Impurity effects on ionic-liquid-based supercapacitors

<p>Small amounts of an impurity may affect the key properties of an ionic liquid and such effects can be dramatically amplified when the electrolyte is under confinement. Here the classical density functional theory is employed to investigate the impurity effects on the microscopic structure and the performance of ionic-liquid-based electrical double-layer capacitors, also known as supercapacitors. Using a primitive model for ionic species, we study the effects of an impurity on the double layer structure and the integral capacitance of a room temperature ionic liquid in model electrode pores and find that an impurity strongly binding to the surface of a porous electrode can significantly alter the electric double layer structure and dampen the oscillatory dependence of the capacitance with the pore size of the electrode. Meanwhile, a strong affinity of the impurity with the ionic species affects the dependence of the integral capacitance on the pore size. Up to 30% increase in the integral capacitance can be achieved even at a very low impurity bulk concentration. By comparing with an ionic liquid mixture containing modified ionic species, we find that the cooperative effect of the bounded impurities is mainly responsible for the significant enhancement of the supercapacitor performance.</p

Phase Separation of Mixed Micelles and Synthesis of Hierarchical Porous Materials

The mixed micelle template approach is one of the most promising synthesis methods for hierarchical porous materials. Although considerable research efforts have been made to explore the formation mechanism, explicit theoretical guidance for appropriately choosing templates is still not available. We found that the phase separation occurring in the mixed micelles would be the key point for the synthesis of hierarchical porous materials. Herein, the pseudophase separation theory for the critical micelle concentration (cmc) combined with the Flory–Huggins theory for the chain molecular mixture were employed to investigate the properties of mixed surfactant aqueous solutions. The cmc values of mixed surfactant solutions were experimentally determined to calculate the Flory–Huggins interaction parameter between two surfactants, χ. When χ is larger than the critical value, χ_c, the phase separation would occur within the micellar phase, resulting in two types of mixed micelles with different surfactant compositions, and hence different sizes, which could be used as the dual-template to induce bimodal pores with different pore sizes. Therefore, the Flory–Huggins theory could be a theoretical basis to judge whether the mixed surfactants were the suitable templates for inducing hierarchical porous materials. We chose cetyltrimethylammonium bromide (CTAB) and <i>n</i>-octylamine (OA) as a testing system. The phase separation behavior of the mixed solutions as well as the successful synthesis of hierarchical porous materials by this dual-template indicated the feasibility of preparing hierarchical porous materials based on the concept of phase separation of the mixed micelles

Differential interference contrast (DIC) and immunofluorescence staining images of WT and MFR <i>L</i>. <i>amazonensis</i> promastigotes treated with DMMB-PDT at 8 J/cm² in the presence of 750 nM of DMMB.

A) Refers to WT untreated control stained directly after DMMB-PDT (WT control D). B) Refers to WT exposed to treatment and stained directly after DMMB-PDT (WT DMMB-PDT D). C) Refers to WT untreated control stained 1h after DMMB-PDT (WT control 1h). D) Refers to WT exposed to treatment and stained 1h after DMMB-PDT (WT DMMB-PDT 1h). E) Refers to MFR untreated control stained directly after DMMB-PDT (MFR control D). F) Refers to MFR exposed to treatment and stained directly after DMMB-PDT (MFR DMMB-PDT D). G) Refers to MFR untreated control stained 1h after DMMB-PDT (MFR control 1h). H) Refers to MFR exposed to treatment and stained 1h after DMMB-PDT (MFR DMMB-PDT 1h). Nuclei were stained with DAPI (blue fluorescence) and mitochondria were stained with Mito tracker red (red fluorescence) directly after PDT. N = Nuclei; k = Kinetoplast; M = Mitochondrion. Scale bar = 5 μm.</p

In Situ Ratiometric Quantitative Tracing of Intracellular Leucine Aminopeptidase Activity via an Activatable Near-Infrared Fluorescent Probe

Leucine aminopeptidase (LAP), one of the important proteolytic enzymes, is intertwined with the progress of many pathological disorders as a well-defined biomarker. To explore fluorescent aminopeptidase probe for quantitative detection of LAP distribution and dynamic changes, herein we report a LAP-targeting near-infrared (NIR) fluorescent probe (DCM–Leu) for ratiometric quantitative trapping of LAP activity in different kinds of living cells. DCM–Leu is composed of a NIR-emitting fluorophore (DCM) as a reporter and l-leucine as a triggered moiety, which are linked together by an amide bond specific for LAP cleavage. High contrast on the ratiometric NIR fluorescence signal can be achieved in response to LAP activity, thus enabling quantification of endogenous LAP with “build-in calibration” as well as minimal background interference. Its ratiometric NIR signal can be blocked in a dose-dependent manner by bestatin, an LAP inhibitor, indicating that the alteration of endogenous LAP activity results in these obviously fluorescent signal responses. It is worth noting that DCM–Leu features striking characteristics such as a large Stokes shift (∼205 nm), superior selectivity, and strong photostability responding to LAP. Impressively, not only did we successfully exemplify DCM–Leu in situ ratiometric trapping and quantification of endogenous LAP activity in various types of living cells, but also, with the aid of three-dimensional confocal imaging, the intracellular LAP distribution is clearly observed from different perspectives for the first time, owing to the high signal-to-noise of ratiometric NIR fluorescent response. Collectively, these results demonstrate preclinical potential value of DCM–Leu serving as a useful NIR fluorescent probe for early detection of LAP-associated disease and screening inhibitor