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1.
Talanta ; 280: 126669, 2024 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-39153254

RESUMO

In this work, a photoelectrochemical (PEC) immunosensor was constructed for the ultrasensitive detection of lung cancer marker neuron-specific enolase (NSE) based on a microflower-like heterojunction of cadmium indium sulfide and magnesium indium sulfide (CdIn2S4/MgIn2S4, CMIS) as photoactive material. Specifically, the well-matched energy level structure and narrow energy level gradients between CdIn2S4 and MgIn2S4 could accelerate the separation of electron-hole (e--h+) pairs in the CMIS heterojunction to enhance the photocurrent of CMIS, which was increased 5.5 and 80 times compared with that of single CdIn2S4 and MgIn2S4, respectively. Meanwhile, using CMIS as photoactive material, increasing the biocompatibility by dropping Pt NPs on the surface of CMIS to immobilize the antibody through Pt-N bond. Fe3O4-Ab2, acting as the quencher, competitively consumes electron donors and absorbs light, leading to photocurrent quenching. With the increasing of quencher, the photocurrent decreased. Hence, the developed "signal-off" PEC immunosensor realized the trace detection of NSE within the range from 1.0 fg/mL to 10 ng/mL with a low detection limit of 0.34 fg/mL. This strategy provided a new perspective for establishing ternary metal sulfide heterojunction to construct PEC immunosensor for sensitive detection of disease biomarkers.


Assuntos
Biomarcadores Tumorais , Índio , Neoplasias Pulmonares , Fosfopiruvato Hidratase , Sulfetos , Humanos , Fosfopiruvato Hidratase/análise , Índio/química , Biomarcadores Tumorais/análise , Sulfetos/química , Limite de Detecção , Técnicas Eletroquímicas , Técnicas Biossensoriais/métodos , Imunoensaio/métodos , Compostos de Cádmio/química , Anticorpos Imobilizados/imunologia , Anticorpos Imobilizados/química
2.
Mol Pharm ; 21(5): 2250-2271, 2024 May 06.
Artigo em Inglês | MEDLINE | ID: mdl-38661388

RESUMO

Charges and their contribution to protein-protein interactions are essential for the key structural and dynamic properties of monoclonal antibody (mAb) solutions. In fact, they influence the apparent molecular weight, the static structure factor, the collective diffusion coefficient, or the relative viscosity, and their concentration dependence. Further, charges play an important role in the colloidal stability of mAbs. There exist standard experimental tools to characterize mAb net charges, such as the measurement of the electrophoretic mobility, the second virial coefficient, or the diffusion interaction parameter. However, the resulting values are difficult to directly relate to the actual overall net charge of the antibody and to theoretical predictions based on its known molecular structure. Here, we report the results of a systematic investigation of the solution properties of a charged IgG1 mAb as a function of concentration and ionic strength using a combination of electrophoretic measurements, static and dynamic light scattering, small-angle X-ray scattering, and tracer particle-based microrheology. We analyze and interpret the experimental results using established colloid theory and coarse-grained computer simulations. We discuss the potential and limits of colloidal models for the description of the interaction effects of charged mAbs, in particular pointing out the importance of incorporating shape and charge anisotropy when attempting to predict structural and dynamic solution properties at high concentrations.


Assuntos
Anticorpos Monoclonais , Coloides , Imunoglobulina G , Coloides/química , Anticorpos Monoclonais/química , Imunoglobulina G/química , Viscosidade , Soluções/química , Concentração Osmolar , Espalhamento a Baixo Ângulo , Difusão Dinâmica da Luz , Simulação por Computador , Difração de Raios X/métodos
3.
J Colloid Interface Sci ; 629(Pt B): 739-749, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36193618

RESUMO

As an efficient photocatalyst, graphitic carbon nitride (g-C3N4) has been widely used in the field of photocatalytic hydrogen production. However, how to prepare hydrogen efficiently and stably has become a challenge. Herein, we successfully realize metal-free edge modification with phenyl groups by one-step thermal polymerization of urea with 4-phenyl-3-thiosemicarbazide. Consequently, the optimal photocatalytic hydrogen production rate for the modified graphitic carbon nitride is increased by three times to a value of 2390.6 µmol h-1 g-1, while the apparent quantum efficiency (AQE) reaches 8.3 % at a wavelength of 420 nm. We also provide a theoretical explanation for the experiments using density functional theory (DFT) calculations, which suggest that energy level changes and electron redistribution for the modified carbon nitride materials contribute to the observed changes in catalytic performance. This work provides an effective solution for improving the photocatalytic activity of carbon nitride materials and provides theoretical support for the edge modification of carbon nitride materials to promote their photocatalytic hydrogen production efficiency.

4.
ACS Appl Mater Interfaces ; 14(45): 50803-50814, 2022 Nov 16.
Artigo em Inglês | MEDLINE | ID: mdl-36321950

RESUMO

Metal-organic frameworks (MOFs) are a class of nanoporous crystalline materials with very high structural tunability. They possess a very low dielectric permittivity εr due to their porosity and hence are favorable for piezoelectric energy harvesting. Even though they have huge potential as piezoelectric materials, a detailed analysis and structure-property relationship of the piezoelectric properties in MOFs are lacking so far. This work focuses on a class of cubic non-centrosymmetric MOFs, namely, zeolitic imidazolate frameworks (ZIFs) to rationalize how the variation of different building blocks of the structure, that is, metal node and linker substituents affect the piezoelectric constants. The piezoelectric tensor for the ZIFs is computed from ab initio theoretical methods. From the calculations, we analyze the different contributions to the final piezoelectric constant d14, namely, the clamped ion (e140) and the internal strain (e14int) contributions and the mechanical properties. For the studied ZIFs, even though e14 (e140 + e14int) is similar for all ZIFs, the resultant piezoelectric coefficient d14 calculated from piezoelectric constant e14 and elastic compliance constant s44 varies significantly among the different structures. It is the largest for CdIF-1 (Cd2+ and -CH3 linker substituent). This is mainly due to the higher elasticity or flexibility of the framework. Interestingly, the magnitude of d14 for CdIF-1 is higher than II-VI inorganic piezoelectrics and of a similar magnitude as the quintessential piezoelectric polymer polyvinylidene fluoride.

5.
Molecules ; 27(18)2022 Sep 19.
Artigo em Inglês | MEDLINE | ID: mdl-36144865

RESUMO

The superionic conductor, solid state, and body-centered cubic structure, silver iodide at room temperature, has been studied via molecular dynamics simulations. The calculated results using pairwise Coulomb-Buckingham potential, zero pressure on the sample, a semi-rigid model system of 1000 Ag and 1000 I ions, (NVE) as a statistical ensemble, and an effective charge of Z=0.63 for the pairs Ag-Ag and I-I, were found to be consistent with experimental data and one study using Z=0.60, different potential, and simulation software. For the pair Ag-I, there is a discrepancy due to the high silver ion diffusion. The calculated value of the diffusion constant of the silver ion is greater than iodide ion. The dynamic transport properties (mean square displacement, velocity autocorrelation function) results indicated typical behavior reported by other authors, using different potentials in their DM simulations for iodine and silver ions.

6.
Environ Sci Pollut Res Int ; 29(26): 39139-39163, 2022 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-35099701

RESUMO

This work presents a new approach and a comprehensive mechanism to study the kinetics of the photodegradation of the organic pollutants. The vital role of various operational factors on the degradation of the organic pollutants is explained using this method. The proposed approach is based on the simple strategies and a powerful computational method. Two new variables "the effective concentration of photon" (Ieff) and "the effective concentration of the reactive centers" (RC) are defined to better understand the effect of operational parameters on the organic pollutant photodegradation. The optimum conditions of the photocatalytic degradation can be determined with the help of this method. This approach was used to study the kinetics of photodegradation of the organic pollutants on the [Formula: see text] photocatalysts. The provided mechanism has been examined with the some experimental data. The high correlations between the experimental data and the fitting results under different conditions prove this mechanism could be reliable.


Assuntos
Poluentes Ambientais , Poluentes Químicos da Água , Catálise , Cinética , Fotólise , Poluentes Químicos da Água/análise
7.
Biosens Bioelectron ; 202: 114006, 2022 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-35091371

RESUMO

Photoelectrochemical immunoassays/immunosensors have been employed for biomarker detection, but most are lack of high-efficiency photo-electron transfer nanomaterials for widespread utilization. Herein we synthesized single-atom platinum-anchored Zn0.5Cd0.5S nanostructures to construct an innovative photoelectrochemical (PEC) immunosensor for photocurrent determination of prostate-specific antigen (PSA). Improvement of the photocurrent on the sensing interface derived from the ion-exchange reaction between cupric oxide nanoparticle (CuO NP)-labeled secondary antibody and single-atom platinum-anchored Zn0.5Cd0.5S. The experimental results showed that the doping of zinc ions and atomically dispersed platinum into CdS could significantly enhance the photocurrent, which further improved the sensitivity of immunoassay. Specifically, upon sensing the target PSA, a CuO-labeled detection antibody was introduced by sandwich immunoreaction and numerous copper ions (Cu2+) were released from CuO by acid to participate in the ion-exchange reaction. Thereafter, the ion-exchange reaction between Cu2+ ions and single-atom platinum-anchored Zn0.5Cd0.5S resulted in the quenching of the photocurrent from single-atom platinum-anchored Zn0.5Cd0.5S owing to weak photoactive material CuxS formation. Under optimized conditions, single-atom platinum-anchored Zn0.5Cd0.5S-based photoelectrochemical immunoassay gave good PEC signals toward PSA from 1.0 to 10000 pg/mL with a limit of detection of 0.22 pg/mL. Additionally, good repeatability, intermediate precision, strong anti-interference and high accuracy (relative to commercialized ELISA kit) for the measurement of human serum specimens were acquired. Importantly, use of single-atom platinum-anchored Zn0.5Cd0.5S can provide an important idea for early tumor screening and diagnosis.


Assuntos
Técnicas Biossensoriais , Antígeno Prostático Específico , Técnicas Biossensoriais/métodos , Cádmio , Técnicas Eletroquímicas/métodos , Humanos , Imunoensaio/métodos , Limite de Detecção , Masculino , Zinco
8.
Appl Radiat Isot ; 179: 110024, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34785444

RESUMO

In this study, the stopping power, CSDA range and radiation yield calculations of electrons and positrons over the 20 eV-1 GeV energy range in some water equivalent polymer gel dosimeters were performed. For collision stopping power calculations of electrons and positrons the effective charge concept proposed by Sugiyama were considered. Here, both the effective charge of incident electrons and positrons (z*) and the effective charge (Z*) and the effective mean excitation energy (I*) of the target material were calculated. For the density effect correction the Fano model was selected. For the radiative stopping power analytical model based on the ratio between the collision and the radiative stopping power discribed by Attix was considered. For CSDA range and radition yield the continuous slowing down approximation (CSDA) was considered and the calculations were performed using numerical integral methods. Because of their water equivalent and 3D dose distribution properties, MAGIC and MAGAS polymer gels were selected as a target materials. The calculations were performed by programming all the equations discribed in this study as a computational code. The results of the stopping power, range and radiation yield were compared with those of ESTAR program and PENELOPE Monte Carlo modelling. Some deviations in low and high energy region between the calculated and reference data were observed. However, the similarity between calculated and reference data is remarkable. For the collision stopping power and CSDA range a good agreement between the calculated and reference data was observed for energies >1 keV. Whereas, for the radiative stopping power a good agreement was observed for energies >100 keV.

9.
Chemosphere ; 280: 130759, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-33964757

RESUMO

A sea urchin-shaped, single-layer, and hollow NiO-NiS photocatalyst with a large surface area was designed for carbon dioxide (CO2) conversion in this study. A d-glucose polymeric hollow frame was fabricated using a d-glucose monomer, and NiO particles were stably grown on it using the hydrothermal method to form a hollow NiO surface. The d-glucose frame was removed by heat treatment to create hollowed NiO; hollowed NiO-NiS (h-NiO-NiS) was subsequently obtained through ion exchange between the O ions in NiO and S ions in the sulfur powder. Additionally, we attempted to determine the correlation among the surface area of the h-NiO-NiS catalyst, CO2 gas adsorption capacity, and catalyst performance. The surface area of the h-NiO-NiS catalyst was ten times larger than that of the nanometer-sized NiO-NiS (n-NiO-NiS, 21.2 m2 g-1) catalyst. The CO2 photocatalytic conversion performance of the hollowed catalyst was approximately seven times larger than that of the nanosized catalyst. As the amount of ion-exchanged S increased, methane selectivity increased, and optimal methane production was obtained when the weight ratio of NiO and sulfur powder was 1 : 4. Using temperature-programmed desorption (TPD) analyses of CO2 and H2O, the adsorption of water molecules on the Ni-S surface and that of CO2 gas on the Ni-O surface during CO2 conversion reaction were confirmed. The h-NiO-NiS catalyst facilitated an effective charge separation through a well-developed interfacial transition between the linked NiS and NiO, and resulted in increased CO2 photoreduction performance under sunlight.


Assuntos
Dióxido de Carbono , Luz , Adsorção , Catálise , Metano
10.
ACS Appl Mater Interfaces ; 13(7): 9252-9259, 2021 Feb 24.
Artigo em Inglês | MEDLINE | ID: mdl-33587596

RESUMO

Hot electron flux, generated by both incident light energy and the heat of the catalytic reaction, is a major element for energy conversion at the surface. Controlling hot electron flux in a reversible manner is extremely important for achieving high energy conversion efficiency. Here we demonstrate that hot electron flux can be controlled by tuning the Schottky barrier height. This phenomenon was monitored by using a Schottky nanodiode composed of a metal-semiconductor. The formation of a Schottky barrier at a nanometer scale inevitably accompanies an intrinsic image potential between the metal-semiconductor junction, which lowers the effective Schottky barrier height. When a reverse bias is applied to the nanodiode, an additional image potential participates in a secondary barrier lowering, leading to the increased hot electron flow. Besides, a decrease of tunneling width results in facile electron transport through the barrier. The increased hot electron flux by the chemical reaction (chemicurrent) and by the photon absorption (photocurrent) indicates hot electrons are captured more effectively by modifying the Schottky barrier. This study can shed light on a quantitative understanding and application of charge behavior at metal-semiconductor interfaces, in solar energy conversion, or in a catalytic reaction.

11.
Nanomaterials (Basel) ; 10(10)2020 Sep 29.
Artigo em Inglês | MEDLINE | ID: mdl-33003531

RESUMO

The construction of heterostructured photocatalyst with an appropriate energy band structure will help realize highly efficient photo-excited charge separation. In this study, ternary CuO/CeO2/ZnO nano-particle (NP) composites were synthesized by a facile two-step sol-gel method, which exhibit significantly enhanced photocatalytic degradation performance for various organic pollutants under UV and visible light excitation. The photo-responses to both UV and visible light, as well as the visible light absorption and utilization rates of ZnO are found to be synergistically intensified by CeO2 and CuO co-coupling. The first-order kinetic constants (K) of 3%CuO/CeO2/ZnO for methylene blue (MB) degradation are ~3.9, ~4.1 and ~4.8 times higher than ZnO under UV light, visible light and simulated sunlight illumination, respectively. The roles of CuO and CeO2 in optical properties and photo-degradation under UV and visible light were explored. Besides, the photogenic holes (h+) of ZnO, CeO2, and the produced hydroxyl radicals (·OH) are proved to be the main active species under UV light. Dissimilarly, under visible light, the superoxide radicals (·O2-) formed by the reactions between oxygen molecules and the photo-generated electrons (e-) of CuO moving towards the catalysts surface are also found to be important for promoting dye decomposition. The improved photo-responses, the well-matched band structure that facilitates charge transfer processes, and the highly efficient utilization of the photo-excited carriers of the ternary nano-heterostructure are suggested to be the key factors for the remarkable enhancement of photocatalytic performance of ZnO nano-photocatalyst. This work offers a low-cost strategy to acquire highly active UV and visible light-driven photocatalyst.

12.
J Magn Reson ; 318: 106796, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32784055

RESUMO

Electrophoretic NMR has the capacity to provide unique physico-chemical information but is limited by a variety of experimental artifacts, such as thermal convection and electrolytic products in the sample. Here we present some simple modifications to the experimental hardware and protocol that, in a significant number of cases, can much improve experimental accuracy and precision. We show that one can strongly reduce artifacts in a symmetric sample cell with an appropriate feeding of current and with a porous plug suitably inserted. This latter feature requires that the electric field pulses across the sensitive volume are implemented as current-controlled pulses applied to the sample. Measurements with current-controlled pulses have the additional advantage of not requiring calibration with samples of known electrophoretic mobility.

13.
ACS Appl Mater Interfaces ; 12(23): 25736-25747, 2020 Jun 10.
Artigo em Inglês | MEDLINE | ID: mdl-32421303

RESUMO

The 70Li2S-30P2S5 glass is a promising solid-state electrolyte for all solid-state lithium-ion batteries. Nevertheless, understanding the Li+ conduction mechanism is limited because of the complex amorphous nature of the glass. Herein, we present an ab initio molecular dynamics study of the 70Li2S-30P2S5 glass using a long simulation run (800 ps), improving the general understanding of its structure, dynamics, and electronic polarizability by comparing the results to those of the Li7P3S11 crystals. The shape difference of the P2S74- between the Li7P3S11 crystal and 70Li2S-30P2S5 glass is clearly observed in P-S-P bond angle, indicating that the P2S74- units in the 70Li2S-30P2S5 glass are relatively free from stress for crystallographic ordering. From the Li trajectories for 800 ps, the diffusion within the limited space in the unit cell is derived as the effective porosity. The lower effective porosity in the 70Li2S-30P2S5 glass compared to the Li7P3S11 crystal implies that a part of volume in the 70Li2S-30P2S5 glass cannot contribute to Li+ conduction. This reduction is attributed to the rotational motion of PS43-, which is observed only in the 70Li2S-30P2S5 glass. The sulfur polarizability is thoroughly analyzed for isotropic and anisotropic span through the Born effective charge tensor. The uniformly anisotropic polarizability of sulfur in the 70Li2S-30P2S5 glass is a characteristic property, which cannot create fast Li+ conduction paths as that in Li7P3S11 crystal.

14.
Biosens Bioelectron ; 134: 1-7, 2019 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-30947036

RESUMO

An all-solid-state metal-mediated Z-scheme photoelectrochemical (PEC) immunoassay was designed for sensitive detection of prostate-specific antigen (PSA) by using WO3-Au-CdS nanocomposite as photoactive material and copper ion (Cu2+) as an inhibitor. The Z-scheme PEC system comprising of CdS nanoparticle (photosystem I; PS I), WO3 nanorod (photosystem II; PS II) and gold nanoparticle (Au NP; solid electron mediator) was reasonably established by a simple and green synthetic method. As an important part of Z-scheme system, the sandwiched gold nanoparticles between electron donor materials and hole provider materials could accelerate electron transfer from positive conduction band (CB) of WO3 to negative valence band (VB) of CdS, thus resulting in high-efficient separation of the carriers. In the presence of target PSA, a sandwiched immunoreaction was executed between capture antibody-coated microplate and CuO nanoparticle-labeled detection antibody. Thereafter, CuO nano labels were dissolved into Cu2+ ions under acidic condition to decrease the photocurrent of Z-scheme WO3-Au-CdS thanks to the formation of exciton trapping center of CuxS (x = 1,2) on the surface. Under optimum conditions, Z-scheme PEC immunoassay exhibited good photocurrents toward target PSA within a linear range of 0.01-50 ng mL-1 at a limit of detection of 1.8 pg mL-1. Moreover, the Z-scheme PEC immunoassay had high selectivity and accuracy. Importantly, this method provides a new horizon for detection of disease-related biomarkers with high sensitivity.


Assuntos
Anticorpos Imobilizados/química , Técnicas Biossensoriais/métodos , Compostos de Cádmio/química , Cobre/química , Imunoensaio/métodos , Nanoestruturas/química , Óxidos/química , Antígeno Prostático Específico/sangue , Sulfetos/química , Tungstênio/química , Técnicas Eletroquímicas/métodos , Transporte de Elétrons , Ouro/química , Humanos , Limite de Detecção , Nanopartículas/química , Nanotubos/química , Processos Fotoquímicos
15.
Methods Mol Biol ; 1804: 57-82, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29926404

RESUMO

Scattering techniques are applied to studying the structural features of ganglioside aggregates in solution. Here it is described how different probing radiations allow to access different structural and dynamical parameters on different lengthscales. Besides a brief but comprehensive description of the scattering measurements, several practical suggestions are given concerning the experiments and the data analysis.


Assuntos
Gangliosídeos/química , Luz , Nêutrons , Espalhamento de Radiação , Micelas , Movimento (Física) , Raios X
16.
Spectrochim Acta A Mol Biomol Spectrosc ; 203: 166-176, 2018 Oct 05.
Artigo em Inglês | MEDLINE | ID: mdl-29864640

RESUMO

A new relation, ΔE = aebq, between the chemical shift ΔE and effective charge 'q' is proposed. It has been shown that the relation generates polynomial relations, between ΔE and 'q' used by earlier investigators and addresses their short-comings effectively. Further, four possible sign combinations of 'q' and ΔE are accounted for using the proposed equation. Units of arbitrary constants 'a' and 'b' are derived. The tendency of 'q' to attain saturation value is also explained. The success of the new relation has been tested using its linearized form ln ∣ ΔE ∣ = ln ∣ a ∣ + bq for a large number of compounds, by taking their experimental X-ray absorption edge shifts along with corresponding values of 'q' from the available literature. In the process, the claim of earlier workers regarding linear relationship between ΔE and 'q' and ΔE and 'qX', where 'X' is the electronegativity, has been found incorrect in the case of 6p6 isoelectronic series of compounds.

17.
Nano Lett ; 18(6): 3773-3779, 2018 06 13.
Artigo em Inglês | MEDLINE | ID: mdl-29688720

RESUMO

We demonstrate the ability to confine a single molecule in solution by spatial modulation of its local configurational entropy. Previously we established electrostatic trapping of a charged macromolecule by geometric tailoring of a repulsive electrical interaction potential in a parallel plate system. However, since the lifetime of the trapped state depends exponentially on the electrical charge of the molecule, the electrostatic interaction alone is often insufficient in magnitude to stably confine molecules carrying a net charge of magnitude ≤5 e. Here we show that the configurational entropy of a thermally fluctuating molecule in a geometrically modulated system can be exploited to spatially confine weakly charged molecules in solution. Measurement of the configurational entropy contribution reveals good agreement with theoretical expectations. This additional translational contribution to the total free energy facilitates direct optical imaging and measurement of the effective charge of molecules on the size scale of ∼1 nm and a charge as low as 1 e, physical properties comparable with those of a monovalent ion in solution.

18.
J Comput Chem ; 38(30): 2559-2569, 2017 11 15.
Artigo em Inglês | MEDLINE | ID: mdl-28718978

RESUMO

A self-consistent scheme combining the molecular dynamics (MD) simulation and density functional theory (DFT) was recently proposed to incorporate the effects of the charge transfer and polarization of ions into non-poralizable force fields of ionic liquids for improved description of energetics and dynamics. The purpose of the present work is to analyze the detailed setups of the MD/DFT scheme by focusing on how the basis set, exchange-correlation (XC) functional, charge-fitting method or force field for the intramolecular and Lennard-Jones interactions affects the MD/DFT results of 1,3-dimethylimidazolium bis(trifluoromethylsulfonyl) imide ( [C1mim][NTf2]) and 1-ethyl-3-methylimidazolium glycinate ( [C2mim][Gly]). It was found that the double-zeta valence polarized or larger size of basis set is required for the convergence of the effective charge of the ion. The choice of the XC functional was further not influential as far as the generalized gradient approximation is used. The charge-fitting method and force field govern the accuracy of the MD/DFT scheme, on the other hand. We examined the charge-fitting methods of Blöchl, the iterative Hirshfeld (Hirshfeld-I), and REPEAT in combination with Lopes et al.'s force field and general AMBER force field. There is no single combination of charge fitting and force field that provides good agreements with the experiments, while the MD/DFT scheme reduces the effective charges of the ions and leads to better description of energetics and dynamics compared to the original force field with unit charges. © 2017 Wiley Periodicals, Inc.

19.
Electrophoresis ; 38(16): 2018-2024, 2017 08.
Artigo em Inglês | MEDLINE | ID: mdl-28493394

RESUMO

Capillary ITP (CITP) and CZE were applied to the determination of effective charges and ionic mobilities of polycationic antimicrobial peptides (AMPs). Twelve AMPs (deca- to hexadecapeptides) containing three to seven basic amino acid residues (His, Lys, Arg) at variable positions of peptide chain were investigated. Effective charges of the AMPs were determined from the lengths of their ITP zones, ionic mobilities, and molar concentrations, and from the same parameters of the reference compounds. Lengths of the ITP zones of AMPs and reference compounds were obtained from their CITP analyses in cationic mode using leading electrolyte (LE) composed of 10 mM NH4 OH, 40 mM AcOH (acetic acid), pH 4.1, and terminating electrolyte (TE) containing 40 mM AcOH, pH 3.2. Ionic mobilities of AMPs and singly charged reference compounds (ammediol or arginine) were determined by their CZE analyses in the BGE of the same composition as the LE. The effective charges numbers of AMPs were found to be in the range 1.65-5.04, i.e. significantly reduced as compared to the theoretical charge numbers (2.86-6.99) calculated from the acidity constants of the analyzed AMPs. This reduction of effective charge due to tightly bound acetate counterions (counterion condensation) was in the range 17-47% depending on the number and type of the basic amino acid residues in the AMPs molecules. Ionic mobilities of AMPs achieved values (26.5-38.6) × 10-9  m2 V-1 s-1 and in most cases were in a good agreement with the ratio of their effective charges and relative molecular masses.


Assuntos
Peptídeos Catiônicos Antimicrobianos/análise , Físico-Química , Eletrólitos/química , Eletroforese Capilar , Concentração de Íons de Hidrogênio , Isotacoforese , Concentração Osmolar
20.
Biochim Biophys Acta Gen Subj ; 1861(7): 1737-1749, 2017 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-28315770

RESUMO

The self-assembling processes underlining the capabilities of facially differentiated ("Janus") polycationic amphiphilic cyclodextrins (paCDs) as non-viral gene nanocarriers have been investigated by a pluridisciplinary approach. Three representative Janus paCDs bearing a common tetradecahexanoyl multitail domain at the secondary face and differing in the topology of the cluster of amino groups at the primary side were selected for this study. All of them compact pEGFP-C3 plasmid DNA and promote transfection in HeLa and MCF-7 cells, both in absence and in presence of human serum. The electrochemical and structural characteristics of the paCD-pDNA complexes (CDplexes) have been studied by using zeta potential, DLS, SAXS, and cryo-TEM. paCDs and pDNA, when assembled in CDplexes, render effective charges that are lower than the nominal ones. The CDplexes show a self-assembling pattern corresponding to multilamellar lyotropic liquid crystal phases, characterized by a lamellar stacking of bilayers of the CD-based vectors with anionic pDNA sandwiched among them. When exposed to human serum, either in the absence or in the presence of pDNA, the surface of the cationic CD-based vector becomes coated by a protein corona (PC) whose composition has been analyzed by nanoLC-MS/MS. Some of the CDplexes herein studied showed moderate-to-high transfection levels in HeLa and MCF-7 cancer cells combined with moderate-to-high cell viabilities, as determined by FACS and MTT reduction assays. The ensemble of data provides a detail picture of the paCD-pDNA-PC association processes and a rational base to exploit the protein corona for targeted gene delivery on future in vivo applications.


Assuntos
Ciclodextrinas/química , DNA/química , Coroa de Proteína/química , Transfecção/métodos , Biofísica , Células HeLa , Humanos , Células MCF-7 , Nanopartículas
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