Latest ArticlesHigh responsivity and sensitivity play essential roles in the development of organic field-effect transistors (OFETs)-based biosensors with regard to biological detections, particularly for disease diagnosis. Nonetheless, how to design a biosensor which improves these two outstanding properties while achieving low cost, easy processing, and time saving is a daunting challenge. Herein, a novel biosensor based on OFET with copolymer thin film, whose surface is illuminated with a suitable light beam is reported. This film can be used as both an organic semiconductor material and as a photoelectric active material. Due to amplification of signals as a result of the film's strong response to light, the biosensor possesses higher responsivity and sensitivity compared to dark condition and even realizes a maximum responsivity of up to 103 for alpha-fetoprotein (AFP) detection. The simple combination of light and transistor builds a bridge between photoelectric effect and biological system. In addition, the emergence of more excellent photoelectric active materials is expected to pave a way for ultrasensitive bio-chemical diagnostic tools.
The electrode/electrlyte interface is of great signifance to photoelectrochemical (PEC) water oxidation as the reaction mainly occur here. Herein, we focus on the effect of supercapactance of the electrode/electrlyte interface on the performance of PEC. It is discovered that the supercapacitor on the interface is crucial because it links the charge transport and solution ion adsorption on its two sides. In this study, we demonstrate an approach to promote the performance of TiO2 nanowire array (TiO2 NWs) photoanode in photoelectrochemical cells (PECs) by increasing its supercapacitance. A 2−5 nm carbon layer was coated and the interface supercapacitance increases by about 150 times. This enhances the separation rate of electron-hole pairs by collecting more holes. Meanwhile, it also promotes the water oxidation rate by adsorbing more OH− on its surface. As a result, the photocurrent density of C-TiO2 NWs was about 8 times higher than that of its carbon-free counterpart. This approach of increasing the supercapacitance of photoanodes would be attractive for enhancement of the efficiency of PECs and this work demonstrate the importance of supercapacitance of the interface for PECs.
Tracking the movement of droplets in digital microfluidics is essential to improve its control stability and obtain dynamic information for its applications such as point-of-care testing, environment monitoring and chemical synthesis. Herein, an intelligent, accurate and fast droplet tracking method based on machine vision is developed for applications of digital microfluidics. To continuously recognize the transparent droplets in real-time and avoid the interferes from background patterns or inhomogeneous illumination, we introduced the correlation filter tracker, enabling online learning of the multi-features of the droplets in Fourier domain. Results show the proposed droplet tracking method could accurately locate the droplets. We also demonstrated the capacity of the proposed method for estimation of the droplet velocity as faster as 20 mm/s, and its application in online monitoring the Griess reaction for both colorimetric assay of nitrite and study of reaction kinetics.
Designing non-noble metal electrocatalysts toward alkaline hydrogen evolution reaction (HER) with high performance at a large current density is urgent. Herein, a CoO/CoP heterostructure catalyst (termed POZ) was designed by a phosphating strategy. The strong electron transfer on the interface of CoO/CoP was experimentally and theoretically proven. POZ showed a low overpotential of 236 mV at 400 mA/cm2, which was 249 mV lower than non-phosphated sample. It also exhibited a remarkable solar-to-hydrogen conversion efficiency of 10.5%. In this work, the construction of CoO/CoP interface realized by a simple phosphating strategy could provide an important reference to boost the HER performance on those materials not merely metal oxides.
At present, frequent outbreaks of bacteria and viruses have seriously affected people's normal lives. Therefore, the study of broad-spectrum antibacterial nanocomposites is very promising. However, most antibacterial materials have some disadvantages, such as single bactericidal mechanisms and unrepeatable use. Based on the current situation, a kind of nanocomposite with three structures of graphene oxide (GO), quaternary ammonium salt (QAs) and N-halamine was prepared, which showed synergistic effect to improve antibacterial activity and combined with a variety of sterilization mechanisms. Meanwhile, GO can provide richer ways of sterilization and high specific surface area, which is conducive to the grafting of quaternarized N-halamine. The advantages of physical sterilization of GO, charge adsorption of QAs, reuse of N-halamine and efficient sterilization are fully utilized. The results showed that the quaternarized N-halamine-grafted GO was obtained successfully. GO grafted with quaternarized N-halamine polymer showed strong speedy bactericidal activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) (99%). It had good storage and regeneration properties.
In this work, hollow Fe2O3/Co3O4 microcubes have been successfully synthesized through a hydrothermal method followed by an annealing process using metal-organic framework of Prussian blue as a soft template. The morphologies, microstructures, surface area and element compositions have been carefully characterized by a series of techniques. Meanwhile, compared with that of pure Fe2O3 and Co3O4, the gas sensor based on the hollow microcubes exhibits enhanced sensing performances towards acetone, e.g., a higher response of 21.2 and a shorter response time of 5 s towards 20 ppm acetone at a relatively low working temperature of 200 ℃. Moreover, the hollow microcubes-based gas sensor still shows perfect long-term stability, excellent repeatability and the ability of sub-ppm level detection, which provides a possibility for its application in real life. The enhanced gas sensing performances can be attributed to the hollow structure with a high surface area and the formed p-n heterojunctions within the microcubes.
Whilst most bioorthogonal reactions focus on targeting binding-site cysteine residues, proximity-induced reactivity effect ensures that reaction also occurs at nucleophilic lysine residues. We report one example here that the propargylated-sulfonium center undergoes a nucleophilic reaction with lysine residue via proximity-induced conjugation. This propargylated-sulfonium tethered peptide resulting from a facile propargylation of thiolethers, enables amino-yne reaction at the selected lysine on MDM4 protein. This strategy represents a viable approach of lysine-targeted covalent inhibition in proximity.
Nonalcoholic fatty liver disease (NAFLD) can cause serious liver damage. Early diagnosis and effective treatment of NAFLD can greatly improve treatment rates. The initiation and development of NAFLD has been closely linked to endoplasmic reticulum (ER) stress, which might cause ER viscosity variations. Therefore, if the internal relationship between ER viscosity and NAFLD is clarified, an effective approach for early diagnosis may result. Herein, we fabricated a novel near-infrared (NIR) fluorescence imaging probe, Er-V, for monitoring ER viscosity through a molecular rotor strategy. Er-V exhibited a strong NIR fluorescence signal (at 626 nm) when the environmental viscosity hindered the rotation of the malononitrile group. Using Er-V, we successfully observed a significant enhancement in viscosity in the liver of mice with NAFLD. Therefore, this imaging method based on Er-V is expected to provide a new approach for early detection and diagnosis of NAFLD.
Up to date, solid-state carbon dots (CDs) with bright red fluorescence have scarcely achieved due to aggregation-caused quenching (ACQ) effect and extremely low quantum yield in deep-red to near infrared region. Here, we report a novel fluorine-defects induced solid-state red fluorescence (λem = 676 nm, the absolute fluorescence quantum yields is 4.17%) in fluorine, nitrogen and sulfur co-doped CDs (F, N, S-CDs), which is the first report of such a long wavelength emission of solid-state CDs. As a control, CDs without fluorine-doping (N, S-CDs) show no fluorescence in solid-state, and the fluorescence quantum yield/emission wavelength of N, S-CDs in solution-state are also lower/shorter than that of F, N, S-CDs, which is mainly due to the F-induced defect traps on the surface/edge of F, N, S-CDs. Moreover, the solid-state F, N, S-CDs exhibit an interesting temperature-sensitive behavior in the range of 80-420 K, with the maximum fluorescence intensity at 120 K, unveiling its potential as the temperature-dependent fluorescent sensor and the solid-state light-emitting device adapted to multiple temperatures.
Zwitterionic polymer materials have been extensively studied, but zwitterionic peptides supramolecular hydrogel materials are rarely studied. In this study, the preparation of two zwitterionic hydrogels using self-assembled peptides were reported. The hydrogels could be fabricated easily by changing the temperature or enzyme catalysis in a short time. And the differences in structure and function of the zwitterion peptide hydrogels caused by the two preparation methods were also be compared. We found that the hydrogel prepared by enzyme induced self-assembly has better solubility and lower cytotoxicity than that prepared by the heating-cooling process. The result showed the enzyme induced self-assembly way to form zwitterionic peptides supramolecular hydrogel materials could have further biomedical applications.
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