Herein, ruthenium (Ru) and iridium (Ir) are introduced to tailor the atomic and electronic structure of self-supported nickel-vanadium (NiV) layered double hydroxide to accelerate water splitting ...kinetics, and the origin of high hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) activities are analyzed at atomic level. X-ray photoelectron spectroscopy and X-ray absorption near-edge structure spectroscopy studies reveal synergistic electronic interactions among Ni, V, and Ru (Ir) cations. Raman spectra and Fourier and wavelet transform analyses of the extended X-ray absorption fine structure indicate modulated local coordination environments around the Ni and V cations, and the existence of V vacancies. The Debye-Waller factor suggests a severely distorted octahedral V environment caused by the incorporation of Ru and Ir. Theoretical calculations further confirm that Ru or Ir doping could optimize the adsorption energy of intermediates in the Volmer and Heyrovsky steps for HER and accelerate the whole kinetic process for OER.
A simple and cost-effective fluorescence immunoassay for the sensitive quantitation of disease biomarker α-fetoprotein (AFP) has been developed based on the phosphate-triggered fluorescence turn-on ...detection of alkaline phosphatase (ALP), with the reversible binding between calcein and Ce3+ as a signaling element. In this immunoassay, fluorescent calcein is readily quenched by Ce3+ via a coordination process. The ALP-catalyzed hydrolysis of p-nitrophenyl phosphate leads to the formation of p-nitrophenol and inorganic orthophosphate, and the newly formed orthophosphate could potently combine with Ce3+ due to the higher affinity, thus, recovering the fluorescence of calcein. The corresponding fluorescence signal triggered by phosphate is related to ALP activities labeled on antibody, and thus could be applied to detect target antigen in an enzyme-linked immunosorbent assay (ELISA) platform. The fluorescence intensity correlated well to the AFP concentration ranges of 0.2–1.0 and 1.0–4.0 ng/mL, with a detection limit of 0.041 ng/mL. The proposed fluorescence ELISA possesses convincing recognition mechanism and exhibits excellent assay performance in the evaluation of the AFP level in serologic test, which unambiguously reveals great application potential in the clinic diagnosis of disease biomarkers.
Poly(o‐phenylenediamine) (POPD)‐derived functional carbon materials with excellent capacitive performance (see figure) are successfully synthesized by means of an integrated one‐step process, in ...which FeCl3 not only oxidizes the polymerization of the organic monomers but also activates the carbonization. Furthermore, extensive research has proved that this strategy to discover novel carbons is useful not only for capacitors but also for other energy storage/conversion devices.
As an essential and universal hydrolase, alkaline phosphatase (ALP) has been identified as a crucial indicator of various diseases. Herein, we, for the first time, expanded the application of ...fluorescent polydopamine (F-PDA) nanoparticles to nanoquencher-based biosensing system, as well as discovered the reversible quenching effect of manganese dioxide (MnO2) nanosheets on the fluorescence of F-PDA nanoparticles and intensively confirmed the quenching mechanism of Förster resonance energy transfer by using transmission electron microscopy, UV–vis, Fourier transform infrared spectroscopy, and fluorescence lifetime experiments. By means of the ALP-triggered generation of ascorbic acid (AA) from the substrate ascorbic acid 2-phosphate, the AA-triggered reduction of MnO2 nanosheets to Mn2+, as well as the clear quenching mechanism of F-PDA nanoparticles by MnO2 nanosheets, we have developed a label-free, low-cost, visual, and facile synthetic fluorescent biosensor for convenient assay of ALP activity. The fluorescent bioassay shows a good linear relationship from 1 to 80 mU/mL (R 2 = 0.999), with a low detection limit of 0.34 mU/mL, and the excellent applicability in human serum samples demonstrates potential applications in clinical diagnosis and biomedical research.
A simple, sensitive and selective colorimetric biosensor for the detection of dopamine (DA) was demonstrated with a 58-mer dopamine-binding aptamer (DBA) as recognition element and unmodified gold ...nanoparticles (AuNPs) as probes. Upon the addition of DA, the conformation of DBA would change from a random coil structure to a rigid tertiary structure like a pocket and this change has been demonstrated by circular dichroism spectroscopic experiments. Besides, the conformational change of DBA could facilitate salt-induced AuNP aggregation and lead to the color change of AuNPs from red to blue. The calibration modeling showed that the analytical linear range covered from 5.4
×
10
−7
M to 5.4
×
10
−6
M and the corresponding limit of detection (LOD) was 3.6
×
10
−7
M. Some common interferents such as 3,4-dihydroxyphenylalanine (DOPA), catechol, epinephrine (EP), 3,4-dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), and ascorbic acid (AA) showed no or just a little interference in the determination of DA.
Here, we describe the synthesis of a novel interwoven NiS/NiS2 structure with an amorphous interface accomplished by carrying out a one-step thermal decomposition of nickel sulfate and thiourea. A ...partial phase transition from NiS2 to NiS induced the amorphous interface in NiS/NiS2 and was expected to separate the H* and H− intermediates onto different interface sites, and to reduce the interfacial energy and charge-transfer resistance as well. When NiS/NiS2 was applied as an electrocatalyst for overall water splitting (OWS), it achieved a geometrical current density of 100 mA cm−2 at a low overpotential of 248 mV for the hydrogen evolution reaction (HER) and 416 mV for the oxygen evolution reaction (OER), obviously superior to those of the single-phase catalysts. In addition, it was also employed as an efficient bifunctional catalyst for OWS, yielding a current density of 10 mA cm−2 at a voltage of 1.62 V.
Inspired by the special reducing capability of ascorbic acid (AA), ascorbic acid 2-phosphate (AA2P) has been extensively utilized as a substrate in current alkaline phosphatase (ALP) activity assays ...owing to the ALP-triggered transformation of AA2P into AA. However, such assays usually require AA-related complicated and laborious synthesis and/or signal generation procedures. Herein, we report an interesting in situ fluorogenic interaction between o-phenylenediamine (OPD) and AA, which inspires us to put forward a novel and simple AA2P/OPD-participated fluorescence turn-on ALP activity assay for the first time, and then the corresponding ALP-based fluorescence enzyme-linked immunosorbent assay (ELISA) has also been developed by means of the conventional ELISA platforms. According to the convenient and facile detection process with clear response mechanism, our fluorogenic reaction-based assay exhibits good sensitivity, selectivity, and excellent sensing performance, which ensures fluorescence ELISA to potentially be applied in clinical diagnosis by employing a well-studied biomarker of hepatocellular carcinoma, α-fetoprotein (AFP) as the model analyte. Such original ELISA via in situ formation of fluorophore from scratch gives a new sight to develop other potential immunoassay platforms in early clinical diagnosis by controlling the target antigens in the near future.
Heteroatom‐doped carbon (HDC) has attracted tremendous attention due to its promising application in energy conversion and storage. Herein, due to its abundance high rate of reproduction, the ...microorganism, Bacillus subtilis, is selected as a precursor. An effective ionothermal process is adopted to produce the HDCs. Using acid activation, the obtained sample exhibits excellent electrocatalytic activity, long‐term stability, and excellent resistance to crossover effects in oxygen reduction. Additionally, the base‐treated sample exhibits superior performance in capacitors to most commercially available carbon materials. Even at a high current density, a relatively high capacitance is retained, indicating a great potential for direct application in energy storage.
Heteroatom‐doped carbon materials obtained from bacteria via an effective ionothermal process exhibit excellent electrocatalytic activity in oxygen reduction and excellent performance as supercapacitors. Their composition and porosity can be controlled with the selection of heating media.
Currently, the synthesis of desired Pt-based electrocatalysts for methanol oxidation reaction (MOR) remains a challenge in terms of controlling the particle morphology, composition, and ...electrochemical property. In this study, we present a rapid and facile method for the formation of bimetallic PtRh nanosponges (NSs) by the co-reduction of two metallic precursors using sodium borohydride at room temperature in the absence of any surfactant. Their compositions can be directly tuned by changing the ratio between Pt and Rh precursors. PtRh NSs were obtained in a high yield of three-dimensional (3D) foam-like nanostructure with interconnected pores. Interestingly, the electrocatalytic performance of as-synthesized PtRh NSs was composition-dependent, and they exhibited remarkably improved methanol oxidation activity as compared to Pt NSs and commercial Pt/C catalyst. PtRh NSs were also found to be much more stable as evidenced by the chronoamperometric measurement. Their superior electrochemical properties are ascribed to the 3D porous nanostructure, alloy effect, and clean particle surface. This work provides a simple and effective method to prepare highly active electrocatalysts toward MOR in acid medium.
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