Peroxidase mimics with dimensions on the nanoscale have received great interest as emerging artificial enzymes for biomedicine and environmental protection. While a variety of peroxidase mimics have been actively developed recently, limited progress has been made toward improving their catalytic efficiency. In this study, we report a type of highly efficient peroxidase mimic that was engineered by depositing Ir atoms as ultrathin skins (a few atomic layers) on Pd nanocubes (i.e., Pd-Ir cubes). The Pd-Ir cubes exhibited significantly enhanced efficiency, with catalytic constants more than 20- and 400-fold higher than those of the initial Pd cubes and horseradish peroxidase (HRP), respectively. As a proof-of-concept demonstration, the Pd-Ir cubes were applied to the colorimetric enzyme-linked immunosorbent assay (ELISA) of human prostate surface antigen (PSA) with a detection limit of 0.67 pg/mL, which is ∼110-fold lower than that of the conventional HRP-based ELISA using the same set of antibodies and the same procedure.

Abstractseries of novel highly water-soluble neutral BODIPY dyes have been obtained by functionalization of BODIPY dyes with branched oligo(ethylene glycol) methyl ether groups at positions 8, 2 and 6 or 4 and 4′. Use of an ortho-substituent group of branched oligo(ethylene glycol)methyl ether on the meso-phenyl ring of BODIPY dyes, and replacement of the fluorine atoms of BODIPY dyes at positions 4 and 4′ with methyloxy or ethynyl subunits significantly enhances fluorescence quantum yields of BODIPY dyes.BODIPY (4,4′-difluoro-4-bora-3a,4a-diaza-s-indacene) dyes have gained a great deal of attention recently because of their many distinctive and desirable properties such as high extinction coefficients, narrow absorption and emission bands, high quantum efficiencies of fluorescence, and relative insensitivity to environmental perturbations, and resistance to photobleaching. 1 Biological and medical applications of the BODIPY dyes require good water solubility and resistance to the formation of nonfluorescent dimer and higher aggregates. Reported strategies to make these dyes water soluble typically involve introduction of oligo(ethylene glycol), N,N-bis(2-hydroxyethyl) amine, carbohydrates, nucleotides, or ionic hydrophilic groups such as carboxylic acid, sulfonic acid, or ammonium groups to BODIPY dyes. 2 However, neutral water soluble BODIPY dyes have advantages over ionic ones because they avoid potential nonspecific interactions through electrostatic interactions between BODIPY dyes and proteins or other biomolecules in We hypothesize that incorporation of branched oligo(ethylene glycol)methyl ether into BODIPY dyes could effectively enhance enthalpic interactions of BODIPY dyes with water and significantly increase water solubility of BODIPY dyes, and that introduction of steric hindrance at the meso or 4-position of BODIPY dyes could significantly reduce their aggregation through π-π stacking interactions between BOIDIPY cores in aqueous solution, and considerably enhance their fluorescence quantum yields. In this letter, we have introduced branched oligo(ethylene glycol)methyl ether to the meso, 2-and 6-, and 4-positions of BODIPY dyes and demonstrated significantly enhanced fluorescence quantum yields of the new dyes (the abstract scheme). These neutral BODIPY dyes are highly water soluble because of the strong hydrophilic nature of oligo(ethylene glycol)methyl ether residues. These approaches offer very efficient ways to prepare different BODIPY dyes with emission ranging from green to deep red regions.In order to demonstrate the feasibility of using branched oligo(ethylene glycol)methyl ether to enhance the water solubility of BODIPY dyes, we first introduced branched oligo(ethylene glycol)methyl ether to BODIPY dyes at the meso position (Scheme 1).Compound 4 was prepared according to a reported procedure 3 and further brominated with PBr 3 in methylene chloride at 40 °C, affording brominated branched oligo(ethylene glycol)methyl ether (5). The benzaldehyde deriviative bearing branched oligo(ethylene g...

In this report, a new polythiophene interface is fabricated containing fused quinone moieties which are then glycosylated to form a carbohydrate platform for bacterial detection. Very importantly, this interface can be used for label-free and reagentless detection, both by electrochemical and Quartz Crystal Microbalance (QCM) transducers and by using the direct pili-mannose binding as well as Concanavalin A (Con A) mediated lipopolysaccharides (LPS)-mannose binding. The conductive polymer's unique collective properties are very sensitive to very minor perturbations, which result in significant changes of electrical conductivity and providing amplified sensitivity and improved limits of detection (i.e., 25 cell/mL for electrochemical sensor and 50 cells/mL for QCM sensor), a widened logarithmic range of detection (i.e., 3-7 for pili-mannose binding and 2-8 for Con A mediated binding), high specificity and selectivity, and an extraordinary reliability by a mechanism of internal validation. With these analytical performances, the described biosensor is envisaged for being capable of differentiating Gram-negative bacterial strain and species, for many important applications.

Four near-infrared fluorescent probes have been synthesized, characterized, and evaluated for detection of lysosomal pH inside living cells.