Using silver nanoparticles (AgNPs) as the nanocatalyst, l ‐cysteine rapidly reduced HAuCl4 to make a stable gold nanoparticle sol (Ag/AuNP) that had a high surface‐enhanced Raman scattering (SERS) activity in the presence of Victoria blue 4R (VB4r) molecular probes. Under the selected conditions, chondroitin sulfate (Chs) reacted with the VB4r probes to form associated complexes that caused the SERS effect to decrease to 1618 cm?1. The decreased SERS intensity was linear to the Chs concentration in the range 3.1–500 ng/ml, with a detection limit of 1.0 ng/ml Chs. Accordingly, we established a simple and sensitive SERS quantitative analysis method to determine Chs in real samples, with a relative standard deviation of 1.47–3.16% and a recovery rate of 97.6–104.2%. 相似文献
The as‐prepared graphene oxide (GO) exhibited a strong catalytic effect on reduction of HAuCl4 by trisodium citrate to form gold nanoplasmons (AuNPs) with a strong surface‐enhanced Raman scattering (SERS) effect at 1615 cm?1 in the presence of molecular probe Victoria blue 4R (VB4r). SERS intensity increased with nanocatalyst GO concentration due to the formation of more AuNP substrates. The aptamer (Apt) of Hg2+ can bind to GO to form Apt–GO complexes, which can strongly inhibit nanocatalysis. When target Hg2+ is present, the formed stable Hg2+–Apt complexes are separated from the GO surface, which leads to GO catalysis recovery. The enhanced SERS signal was linear to Hg2+ concentration in the range 0.25–10 nmol/L, with a detection limit of 0.08 nmol/L Hg2+. Thus, a new gold nanoplasmon molecular spectral analysis platform was established for detecting Hg2+, based on Apt regulation of GO nanocatalysis. 相似文献
For the first time, the plasmonic gold bipyramids (Au BPs) are introduced to the PbS colloidal quantum dot (CQD) solar cells for improved infrared light harvesting. The localized surface plasmon resonance peaks of Au BPs matches perfectly with the absorption peaks of conventional PbS CQDs. Owing to the geometrical novelty of Au BPs, they exhibit significantly stronger far‐field scattering effect and near‐field enhancement than conventional plasmonic Au nanospheres (NSs). Consequently, device open‐circuit voltage (Voc) and short‐circuit current (Jsc) are simultaneously enhanced, while plasmonic photovoltaic devices based on Au NSs only achieve improved Jsc. The different effects and working mechanisms of these two Au nanoparticles are systematically investigated. Moreover, to realize effective broadband light harvesting, Au BPs and Au NSs are used together to simultaneously enhance the device optical and electrical properties. As a result, a significantly increased power conversion efficiency (PCE) of 9.58% is obtained compared to the PCE of 8.09% for the control devices due to the synergistic effect of the two plasmonic Au nanoparticles. Thus, this work reveals the intriguing plasmonic effect of Au BPs in CQD solar cells and may provide insight into the future plasmonic enhancement for solution‐processed new‐generation solar cells. 相似文献
Gold nanoparticles serve as imaging contrast agents useful for two‐photon nonlinear microscopy of biological cells and tissues. In this study, 100‐nm‐sized gold particles with a multitude of nanopores embedded inside have been physically synthesized and investigated for the plasmonic enhancement in two‐photon luminescence. Exhibiting remarkable potential for two‐photon imaging, the porous gold nanoparticles boost near‐infrared light absorption substantially and allow emission signals 20 times brighter than gold nanorods being currently used as typical imaging agents. Further details can be found in the article by Joo H. Park et al. ( e201700174 )
Association studies of polygenic traits are notoriously difficult when those studies are conducted at large geographic scales. The difficulty arises as genotype frequencies often vary in geographic space and across distinct environments. Those large‐scale variations are known to yield false positives in standard association testing approaches. Although several methods alleviate this problem, no tools have been proposed to evaluate the power that association tests could achieve for a specific study design and set of genotypes. Our goal here is to present an R program fulfilling this objective, by allowing users to simulate phenotypes from observed genotypes and to estimate upper bounds on achievable power. The simulation model can incorporate realistic features such as population structure and gene‐by‐environment interactions, and the package implements a gold‐standard test that evaluates power using information on confounders. We illustrated the use of the program with example studies based on data for the plant species Arabidopsis thaliana. Simulated phenotypes were used to compare the ability of two recent association methods to correctly remove confounding factors, to evaluate power to detect causal variants, and to assess the influence various parameters. For the simulated data, the new tests reached performances close to the gold‐standard test and could be reasonably used with measured phenotypes. Power to detect causal variants was influenced by the number of variants and by the strength of their effect sizes, and specific thresholds were obtained from the simulation study. In conclusion, our program provides guidance on methodological choice of association tests, as well as useful knowledge on test performances in a user‐specific context. 相似文献
This paper describes a study on the uptake of gold (III) ions by viable and treated cells of the unicellular alga, Chlorella vulgaris. Inactivating the algal cells by various physical/chemical treatments resulted in a considerable enhancement in the uptake
capacity over the pristine cells. X-ray Photoelectron Spectroscopy (XPS) analyses confirmed the deposition of elemental gold,
Au (O), on the cell surface, indicating that a reduction process has taken place. XPS results also suggested an increase in
the oxidized carbon species, carboxyl species in particular, on the surfaces of the treated cells. FTIR spectroscopy results
revealed that the carboxyl group was involved mainly in the binding of the gold on the surface of both the viable and treated
cells. 相似文献
For a hematite (α‐Fe2O3) photoanode, multiple electron/hole recombination pathways occurring in the bulk, interfaces, and surfaces largely limit its low‐bias performance (low photocurrent density at low‐bias potential) for photoelectrochemical water splitting. Here, a facile and rapid three‐step approach is reported to simultaneously reduce these recombinations for hematite nanorods (NRs) array photoanode, leading to a greatly improved photocurrent density at low bias potential. First, flame‐doping enables high concentration of Ti doping without hampering the morphology and surface properties of the hematite NRs, which reduces both the bulk and surface recombinations effectively. Second, the addition of a dense‐layer between the hematite NRs and fluorine‐doped SnO2 substrate effectively reduces the interfacial recombination by suppressing the electron back‐injection into electrolyte. Finally, the sequential oxalic acid etching and FeOOH deposition improves both the interface quality between FeOOH electrocatalyst and hematite NRs and the surface catalytic activity. Significantly, the combination of flame‐doping, dense‐layer deposition, surface etching, and electrocatalyst deposition effectively reduces the multiple electron/hole recombination pathways in a hematite NRs photoanode, which decreases the photocurrent onset potential from 1.02 VRHE to 0.64 VRHE, a reduction of 380 mV. 相似文献