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Potentiometric enzymatic aptasensing of paralytic shellfish toxins using graphene-wrapped magnetic nanospheres and an all-solid-state cadmium-selective microelectrode
No full textA highly sensitive potentiometric enzymatic aptasensing system for the detection of paralytic shellfish toxins (PSTs) is developed by integrating graphene-wrapped magnetic nanospheres (Fe3O4@SiO2@rGO) with an allsolid-state ion-selective microelectrode. The multilayered core-shell structure of Fe3O4@SiO2@rGO enhances the efficient adsorption of aptamer molecules tagged with cadmium sulfide (CdS) nanoparticles. These CdSaptamer conjugates, when bound with PST molecules, can be desorbed from the Fe3O4@SiO2@rGO surface into the sample solution and subsequently digested by deoxyribonuclease I (DNase I). This digestion process releases the PST molecules for recirculation, significantly reducing the retention of CdS on the surface of Fe3O4@SiO2@rGO. After magnetic separation and acid dissolution, the released Cd2+ from the magnetic nanospheres are measured using an all-solid-state Cd2+-selective microelectrode, enabling sensitive potentiometric detection of PSTs. Using gonyautoxin 1/4 (GTX 1/4) as a model, the sensing system exhibits a linear concentration range from 5 to 150 pM and a low detection limit of 1.7 pM for GTX 1/4, and has been successfully applied in the analysis of seawater samples
Water and sediment regulation eluting and washland planting lead to nitrogen increase in the lower reaches of the Yellow River
No full textThe Yellow River is an important agricultural production base in China, plays a key role in terrestrial sea transport and nitrogen transformation. However, the reason for the transient nitrogen increase in the lower Yellow River remains unclear. This study explored the contributions to transient nitrogen elevation from the water column, suspended particulate matter, surface sediments in the lower Yellow River, and washland soils along it throughout the water and sediment regulation event in 2023. Results indicated that the average dissolved nitrate concentrations in the lower Yellow River were 1.38 and 1.12 times higher before and during water and sediment regulation than after, because of excess reactive nitrogen elution from the beach by the water and sediment regulation. The nitrogen release risk was low in suspended particulate matter and surface sediments (ion exchangeable form nitrogen content was 0.007-0.033 mg center dot g- 1) but high in soil (average ion exchangeable form nitrogen content was 0.092 mg center dot g- 1). Leaching results indicated that nitrate concentration in the water was not significantly influenced by the reduction in suspended particulate matter or surface sediments. In contrast, in soil S-13 (ion exchangeable form nitrogen content was 0.371 mg center dot g- 1), the estimated leaching rate of nitrate averaged 14.74 %, and ion exchangeable form nitrogen accounted for 19.25 % of total nitrogen, with 76.56 % of ion exchangeable form nitrogen leached. Therefore, the water and sediment regulation elution and the continuous leaching of nitrogen from washland soils around the lower Yellow River notably increased the nitrogen concentration in the lower Yellow River
Ultra-highly conductive optoelectronic modulated single-molecule nickel bis(dithiolene) junctions with strong molecule-electrode coupling
No full textStrong molecule-electrode coupling originating from orbit hybridization between gold and the delocalized molecular wires in single-molecule junctions facilitates facile transport towards smart molecular devices. In this paper, we report ultra-highly conductive single-molecule circuits based on highly delocalized nickel bis (dithiolene) (NiS4) molecular junctions using scanning tunneling microscope break junction technique. Single- molecule charge transport measurement of both NiS4 reveals they exhibits high conductance of 10- 1.49 G 0 and 10-1.51 G 0 , respectively. Moreover, under intervention of high bias voltage the molecular conductance could be further improved to approximately 10- 1.00 G 0 , the highest value reported to date with similar molecular lengths. Theoretical calculations suggest that the strong hybridization of the it-channels and the gold electrodes in both junctions exists and it further extends from molecule-electrode interfaces to metal electrodes as visualized by the isosurface plots of the transmitting eigenstate, which lead to not only a distinct energy shift of the dominated LUMO peaks toward Fermi level, but also broad peaks in the LUMO resonance in the transmission functions. In addition, the both molecular junctions show remarkable photoconductance of approximately 10- 1.00 G 0 under resonant light excitation, due to possible exciton binding in these junctions. Interestingly, the conductance switching of both molecular junctions under optoelectronic modulation is highly reversible, forming a multi-stimulus responsive molecular switch. This work not only provides a building block for fabri- cating highly conducting molecular wires with strong molecule-electrode coupling, but also lays a foundation for designing optoelectronic modulated functional molecule-scale devices
Influences of marine biofouling on the potential responses of polymeric membrane ion-selective electrodes
No full textUsing polymeric membrane ion-selective electrodes (ISEs) for reliable long-term marine environmental observations is still a challenge due to the formation of biofilms on electrode surfaces. Unfortunately, the contributions of the specific biofilm components to sensor failure have not been studied. Herein, the influences of the specific biofilm components on the performance of the neutral carrier-based polymeric membrane ISEs are systematically investigated in terms of sensitivity, selectivity, and stability. More importantly, the spatial distributions of these foulants in the fouled sensing membrane phase are studied by confocal laser scanning microscopy for the first time to give insight into the fouling mechanisms. Three typical biochemicals (i.e., proteins, polysaccharides, microbial lipids) in biofilms are selected as the representative foulants. The poly (vinyl chloride)-based CO32-ISEs and K+-ISEs/Ca2+-ISEs have been selected as the model sensors for detection of anions and cations, respectively. Experiments show that depending on the type of the biofoulants, the adsorption of the foulants on the polymeric membrane surface and/or their extraction into the organic membrane phase could occur and induce a change in the potential responses. This study provides a deep insight into the influences of the specific biofilm components on the polymeric membrane ISEs, which is of importance for development of the polymeric membrane marine sensors with high antifouling capabilities for long-term marine monitoring
Advance on the effects of algal carotenoids on inflammatory signaling pathways
No full textThe development of inflammation has an indispensable importance in the self-protection of the human body. However, over-inflammation may damage human health, and inflammatory pathways and inflammasomes have a significant impact on the onset of inflammation. Therefore, how to constrain the development of inflammation through inflammatory pathways or inflammasomes becomes a hot research issue. Carotenoids are a natural pigment and an active substance in algae, with anti-inflammatory and antioxidant effects. Many studies have shown that carotenoids have inhibitory effects on the inflammatory pathways and inflammasomes. In this review, we discussed the mechanism of carotenoids targeting those important inflammatory pathways and their effects on common inflammasome NLRP3 and inflammation-related diseases from the perspective of several inflammatory pathways, including p38 MAPK, IL-6/JAK/STAT3, and PI3K, with a focus on the targets and targeting effects of carotenoids on different inflammatory signaling pathways, and at last proposed possible antiinflammatory targets
A method for breeding new anti-vibrio variety of clam
No full text本发明涉及海产经济贝类遗传育种技术领域，特别是一种毛蚶抗弧菌新品种的育种方法。具体为利用半致死浓度的副溶血弧菌胁迫成体毛蚶，对15％存活的个体进行恢复以8％留种率筛选获得抗弧菌毛蚶种贝，进行室内车间育肥将毛蚶培育至性腺发育成熟，并于诱导产卵前通过灭活的副溶血弧菌诱导毛蚶产生可遗传的免疫因子；而后诱导毛蚶产卵，获得毛蚶F1代抗弧菌品系，再将F1代采用“北育南养”的繁育和养殖技术快速将毛蚶苗种培育至性成熟；此后，每年按照胁迫筛选种贝、增强子代免疫力和“北育南养”的方式连续选育即获得遗传稳定、性状优良的毛蚶抗弧菌新品种。本发明方法可显著提高毛蚶的抗弧菌能力和养殖存活率，提高毛蚶养殖业的良种保存与供应能力
Efficient purification and excitation energy transfer characterization of phycoerythrin 545 from<i> Rhodomonas</i> sp.
No full textCryptomonad phycoerythrin 545 (PE545) is an important type of phycobiliprotein in basic research and technological innovations. Herein, we report a minimalistic hydrophobic chromatography method for its purification. High purity was achieved, with a purity ratio (A545/A280) of 13.66 and a recovery ratio of 78.63 %. Following SDS-PAGE, Coomassie Brilliant Blue staining revealed three bands at 9 kDa, 10 kDa, and 20 kDa, corresponding to alpha 1, alpha 2 and beta subunits. Multiple spectral characteristics were analyzed to ensure that optical activity was consistent with that of the natural protein. Absorption and fluorescence spectroscopies of purified PE545 displayed a strong absorption peak at 545 nm, a shoulder peak at 564 nm, and a fluorescence emission peak at 587 nm, which confirmed unchanged energy transfer properties. Furthermore, the structural and functional integrity, especially the existence of strongly coupled central chromophore pairs with excitation delocalization, was verified by circular dichroism and ultrafast absorption spectroscopy. From the studies of ultrafast absorption spectroscopy of excitation energy transfer (EET) of PE545, four decay components with lifetimes at 0.5 ps, 2.2 ps, 63 ps, and 3000 ps were obtained. In addition, the dynamics of these components confirmed the EET pathways from the central PEB chromophore pairs to the peripheral pigments and localized in the lowest state. Our work will be of considerable value for both fundamental research and applications of PE545
Field and numerical investigation of groundwater flow and dissolved inorganic nitrogen (DIN) dynamics in a sandy nearshore aquifer
No full textNutrients delivered to the coastal ocean via submarine groundwater discharge (SGD) can have a major impact on marine ecosystems. The flux of nutrients delivered via this pathway can be modified by biogeochemical processes occurring in coastal nearshore aquifers. This study combines field investigations with numerical simulations to characterize patterns of groundwater flow, salinity and dissolved inorganic nitrogen (DIN) in a permeable nearshore aquifer and to quantify SGD and associated DIN fluxes to the ocean. At the field study site, an upper saline plume (USP) and saltwater wedge with low DIN concentrations were observed together with a fresh groundwater zone with high DIN concentrations. Seawater infiltration predominantly occurred in the intertidal zone, contributing 85% of the total infiltration, with the greatest infiltration occurring in the upper-middle intertidal zone. The simulations indicate that the USP expanded and contracted through the tidal cycle, and the width of the high-DIN freshwater discharge zone also varying. The freshwater discharge zone was narrower around the high tide period due to expansion of the overlying low-DIN zone associated with the USP. Over the simulated period, only approximately 30% of the DIN entering the nearshore aquifer ultimately discharged to the ocean. The findings of this combined field and numerical study are needed to inform future field and numerical investigations examining the fate of DIN in nearshore aquifers
Influences of marine biofouling on the potential responses of polymeric membrane ion-selective electrodes
No full textUsing polymeric membrane ion-selective electrodes (ISEs) for reliable long-term marine environmental observations is still a challenge due to the formation of biofilms on electrode surfaces. Unfortunately, the contributions of the specific biofilm components to sensor failure have not been studied. Herein, the influences of the specific biofilm components on the performance of the neutral carrier-based polymeric membrane ISEs are systematically investigated in terms of sensitivity, selectivity, and stability. More importantly, the spatial distributions of these foulants in the fouled sensing membrane phase are studied by confocal laser scanning microscopy for the first time to give insight into the fouling mechanisms. Three typical biochemicals (i.e., proteins, polysaccharides, microbial lipids) in biofilms are selected as the representative foulants. The poly (vinyl chloride)-based CO32-ISEs and K+-ISEs/Ca2+-ISEs have been selected as the model sensors for detection of anions and cations, respectively. Experiments show that depending on the type of the biofoulants, the adsorption of the foulants on the polymeric membrane surface and/or their extraction into the organic membrane phase could occur and induce a change in the potential responses. This study provides a deep insight into the influences of the specific biofilm components on the polymeric membrane ISEs, which is of importance for development of the polymeric membrane marine sensors with high antifouling capabilities for long-term marine monitoring
Synthesis and antioxidant evaluation of coumarin-functionalised chitosan: A potent, non-toxic free radical scavenging compound
No full textIn the present study, we designed to link the coumarin molecule to chitosan via a triazole group and synthesized chitosan-coumarin derivatives, which were further quaternized in one step in order to further improve their solubility to obtain a second series of chitosan-coumarin ammonium salt derivatives. The structures of these chitosan derivatives were verified by FT-IR and 1 H NMR. They were tested for their antioxidant activities. The experimental results showed that the derivatives had excellent free radical scavenging ability. The introduction of the coumarin moiety significantly improved the antioxidant activity, and the scavenging capacity was much higher than that of the chitosan feedstock in all three antioxidant tests. Overall, the scavenging capacity of chitosan-coumarin ammonium salt derivatives was slightly higher than that of chitosan-coumarin derivatives, with the highest scavenging rates in all three tests. Compound 8B scavenged 98.74 % (0.01 mg/mL) of superoxide anion radicals, compound 8D scavenged 95.5 % (0.3 mg/mL) of DPPH radicals and compound 8A scavenged 92.97 % (0.2 mg/mL) of hydroxyl radicals. Toxicity assays used L929 cells demonstrated that there was no significant toxicity of the derivatives. The results indicated that the chitosan derivatives described herein were safe and non-toxic and have good antioxidant activity