Latest ArticlesRapid screening of foodborne pathogens is of great significance to ensure food safety. A microfluidic biosensor based on immunomagnetic separation, enzyme catalysis and electrochemical impedance analysis was developed for rapid and sensitive detection of S. typhimurium. First, the bacterial sample, the magnetic nanoparticles (MNPs) modified with capture antibodies, and the enzymatic probes modified with detection antibodies and glucose oxidase (GOx) were simultaneously injected into the microfluidic chip, followed by mixing and incubation to form MNP-bacteria-probe sandwich complexes. Then, glucose with high impedance was injected into the chip and catalyzed by the GOx on the complexes into hydrogen peroxide with high impedance and gluconic acid with low impedance, which was finally measured using the low-cost interdigitated microelectrode and the electrochemical impedance analyzer to determine the target bacteria. Under the optimal conditions, this biosensor could quantitatively detect S. typhimurium at the concentrations from 1.6 × 102 CFU/mL to 1.6 × 106 CFU/mL in 1 h with the low detection limit of 73 CFU/mL. Besides, this biosensor was demonstrated with good feasibility for practical applications by detecting the S. typhimurium spiked chicken meat samples.
Peracetic acid (PAA)-based system is becoming an emerging advanced oxidation process (AOP) for effective removal of organic contaminants from water. Various approaches have been tested to activate PAA, while no previous researches reported the application of metal-organic frameworks (MOFs) materials for PAA activation. In this study, zeolitic imidazole framework (ZIF)-67, a representative MOFs, was facile synthesized via direct-mixing method at room temperature, and tested for PAA activation and sulfachloropyridazine (SCP) degradation. The as-synthesized ZIF-67 exhibited excellent performance for PAA activation and SCP degradation with 100% of SCP degraded within 3 min, owing to the specific MOFs structure and abundant Co2+ sites. The pseudo-first-order kinetic model was applied to fit the kinetic data, with rate constant k1 of ZIF-67 activated PAA system 34.2 and 156.5 times higher than those of conventional Co3O4 activated PAA and direct oxidation by PAA. Radical quenching experiments and electron paramagnetic resonance (EPR) analysis indicated that CH3C(O)OO· played a major role in this PAA activation system. Then, the Fukui index based on density functional theory (DFT) calculation was used to predict the possible reaction sites of SCP for electrophilic attack by CH3C(O)OO·. In addition, the degradation pathway of SCP was proposed based on Fukui index values and intermediates detection, which mainly included the S-N bond cleavage and SO2 extrusion and followed by further oxidation, dechlorination, and hydroxylation. Therefore, ZIF-67 activated PAA is a novel strategy and holds strong potential for the removal of emerging organic contaminants (EOCs) from water.
Liver is the foremost organ of human being for drug metabolism, and it played a significant role in toxicity evaluation of drugs. Establishing a liver model in vitro can accelerate the process of the drug screening and new drug research and development. We provide a 3D printing based hepatic sinusoid-on-a-chip microdevice that reconstitutes organ-level liver functions to create a drug screening model of toxicity evaluation on chip. The microfluidic device, which recapitulates the hepatic sinusoid microenvironment, consists of PET polyporous membranes which mimic the perisinusoidal space, and experience fluid flow to mimic the hepatic arterial capillaries. The PET membrane was used to separate the hepatocyte and endotheliocyte. The endotheliocyte was cultured on the downside of the membrane and the hepatocyte were 3D seeded on the membrane via the 3D printer. This device was used to reproduce the in vitro liver model for drug toxicity assays. The expression of several biomarkers of liver was compared with the monoculture and 2D cultured conditions, and the results reveal that this organ-on-a-chip microdevice mimics the drug hepatoxicity that has not been possible by 2D cell-based and animal models, providing a useful platform for screening the drugs and developing an effective therapy in hepatopathy.
Waste utilization is not only the protection of the environment and the practice of green chemistry, but also one of the ways to develop new materials. Herein, we report two biomass carbon dots which prepared from bee pollen waste by one-step hydrothermal method. The new two carbon dots were used in sensing, cell imaging and plant growth regulation. The differences in the structure and properties of the two carbon dots were evaluated by TEM, XPS, TG and various spectroscopic methods. Both two carbon dots contain abundant functional groups, polyatomic doping, excellent water solubility and stable photoluminescence. Due to these good properties, we have demonstrated its versatile applications in Fe3+ sensing, cell imaging and plant growth regulation. It shows sensitive and specific Fe3+ responsiveness and good biocompatibility. This research provides a green and simple method for the recycling and reuse of bee pollen waste, and also provides a reference for the application of biomass carbon dots.
In this work, we developed a novel photoelectrochemical (PEC) sensor based on n-p organic semiconductor heterojunction for sensitive detecting MCF-7 cancer cells. BTA-C4Ph and PM6 were designed as photoactive materials to form n-p heterojunction, which greatly enhanced the photoelectric conversion efficiency. Antibody-modified magnetic nanoparticles were utilized to capture and separate MCF-7 cells from samples. Detection of MCF-7 is ascribed to the loading of MCF-7 onto BTA-C4Ph-PM6 modified electrode that resulted in the decrease of photocurrent intensity. The PEC immunosensor displayed a linear concentration ranging from 50 cell/mL to 1 × 104 cell/mL with a limit of detection (LOD) of 41 cell/mL (S/N = 3) for MCF-7. Additionally, the senor also exhibited good stability, excellent selectivity and prominent reproducibility. Furthermore, the sensor was successfully applied to detect MCF-7 in whole blood. This work illustrates that n-p heterojunction of organic semiconductor may find wide applications for the preparation of different photoelectrochemical sensors.
Medical cotton dressing is cheap and widely used in diversified fields, but in the application of promoting wound healing, the continuous research of multifunctional medical cotton dressing is still of great significance. Here, we developed a fresh type of antibacterial cotton dressing through a succinct strategy based on chemically anchoring polyhexamethylene biguanide (PHMB). Intriguingly, after PHMB modification, the cotton dressing exhibited outstanding antibacterial performance which could maintain > 99.99% antibacterial rate after several treatments, including washing 50 times, repeated use 10 times, UV irradiation for 7 days, cationic dyes dying, and conditioned under 90 ℃ water bath for 2 h. In addition, the water contact angle of cotton dressing increased dramatically from 0° to 111°, which could facilitate bacterial adhesion, thus further enhance the antibacterial efficiency, and easily remove the bacterial debris. Apart from that, the developed cotton dressing showed good cytocompatibility, promoted blood clotting and expression of platelets, and promoted the wound healing process in the infection intervened skin wound model. Taken together, this antibacterial cotton dressing with desirable blood clotting, sustained protection against bacterial infection and bacterial removal features shows the potential to be a candidate for infected skin wound healing.
A gold nanoparticle (AuNP) aggregation-induced colorimetric aptasensing method for quantitative detection of sulfadimethoxine (SDM) with a smartphone was developed. AuNPs were complexed with aptamers which protected AuNPs from aggregating in high-concentration salt solutions. In the presence of SDM, SDM bound with the aptamer on the surface of AuNPs with higher affinity, which competitively desorbed the aptamer from the AuNP surface and resulted in AuNPs aggregation, accompanied with a color change from red to purple-blue. The R, G and B values of images taken by a smartphone camera were analyzed with an app on the smartphone, and were utilized for quantitative analysis of SDM. Under the optimized conditions, the colorimetric aptasensing method using a smartphone showed high sensitivity for SDM, with the limit of detection of 0.023 ppm, lower than the allowed maximum SDM residue limit. This study provides a simple, fast, and easy to read method for on-site quantitative biochemical and cellular analysis.
Pure organic room-temperature phosphorescence (RTP) materials have attracted wide attention owing to their excellent luminescent properties and great potential in various applications. In this work, iminostilbene and its analogues are applied to realize RTP emission by copolymerizing with acrylamide. It can be concluded that the growth of alkane chain in monomers can enhance the lifetime and photoluminescence quantum yield of RTP emission, and polymers with the larger conjugated structure of the monomer show a longer RTP emission wavelength. This work provides a series of new pure organic RTP materials and might provide new thoughts for designing more advanced and superior RTP materials.
Naphthyridine-fused bisimidazolium salts were designed and synthesized for the first time. The study of the Cu(Ⅱ) and Pd(Ⅱ) complexes demonstrated that the deprotonated dicarbene ligands are rigid chelating C, C-ligands with strong electron-donating ability in analogy with the classic phenanthroline N, N-ligands.
The photocatalytic reduction of CO2 to energy-rich chemicals is highly appealing for alleviation of energy crisis and environment pollution. The introduction of different active sites is a key factor to determine the reaction activity and selectivity. Here, we demonstrate the metal ion-dependent performance for photocatalytic CO2 reduction by anchoring transition metal ions (Co2+ and Ni2+) in an amine-functionalized boron imidazolate framework (BIF-43). As a result, Ni@BIF-43 realized a high selectivity of 90.2% for the CO2-to-CO, while Co@BIF-43 achieved more efficient conversion with a high CO production rate of 2036.0 µmol g−1 h−1. Significantly, precise control of isolated metal site on a well-defined structure through coordination-assisted strategies enables us to better understand the specific effects of different metal-ion species on photoreduction of CO2 as well as the catalytic mechanism.
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