Nanozyme-induced deep learning-assisted smartphone integrated colorimetric and fluorometric dual-mode for detection of tetracycline analogs.

In this work, a colorimetric and fluorescent dual-mode probe controlled by NH2-MIL-88 B (Fe, Ni) nanozymes was developed to visually detect tetracycline antibiotics (TCs) residues quantitatively, as well as accurately distinguish the four most widely used tetracycline analogs (tetracycline (TC), chrycline (CTC), oxytetracycline (OTC), and doxycycline (DC)). Colorless substrate 3,3',5,5'-tetramethylbenzidine (TMB) may be oxidized to blue oxidized TMB by the Fe Fenton reaction, which was catalyzed by the NH2-MIL-88 B (Fe, Ni) nanozyme with POD-like activity. The colorimetric detection system allows TCs to interact with NH2-MIL-88 B (Fe, Ni). This inhibits the production of ·OH, weakens the oxidation process of TMB, and ultimately lightens the blue color in the system by blocking the electron transfer between NH2-MIL-88 B (Fe, Ni) and H2O2. Furthermore, TCs can interact with NH2-MIL-88 B (Fe, Ni) as a result of the internal filtering effect, which causes the fluorescence intensity to decrease as TCs concentration increases. Additionally, a portable instrument that combines a smartphone sensing platform with colorimetric and fluorescent signals was created for the quick, visual quantitative detection of TCs. The colorimetric and fluorescent dual-mode nano platform enables color change, with detection limits (LODs) of 0.182 µM and 0.0668 µM for the spectrometer and smartphone sensor, respectively, based on the inhibition of fluorescence and enzyme-like activities by TCs. Overall, the colorimetric and fluorescence dual-mode sensor has good stability, high specificity, and an efficient way to eliminate false-positive issues associated with a single detection mode.

Metal-Organic Framework Derived Bi-O-Sn/C Nanostructure: Tailoring the Adsorption Site of Dominant Intermediate for Highly Efficient CO2 Electroreduction to Formate.

Electrochemical CO2 reduction into high-value-added formic acid/formate is an attractive strategy to mitigate global warming and achieve energy sustainability. However, the adsorption energy of most catalysts for the key intermediate *OCHO is usually weak, and how to rationally optimize the adsorption of *OCHO is challenging. Here, an effective Bi-Sn bimetallic electrocatalyst (Bi1 -O-Sn1 @C) where a Bi-O-Sn bridge-type nanostructure is constructed with O as an electron bridge is reported. The electronic structure of Sn is precisely tuned by electron transfer from Bi to Sn through O bridge, resulting in the optimal adsorption energy of intermediate *OCHO on the surface of Sn and the enhanced activity for formate production. Thus, the Bi1 -O-Sn1 @C exhibits an excellent Faradaic efficiency (FE) of 97.7% at -1.1 V (vs RHE) for CO2 reduction to formate (HCOO- ) and a high current density of 310 mA cm-2 at -1.5 V, which is one of the best results catalyzed by Bi- and Sn-based catalysts reported previously. Impressively, the FE exceeds 93% at a wide potential range from -0.9 to -1.4 V. In-situ ATR-FTIR, in-situ Raman, and DFT calculations confirm the unique role of the bridge-type structure of Bi-O-Sn in highly efficient electrocatalytic reduction of CO2 into formate.

Hollow nitrogen-doped carbon nanospheres as cathode catalysts to enhance oxygen reduction reaction in microbial fuel cells treating wastewater.

Hollow nanospheres play a pivotal role in the electro-catalytic oxygen reduction reaction (ORR), which is a crucial step in microbial fuel cell (MFC) device. Herein, the hollow nitrogen-doped carbon nanospheres (HNCNS) were synthesized with the sacrifice of silica coated carbon nanospheres (CNS@SiO2) as template. HNCNS remarkably enhanced the ORR activity compared to the solid carbon and solid silica spheres. By tuning calcination temperature (800-1100 °C), the surface chemistry properties of HNCNS were effectively regulated. The optimal HNCNS-1000 catalyst which was calcined at 1000 °C exhibited the highest ORR activity in neutral media with the onset potential of 0.255 V and half-wave potential of -0.006 V (vs. Ag/AgCl). Single chamber MFC (SCMFC) assembled with HNCNS-1000 cathode unveiled comparable activity to a conventional Pt/C reference. It showed the highest maximum power density of 1307 ± 26 mW/m2, excellent output stability of 5.8% decline within 680 h, chemical oxygen demand (COD) removal of 94.0 ± 0.3% and coulombic efficiency (CE) of 7.9 ± 0.9%. These excellent results were attributed to a cooperative effect of the optimized surface properties (e.g., structural defects, relative content of pyrrolic nitrogen and specific surface area) and the formation of hollow nanosphere structure. Furthermore, the positive linear relationship of the structural defects and pyrrolic nitrogen species with the maximum power generation in SCMFC were clearly elucidated. This study demonstrated that the cost effective HNCNS-1000 was a promising alternative to commercial Pt/C catalyst for practical application in MFCs treating wastewater. Our result revealed the effectiveness of MFC fabricated with HNCNS-1000 cathode catalyst in terms of power generation and wastewater treatment.

Enhancement of Mass Transport for Oxygen Reduction Reaction Using Petal-Like Porous Fe-NC Nanosheet.

Nitrogen-coordinated single-atom catalysts (SACs) have emerged as a new frontier for accelerating oxygen reduction reaction (ORR) owing to the optimal atom efficiency and fascinating properties. However, augmenting the full exposure of active sites is a crucial challenge in terms of simultaneously pursuing high metal loading of SACs. Here, petal-like porous carbon nanosheets with densely accessible Fe-N4 moieties (FeNC-D) are constructed by combining the space-confinement of silica and the coordination of diethylenetriaminepentaacetic acid. The resulted FeNC-D catalyst possesses an enhanced mesoporosity and a balanced hydrophobicity/hydrophilicity, which can facilitate mass transport and advance the exposure of inaccessible Fe-N4 sites, resulting in efficient utilization of active sites. By virtue of the petal-like porous architecture with maximized active site density, FeNC-D demonstrates superior ORR performance in a broad pH range. Remarkably, when utilized as the air cathode in Zn-air battery (ZAB) and microbial fuel cell (MFC), the FeNC-D-based device displays a large power density (356 mW cm-2 for ZAB and 1041.3 mW m-2 for MFC) and possesses remarkable stability, substantially outperforming the commercial Pt/C catalyst.

Enhancing oxygen reduction reaction in air-cathode microbial fuel cells treating wastewater with cobalt and nitrogen co-doped ordered mesoporous carbon as cathode catalysts.

The sluggish oxygen reduction reaction (ORR) on the cathode severely limits the energy conversion efficiency of microbial fuel cells (MFCs). In this study, cobalt and nitrogen co-doped ordered mesoporous carbon (Cox-N-OMC) was prepared by heat-treating a mixture of cobalt nitrate, melamine and ordered mesoporous carbon (OMC). The addition of cobalt nitrate remarkably improved the ORR reactivity, compared to the nitrogen-doped OMC catalyst. By optimizing the dosage of cobalt nitrate (x = 0.6, 0.8 and 1.0 g), the Co0.8-N-OMC catalyst displayed excellent ORR catalytic performances in neutral media with the onset potential of 0.79 V (vs. RHE), half-wave potential of 0.59 V and limiting current density of 5.43 mA/cm2, which was comparable to the commercial Pt/C catalyst (0.86 V, 0.60 V and 4.76 mA/cm2). The high activity of Co0.8-N-OMC catalyst was attributed to the high active surface area, higher total nitrogen amount, and higher relative distribution of graphitic nitrogen and pyrrolic nitrogen species. Furthermore, single chamber microbial fuel cell (SCMFC) with Co0.8-N-OMC cathode exhibited the highest power density of 389 ± 24 mW/m2, chemical oxygen demand (COD) removal of 81.1 ± 2.2% and coulombic efficiency (CE) of 17.2 ± 2.5%. On the other hand, in the Co1.0-N-OMC catalyst, increasing the cobalt dosage from 0.8 to 1.0 g resulted in more oxidized-N species, and the reduced power generation in SCMFC (360 ± 8 mW/m2). The power generated by these catalysts and results of electrochemical evaluation were strongly correlated with the total nitrogen contents on the catalyst surface. This study demonstrated the feasibility of optimizing the dosage of metal to enhance wastewater treatment capacity.

Enhancing oxygen reduction reaction by using metal-free nitrogen-doped carbon black as cathode catalysts in microbial fuel cells treating wastewater.

Microbial fuel cells (MFCs) is promising to combat environmental pollution by converting organic waste to electricity. One critical problem for practical application of MFCs treating wastewater is sluggish oxygen reduction reaction (ORR) on cathode. This study focused on developing novel metal-free cost-effective cathodic catalysts to enhance power generation of MFCs. Specifically, carbon powder (Vulcan XC-72R) was modified with acid treatment and pyrazinamide (as nitrogen precursor), and subsequently pyrolyzed at different temperatures. For CN-X (X = 700-1000 °C) materials, chemical compositions (the doping contents of nitrogen species, oxygen-containing groups, and sulfur-containing groups) were altered with pyrolysis temperature. Linear sweep voltammetry showed that CN-800 exhibited the highest ORR activity, with an onset potential of 0.215 V and a half-wave potential of -0.096 V (vs. Ag/AgCl). Electrochemical measurements clearly presented an enhancement of ORR activity by treating carbon powder with sulfuric acid and nitrogen doping, which was well correlated with voltage output in single chamber MFCs (SCMFCs). On the other hand, for the nitrogen-doped cathode catalysts, the best performance in SCMFCs was directly related with the amount of pyridinic nitrogen species and total nitrogen amount. The MFC operated with CN-800 exhibited a maximum power density of 371 ± 3 mW/m2 with the chemical oxygen demand (COD) removal of 77.2 ± 1.5% and coulombic efficiency (CE) of 8.6 ± 0.3%. Furthermore, the MFC with CN-800 exhibited an excellent stability over longer than 580 h of operation with 1.5% voltage reduction. CN-800 possessed comparable COD removal efficiency to conventional costly Pt/C, and exhibited distinct cost-effectiveness for MFC practical applications in wastewater treatment.

Pyrrolidine dithiocarbamate attenuates paraquat-induced lung injury in rats.

Paraquat (PQ) has been demonstrated that the main target organ for the toxicity is the lung. This study aimed to investigate the potential protective effect of PDTC on the PQ-induced pulmonary damage. Fifty-four rats were divided into control, PQ-treated and PQ+PDTC-treated groups. Rats in the PQ group were administrated 40 mg/kg PQ by gastric gavage, and PDTC group with 40 mg/kg PQ followed by injection of 120 mg/kg PDTC (IP). On the days 3, 7, 14 and 21 after treatments, the activities of GSH-Px, SOD, MDA level and the content of HYP were measured. TGF-beta1 mRNA and protein were assayed by RT-PCR and ELISA. MDA level in plasma and BALF was increased and the activities of GSH-Px and SOD were decreased significantly in the PQ-treated groups (P < .05) compared with control group. While the activities of GSH-Px and SOD in the PQ+PDTC-treated groups was markedly higher than that of PQ-treated groups (P < .05), and in contrast, MDA level was lower. TGF-beta1 mRNA and protein were significantly lower in the PQ+PDTC-treated groups than that of PQ-treated groups (P < .05). The histopathological changes in the PQ+PDTC-treated groups were milder than those of PQ groups. Our results suggested that PDTC treatment significantly attenuated paraquat-induced pulmonary damage.

[Influence of pyrrolidine dithiocarbamate (PDTC) on expression of transforming growth factor beta(1), matrix metalloproteinase-2 and tissue inhibitor-1 of metalloproteinase in rats with pulmonary damage induced by paraquat].

OBJECTIVE: To investigate the influence of pyrrolidine dithiocarbamate (PDTC) on the expression of transforming growth factor beta(1) (TGF-beta(1)), matrix metalloproteinase-2 (MMP-2) and tissue inhibitor-1 of metalloproteinase (TIMP-1) in rats with pulmonary damage induced by paraquat (PQ). METHODS: Fifty-four healthy male SD rats were randomly assigned into the control group (normal saline), the PQ-treatment groups (4 groups) and the PDTC treatment groups (4 groups). Except the rats in the control group, the rats in the PQ group were gavaged only with 40 mg/kg PQ, and PDTC group with 40 mg/kg PQ plus immediate injection 120 mg/kg PDTC (i.p). On the 3rd, the 7th, the 14th and 28th day after treatments, one group rats of each treatments were sacrificed and lung and blood samples were collected. The level of TGF-beta(1) protein in the plasma, the mRNA expression of TGF-beta(1), MMP-2 and TIMP-1 were evaluated using RT-PCR and real-time quantitative PCR, while pathological changes of lung were examined under optical microscope and electrical microscope. RESULTS: The TGF-beta(1) protein, TGF-beta(1) and MMP-2 mRNA expression were increased significantly in the earlier stage and then decreased after PQ administration (P < 0.05 or P < 0.01), while the mRNA level of TIMP-1 was augmented continuously (P < 0.01) throughout the study compared to the control group. In comparison with the PQ group, in the PDTC treatment group, the TGF-beta(1) mRNA expression on the 3rd and the 14th day, 0.54 +/- 0.08 and 0.72 +/- 0.04 respectively, the MMP-2 mRNA expression on the 7th and 14th day, 1.62 +/- 0.50 and 1.97 +/- 0.34 respective-ly, and the TIMP-1 mRNA on the 7th and 21st day, 1.79 +/- 0.21 and 2.00 +/- 0.34 respectively, were significantly decreased (P < 0.05 or P < 0.01). CONCLUSION: PDTC could attenuate paraquat-induced up-regulation of TGF-beta(1) and its mRNA expression, MMP-2 and TIMP-1 mRNA levels, which indicates that PDTC may exert its protective effects on paraquat-induced pulmonary damage by alleviating the earlier inflammation damage and adjust-ing the balance between MMPs and TIMPs. However, further studies are still warranted to investigate and clarify the underlying mechanisms involved in this complicated process.

[Effects of 90-day oral dimethoate exposure on glutamatergic system and neurobehavioral performance in rats].

OBJECTIVE: To investigate the spatial learning and exploration along with the CNS excitatory amino acid neurotransmitters profiles in adult rats subchronically exposed to the anticholinesterase organophosphorus insecticide dimethoate. METHODS: Rats were gavaged daily with dimethoate (0, 5, 10 or 20 mg/kg via oral) in NS. for 90 days. Morris water maze tasks were used to test the spatial learning and memory in the rats after the dimethoate exposure. Simultaneously, rats were decapitated for the determination of brain cholinesterase AChE activities, glutamate concentrations, and the NMDA receptor NMDA-R densities and affinities in hippocampus. RESULTS: Latencies to find a hidden escape platform were significantly longer in dimethoate dosed groups than that of the control group in the place navigation tests. Subsequently, the times of crossing the location of platform which had been removed obviously decreased in the highest dose group compared with that of the control in the spatial probe tests (P < 0.05). AChE activity was significantly reduced 42% approximately 78% by all three doses of dimethoate (P < 0.05). Glutamate concentrations were increased significantly 132.9% approximately 134.5% by the two highest doses of dimethoate (P < 0.05). In addition, the NMDA receptor bindings were reduced 21.2% approximately 23.2% with the statistical significance at the same two highest doses (P < 0.05). Furthermore, the receptor affinities was reduced 33.1% by the highest dose group (P < 0.05). The lesions of spatial memory were statistically corrected with the decrease of the NMDA-R affinities (P < 0.05). CONCLUSION: The cholinergic lesion as well as the excitatory amino acid system alteration might attribute to the inferior ability in spatial learning and memory in dimethoate subchronically exposed rats.

[Effect of dimethoate on the expression of heat shock protein 70 in peripheral blood lymphocytes of human beings].

OBJECTIVE: To study the effect of dimethoate on the expression of heat shock protein 70 (HSP70) in peripheral blood lymphocytes of human beings and to explore the feasibility of HSP70 in biomonitoring among workers exposed to organophosphorous pesticides. METHODS: Peripheral blood lymphocytes were isolated from subjects, comprising 11 people of the control group and 35 workers of the exposure group exposed to dimethoate. Flow cytometry was used for detecting both the basic level and the level of the dimethoate-induced expression of HSP70. The activity of whole blood acetylcholinesterase (AChE) was examined at the same time. Then the potential influential factors to HSP70 expression and AChE activity were analyzed. RESULTS: The basic level of HSP70 expression in the exposure group and the control group was 41.24% +/- 10.45% and 23.97% +/- 4.29% respectively. The activity of AChE in these two groups were (125.23 +/- 7.97) and (145.36 +/- 8.78) U/ml respectively. Both differences were statistically significant (P < 0.01). Among the exposure group, the basic level of HSP70 expression of the two categories comprising operators and packers, were 47.34% +/- 11.87% and 38.05% +/- 8.20% respectively (P < 0.05), while there was no significant difference (P > 0.05) in AChE activity between these two categories. The factors that had significant influence on the HSP70 basic level of the exposure group were the health condition, the environmental concentration of dimethoate and the exposure time in order, according to their significance of influence. At least 88% variance of HSP70 could be explained by these factors. The only factor that could influence AChE activity significantly was the exposure time, and it could only explain about 12% variance of AChE activity. After the treatment of dimethoate in vitro, the level of the induced expression of HSP70 in the control group was significantly higher than that of the exposure group (P < 0.01). The increasing order was the control group, the group of packers and the group of operators according to the increasing extent and there were significant difference among them (P < 0.01). The factors that could significantly influence the change ratio of HSP70 expression were the environmental concentration and the exposure time. CONCLUSION: HSP70 is a potential index that can reflect the individual and environmental conditions of workers exposed to dimethoate comprehensively.