Search

Nanocarriers are employed to deliver photosensitizers for photodynamic therapy (PDT) through the enhanced penetration and retention effect, but disadvantages including the premature leakage and non‐selective release of photosensitizers still exist. Herein, we report a 1O2‐responsive block copolymer (POEGMA‐b‐P(MAA‐co‐VSPpaMA) to enhance PDT via the controllable release of photosensitizers. Once nanoparticles formed by the block copolymer have accumulated in a tumor and have been taken up by cancer cells, pyropheophorbide a (Ppa) could be controllably released by singlet oxygen (1O2) generated by light irradiation, enhancing the photosensitization. This was demonstrated by confocal laser scanning microscopy and in vivo fluorescence imaging. The 1O2‐responsiveness of POEGMA‐b‐P(MAA‐co‐VSPpaMA) block copolymer enabled the realization of self‐amplified photodynamic therapy by the regulation of Ppa release using NIR illumination. This may provide a new insight into the design of precise PDT. [ABSTRACT FROM AUTHOR]

Abstract: The performance of electrochemical sensors is mainly limited by the intrinsic properties of electrocatalysts fabricated on the electrode. Introducing a p‐n heterojunction into semiconducing electrocatalysts is an effective strategy to enhance the sensing performance. In this paper, p‐n‐heterojunction‐based CuO/CeO2 nanocomposites were synthesized by a simple hydrothermal process, and the effect of different Cu/Ce molar ratios was explored. p‐CuO/n‐CeO2 was found to exhibit higher conductivity and electrocatalytic activity toward the target superoxide anion (O2.−) when compared to both bare CuO and CeO2. Characterization shows that different Cu/Ce ratios in p‐CuO/n‐CeO2 materials result in a considerable variation in the Ce3+/Ce4+ level, and energy band gap of CeO2, greatly affecting the electrochemical performance of p‐CuO/n‐CeO2. Under optimized conditions, these sensors exhibit high sensitivity and low detection limit toward O2.−. These results demonstrate that the performance of semiconductor‐based electrochemical sensors may be enhanced by the electron‐transfer process of p‐n junction interfaces. [ABSTRACT FROM AUTHOR]

The authors describe a photometric method for the determination of free cholesterol based on the oxidation of cholesterol by the catalytic action of the enzyme cholesterol oxidase. The hydrogen peroxide formed is used to oxidize the chromogenic compound 3,3′,5,5′-tetramethylbenzidine (TMB) by exploiting the peroxidase-like activity of carbon nanotube-supported Prussian blue (PB). This enzyme mimic was synthesized from a mixture of ferric chloride and hexacyanoferrate(III) in the presence of intrinsically reducing multi-walled carbon nanotubes. The composite can trigger the formation of a blue-green dye from TMB in the presence of HO. The findings were exploited to design a photometric (652 nm) assay that has a linear response in the 4 to 100 μM cholesterol concentration range and a 3 μM detection limit. The practicability of the method was verified by the successful analysis of free cholesterol in human blood samples. [ABSTRACT FROM AUTHOR]

A sensitive and selective amperometric H2O2 biosensor was obtained by utilizing the electrodeposition of Pt flowers on iron oxide-reduced graphene oxide (Fe3O4/rGO) nanocomposite modified glassy carbon electrode (GCE). The morphology of Fe3O4/rGO and Pt/Fe3O4/rGO was characterized by transmission electron microscopy (TEM) and scanning electron microscopy (SEM), respectively. The step-wise modification and the electrochemical characteristics of the resulting biosensor were characterized by cyclic voltammetry (CV) and chronoamperometry methods. Thanks to the fast electron transfer at the Pt/Fe3O4/rGO electrode interface, the developed biosensor exhibits a fast and linear amperometric response upon H2O2. The linear range of Pt/Fe3O4/rGO is 0.1∼2.4 mM (R2=0.998), with a sensitivity of 6.875 μA/mM and a detection limit of 1.58 μM (S/N=3). In addition, the prepared biosensor also provides good anti-interferent ability and long-term stability due to the favorable biocompatibility of the electrode interface. The proposed sensor will become a reliable and effective tool for monitoring and sensing the H2O2 in complicate environment. [ABSTRACT FROM AUTHOR]

Whereas metal-organic frameworks (MOFs) are being widely explored in the application of electrocatalysis, the electro-inert organic ligands in MOFs have negative effects on electron transfer. Here, we suggest a facile electrochemical cathodization treatment for the controllable evolution of a Cu-MOF to improve its electrocatalytic performance. When a cathodic potential was applied, Cu-based structures evolving from Cu-MOF with different crystal phases, surface compositions, and morphologies were harvested by controlling the cathodization time. The obtained copper-based structures were found to have much higher activities than the as-synthesized Cu-MOF for glucose electrocatalysis in alkaline media. A 60 second cathodization treatment resulted in the largest sensitivity for glucose electrocatalytic sensing. [ABSTRACT FROM AUTHOR]