro and in vivo experiments of upconversion luminescence imaging