Hydrogen is considered as sustainable and environmentally friendly energy for global energy demands in the future. Here a Co‐FeS2 catalyst with surface phosphide doping (P/Co‐FeS2) for hydrogen ...evolution reaction (HER) in acidic solutions is developed. The P/Co‐FeS2 exhibits superior HER electrochemical performance with overpotential of ‐90 mV at 100 mA cm−2 and Tafel slope of 41 mV/decade and excellent durability.
Purpose: Antibiotic resistance issues associated with microbial pathogenesis are considered to be one of the most serious current threats to health. Fortunately, TiO2, a photoactive semiconductor, ...was proven to have antibacterial activity and is being widely utilized. However, its use is limited to the short range of absorption wavelength. Methods: In this work, heterostructured TiO2-FeS2 nanocomposites (NCs) were successfully prepared by a facile solution approach to enhance light-induced antibacterial activity over a broader absorption range. Results: In TiO2-FeS2 NCs, FeS2 NPs, as light harvesters, can effectively increase light absorption from the visible (Vis) to near-infrared (NIR). Results of light-induced antibacterial activities indicated that TiO2-FeS2 NCs had better antibacterial activity than that of only TiO2 nanoparticles (NPs) or only FeS2 NPs. Reactive oxygen species (ROS) measurements also showed that TiO2-FeS2 NCs produced the highest relative ROS levels. Unlike TiO2 NPs, TiO2-FeS2 NCs, under light irradiation with a 515-nm filter, could absorb light wavelengths longer than 515 nm to generate ROS. In the mechanistic study, we found that TiO2 NPs in TiO2-FeS2 NCs could absorb ultraviolet (UV) light to generate photoinduced electrons and holes for ROS generation, including ⋅O2− and ⋅OH; FeS2 NPs efficiently harvested Vis to NIR light to generate photoinduced electrons, which then were transferred to TiO2 NPs to facilitate ROS generation. Conclusion: TiO2-FeS2 NCs with superior light-induced antibacterial activity could be a promising antibacterial agent against bacterial infections.
A powerful technique to detect bone biomarkers has been developed for assessment of osteoporosis at the early stage. Two-dimensional multilayered gold-nanoparticle thin film (MTF-AuNPs) was ...demonstrated as a promising test platform for detection of bone biomarker, hydroxyproline (HYP), measured by surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS). With strong surface plasmon resonance and excellent homogeneity, facilely prepared, highly ordered, and large-scale MTF-AuNPs revealed high sensitivity of HYP in the SALDI-MS measurement without additional matrixes, such as α-cyano-4-hydroxycinnamic acid (CHCA) and 2,5-dihydroxybenzoic acid (DHB). Furthermore, the mass spectrum of HYP with MTF-AuNPs was significantly improved in signal intensity enhancement, background noise reduction, and signal-to-noise ratio amplification. The excellent reproducibility of HYP spectra with only 9.3% relative signal variation could be attributed to MTF-AuNPs’ high absorbance at a wavelength of 337 nm, low heat capacity, superior thermal conductivity, and outstanding homogeneity. The calibration curve showed high linear correlation between mass spectrum intensity and HYP concentration in the range of 1 to 100 μM, covering the whole level in healthy people and osteoporosis patients. In particular, the serum sample was directly deposited onto the MTF-AuNP sample substrate without any pretreatment and its HYP concentration was then successfully determined. We believe that the combination of SALDI-MS and MTF-AuNP sample substrates would be a potential approach for bone biomarker detection in the osteoporosis risk assessment.
Graphical abstract
An outbreak of a bacterial contagion is a critical threat for human health worldwide. Recently, light-activated heterostructured nanomaterials (LAHNs) have shown potential as antibacterial agents, ...owing to their unique structural and optical properties. Many investigations have revealed that heterostructured nanomaterials are potential antibacterial agents under light irradiation. In this review, we summarize recent developments of light-activated antibacterial agents using heterostructured nanomaterials and specifically categorized those agents based on their various light harvesters. The detailed antibacterial mechanisms are also addressed. With the achievements of LAHNs as antibacterial agents, we further discuss the challenges and opportunities for their future clinical applications.
Quantum dot light-emitting diodes (QD-LEDs) have been considered as potential display technologies with the characterizations of high color purity, flexibility, transparency, and cost efficiency. For ...the practical applications, the development of heavy-metal-free QD-LEDs from environment-friendly materials is the most important issue to reduce the impacts on human health and environmental pollution. In this work, heavy-metal-free InP/ZnS core/shell QDs with different fluorescence were prepared by green synthesis method with low cost, safe, and environment-friendly precursors. The InP/ZnS core/shell QDs with maximum fluorescence peak at ~ 530 nm, superior fluorescence quantum yield of 60.1%, and full width at half maximum of 55 nm were applied as an emission layer to fabricate multilayered QD-LEDs. The multilayered InP/ZnS core/shell QD-LEDs showed the turn-on voltage at ~ 5 V, the highest luminance (160 cd/m
2
) at 12 V, and the external quantum efficiency of 0.223% at 6.7 V. Overall, the multilayered InP/ZnS core/shell QD-LEDs reveal potential to be the heavy-metal-free QD-LEDs for future display applications.
C-Reactive protein (CRP) is an essential biomarker relevant to various disease prognoses. Current biosensors require a significant amount of time for detecting CRP. To address this issue, this work ...proposes electrokinetic flow-assisted molecule trapping integrated with an impedance biosensor, where a driving signal in terms of a gated sine wave is provided to circularly arranged electrodes which detect proteins. To verify the biosensor's efficacy, protein aggregation on the electrode surface was evaluated through a fluorescence analysis and measurement of the electrochemical impedance spectrum (EIS). The fluorescence analysis with avidin showed that target samples largely accumulated on the electrode surface upon provision of the driving signal. The EIS measurement of CRP accumulation on the electrode surface further confirmed a significant electrokinetic phenomenon at the electrode/electrolyte interface. Even at the low CRP concentration of 10 pg/ml, the proposed device's sensitivity and reliability were as high as 3.92 pg/ml with a signal-to noise ratio (SNR) of ≥3, respectively. In addition, the protein detection time (without considering the preparation time) was minimized to as low as 90 s with the proposed device. This device's advantage is its minimal time consumption, and simple drop-analysis process flow; hence, it was used for monitoring clinical serum samples.
Improving the charge diffusion length and water oxidation kinetics of bismuth vanadate (BiVO4) is essential to achieve better photoelectrochemical catalytic ability for water oxidation. Establishing ...heterojunctions and incorporating co-catalysts with BiVO4 create facile charge transfer paths and generate more water oxidation reactions. In this work, nickel molybdenum oxide (NM) and carbon quantum dot (CQD) are firstly deposited on BiVO4 by hydrothermal and soaking processes to design an efficient co-catalyst/photocatalyst system for water oxidation. The depositing amount of CQD is optimized to balance contributions of CQD and NM as the hole sink and the light-to-electron generator, respectively. The highest photocurrent densities of 2.2 and 3.9 mA/cm2 are achieved for BiVO4/NM/CQD in the electrolyte without and with hole scavenger, respectively. The BiVO4 electrode only shows a photocurrent density of 1.2 mA/cm2 in the electrolyte without hole scavenger. The best photoelectrochemical catalytic ability of BiVO4/NM/CQD is approached by the reduced charge-transfer resistance and charge recombination as well as the enhancement on carrier densities. The excellent long-term stability with the photocurrent retention of 90% under illumination for 24 h is also obtained for BiVO4/NM/CQD. This study opens a blueprint on designing efficient catalysts for water oxidation by incorporating heterojunction and co-catalyst materials simultaneously.
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•Nickel molybdenum oxide (NM) and carbon quantum dot (CQD) are deposited on BiVO4.•BiVO4/NM/CQD acts as efficient co-catalyst/photocatalyst for water oxidation.•BiVO4/NM/CQD shows a photocurrent density of 3.9 mA/cm2 without hole scavenger.•BiVO4/NM/CQD shows a photocurrent retention of 90% under illumination for 24 hr.
Bismuth vanadate with suitable band edges is one of the efficient photocatalysts for water oxidation. Establishing heterojunction can improve electron diffusion lengths and photocatalytic ability of ...BiVO4. In this work, nickel molybdenum oxide (Ni–Mo–O) and BiVO4 heterojunction is established by the hydrothermal process with different nickel to molybdenum precursor ratios. The Ni–Mo–O/BiVO4 electrode is applied as photoanodes for water oxidation. The growth mechanism of Ni–Mo–O on BiVO4 surface is proposed. The Ni–Mo–O deposition amount is optimized regarding to light absorbance and charger transportation. The largest photocurrent density of 1.72 mA/cm2 at 1.23 VRHE is obtained for the optimal NiMoO4/BiVO4 electrode (NM12) in the electrolyte without hole scavenger, while the pure BiVO4 electrode only shows a photocurrent density of 0.90 mA/cm2. The NM12 electrode even presented an impressive photocurrent density of 5.39 mA/cm2 at 1.23 VRHE in the electrolyte with the hole scavenger, owing to the abundant active sites and higher light absorbance as well as the favorable synergistic effects from its suitable Ni to Mo ratio. The NM12 electrode also shows excellent long-term stability with the photocurrent retention of 83% after illumination for 6500 s. This work opens a blueprint for establishing a novel heterojunction with the adjustable metal ratio and coverage on BiVO4.
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•Nickel molybdenum oxide (Ni–Mo–O) and BiVO4 heterojunction is made by hydrothermal.•Ni–Mo–O/BiVO4 photoanode with varied Ni to Mo ratios is used for water oxidation.•The growth mechanism of Ni–Mo–O on BiVO4 surface is proposed.•Photocurrent density of 5.39 mA/cm2 at 1.23 VRHE is got for optimal NM12 electrode.•The NM12 electrode shows an excellent photocurrent retention of 83 % after 6500 s.
With single‐molecule sensitivity, surface‐enhanced Raman scattering (SERS) has promised to be a powerful tool from chemical analysis to biosensors. However, problem with large signal fluctuations for ...reproducibility has impeded SERS from widespread application. The fabrication of SERS substrate with large and uniform enhancement in combination with an effective target analyte‐transfer process is crucial for applications of SERS for trace molecule detection. In this study, we performed laser‐scanning confocal mapping to characterize 3 SERS substrate samples. The substrate consists of a monolayer of cuboctahedral silver nanocrystals (AgNCs) made with Langmuir–Blodgett technique. The synthesis of the cuboctahedral AgNCs involves the use of polyvinylpyrrolidone (PVP) as a shape‐controlling agent that remains on the surface of the nanocrystals. Using PVP as an analyte, we investigate the temporal and spatial variation of PVP SERS signals from the cuboctahedral AgNC Langmuir–Blodgett film. Analyzing the enhancement probability distribution with a model allows quantitative characterization of the cuboctahedral AgNC SERS substrates. The results help to identify important SERS substrate characteristics that influence the performance of the SERS substrate.
Laser‐scanning confocal mapping has been performed to characterize SERS substrate composed by a monolayer of cuboctahedral silver nanocrystals made with Langmuir–Blodgett technique. Statistical analysis of the enhancement probability distribution allows quantitative characterization of the performance of the SERS substrate.
The sensitive interfacial interaction of liquid crystals (LC) holds potential for precision biosensors. In the past, the developments of LC biosensors were limited by the complicated manufacturing ...process, which hinders commercialization and wider applications of such devices. In this report, we demonstrate the first nano-structural polymeric stabilized-cholesteric LC (PSCLC) thin films to be a new label-free biosensing technology.
The transmission spectra of PSCLC devices were measured by the fiber-optic spectrometer with high-resolution. In addition, a smartphone was set on the stage, and the camera of smartphone was placed and aligned with a set of lenses embedded in the designed stage. To decrease the chromatic and spherical aberrations, an achromatic lens set composition, consisting of both dual-convex lens and concave-plane lens, was applied for measuring and imaging the PSCLC texture. The average and the estimated standard deviation (SD) were used to present quantitative experimental results. The test BSA was immobilized and fulfilled by the ceramic silicon-constructed DMOAP-coated glass in aqueous BSA solutions at 1 mg/mL, 1 µg/mL, and 1 ng/mL.
The fabrication process of PSCLC is much simplified compared to previous LC biosensors. The color of PSCLC biosensor altered with the BSA concentration, making detection result easy to read. The detection limit of 1 ng/mL is achieved for label-free PSCLC biosensor. The PSCLC biosensor was able to successfully detect due to the albumin concentration's alteration, with a linear range of 1 ng/mL-2 mg/mL. Thus, the label-free-proposed design-integrated nanoscale PSCLCs smartphone-based biosensor could successfully detect BSA in a preclinical urine sample.
Finally, we propose a design to integrate the PSCLC biosensor with a smartphone. The PSCLC owns potential for high performance, low cost for detecting various disease biomarkers in home use. Owing to its great potential for high performance and low cost, the PSCLC biosensors can be used as a label-free point-of-care for detecting various disease biomarkers for patients in care homes.
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