Latest ArticlesCarbon nanodots (CDs) based fluorescent nanoprobes have recently drawn much attention in chemo-/bio-sensing and bioimaging. However, it is still challenging to integrate the colorimetric and fluorometric dual readouts into a single CD. Herein, novel hybrid CDs (HCDs) are prepared by a simple microwave-assisted reaction of citric acid (CA), branched polyethyleneimine (BPEI) and potassium thiocyanate (KSCN). As-prepared HCDs show extraordinary properties, including excitation-dependent emission, satisfactory fluorescence quantum yield (46.8%), excellent biocompatibility and optical stability. Significantly, the fluorescence intensity at 450 nm exhibits linear correlation over the Fe3+ concentration from 1 μmol/L to 150 μmol/L with a detection limit (LOD) of 52 nmol/L. Meanwhile, the solution color changes from colorless to orange, and the absorbance at 460 nm increased linearly with Fe3+ concentration ranging from 0.02 mmol/L to 5 mmol/L (LOD: 3.4 μmol/L). All the evidence illustrates that the HCDs can be conditioned for specific Fe3+ sensing with colorimetric and fluorometric dual readouts, which has also been verified with paper-based microchips. The possible mechanism is attributed to the specific interactions between surface functional groups on the HCDs and Fe3+. Additionally, the HCDs are successfully applied in sensing Fe3+ in wastewater and living cells, demonstrating its potential applications in future environment monitoring and disease diagnosis.
In this paper, a novel BC3N2 monolayer has been found with a graphene-like structure using the developed particle swarm optimization algorithm in combination with ab initio calculations. The predicted structure meets the thermodynamical, dynamical, and mechanical stability requirements. Interestingly, the BC3N2 plane shows a metallic character. Importantly, BC3N2 has an in-plane stiffness comparable to that of graphene. We have also investigated the adsorption characteristics of CO2 on pristine monolayer and Mo functionalized monolayer using density functional theory. Subsequently, electronic structures of the interacting systems (CO2 molecule and substrates) have been preliminarily explored. The results show that Mo/BC3N2 has a stronger adsorption capacity towards CO2 comparing with the pristine one, which can provide a reference for the further study of the CO2 reduction mechanism on the transition metal-functionalized surface as well as the new catalyst's design.
Although magnetic stirring is frequently used to enhance the kinetics for adsorption, chemical and biochemical reactions, the introduction of stirrers inevitably leads to the adsorption of analytes and thus interferes with the efficiency of the chemical process or reaction. In this work, magnetic Fe3O4 nanorods with tunable length-to-diameter ratio were synthesized via a hydrothermal method and used as templates for the in-situ depositing of MIL-100(Fe) and gold nanoparticles. Such nanorod-based material can not only function as an adsorbent, nanozyme, and a heterogeneous catalyst for corresponding applications but also serve as a magnetic nanostirrer to enhance kinetics. As a proof-of-concept, the capture of bacteria pathogen, mimic-peroxidase-based colorimetric detection of hydrogen peroxide, and the catalytic reduction of selected organic pollutants were conducted using the as-synthesized Fe3O4@MIL-100(Fe)-Au nanostirrer with and without magnetic field. The results show that the rates of bacteria capture, mimetic enzyme reaction and catalysis were tremendously expedited. We believe this magnetic field-assisted approach holds great promise for future applications, because, not only does it eliminate the use of external magnetic stirrers and thereby decrease the risk of foreign pollution but also, is adaptable for nanoscale reaction systems where conventional stirring is not applicable due to size limitations.
Low-efficiency charge transfer is a critical factor to limit the photocatalytic H2 evolution activity of semiconductor photocatalysts. The interface design is a promising approach to achieve high charge-transfer efficiency for photocatalysts. Herein, a new 2D/2D atomic double-layer WS2/Nb2O5 shell/core photocatalyst (DLWS/Nb2O5) is designed. The atom-resolved HAADF-STEM results unravel the presence of an unusual 2D/2D shell/core interface in DLWS/Nb2O5. Taking advantage of the advanced femtosecond-resolved ultrafast TAS spectra, the average lifetime of charge carriers for DLWS/Nb2O5 (180.97 ps) is considerably shortened as compared to that of Nb2O5 (230.50 ps), strongly indicating that the 2D/2D shell/core interface enables DLWS/Nb2O5 to achieve ultrafast charge transfer from Nb2O5 to atomic double-layer WS2, thus yielding a high photocatalytic H2 evolution rate of 237.6 μmol/h, up to 10.8 times higher than that of pure Nb2O5 nanosheet. This study will open a new window for the development of high-efficient photocatalytic systems through the interface design.
Natural isoquinolinium alkaloids possess a wide range of biological activities. The design and synthesis of mesoionic isoquinoliniums is of great importance. This paper reports the synthesis of unique mesoionic thiazoloisoquinolinium thiolates stabilized by aromatization and 1, 3-dipolarization. Such compounds can be synthesized via the three component [2 + 2 + 1] cycloaddition reaction of isoquinolines with ethyl propionate and elemental sulfur in the absence of any metal catalyst and additives. Importantly, thiazoloisoquinolinium thiolates can be transformed to thioether-containing thiazoloisoquinolinium halides. A selective [4 + 2] cycloaddition can also be used to form S-bridged fused tetracyclic compounds with a thiothiamide ring unit and two quarternary carbon centres. Compound I-1 shows good bioactivity against the chlorophyll of duckweed (Lemna minor) with inhibition rate of 51.5 μg/mL.
We have developed a versatile, mild protocol for trifluoromethylthiolation reactions of aldehydes with catalysis by a decatungstate hydrogen atom transfer photocatalyst under redox-neutral conditions. The protocol is highly selective, operationally simple, and compatible with a wide array of sensitive functional groups. It can be used for late-stage functionalization of bioactive molecules, which makes it convenient for drug discovery.
A NIR fluorescent probe (DDAA) derived from fluorophore DDAO with alanine as the recognition group was developed for sensing aminopeptidase N (APN) in gut microbiota. Using DDAA as the real-time guidance tool for the fluorescence imaging of intestinal microorganism, target bacteria and saccharomycete possessing active APN were identified successfully from human feces.
In this study, Si-doped ferrihydrite (Si-Fh) was successfully synthesized by a simple coprecipitation method for removal of heavy metals in water. Subsequently, the physicochemical properties of Si-Fh before and after adsorption were further studied using several techniques. The Si-Fh exhibited good adsorption capacity for heavy metal ions such as Pb(Ⅱ) and Cd(Ⅱ). The maximum adsorption capacities of lead and cadmium are respectively 105.807, 37.986mg/g. The distribution coefficients of the materials for Pb(Ⅱ) and Cd(Ⅱ) also showed a great affinity (under optimal conditions). Moreover, it was found that the adsorption fit well with the Freundlich isotherm and pseudo-second-order kinetic model which means this was a chemical adsorption process. It can be conducted from both characterization and model results that adsorption of Pb(Ⅱ) and Cd(Ⅱ) was mainly through the complexation interaction of abundance oxygen functional groups on the surface of Si-Fh. Overall, the Si-Fh adsorbents with many superiorities have potential for future applications in the removal of Pb(Ⅱ) and Cd(Ⅱ) from wastewater.
A series of probes KJ-x (x = 1−3) with carbon chains of different lengths based on the matrix of rhodamine B were engineered to detect Ag+ in aqueous solution in this work. Among them, KJ-1 is selected as the best option after in vitro investigation in view of its most sensitive and rapid response to Ag+, whose possible sensing mechanism is studied by experimental investigation and theoretical calculation. To identify the practical application of the probe, the detection of Ag+ in nonantibiotic fungicide Silver & Health and differentiation between normal hepatocytes and hepatoma cells using confocal imaging was conducted.
A facile and efficient strategy was established for the construction of RC-529 and its derivatives. Four conjugates of RC-529 derivatives with Tn antigen were synthesized and all elicited strong and T cell-dependent immune responses in mice without requiring external adjuvants. In addition, all antisera induced by these conjugates could specifically recognize, bind to and kill Tn-overexpressing cancer cells. Thus, RC-529 shows promise as a useful platform for the development of new vaccine carriers with self-adjuvanting properties for the treatment of cancer. Moreover, preliminary structure-activity relationship analysis provides convincing support for further optimization of, and additional investigation into, RC-529.
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