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1.
Proc Natl Acad Sci U S A ; 119(26): e2117083119, 2022 06 28.
Artículo en Inglés | MEDLINE | ID: mdl-35737841

RESUMEN

There are still significant knowledge gaps in understanding the intrusion and retention of exogeneous particles into the central nervous system (CNS). Here, we uncovered various exogeneous fine particles in human cerebrospinal fluids (CSFs) and identified the ambient environmental or occupational exposure sources of these particles, including commonly found particles (e.g., Fe- and Ca-containing ones) and other compositions that have not been reported previously (such as malayaite and anatase TiO2), by mapping their chemical and structural fingerprints. Furthermore, using mouse and in vitro models, we unveiled a possible translocation pathway of various inhaled fine particles from the lung to the brain through blood circulation (via dedicated biodistribution and mechanistic studies). Importantly, with the aid of isotope labeling, we obtained the retention kinetics of inhaled fine particles in mice, indicating a much slower clearance rate of localized exogenous particles from the brain than from other main metabolic organs. Collectively, our results provide a piece of evidence on the intrusion of exogeneous particles into the CNS and support the association between the inhalation of exogenous particles and their transport into the brain tissues. This work thus provides additional insights for the continued investigation of the adverse effects of air pollution on the brain.


Asunto(s)
Encéfalo , Pulmón , Material Particulado , Animales , Sangre , Encéfalo/metabolismo , Humanos , Pulmón/química , Pulmón/metabolismo , Ratones , Tamaño de la Partícula , Material Particulado/análisis , Material Particulado/sangre , Material Particulado/química , Material Particulado/metabolismo , Distribución Tisular
2.
Cell Mol Biol Lett ; 29(1): 81, 2024 May 30.
Artículo en Inglés | MEDLINE | ID: mdl-38816685

RESUMEN

Sepsis is defined as life-threatening organ dysfunction caused by a dysregulated host response to infection. Studies have indicated that immune dysfunction plays a central role in the pathogenesis of sepsis. Dendritic cells (DCs) play a crucial role in the emergence of immune dysfunction in sepsis. The major manifestations of DCs in the septic state are abnormal functions and depletion in numbers, which are linked to higher mortality and vulnerability to secondary infections in sepsis. Apoptosis is the most widely studied pathway of number reduction in DCs. In the past few years, there has been a surge in studies focusing on regulated cell death (RCD). This emerging field encompasses various forms of cell death, such as necroptosis, pyroptosis, ferroptosis, and autophagy-dependent cell death (ADCD). Regulation of DC's RCD can serve as a possible therapeutic focus for the treatment of sepsis. Throughout time, numerous tactics have been devised and effectively implemented to improve abnormal immune response during sepsis progression, including modifying the functions of DCs and inhibiting DC cell death. In this review, we provide an overview of the functional impairment and RCD of DCs in septic states. Also, we highlight recent advances in targeting DCs to regulate host immune response following septic challenge.


Asunto(s)
Células Dendríticas , Sepsis , Células Dendríticas/inmunología , Sepsis/inmunología , Sepsis/patología , Humanos , Animales , Muerte Celular Regulada , Autofagia , Apoptosis , Piroptosis
3.
Small ; 19(17): e2207332, 2023 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-36719997

RESUMEN

Delicate electrochemical active surface area (ECSA) engineering over the exposed catalytic interface and surface topology of platinum-based nanomaterial represents an effective pathway to boost its catalytic properties toward the clean energy conversion system. Here, for the first time, the facial and universal production of dendritic Pt-based nanoalloys (Pt-Ni, Co, Fe) with highly porous feature via a novel Zn2+ -mediated solution approach is demonstrated. In the presence of Zn2+ during synthesis, the competition of different galvanic replacement reactions and consequently generated "branch-to-branch" growth mode are believed to play key roles for the in situ fabrication of such unique nanostructure. Due to the fully exposed active sites and ligand effect-induced electronic optimization, electrochemical hydrogen evolution in alkaline media on these catalysts exhibit dramatic activity enhancement, delivering a current density of 30.6 mA cm-2 at a 70 mV overpotential for the Pt3 Ni nanodendrites and over 7.4 times higher than that of commercial Pt/C. This work highlights a general and powerful ion-assisted strategy for exploiting dendritic Pt-based nanostructures with efficient activities for water electrolysis.

4.
Proc Natl Acad Sci U S A ; 117(47): 29462-29468, 2020 Nov 24.
Artículo en Inglés | MEDLINE | ID: mdl-33172992

RESUMEN

Using renewable electricity to synthesize ammonia from nitrogen paves a sustainable route to making value-added chemicals but yet requires further advances in electrocatalyst development and device integration. By engineering both electrocatalyst and electrolyzer to simultaneously regulate chemical kinetics and thermodynamic driving forces of the electrocatalytic nitrogen reduction reaction (ENRR), we report herein stereoconfinement-induced densely populated metal single atoms (Rh, Ru, Co) on graphdiyne (GDY) matrix (formulated as M SA/GDY) and realized a boosted ENRR activity in a pressurized reaction system. Remarkably, under the pressurized environment, the hydrogen evolution reaction of M SA/GDY was effectively suppressed and the desired ENRR activity was strongly amplificated. As a result, the pressurized ENRR activity of Rh SA/GDY at 55 atm exhibited a record-high NH3 formation rate of 74.15 µg h-1⋅cm-2, a Faraday efficiency of 20.36%, and a NH3 partial current of 0.35 mA cm-2 at -0.20 V versus reversible hydrogen electrode, which, respectively, displayed 7.3-, 4.9-, and 9.2-fold enhancements compared with those obtained under ambient conditions. Furthermore, a time-independent ammonia yield rate using purified 15N2 confirmed the concrete ammonia electroproduction. Theoretical calculations reveal that the driving force for the formation of end-on N2* on Rh SA/GDY increased by 9.62 kJ/mol under the pressurized conditions, facilitating the ENRR process. We envisage that the cooperative regulations of catalysts and electrochemical devices open up the possibilities for industrially viable electrochemical ammonia production.

5.
BMC Med Educ ; 23(1): 554, 2023 Aug 07.
Artículo en Inglés | MEDLINE | ID: mdl-37550684

RESUMEN

BACKGROUND: The application of virtual reality (VR) in gastroscopic operation teaching can be safe and effective, but the advantages can be realized only when students accept and use it. This study aims to identify the factors influencing Chinese clinical medical postgraduates on their intention to use the 3D gastroscopic model constructed based on VR technology using Unified Theory of Acceptance and Use of Technology (UTAUT) model. Students' demographic factors are also taken into consideration. METHODS: All methods were carried out in accordance with relevant guidelines. Data were collected from clinical medical postgraduates students in China using stratified sampling. A total of 292 questionnaires including valid responses were used in this study. Data were processed using Amos 24.0 and SPSS 26.0 software and the statistical analysis technique was based on structural equation modeling (SEM). RESULTS: The results showed that different from the mediator of home location and year of clinical learning, mediator of gender, university kind and graduate degree did not affect the behavioral intention. In addition, performance expectancy, facilitating condition, and social influence directly and indirectly have effect on behavioral intention. Also, the significance between social influence and performance expectancy, social influence and effort expectancy were verified. CONCLUSIONS: This study manifested that the proposed framework based on the UTAUT had explanatory power to identify the factors influencing the students' behavioral intention to use the 3D gastroscopic model constructed based on VR technology. Whereas, an important variable of effort expectancy in the frame of the SEM were not certified, thereby indicating that particular attention should be paid to this variable by universities and teachers before applying 3D gastroscopic model constructed based on VR technology in teaching. Added preparatory work is required such as explaining the basic knowledge of the operating steps of VR model and make students adequately understand its accessibility, which can probably improve the intentions of them to use it. The positive effects of social influence on performance expectancy and effort expectancy we proposed was also verified in this study, which provided a direction for future research.


Asunto(s)
Intención , Estudiantes de Medicina , Humanos , Gastroscopios , Programas Informáticos , Aprendizaje
6.
Nano Lett ; 22(2): 751-760, 2022 01 26.
Artículo en Inglés | MEDLINE | ID: mdl-35030010

RESUMEN

In recent years, targeted therapies and immunotherapeutics, along with conventional chemo- and radiotherapy, have greatly improved cancer treatments. Unfortunately, in cancer patients, anemia, either as a complication of cancer progression or as the result of cancer treatment, undermines the expected therapeutic efficacy. Here, we developed a smart nanosystem based on the palladium nanoplates (PdPLs) to deliver tocilizumab (TCZ, a widely used IL-6R antibody) to the liver for specific blockade of IL-6/IL-6R signaling to correct anemia. With chemical modifications, this nanosystem delivered a large mass of TCZ and enhanced liver delivery, inducing a marked suppression of hepcidin expression as a result of diminished IL-6 signaling. Through this mechanism, significant suppression of tumor progression was realized (at least in part) because of the corrected anemia after treatment.


Asunto(s)
Anemia , Neoplasias , Anemia/tratamiento farmacológico , Anemia/etiología , Regulación Neoplásica de la Expresión Génica/efectos de los fármacos , Humanos , Interleucina-6/genética , Interleucina-6/metabolismo , Neoplasias/complicaciones , Neoplasias/tratamiento farmacológico , Paladio/farmacología , Paladio/uso terapéutico , Receptores de Interleucina-6/antagonistas & inhibidores , Receptores de Interleucina-6/genética , Receptores de Interleucina-6/metabolismo
7.
Small ; 18(45): e2203442, 2022 11.
Artículo en Inglés | MEDLINE | ID: mdl-36156407

RESUMEN

Accurate control over the coordination circumstances of single-atom catalysts (SACs) is decisive to their intrinsic activity. Here, two single-site heterogeneous organometallic catalysts (SHOCs), Cp*Ir-L/GDY (L = OH- and Cl- ; Cp* = pentamethylcyclopentadienyl), with the fine-tuned local coordination and electronic structure of Ir sites, are constructed by anchoring Cp*Ir complexes on graphdiyne (GDY) matrix via a one-pot procedure. The spectroscopic studies and theoretical calculations indicate that the Ir atoms in Cp*Ir-Cl/GDY and Cp*Ir-OH/GDY have a much higher oxidation state than Ir in the SAC Ir/GDY. As a proof-of-principle demonstration, the GDY-supported SHOCs are used for formic acid dehydrogenation, which display a fivefold enhancement of catalytic activity compared with SAC Ir/GDY. The kinetic isotope effect and in situ Fourier-transform infrared studies reveal that the rate-limiting step is the ß-hydride elimination process, and Cp* on the Ir site accelerates the ß-hydride elimination reaction. The GDY-supported SHOCs integrate the merits of both SACs and molecular catalysts, wherein the isolated Ir anchored on GDY echoes with SACs' behavior, and the Cp* ligand enables precise structural and electronic regulation like molecular catalysts. The scheme of SHOCs adds a degree of freedom in accurate regulation of the local structure, the electronic property, and therefore the catalytic performance of single-atom catalysts.


Asunto(s)
Carbono , Grafito , Carbono/química , Catálisis , Grafito/química , Oxidación-Reducción
8.
Br J Haematol ; 192(3): 643-651, 2021 02.
Artículo en Inglés | MEDLINE | ID: mdl-32866306

RESUMEN

Spontaneous abortion is a common, detrimental outcome of pregnancy, and can be induced by a variety of factors, including pathophysiological conditions and socioeconomic circumstances. Despite numerous studies examining the aetiology of spontaneous abortion, there is limited understanding of the disordered iron transportation between mother and fetus through the placenta. Recently, erythroferrone (ERFE) was recognized as a novel negative regulator of hepcidin that can elevate nutritional iron absorption and macrophagic iron egress for enhanced erythropoiesis. However, its diagnostic significance in different disease conditions associated with iron remains poorly understood. In the current study, we discovered disordered maternal iron homeostasis in women who had spontaneous abortions during early pregnancy, as characterized by increased serum iron and hepcidin levels, and conversely, reduced serum ERFE levels, compared to healthy control individuals and women with normal pregnancy. Comprehensive statistical analyses revealed the correlation between different variables and pregnancy status, signifying the pronounced diagnostic value of an increased ratio of serum hepcidin and ERFE (HE ratio) in recognizing adverse pregnancy status. In contrast to previous non-selective discrete surrogates, such as iron, hepcidin and ferritin, the HE ratio may otherwise stand for a novel and more representative hallmark for early spontaneous abortion.


Asunto(s)
Aborto Espontáneo/sangre , Hepcidinas/sangre , Hormonas Peptídicas/sangre , Aborto Espontáneo/metabolismo , Adulto , Femenino , Humanos , Hierro/metabolismo , Embarazo , Pronóstico
9.
Angew Chem Int Ed Engl ; 60(1): 466-472, 2021 Jan 04.
Artículo en Inglés | MEDLINE | ID: mdl-32946193

RESUMEN

As a favorite descriptor, the size effect of Cu-based catalysts has been regularly utilized for activity and selectivity regulation toward CO2 /CO electroreduction reactions (CO2 /CORR). However, little progress has been made in regulating the size of Cu nanoclusters at the atomic level. Herein, the size-gradient Cu catalysts from single atoms (SAs) to subnanometric clusters (SCs, 0.5-1 nm) to nanoclusters (NCs, 1-1.5 nm) on graphdiyne matrix are readily prepared via an acetylenic-bond-directed site-trapping approach. Electrocatalytic measurements show a significant size effect in both the activity and selectivity toward CO2 /CORR. Increasing the size of Cu nanoclusters will improve catalytic activity and selectivity toward C2+ productions in CORR. A high C2+ conversion rate of 312 mA cm-2 with the Faradaic efficiency of 91.2 % are achieved at -1.0 V versus reversible hydrogen electrode (RHE) over Cu NCs. The activity/selectivity-size relations provide a clear understanding of mechanisms in the CO2 /CORR at the atomic level.

10.
Nano Lett ; 19(5): 2758-2764, 2019 05 08.
Artículo en Inglés | MEDLINE | ID: mdl-30958673

RESUMEN

Metallic 1T-phase transition metal dichalcogenides (TMDs) are of considerable interest in enhancing catalytic applications due to their abundant active sites and good conductivity. However, the unstable nature of 1T-phase TMDs greatly impedes their practical applications. Herein, we developed a new approach for the synthesis of highly stable 1T-phase Au/Pd-MoS2 nanosheets (NSs) through a metal assembly induced ultrastable phase transition for achieving a very high electrocatalytic activity in the hydrogen evolution reaction. The phase transition was evoked by a novel mechanism of lattice-mismatch-induced strain based on density functional theory (DFT) calculations. Raman spectroscopy and transmission electron microscopy (TEM) were used to confirm the phase transition on experimental grounds. A novel heterostructured 1T MoS2-Au/Pd catalyst was designed and synthesized using this mechanism, and the catalyst exhibited a 0 mV onset potential in the hydrogen evolution reaction under light illumination. Therefore, this method can potentially be used to fabricate 1T-phase TMDs with remarkably enhanced activities for different applications.

11.
Mikrochim Acta ; 185(2): 124, 2018 01 24.
Artículo en Inglés | MEDLINE | ID: mdl-29594748

RESUMEN

A disposable needle-type of hybrid electrode was prepared from a core of stainless steel needle whose surface was modified with a 3D nanoporous gold/NiCo2O4 nanowall hybrid structure for electrochemical non-enzymatic glucose detection. This hybrid electrode, best operated at 0.45 V (vs. SCE) in solutions of pH 13 has a linear response in the 0.01 to 21 mM glucose concentration range, a response time of <1 s, and a 1 µM detection limit (at an S/N ratio of 3). The remarkable enhancement compared to the solid gold/NiCo2O4 and stainless steel/NiCo2O4 hybrid electrodes in electrochemical performance is assumed to originate from the good electrical conductivity and large surface area of the hybrid electrode, which enhance the transport of mass and charge during electrochemical reactions. This biosensor was also applied to real sample analysis with little interferences. The electrode is disposable and considered to be a promising tool for non-enzymatic sensing of glucose in a variety of practical situations. Graphical abstract Ultrathin NiCo2O4 nanowalls supported on nanoporous gold that is coated on a stainless steel needle was fabricated for sensitive non-enzymatic amperometric sensing of glucose.


Asunto(s)
Técnicas Electroquímicas/métodos , Glucosa/análisis , Técnicas Electroquímicas/normas , Electrodos , Oro/química , Nanopartículas del Metal/química , Nanoporos , Agujas , Acero Inoxidable
12.
Nanomaterials (Basel) ; 12(7)2022 Mar 28.
Artículo en Inglés | MEDLINE | ID: mdl-35407230

RESUMEN

We propose a terahertz frequency multiplier based on high order harmonic generation in a GaAs-based miniband superlattice driven by an electric field. The performance of the frequency multiplier is analyzed using the balance equation approach, which incorporates momentum and energy relaxation processes at different lattice temperatures. It is found that the generated high-order harmonic power is sensitive to temperature changes. The peak power appears around resonance between driving terahertz frequency and intrinsic Bloch frequency. In the presence of the magnetic field, the peak power shifts towards a stronger static electric field region. The simulated results about the dependence of the second and third harmonic powers on a DC electric field are in qualitative consistence with the experiments. The proposed terahertz frequency multiplier based on semiconductor superlattice, being compact and efficient, is provided as a good candidate for terahertz wave generation.

13.
Front Public Health ; 10: 986430, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-36330111

RESUMEN

Objective: Cigarettes have become the the biggest killer of contemporary female's health and beauty. What kind of health information is suitable for the general public is an important issue to be discussed globally. The purpose of this study is to generate systematic, rigorous, public-demand-oriented and appropriate core information relevant to tobacco control based on the best available evidence, combined with audience preferences and pre-dissemination content review from multidisciplinary expertise in order to improve the effectiveness of health communication of tobacco control. Methods: Relevant systematic reviews meta-analysis that reported smoking on risks of female disease were identified by searching PubMed, Embase, the Cochrane Library, Web of Science, Clinical Trials.gov, and the International Clinical Trial Registry Platform. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) process was applied to assess the evidence in order to make rigorous core information. The audience prevalence survey was conducted to ensure that core information was targeted and tailored. Finally, the expert assessment was used for a pre-dissemination content review and to evaluate whether the core information was appropriate or not. Results: The final core information consisted of eight parts concerning the effects of smoking and female cardiovascular disease, diabetes, rheumatoid arthritis, respiratory disease, digestive system disease, mental disease, non-pregnant female reproductive system disease, as well as pregnant women and their fetuses. A total of 35 items of core information suitable for dissemination was included and the quality of evidence, the degree of public demand and the outcome of pre-dissemination content review were reported. Conclusion: The core information related to female cardiovascular system diseases, as well as liver cancer and upper gastrointestinal cancer is the preferred content for health communication of tobacco control. The quality of evidence for core information related to pregnant women and their infants, as well as diseases of reproductive system, respiratory system, and diabetes needs to be improved to meet high public demand. The core information related to mental disease is more suitable for dissemination to patients with mental illness than to the general public. Besides, dissemination of core information should be individualized. Evidence-based Core Information for Health Communication of Tobacco Control would be helpful to provide evidence support for health communication related to tobacco control and enhance public health literacy for international communities that have high smoking prevalence and related disease burden.


Asunto(s)
Diabetes Mellitus , Comunicación en Salud , Cese del Hábito de Fumar , Lactante , Femenino , Humanos , Embarazo , Fumar/epidemiología , Nicotiana
15.
Biosens Bioelectron ; 144: 111697, 2019 Nov 01.
Artículo en Inglés | MEDLINE | ID: mdl-31536930

RESUMEN

Surface plasmon resonance (SPR) has become a leading technique for in situ bioaffinity assay of diverse targets without need of fluorescent or enzymatic labeling. Nanomaterials-enhanced SPR sensors have developed rapidly and widened the application scope of SPR sensing technology. In this report we describe an ultrasensitive SPR biosensor for detecting carcinoembryonic antigen (CEA). Our SPR biosensor utilizes a Ti3C2-MXene-based sensing platform and multi-walled carbon nanotube (MWCNTs)-polydopamine (PDA)-Ag nanoparticle (AgNPs) signal enhancer. Ti3C2-MXene, a new class of two-dimensional (2D) transition metal carbides, offers a large hydrophilic-biocompatible surface ideal for SPR biosensing. Ti3C2-MXene/AuNPs composites after synthesis are then decorated with staphylococcal protein A (SPA) to orient and immobilize monoclonal anti-CEA antibody (Ab1) through its Fc region. By introducing MWCNTs-PDA-AgNPs-polyclonal anti-CEA antibody (MWPAg-Ab2) conjugate combined with a sandwich format, the present method provides a dynamic range for CEA determination of 2×10-16 to 2×10-8 M and a detection limit of 0.07 fM. This biosensing approach demonstrates good reproducibility and high specificity for CEA in real serum samples providing a promising method to evaluate CEA in human serum for early diagnosis and monitoring of cancer.


Asunto(s)
Técnicas Biosensibles , Antígeno Carcinoembrionario/aislamiento & purificación , Nanopartículas del Metal/química , Resonancia por Plasmón de Superficie , Anticuerpos Antiidiotipos/química , Anticuerpos Antiidiotipos/inmunología , Antígeno Carcinoembrionario/química , Oro/química , Humanos , Nanoestructuras/química , Nanotubos de Carbono/química , Plata/química , Elementos de Transición/química
16.
Nanoscale ; 10(45): 21161-21167, 2018 Dec 07.
Artículo en Inglés | MEDLINE | ID: mdl-30407474

RESUMEN

Engineering the interfacial structure of bimetallic nanocrystals is an effective method to improve their electrocatalytic performances. Here, we design a facile strategy for controlling the surface morphology evolution of Au@Pd core-shell nanorods by adjusting the solution supersaturation. The Pd shell of the as-prepared Au@Pd bimetallic nanorods can be modulated from a (111) facet-exposed island to a (100) facet-exposed conformal shell. The conformal shell structure exhibited enhanced catalytic performance toward the ethanol oxidation reaction, while the core-island structure possessed better catalytic stability. This work provides a facile method for interfacial engineering of bimetallic nanocrystals with desired morphology and properties.

17.
ACS Appl Mater Interfaces ; 10(1): 745-752, 2018 Jan 10.
Artículo en Inglés | MEDLINE | ID: mdl-29265797

RESUMEN

Developing active and bifunctional noble metal-free electrocatalysts is crucial for both the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in the full water splitting process. A ternary nanoporous sulfur-doped copper oxide (Cu2OxS1-x) was successfully synthesized on Cu foam. The obtained Cu2OxS1-x/Cu shows robust electrocatalytic activity toward HER with a low overpotential of 40 mV at 10 mA cm-2 and a Tafel slope of 68 mV dec-1 and exhibits long-term stability in acid solution. Moreover, Cu2OxS1-x shows excellent electrocatalytic activity for OER, HER, and overall water splitting as a bifunctional catalyst in 1.0 M KOH electrolyte. The sulfur doping strategy implemented here can greatly improve the catalytic performance and stability in both acidic and alkaline water electrolyzers and presents an efficient catalyst for overall water splitting.

18.
Biosens Bioelectron ; 23(2): 201-9, 2007 Sep 30.
Artículo en Inglés | MEDLINE | ID: mdl-17540554

RESUMEN

The variety of applications utilizing molecularly imprinted polymers (MIPs) requires synthetic strategies yielding different MIP formats including films, irregular particles, or spheres, along with precise knowledge on the specific material characteristics, such as binding capacity and binding efficiency of these materials. In response to this demand, MIPs are prepared in different formats by variation of the polymerization methodology. It is commonly agreed that micro- and sub-microspheres are particularly advantageous MIP formats, due to their monodispersity and facile synthesis procedures in contrast to conventional imprinted polymers prepared by bulk polymerization. However, the differences in actual rebinding characteristics of different MIP formats based on molecular interactions under a variety of binding/rebinding conditions have not been studied in detail to date. Consequently, the present work details an analytical strategy generically applicable to MIP systems for rebinding studies including equilibrium binding, non-equilibrium binding, and release experiments enabling more profound understanding on the molecular interactions between the imprinted materials and the template molecules. In this study, three MIP formats were considered for the same template molecule, 17beta-estradiol: irregularly shaped particulate polymers prepared by bulk polymerization and grinding, microspheres, and sub-microspheres. The latter two formats were synthesized via precipitation polymerization using different processing strategies. The morphologies and porosities of the resulting imprinted materials were characterized by scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET) analysis, respectively. The obtained results indicate that microspheres prepared by precipitation polymerization provide superior rebinding properties during equilibrium binding in contrast to bulk polymers and sub-microspheres, and that the rebinding properties are different during equilibrium binding versus non-equilibrium binding. The median binding affinity constant determined during non-equilibrium rebinding is higher than the values obtained from equilibrium rebinding. Furthermore, the binding site distribution appears more homogeneous thief derived from non-equilibrium rebinding, as reflected in a heterogeneity index of m=0.725. Moreover, it is hypothesized that the specific interactions between template and monomers are related to the porosity of the imprinted polymers, which implies that the amount of binding sites and the pore sized distribution of the imprinted materials are a critical factor in achieving the desired MIP performance in various analytical applications. The BET results indicate that particles prepared with lower cross-linker-to-template ratio have a reduced surface area. Furthermore, it can be expected that there are less specific binding sites available at particles with reduced surface area and pore volume given similar distribution of the binding sites, as confirmed by the equilibrium binding isotherm studies. The pore size distribution results reveal that control of the pore size in the range of 100-180 A is essential to obtain the desired retention properties and Gaussian peak shape during HPLC analysis of small molecules.


Asunto(s)
Materiales Biocompatibles/química , Estradiol/química , Polímeros/química , Sitios de Unión , Ensayo de Materiales , Porosidad , Propiedades de Superficie
19.
Biosens Bioelectron ; 21(10): 1943-51, 2006 Apr 15.
Artículo en Inglés | MEDLINE | ID: mdl-16326090

RESUMEN

A one-step precipitation polymerization procedure for the synthesis of molecularly imprinted polymers selective for 17beta-estradiol yielding imprinted micro and nanospheres was developed in this study and compared to templated materials obtained by conventional bulk polymerization. The polymer particles prepared by precipitation polymerization exhibited a regular spherical shape at the micro and nanoscale with a high degree of monodispersity. Moreover, the influence of the polymerization temperature, and the ratio of functional monomer to cross-linker on the size of the obtained particles was investigated. The selectivity of the imprinted micro and nanospheres was evaluated by HPLC analysis and via radioligand binding assays. HPLC separation experiments revealed that the imprinted microspheres provide higher or similar affinity to the template in contrast to imprinted polymers prepared by conventional bulk polymerization or synthesized by multi-step swelling/polymerization methods. The dimensions of the imprinted nanospheres facilitate suspension in solution rendering them ideal for binding assay applications. Results from saturation and displacement assays prove that the imprinted nanospheres exhibit superior specific affinity to the target molecule in contrast to control materials. The binding properties of the nanospheres including binding isotherms and affinity distribution were studied via Freundlich isotherm affinity distribution (FIAD) analysis. Moreover, release experiments show that 70% of rebound 17beta-estradiol was released from the imprinted nanospheres within the first 2 h, while more intimately bound 17beta-estradiol molecules (approx. 16%) were released in the following 42 h. Fitting Brunnauer-Emmet-Teller (BET) multi-point adsorption isotherms to the obtained results indicated that the micro and nanospheres are characterized by a comparatively homogenous and narrow distribution of mesopores in contrast to the corresponding bulk polymers.


Asunto(s)
Técnicas Biosensibles , Estradiol/análisis , Microesferas , Nanosferas/ultraestructura , Cinética , Microscopía Electrónica de Rastreo
20.
ACS Omega ; 1(6): 1367-1373, 2016 Dec 31.
Artículo en Inglés | MEDLINE | ID: mdl-31457202

RESUMEN

Developing cheap, stable, and efficient electrocatalysts is of extreme importance in the effort to replace noble metal electrocatalysts for use in the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). We report a three-dimensional self-supported Cu3P nanobush (NB) catalyst directly grown on a copper mesh via a one-step method. This nanostructure exhibits a superior catalytic activity of achieving a current density of 10 mA cm-2 at 120 mV and exhibits a long-term stability in acid solutions. It shows a Tafel slope of 72 mV dec-1 and an onset potential of -44 mV. This catalyst displays a good catalytic activity in basic electrolytes, reaching a current density of 10 mA cm-2 at the overpotential values of 252 and 380 mV for HER and OER, respectively. The bifunctional Cu3P NB/Cu catalyst exhibits better catalytic performances than the Pt/C and IrO2 catalysts in a two-electrode electrolyzer for overall water splitting.

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