No abstract

Numerous compounds such as protein and double-stranded DNA have been shown to efficiently inhibit intrinsic peroxidase-mimic activity in FeO nanoparticles (NP) and other related nanomaterials. However, only a few studies have focused on finding new compounds for enhancing the catalytic activity of FeO NP-related nanomaterials. Herein, phosphate containing adenosine analogs are reported to enhance the oxidation reaction of hydrogen peroxide (HO) and amplex ultrared (AU) for improving the peroxidase-like activity in FeO NPs. This enhancement is suggested to be a result of the binding of adenosine analogs to Fe/Fe sites on the NP surface and from adenosine 5'-monophosphate (AMP) acting as the distal histidine residue of horseradish peroxidase for activating HO. Phosphate containing adenosine analogs revealed the following trend for the enhanced activity of FeO NPs: AMP > adenosine 5'-diphosphate > adenosine 5'-triphosphate. The peroxidase-like activity in the FeO NPs progressively increased with increasing AMP concentration and polyadenosine length. The Michaelis constant for AMP attached FeO NPs is 5.3-fold lower and the maximum velocity is 2.7-fold higher than those of the bare FeO NPs. Furthermore, on the basis of AMP promoted peroxidase mimicking activity in the FeO NPs and the adsorption of protein on the NP surface, a selective fluorescent turn-off system for the detection of urinary protein is developed.

Among many isolates that resulted from four independent surveys of yeasts associated with plants in Brazil, the USA, Portugal and Taiwan, we have characterized eighteen basidiomycetous strains, two of which were conspecific with the type strain of Rhodotorula acheniorum, whereas the remaining sixteen isolates appeared not to correspond to any previously described species. Microsatellite-PCR fingerprinting with primers M13 and (GTG)5 confirmed that the latter strains formed three genetically distinct groups. Each group was considered to represent a distinct species based on nucleotide sequences of the D1/D2 domains of the 26S rRNA gene and the internal transcribed spacer (ITS) region. Phylogenetic analyses of sequence data placed the putative novel species in a clade with R. acheniorum and the dimorphic smut fungus Farysia chardoniana. A novel anamorphic genus, Farysizyma, is created to accommodate the three undescribed species, which were named Farysizyma itapuensis, Farysizyma setubalensis and Farysizyma taiwaniana. A new combination, Farysizyma acheniorum, is proposed for R. acheniorum, which may represent the yeast-phase anamorph of Farysia thuemenii.

A variety of compounds, such as DNA and protein, have been demonstrated to be effective in suppressing the catalytic activity of peroxidase-like nanomaterials. However, little investigations have been conducted to discover new chemical compounds for amplifying the catalytic activity of peroxidase-mimicking nanomaterials. This study discloses that adenosine analogues were useful as a universal enhancer for peroxidase-mimicking nanomaterials in the hydrogen peroxide-mediated oxidation of amplex ultrared at neutral pH. The optimal adenosine analogues for improving the peroxidase-like performance of citrate-stabilized gold nanoparticles (Au NPs), citrate-capped platinum NPs, bovine serum albumin-encapsulated gold nanoclusters, and unmodified magnetite NPs were found to be adenosine diphosphate (ADP), ADP, ADP, and adenosine monophosphate, respectively. The results show that adenosine analogue-induced enhancement in the peroxidase-like activity of nanomaterials was heavily associated with the number of adsorbed adenosine analogues onto the nanomaterial surface. The analysis of ADP-modified Au NPs by electron paramagnetic resonance spectroscopy indicates that the adsorbed ADP molecules on the Au NP surface not only activated H2O2 but also strengthened the interaction between hydroxyl radicals and nanomaterials. By integrating the ADP-boosted catalytic activity of peroxidase-like Au NPs, surfen-triggered NP aggregation, and specific surfen-sulfated glycosaminoglycan (GAG) interaction, a turn-on fluorescent probe was constructed to quantify the heparin level in human plasma and total sulfate GAG content in synthetic cerebrospinal fluid.

The carrier dynamics of vertically aligned InAs/GaAsSb type-II quantum dot (QD) structure are comprehensively analyzed by time-resolved photoluminescence (TRPL) in this study. A columnar InAs QD structure with an overgrown layer of GaAsSb is proposed to enhance the thermal stability and carrier lifetime through the type-II energy band alignment and carrier tunneling effect. The carrier lifetimes of columnar QD structures were in accordance with the PL spectra in wavelength-dependent TRPL measurements because of the electronic coupling effect and the dot-sizedependent oscillator strength. The improved results in this work make columnar type-II QDs promising candidates for novel optoelectronic device application. #