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Effective photosensitizers (PSs) are at the heart of the key role of photo-driven antibacterial therapy. However, relative high temperature required for bactericidal activity, stimulating at multiple wavelengths, and multi-step synthesis of the photothermal and photodynamic agents challenge their applications in antibacterial treatment. In this study, silver nanoparticles (AgNPs) functionalized by kaempferol (Kae) are implanted into Prussian blue (PB) to construct photo-responsive nanocubes (AgPB) by a simple synthetic process. The as-synthesized AgPB nanocomposites were found to have an average size of ∼140 nm, and the particle size range of the loaded-AgNPs was 5–15 nm. The structure of AgPB was characterized, and the photothermal and photodynamic evaluation of antibacterial activity of AgPB was investigated under single 808 nm near-infrared (NIR) light. By adjusting the doping ratio of AgNPs, the band gap can be tuned from 2.78 to 2.56 eV to further enhance the photothermal conversion of AgPB and its ability to generate reactive oxygen species (ROS). When compared with AgPB without NIR illumination, in vitro antibacterial studies by using Escherichia coli and Staphylococcus aureus showed that AgPB under 808 nm NIR light could rapidly heat up to 50 °C, enhance the formation of ROS, and promote the ion release amount of Fe2+, Fe3+, and Ag+ to increase oxidative stress, leading to inhibition of bacterial proliferation significantly. Both E. coli and S. aureus were completely killed within 10 min. Moreover, the biofilm formation was remarkably inhibited, and the eradication ratio against E. coli and S. aureus biofilms was 69.73 and 60.01%, respectively. In addition, the hemolytic activity test proved that AgPB had good biocompatibility. The results showed that AgPB with triple bactericidal modalities could expand the application of PSs and serve as a promising nanocomposite for antibacterial therapy. [ABSTRACT FROM AUTHOR]

The modification of the surface atomic arrangements, especially the exposure of high-index facets, has been considered as a valid strategy to strengthen the catalytic performance of Pt-based nanocrystals. In this article, Pt concave nanocubes (Pt CNCs) with exposed high-index (510) facets are facilely synthesized through a hydrothermal method. Polyvinylpyrrolidone (PVP) and glycine are required for shape control. The mechanism of electrocatalytic oxidation toward glucose by Pt CNCs is fully discussed. The exposed high-index facets consist of abundant low-coordinated atoms (containing edges, steps, and kinks), can supply sufficient active sites for the adsorption of reactants and intermediate species, and thus enhance the catalytic activity in glucose oxidation. By using saturated calomel electrode as the reference electrode, a 1 cm2 platinum sheet as the counter electrode, and glassy carbon electrode (GCE) as the working electrode, the Pt CNC catalyst-decorated GCE exhibits higher peak current densities of 0.25, 0.15, and 0.56 mA cm–2 than those of the commercial Pt/C (10 wt. %)-modified GCE. The Pt CNC catalyst shows a rapid response toward the changes in glucose concentration. The electrocatalytic oxidation of glucose exhibits better performance in neutral and alkaline conditions than in an acidic electrolyte. Above all, the prepared Pt CNC catalysts with high-index (510) facets are expected for their wide use as abiotic catalysts in the electrocatalytic oxidation of glucose. [ABSTRACT FROM AUTHOR]

Dissipativeparticle dynamics simulations are performed to investigatethe self-assembly of rod–coil diblock copolymers RNRCN–NRwithin a rod-selective slit. The self-assembled structureof the confined system is sensitively dependent on the rigidity kθand the fraction fRof the rod block and the slit height H.From the phase diagram of structures with respect to kθand fRfor N= 12 and H= 6, we observe four mainstructures including disordered cylinder (DC) structure, hexagonallypacked cylinders (HPC) perpendicular to the slit surfaces, and lamellarstructures parallel (L∥) and perpendicular (L⊥) to surfaces. And structure transitions can be achievedby tuning kθ. The effect of theslit height on the self-assembled structure is also studied for R6C6and R7C5copolymers withlarge kθ. For R6C6, different structures near surfaces and in the interior ofslit are observed in relatively wide slits. Whereas for R7C5, L⊥structure, whose lamellar domainspacing decays exponentially with H, is generallygenerated. Our results suggest an effective way to control the orderingof rod–coil diblock copolymers under nanoscale confinement. [ABSTRACT FROM AUTHOR]

Monolithic optoelectronic integration based on a single material is a major pursuit in the fields of nanophotonics and nanoelectronics in order to meet the requirements of future fiber-optic telecommunication systems and on-chip optical interconnection systems. However, the incompatibility between silicon-based electronics and germanium or compound semiconductor-based photonics makes it very challenging to realize optoelectronic integration based on a single material. Here, the integration between silicon waveguides and a carbon nanotube (CNT) optoelectronic system is demonstrated. Waveguide-integrated photodetectors based on the CNT exhibit 12.5 mA/W photoresponsivity at 1530 nm, which presents an improvement of 97.6 times enhanced absorption efficiency compared to that without the waveguide. Multiplied output signals of cascading photodetectors are used to control the output of CNT-based logic gates, thereby demonstrating that the CNT-based optoelectronic integration system is compatible with silicon photonics. Our work indicates that carbon nanotubes have the potential for future integration between nanophotonics and nanoelectronics on a single chip.

Various mycotoxins widely co-exist in agro-products, and their combined effects cause toxicity and potential carcinogenicity to humans and animals. In this work, we developed an economical and sensitive quantum dots (QDs)/QD microbead (QDs/QB)-based multiplex immunochromatographic assay (mICA) for the rapid detection of fumonisin B 1 (FB 1 ), zearalenone (ZEN), and ochratoxin A (OTA) without the building-up process of mycotoxin conjugates. QDs and QBs were selected as fluorescent reporters and conjugated with antimycotoxin monoclonal antibodies for improving sensitivity. Furthermore, phage-displayed FB 1 , ZEN, and OTA mimotope peptide-based soluble and monovalent fusions to maltose-binding protein (MBP) were applied onto the test line of the mICA as the mimetic coating antigen. Under the optimized conditions, the visual detection limits (vLODs) of peptide-MBP-based mICA could be obtained as 0.25 ng/mL for FB 1 , 3.0 ng/mL for ZEN, and 0.5 ng/mL for OTA within 10 min. The results for spiked real sample detection indicate good accuracy, reproducibility, and practicability. In addition, the proposed mICA was comparable with ultraperformance liquid chromatography coupled to tandem mass spectrometry (UPLC-MS/MS) in terms of reliability in detecting FB 1 , ZEN, and OTA using natural samples. From the point of promoting commercial production, these time-saving and low-cost peptide-MBP antigens applied in ICA might provide promising potential for promoting productivity and decreasing the cost of production.

A photodetector is a key device to extend the cognition fields of mankind and to enrich information transfer. With the advent of emerging nanomaterials and nanophotonic techniques, new explorations and designs for photodetection have been constantly put forward. Here, we report the asymmetric-light-excitation photoelectric detectors with symmetric electrical contacts working at zero external bias. Unlike conventional photodetectors with symmetric contacts which are usually used as photoconductors or phototransistors showing no photocurrent at zero bias, in this device, the asymmetric-light-excitation structure is designed to ensure that only one Schottky junction between two metallic electrodes and semiconductors is illuminated. In this condition, a device can contribute to a photocurrent without bias. Furthermore, incident light with global illumination will be redistributed by the top Au patterns on devices. The achievement of detectors benefits from the designed redistribution of optical field on specific Schottky barriers within optically active regions and effective carrier collection, producing unidirectional photocurrent for large-scale detection applications. The response mechanisms, including excitations under different polarizations, wavebands, and tilted incidences, were systematically elaborated. Device performances including photocurrent, dynamic response, and detectivity were also carefully measured, demonstrating the possibility for applications in high-speed imaging sensors or integrated optoelectronic systems. The concept of asymmetric-light-excitation photodetectors shows wider availability to other nanomaterials for modern optoelectronics.

Carbon nanotubes (CNTs) are considered to be highly promising nanomaterials for multiwavelength, room-temperature infrared detection applications. Here, we demonstrate a single-tube diode photodetector monolithically integrated with a Fabry-Pérot microcavity. A ∼6-fold enhanced optical absorption can be achieved, because of the confined effect of the designed optical mode. Furthermore, taking advantage of Van-Hove-singularity band structures in CNTs, we open the possibility of developing chirality-specific (n,m) CNT-film-based signal detectors. Utilizing a concept of the "resonance and off-resonance" cavity, we achieved cavity-integrated chirality-sorted CNT-film detectors working at zero bias and resonance-allowed mode, for specific target signal detection. The detectors exhibited a higher suppression ratio until a power density of 0.07 W cm(-2) and photocurrent of 5 pA, and the spectral full width at half-maximum is ∼33 nm at a signal wavelength of 1200 nm. Further, with multiple array detectors aiming at different target signals integrated on a chip, a multiwavelength signal detector system can be expected to have applications in the fields of monitoring, biosensing, color imaging, signal capture, and on-chip or space information transfers. The approach can also bring other nanomaterials into on-chip or information optoelectronics, regardless of the available doping polarity.

LC-MS/MS-based proteomics studies rely on stable analytical system performance that can be evaluated by objective criteria. The National Institute of Standards and Technology (NIST) introduced the MSQC software to compute diverse metrics from experimental LC-MS/MS data, enabling quality analysis and quality control (QA/QC) of proteomics instrumentation. In practice, however, several attributes of the MSQC software prevent its use for routine instrument monitoring. Here, we present QuaMeter, an open-source tool that improves MSQC in several aspects. QuaMeter can directly read raw data from instruments manufactured by different vendors. The software can work with a wide variety of peptide identification software for improved reliability and flexibility. Finally, QC metrics implemented in QuaMeter are rigorously defined and tested. The source code and binary versions of QuaMeter are available under Apache 2.0 License at http://fenchurch.mc.vanderbilt.edu.

In shotgun proteomics, protein identification by tandem mass spectrometry relies on bioinformatics tools. Despite recent improvements in identification algorithms, a significant number of high quality spectra remain unidentified for various reasons. Here we present ScanRanker, an open-source tool that evaluates the quality of tandem mass spectra via sequence tagging with reliable performance in data from different instruments. The superior performance of ScanRanker enables it not only to find unassigned high quality spectra that evade identification through database search but also to select spectra for de novo sequencing and cross-linking analysis. In addition, we demonstrate that the distribution of ScanRanker scores predicts the richness of identifiable spectra among multiple LC-MS/MS runs in an experiment, and ScanRanker scores assist the process of peptide assignment validation to increase confident spectrum identifications. The source code and executable versions of ScanRanker are available from http://fenchurch.mc.vanderbilt.edu.

Tandem mass spectrometry-based shotgun proteomics has become a widespread technology for analyzing complex protein mixtures. A number of database searching algorithms have been developed to assign peptide sequences to tandem mass spectra. Assembling the peptide identifications to proteins, however, is a challenging issue because many peptides are shared among multiple proteins. IDPicker is an open-source protein assembly tool that derives a minimum protein list from peptide identifications filtered to a specified False Discovery Rate. Here, we update IDPicker to increase confident peptide identifications by combining multiple scores produced by database search tools. By segregating peptide identifications for thresholding using both the precursor charge state and the number of tryptic termini, IDPicker retrieves more peptides for protein assembly. The new version is more robust against false positive proteins, especially in searches using multispecies databases, by requiring additional novel peptides in the parsimony process. IDPicker has been designed for incorporation in many identification workflows by the addition of a graphical user interface and the ability to read identifications from the pepXML format. These advances position IDPicker for high peptide discrimination and reliable protein assembly in large-scale proteomics studies. The source code and binaries for the latest version of IDPicker are available from http://fenchurch.mc.vanderbilt.edu/ .

In shotgun proteomics, tandem mass spectra of peptides are typically identified through database search algorithms such as Sequest. We have developed DirecTag, an open-source algorithm to infer partial sequence tags directly from observed fragment ions. This algorithm is unique in its implementation of three separate scoring systems to evaluate each tag on the basis of peak intensity, m/ z fidelity, and complementarity. In data sets from several types of mass spectrometers, DirecTag reproducibly exceeded the accuracy and speed of InsPecT and GutenTag, two previously published algorithms for this purpose. The source code and binaries for DirecTag are available from http://fenchurch.mc.vanderbilt.edu.

Two divalent metal ions are commonly seen in the active-site cavity of methionine aminopeptidase, and at least one of the metal ions is directly involved in catalysis. Although ample structural and functional information is available for dimetalated enzyme, methionine aminopeptidase likely functions as a monometalated enzyme under physiological conditions. Information on structure, as well as catalysis and inhibition, of the monometalated enzyme is lacking. By improving conditions of high-throughput screening, we identified a unique inhibitor with specificity toward the monometalated enzyme. Kinetic characterization indicates a mutual exclusivity in binding between the inhibitor and the second metal ion at the active site. This is confirmed by X-ray structure, and this inhibitor coordinates with the first metal ion and occupies the space normally occupied by the second metal ion. Kinetic and structural analyses of the inhibition by this and other inhibitors provide insight in designing effective inhibitors of methionine aminopeptidase.

Methionine aminopeptidase (MetAP) enzymes require a divalent metal ion such as Mn(II), Fe(II), Co(II), Ni(II), or Zn(II) for its removal of the N-terminal methionine from newly synthesized proteins, but it is not certain which of these ions is most important in vivo. Metalloform-selective MetAP inhibitors could be valuable for defining which metals are physiologically relevant for MetAP activation and could serve as leads for development of new therapeutic agents. We have screened a library of 43 736 small drug-like molecules against Escherichia coli MetAP and identified two groups of potent and highly metalloform-selective inhibitors of the Co(II)-form, and of the Mn(II)-form, of this enzyme. Compound 1 is 790-fold more selective for the Co(II)-form, while compound 4 is over 640-fold more potent toward the Mn(II)-form. The X-ray structure of a di-Mn(II) form of E. coli MetAP complexed with the Mn(II)-form-selective compound 4 was obtained, and it shows that the inhibitor interacts with both Mn(II) ions through the two oxygen atoms of its free carboxylate group. The preferential coordination of the hard (oxygen) donors to Mn(II) may contribute to its superb selectivity toward the Mn(II)-form.