查找使用阿拉丁产品的科研文献

Engineering DNA/Fe–N–C single-atom nanozymes interface for colorimetric biosensing of cancer cells

Liping Sun,Chao Li,Yong Yan,Yue Yu,Hao Zhao,Zijue Zhou,Feng Wang,Yi Feng

Single atom nanozymes (SAzymes) represent the state-of-the-art technology in nanomaterial-based catalysis, which have attracted attentions in catalysis, cancer treatment, disinfection and biosensing fields. However, numerous SAzymes suffered from low aqueous dispersion and without recognition capacity, which impeded their applications in bioanalysis . Herein, we engineered DNA onto SAzymes to obtain the DNA/SAzymes conjugates , which significantly improved the aqueous dispersion and recognition ability of SAzymes. We synthesized iron SAzymes (Fe–N–C SAzymes) as the catalytic nanomaterials, and investigated the interactions between Fe–N–C SAzymes and DNA. We compared A 15 , T 15 and C 15 adsorption of Fe–N–C SAzymes in HEPES containing 2 mM MgCl 2 . We found that 50 μg mL −1 Fe–N–C SAzymes produced nearly 100% A 15 adsorption, 90% T 15 adsorption and only 69% C 15 adsorption, indicating that adenine and thymine had higher adsorption affinity on Fe–N–C SAzymes. More importantly, DNA modification did not affect the peroxidase-like activity of Fe–N–C SAzymes and the bioactivity of the adsorbed DNA. Taking the advantage of the diblock DNA with one DNA sequence (adenine) binding to Fe–N–C SAzymes and the other DNA sequence (i.e., aptamer) binding to cancer cells, we designed Apt/Fe–N–C SAzymes for colorimetric detection of cancer cells, which offered new insights for the use of SAzymes in biomedicine .

Glucose Stimulation of Cytochrome C Reduction and Oxygen Consumption as Assessment of Human Islet Quality

Sweet Ian R.,Gilbert Merle,Jensen Rich,Sabek Omaima,Fraga Daniel W.,Gaber Ahmed O.,Reems JoAnna

Background. An in vitro method to assess human islets could prevent transplantation of nonviable islets and facilitate the optimization of islet preparation. We hypothesize that glucose-stimulated cytochrome c reduction and oxygen consumption by human islets can be used as predictors of transplant success. Methods. Isolated human islets were obtained from research-grade pancreata. Using a previously developed islet flow culture system, the response of cytochrome c reduction and oxygen consumption to glucose was compared to the ability of islets transplanted into nondiabetic NOD-SCID mice to secrete C-peptide in response to a glucose tolerance test conducted 7 days following transplant (n=10). Results. In vitro responses by human islets were qualitatively similar to those seen in rat islets: glucose increased both oxygen consumption and cytochrome c reduction. However, the responses were smaller in magnitude and quite variable. Scatter plots of C-peptide and quantiles for ln(C-peptide) indicated that 12 ng/ml could be used as threshold of transplant success with which to evaluate the diagnostic potential of cytochrome c and oxygen consumption. Data was analyzed by generating receiver operating curves and the area under the curve was 0.889 (95% CI: 0.645–1.000) and 0.738 (95% CI: 0.413–1.000) for cytochrome c reuction and oxygen consumption respectively (1 indicates absolute predictive capability and 0.5 indicates no predictive capability). Conclusions. The detection of glucose-stimulated cytochrome c reduction and oxygen consumption may have utility as criteria for the assessment of human islet quality.

Facile synthesis of SiO2/C anode using PVC as carbon source for lithium-ion batteries

Li Jian,Yang Shengliang,Zhou Hongming,Wang Lihua,Yang Zhaohui,Meng Pengyu,Hu Leshan,Hu Rong

SiO 2 /C composites using polyvinyl chloride (PVC) as carbon sources are prepared successfully via a facile and low-cost approach. In this paper, the effect of four coating ratios on the SiO 2 /C materials is investigated. When tested as an anode material for lithium-ion batteries, the samples possessing a high carbon content display a better electrochemical stability. The high-content PVC pyrolytic carbon can provide a malleable and high electrical conductivity carbon layer for SiO 2 , which has more defects and benefits the diffusion of Li ions between the electrolyte and SiO 2 /C. However, considering the low capacity of the PVC pyrolytic carbon, a carbon content of 25% was chosen as the best coating ratio. This SiO 2 /C electrode shows a reversible capacity of 695 mAh g −1 at a current density of 100 mA g −1 after 200 cycles, with a capacity retention of 86.4% after the first cycle. The electrode also displays a discharge capacity of 535 mAh g −1 at a current density of 1 A g −1 . Taking into consideration the facileness and the low cost of the synthetic method, this SiO 2 /C composite anode material may have a great prospect of industrialization.

Highly Sensitive Surface Plasmon Resonance Sensor Modified With 2D Ti₂C MXene for Solution Detection

Shuaiwen Gan,Banxian Ruan,Yuanjiang Xiang,Xiaoyu Dai

Wastewater Purification and All-Solid Z-Scheme Heterojunction ZnO-C/MnO2 Preparation: Properties and Mechanism

Lei Zhao,Tingting Yu,Bing Yang,Huilin Guo,Lifen Liu,Jinlong Zhang,Changfei Gao,Tao Yang,Mingyan Wang,Yu Zhang

Unlike many studies on the preparation of Z-scheme heterojunctions by doping precious metals, in this paper we first prepared a core-shell material obtained by C doping in ZnO and then composite with MnO2to form a heterojunction; that is, a low-cost and highly catalytic ternary composite catalyst was prepared by a simple hydrothermal reaction. Meanwhile, a large amount of experimental data have enabled the heterostructure type as well as the mechanism of photocatalytic performance to be fully demonstrated. It is proven that C as an intermediate medium achieves electron transport while making up the deficiency of ZnO, and constitutes an all-solid state Z-scheme heterojunction, which enables the rapid transfer of photogenerated electron pairs and visible light irradiation to the stream to improve the photocatalytic performance of the composite photocatalyst. In terms of examination of degradation performance, this catalyst showed a high photodegradation rate of tetracycline hydrochloride (TC) of 92.6% within 60 min, and the surface ZnO-C/MnO2catalysts also showed good degradation effect on practical petrochemical wastewater in CODcr degradation experiments.Keywords:ZnO-C/MnO2;Z-scheme heterojunction;wastewater purification;mechanism exploring

Construction of Co@C Hybrid Nanostructure: Electrochemical Biosensor for Detection of Penicillin Sodium in Milk

Xiu Yi,Luo Ruiping,Han Baoqing,Liu Lu,Wang Hongsu

In this study, a cobalt-based mesoporous carbon material (Co@C) was prepared by self-assembly method and impregnation method, and carboxyl functionalization was carried out to obtain COOH-Co@C. Then, the penicillinase (Pen X) was immobilized on the carrier material by covalent binding. The methylene blue was electropolymerized onto the glassy carbon electrode, and then the immobilized enzyme material was modified onto the modified electrode to prepare a biosensor. After optimization of experimental conditions, the differential pulse method was used to detect penicillin sodium (Pen G) as an antibiotic model. Notably, measurement was performed without any pH redox probe, and a low limit of detection was obtained. The results showed that when the concentration of Pen G was 0.1–10 ng mL −1 , the corresponding current and concentration of the sensor showed a good linear relationship. The linear equation is y = 0.3881x + 17.20 ( r 2 = 0.9974); when the concentration range is 10–100 ng mL −1 , the linear equation is y = 0.1170x + 19.73 ( r 2 = 0.9959). The limit of detection is 0.64 ng mL −1 . The sensor is not only simple to prepare but also has high sensitivity and accurate detection. Finally, using the spike method, the actual sample detection was successfully realized.

Effect of Carbon Supports on Enhancing Mass Kinetic Current Density of Fe-N/C Electrocatalysts

Xinghua Chen,Fei He,Yanfei Shen,Yiran Yang,Hao Mei,Songqin Liu,Toshiyuki Mori,Yuanjian Zhang

Graphical Interface effect : A study into the intrinsic role of carbon supports for Fe-N/C alternatives to Pt/C catalysts for oxygen reduction in fuel cells revealed that when immobilized on suitable support, the Fe−N/C demonstrated an improved mass J K that was comparable to that of Pt/C and higher than most reported M−N/C catalysts (see scheme). The mass kinetic current density (mass J K ) of most extensively reported M−N/C catalysts (M represents non-precious metal elements such as Fe, Co, and Cu), a potential alternative to noble metal catalysts in fuel cells, is poorer than that of commercial Pt/C. Thus, deep understanding of the intrinsic roles of carbon supports may contribute to the development of M−N/C catalysts from a practical point of view. Herein, the routinely used carbon supports, i.e. carbon black (CB) and carbon nanotubes (CNT) that have different morphology and crystallinity, were investigated to uncover the factors that affected the mass J K of Fe−N/C in electrocatalytic oxygen reduction. When immobilized on CB, the ionic liquids-derived Fe−N/C exhibited an enhanced mass J K (4.45 A g −1 at 0.80 V vs. RHE) by a factor of 2.14 times, comparable to that of Pt/C (5.79 A g −1 ) and higher than most reported M−N/C catalysts to our best knowledge. In contrast, the CNT support system showed no improvement. It was revealed that a compatible interface between the Fe−N/C precursors and the carbon supports was vital to ensure in-situ growth of a uniform catalyst layer on the supports during pyrolysis. This subsequently promotes the mass J K by exposing more embedded active sites and introducing favorable slit pores for effective mass-diffusion. This work would be promising to address the long-term overlooked challenge of the low mass J K of M−N/C catalysts in replacing noble-metal catalysts for practical fuel cell applications.

Quinazoline-Assisted ortho-Halogenation with N-Halosuccinimides through Pd(II)-Catalyzed C(sp2)−H Activation

Yong Wang,Hui Wang,Qifan Yang,Shihua Xie,Hongjun Zhu

Graphical Herein, palladium(II)-catalyzed halogenation of 2-phenylquinazolines using N -halosuccinimides as halogen sources was described via C−H activation under mild reaction conditions. A series of halogen-substituted 2-arylquinazolines were synthesized through C−H functionalization. An efficient quinazoline-assisted ortho -halogenation of 2-arylquinazolines has been developed using N -halosuccinimides as halogen sources with Pd(II)-catalyzed C−H bond activation. No additional ligand and oxidant are required. This protocol is highly regioselective and applicable to a broad range of quinazoline substrates bearing different functional groups, giving yields of up to 98 %. The mechanism of the quinazoline ortho -halogenation was investigated by comprehensive experimentation.

A hierarchically porous TiN/N-C electrocatalyst with high interface utilization for lithium-sulfur batteries

Xianyi Tang,Cheng Tong,Lianqiao Tan,Zidong Wei,Meng Wang

Lithium-Sulfur Batteries (LiSBs) are prevented to apply in practice by the irreversible loss from the cathode and difficult conversation kinetics of lithium polysulfides (LiPSs). An ideal S host material should possess high conductivity and sufficiently dispersed catalytic active sites to precisely restore the dissolved LiPSs to the surface of the S host material. In traditional catalyst design, porous carbonaceous materials are often selected as carriers for the nano-catalytic activity sites. However, non-polar pure carbon interfaces, where without nano-catalytic activity sites covered, have a very weak affinity to LiPSs. Here, we use ammonia as a nitrogen source to anneal the reduced aerogel (graphene oxide (rGO) supported nano-TiO 2 ) at high temperatures. The N element is atomically doped into the lattice of   the carbon matrix, and the nano-TiO 2 is converted to nano-TiN. A hierarchically porous and high conductivity TiN/N-C is prepared, in which the nano-TiN is well dispersed on the surface of N-doped rGO as an active center for catalyzing LiPSs conversion. The doped-N elements significantly increase the proportion of the polar surface. The S@TiN/N-C composite cathode delivered an excellent long-life cycling performance, and the reversible discharge specific capacity faded from 1224 ± 16 to 675 ± 31 mAh g −1 after 930 cycles. More importantly, after 150 cycles with a high S loading, a reversible areal capacity of 4.1 mAh cm −2 can be achieved.

Pt–C Interfaces Based on Electronegativity-Functionalized Hollow Carbon Spheres for Highly Efficient Hydrogen Evolution

Xiao Shang,Zi-Zhang Liu,Shan-Shan Lu,Bin Dong,Jing-Qi Chi,Jun-Feng Qin,Xien Liu,Yong-Ming Chai,Chen-Guang Liu

The hydrogen evolution reaction activity of carbon-supported Pt catalyst is highly dependent on Pt–C interfaces. Herein, we focus on the relationships between Pt activity and N/O-functionalized hollow carbon sphere (HCS) substrate in acidic media. The electrochemical dissolution of Pt counter electrode is performed to prepare Pt nanoparticles in low loading. The N groups are beneficial for homogeneously sized Pt nanoparticles, whereas the O groups lead to aggregated nanoparticles. Moreover, the proper electronegativity of the N groups may enable capturing of protons to create proton-rich Pt–C interfaces and transfer them onto the Pt sites. The O groups may also capture protons by hydrogen bonding, but the subsequent release of protons is more difficult due to a stronger electronegativity and result in an inferior Pt activity. Consequently, the N-doped HCS with a low Pt loading (1.7 μg cm–2 and 0.05 wt %) possesses a higher intrinsic activity compared with Pt on O-doped HCS. Moreover, it outperforms the commercial 20% Pt/C with a stable operation for 12 h. This work may provide suggestions for constructing the advantageous Pt–C interfaces by proper functional groups for high catalytic efficiencies.

Synthesis of MoS2@N-MXene/C Heterogeneous Nanosheets and its Enhanced Pseudocapacitance Effects for NIBs

Wei-Xiang Cheng,Yi-Zhao Chen,Song-Yi Liao,Jun-Qi Hu,Cun-Sheng Liu,Shuai-Fu Cui,Xing-Wen Huang,Yidong Liu,Yonggang Min

Graphical NIB news : MoS 2 anchored on nitrogen-doped MXene nanosheets with carbon coating were prepared and applied in Na-ion batteries (NIBs). It remained at ∼308 mAh g −1 at 0.5 A g −1 after 300 cycles and showed higher rate performance of ∼189 mAh g −1 at 4 A g −1 . The MoS 2 @N-MXene/C heterogeneous nanosheets showed enhanced pseudocapacitance effects of 84.5 % at a scan rate of 2 mV s −1 according to CV curves simulation. Currently, Na-ion batteries (NIBs) have emerged as a new generation of energy storage devices. However, due to the lack of suitable anode materials, the large-scale practical application of NIBs is still greatly limited. Therefore, to address this issue, an effective strategy towards an advanced NIBs anode was developed by achieving MoS 2 anchored on nitrogen-doped MXene nanosheets with carbon coating (shorten as MoS 2 @N-MXene/C). The structure, surface chemistry state and micromorphology of MoS 2 @N-MXene/C were carefully analyzed and characterized by XRD, XPS and SEM/TEM, respectively. It was shown that MoS 2 was loaded on N-MXene to form a heterogeneous nanosheets structure. When applied to the anode of NIBs, MoS 2 @N-MXene/C delivered ∼189 mAh g −1 at 4 A g −1 and remained at ∼308 mAh g −1 after 300 cycles at 0.5 A g −1 . Moreover, based on the simulation and calculation from CV curves, the enhanced electrochemical performances of MoS 2 @N-MXene/C was assigned to its high pseudocapacitance-dominated contribution (84.5 % at a scan rate of 2 mV s −1 ). Therefore, owing to the highly conductive N-MXene and the actively anchored MoS 2 , MoS 2 @N-MXene/C could effectively provide efficient channels for charge transfer and ionic diffusion. The presented design strategy may provide a guidance for developing more-efficient NIBs anode.

Rapid calcination synthesis of Zn2SnO4@C/Sn composites for high-performance lithium ion battery anodes

Hongyun Yue,Zhenpu Shi,Lan Wang,Xiangnan Li,Hongyu Dong,Yanhong Yin,Shuting Yang

Zn 2 SnO 4 @C/Sn composites were synthesized via the rapid calcination of a zinc-tin binary MOF under a reducing atmosphere for 1 min. Nanometal Sn, which has a good conductivity, and Zn 2 SnO 4 nanoparticles were assembled into secondary particles in the synthesized composites. The metal Sn acted as an active material and a conductive agent. The nanosized Zn 2 SnO 4 @C/Sn composites reduced the volume expansion and enhanced the electrochemical performance. Additionally, the carbon provided buffer spaces for the volume expansion of the active material. The metal Sn grew into large particles as the calcination time increased, which transformed the lithium storage process from surface controlled to diffusion controlled. When the Zn 2 SnO 4 @C/Sn composites were used as anode materials for LIBs , a superior electrochemical performance was achieved. A reversible capacity of up to 1140 mA h g −1 was obtained at a current density of 100 mA g −1 after 100 cycles. The reason for the capacity fading in the samples that were calcined for a long time was also analyzed, and the results might be helpful for researchers when designing new anode materials.