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1.
Langmuir ; 40(18): 9622-9629, 2024 May 07.
Artigo em Inglês | MEDLINE | ID: mdl-38652583

RESUMO

The detection and identification of nanoscale molecules are crucial, but traditional technology comes with a high cost and requires skilled operators. Solid-state nanopores are new powerful tools for discerning the three-dimensional shape and size of molecules, enabling the translation of molecular structural information into electric signals. Here, DNA molecules with different shapes were designed to explore the effects of electroosmotic forces (EOF), electrophoretic forces (EPF), and volume exclusion on electric signals within solid-state nanopores. Our results revealed that the electroosmotic force was the main driving force for single-stranded DNA (ssDNA), whereas double-stranded DNA (dsDNA) was primarily dominated by electrophoretic forces in nanopores. Moreover, dsDNA caused greater amplitude signals and moved faster through the nanopore due to its larger diameter and carrying more charges. Furthermore, at the same charge level and amount of bases, circular dsDNA exhibited a tighter structure compared to brush DNA, resulting in a shorter length. Consequently, circular dsDNA caused higher current-blocking amplitudes and faster passage speeds. The characterization approach based on nanopores allows researchers to get molecular information about size and shape in real time. These findings suggest that nanopore detection has the potential to streamline nanoscale characterization and analysis, potentially reducing both the cost and complexity.


Assuntos
DNA , Nanoporos , DNA/química , Conformação de Ácido Nucleico , DNA de Cadeia Simples/química , Eletro-Osmose/métodos
2.
PLoS One ; 19(4): e0302150, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38625994

RESUMO

Electroosmosis has been proposed as a technique to reduce moisture and thus increase the stability of soft clay. However, its high energy consumption and uneven reinforcement effect has limited its popularization and application in practical engineering. This paper presents the results of some electrokinetic tests performed on clayey specimens with different electrification time and anode boundary conditions. The results indicate that the timing of the formation of electroosmotic flow (EF) by the water originally contained in different soil cross sections, from the anode to the cathode, varies. The measuring soil cross section nearest the anode first reached the limiting water content of 22%±3% and electroosmosis had to be stopped. Water injection into the anode during electroosmosis enhanced further drainage of other four measuring soil cross sections until the second soil cross section from the anode reached the limiting water content of 30%±2%. Electroosmosis with water injection into the anode technique provides more uniform reinforcement, increasing EF, and environmental protection. The experimental results highlighted the relevant and expected contribution of water injection into the anode on the effectiveness of the electroosmotic treatment as a soft clay improvement technique.


Assuntos
Eletro-Osmose , Poluentes do Solo , Argila , Eletro-Osmose/métodos , Poluentes do Solo/análise , Solo , Água
3.
Biosensors (Basel) ; 14(3)2024 Feb 20.
Artigo em Inglês | MEDLINE | ID: mdl-38534219

RESUMO

The rotation of cells is of significant importance in various applications including bioimaging, biophysical analysis and microsurgery. Current methods usually require complicated fabrication processes. Herein, we proposed an induced charged electroosmosis (ICEO) based on a chip manipulation method for rotating cells. Under an AC electric field, symmetric ICEO flow microvortexes formed above the electrode surface can be used to trap and rotate cells. We have discussed the impact of ICEO and dielectrophoresis (DEP) under the experimental conditions. The capabilities of our method have been tested by investigating the precise rotation of yeast cells and K562 cells in a controllable manner. By adjusting the position of cells, the rotation direction can be changed based on the asymmetric ICEO microvortexes via applying a gate voltage to the gate electrode. Additionally, by applying a pulsed signal instead of a continuous signal, we can also precisely and flexibly rotate cells in a stepwise way. Our ICEO-based rotational manipulation method is an easy to use, biocompatible and low-cost technique, allowing rotation regardless of optical, magnetic or acoustic properties of the sample.


Assuntos
Eletricidade , Eletro-Osmose , Acústica , Eletrodos , Eletro-Osmose/métodos , Rotação , Humanos
4.
Electrophoresis ; 45(7-8): 676-686, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38350722

RESUMO

Understanding electrokinetic transport in nanochannels and nanopores is essential for emerging biological and electrochemical applications. The viscoelectric effect is an important mechanism implicated in the increase of local viscosity due to the polarization of a solvent under a strong electric field. However, most analyses of the viscoelectric effect have been limited to numerical analyses. In this work, we present a set of analytical solutions applicable to the physical description of viscoelectric effects in nanochannel electrokinetic systems. To achieve such closed-form solutions, we employ the Debye-Hückel approximation of small diffuse charge layer potentials compared to the thermal potential. We analyze critical parameters, including electroosmotic flow profiles, electroosmotic mobility, flow rate, and channel conductance. We compare and benchmark our analytical solutions with published predictions from numerical models. Importantly, we leverage these analytical solutions to identify essential thermophysical and nondimensional parameters that govern the behavior of these systems. We identify scaling parameters and relations among surface charge density, ionic strength, and nanochannel height.


Assuntos
Eletro-Osmose , Eletro-Osmose/métodos , Viscosidade , Nanotecnologia/métodos , Técnicas Analíticas Microfluídicas/instrumentação , Técnicas Analíticas Microfluídicas/métodos , Nanoporos , Concentração Osmolar , Nanoestruturas/química
5.
Electrophoresis ; 45(13-14): 1265-1266, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38376122

RESUMO

A serious error exists in the paper: Alharbi KAM, Riaz A, Sikandar S. An entropy model for Carreau nanofluid ciliary flow with electroosmosis and thermal radiations: a numerical study. Electrophoresis. 2024;45:1112-1129.


Assuntos
Eletro-Osmose , Entropia , Eletro-Osmose/métodos , Modelos Teóricos , Eletroforese/métodos
6.
Electrophoresis ; 45(13-14): 1155-1170, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38115169

RESUMO

Drug delivery systems, where the nanofluid flow with electroosmosis and mixed convection can help in efficient and targeted drug delivery to specific cells or organs, could benefit from understanding the behavior of nanofluids in biological systems. In current work, authors have studied the theoretical model of two-dimensional ciliary flow of blood-based (Eyring-Powell) nanofluid model with the insertion of ternary hybrid nanoparticles along with the effects of electroosmosis, magnetohydrodynamics, thermal radiations, and mixed convection. Moreover, the features of entropy generation are also taken into consideration. The system is modeled in a wave frame with the approximations of large wave number and neglecting turbulence effects. The problem is solved numerically by using the shooting method with the assistance of computational software "Mathematica" for solving the governing equation. According to the temperature curves, the temperature will increase as the Hartman number, fluid factor, ohmic heating, and cilia length increase. It is also disclosed that ternary hybrid nanoparticles result in a change in flow rate when other problem parameters are varied, and the same is true for temperature graphs. Engineers and scientists can make better use of nanofluid-based cooling systems in electronics, automobiles, and industrial processes with the aid of the study's findings.


Assuntos
Convecção , Eletro-Osmose , Entropia , Eletro-Osmose/métodos , Nanopartículas/química , Modelos Teóricos , Nanotecnologia/instrumentação , Nanotecnologia/métodos , Hidrodinâmica , Sistemas de Liberação de Medicamentos/instrumentação
7.
Anal Bioanal Chem ; 415(20): 4861-4873, 2023 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-37382654

RESUMO

Determining the physical and chemical properties of biologically important particles such as cells, organelles, viruses, exosomes, complexes, nucleotides, and proteins is needed to understand their function. These properties are determined with common analytical tools (mass spectrometry, cryo-EM, NMR, various spectroscopies, nucleotide sequencing, etc.) whose function can be improved when samples are pure and concentrated. Separations science plays a central role in conditioning samples, ranging from low-resolution benchtop operations like precipitations or extractions to higher-resolution chromatography and electrophoresis. In the last two decades, gradient insulator-based dielectrophoresis (g-iDEP) has emerged as a high-resolution separation technique capable of highly selective enrichment of cells, viruses, exosomes, and proteins. Specific evidence has been shown that pure homogeneous and concentrated fractions of cells and exosomes can be generated from complex mixtures. However, recovering those fractions for analysis has not been developed, limiting the technique to an analytical rather than a preparative one. Here, a finite element analysis was undertaken to identify geometries and operational parameters to efficiently remove the enriched fraction while retaining maximum concentration and providing total mass transfer. Geometric factors (e.g., side channel width and distance from the gradient-inducing gap) were studied, along with the addition of a second inlet side channel. Two flow-generating mechanisms-electroosmosis and hydrostatic pressure-were evaluated for semi-optimized device designs, including a comparison of the one- and two-inlet designs. Simulations indicate effectively one hundred percent mass transfer and a concentration increase by an order of magnitude for several device configurations and operational parameters.


Assuntos
Eletro-Osmose , Técnicas Analíticas Microfluídicas , Eletroforese/métodos , Eletro-Osmose/métodos , Dispositivos Lab-On-A-Chip
8.
Electrophoresis ; 44(1-2): 44-52, 2023 01.
Artigo em Inglês | MEDLINE | ID: mdl-35775948

RESUMO

We have investigated the role of viscoelectric effect on diffusioosmotic flow (DOF) through a nanochannel connected with two reservoirs. The transport equations governing the flow dynamics are solved numerically using the finite element technique. We have extensively analyzed the variation of induced field due to electric double layer (EDL) phenomenon, relative viscosity as modulated by the viscoelectric effect as well as reservoir's concentration difference, and their eventual impact on the underlying flow characteristics. It is revealed that the induced electric field in the EDL enhances fluid viscosity substantially near the charged wall at a higher concentration. We have shown that neglecting viscoelectric effect in the paradigm of diffusioosmotic transport overestimates the net throughput, particularly at a higher concentration difference. Furthermore, we show that pertaining to chemiosmosis dominated regime, the average flow velocity modifies with the increase in concentration difference up to a critical value. In comparison, the rise in the strength of resistive electroosmotic actuation by the accumulation of anions in the upstream reservoir reduces the average flow velocity at a higher concentration difference. We have reported a reduction in critical concentration with the increase in viscoelectric effect. The inferences of this analysis are deemed pertinent to reveal the bearing of viscoelectric effect as a flow control mechanism pertaining to DOF at nanoscale.


Assuntos
Eletricidade , Eletro-Osmose , Eletro-Osmose/métodos
9.
Electrophoresis ; 44(5-6): 558-562, 2023 03.
Artigo em Inglês | MEDLINE | ID: mdl-36495094

RESUMO

Electroosmotic flow (EOF) was determined in tridimensional (3D)-printed microchannels with dimensions smaller than 100 µm. Fused deposition modeling 3D printing using thermoplastic filaments of PETG (polyethylene terephthalate glycol), PLA (polylactic acid), and ABS (acrylonitrile butadiene styrene) were used to fabricate the microchannels. The current monitoring method and sodium phosphate solutions at different pH values (3-10) were used for the EOF mobility (µEOF ) measurements, which ranged from 2.00 × 10-4 to 12.52 × 10-4  cm2  V-1  s-1 . The highest and the smallest µEOF were obtained for the PLA and PETG microchannels, respectively. Adding the cationic surfactant cetyltrimethylammonium bromide to the sodium phosphate solution caused EOF direction reversion in all the studied microchannels. The obtained results can be interesting for developing 3D-printed microfluidic devices, in which EOF is relevant.


Assuntos
Eletro-Osmose , Fosfatos , Eletro-Osmose/métodos , Impressão Tridimensional
10.
Biosensors (Basel) ; 12(10)2022 Sep 23.
Artigo em Inglês | MEDLINE | ID: mdl-36290922

RESUMO

The performance of receptor-based biosensors is often limited by either diffusion of the analyte causing unreasonable long assay times or a lack of specificity limiting the sensitivity due to the noise of nonspecific binding. Alternating current (AC) electrokinetics and its effect on biosensing is an increasing field of research dedicated to address this issue and can improve mass transfer of the analyte by electrothermal effects, electroosmosis, or dielectrophoresis (DEP). Accordingly, several works have shown improved sensitivity and lowered assay times by order of magnitude thanks to the improved mass transfer with these techniques. To realize high sensitivity in real samples with realistic sample matrix avoiding nonspecific binding is critical and the improved mass transfer should ideally be specific to the target analyte. In this paper we cover recent approaches to combine biosensors with DEP, which is the AC kinetic approach with the highest selectivity. We conclude that while associated with many challenges, for several applications the approach could be beneficial, especially if more work is dedicated to minimizing nonspecific bindings, for which DEP offers interesting perspectives.


Assuntos
Técnicas Biossensoriais , Tempo de Reação , Técnicas Biossensoriais/métodos , Eletro-Osmose/métodos , Difusão , Eletroforese/métodos
11.
Small Methods ; 6(8): e2200318, 2022 08.
Artigo em Inglês | MEDLINE | ID: mdl-35656741

RESUMO

During the past decades, scientists have developed different kinds of nanorobots based on various driving principles to realize controlled manipulation of them for potential applications like medical diagnosis and directed cargo delivery. In order to design a nanorobot with advantages of simple operation and precise control that can enrich the family of intelligent nanorobots, an encoding manipulation method is proposed to control the movement of a DNA-nanoparticle assembled nanorobot by combing electrophoresis and electroosmosis effect in independently charged array nanopores. The nanorobot is composed of one nanoparticle and one or two ssDNAs. ssDNAs act as the legs of the nanorobot. The selective ion transport through charged nanopores can induce cooperation and competition between the electroosmosis and electrophoresis, which is the main power to activate the nanorobot. Thus by simply switching the applied electric field and surface charge density of each nanopore which is defined as the encoded nanopore according to a predetermined strategy, the well-controlled encoding manipulation including capturing, releasing, jumping, and crawling of the nanorobot is realized in this work. The study is expected to realize its value in many interesting applications like drug delivery, nanosurgery, and so on in the near future.


Assuntos
Nanopartículas , Nanoporos , DNA , Sistemas de Liberação de Medicamentos , Eletro-Osmose/métodos
12.
Electrophoresis ; 43(16-17): 1755-1764, 2022 09.
Artigo em Inglês | MEDLINE | ID: mdl-35736538

RESUMO

This study presents on-chip continuous accumulation and concentration of nanoscale samples using a cascade alternating current electroosmosis (cACEO) flow. ACEO can generate flow motion caused by ion movement due to interactions between the AC electric field and the induced charge layer on the electrode surface, with the potential to accumulate particles, especially in low-conductive liquid. However, the intrinsic particle diffusive motion, which is sensitive to particle size, is an essential element influencing accumulation efficiency. In this study, an electrode combining chevron and double-gap geometry embedded in a microfluidic channel was developed to perform efficient three-dimensional (3D) nanoparticle focusing using ACEO. The chevron electrode pattern was introduced upstream of the focusing zone to overcome particle accumulation in scattering zones near the channel sidewall. To demonstrate the efficiency of the proposed device for particle accumulation, three nanoparticle types were used: latex, metal, and biomaterial. Continuous 3D concentration of 50-nm polystyrene particles was confirmed. The concentration factor, determined based on image processing, became quite high when 50-nm gold nanoparticles were used. Moreover, nanoparticles with a 20-nm diameter were accumulated using cACEO. Finally, we used the concentrator chip to accumulate 50-nm liposome particles, confirming that the device could also successfully concentrate biomaterials.


Assuntos
Nanopartículas Metálicas , Técnicas Analíticas Microfluídicas , Eletrodos , Eletro-Osmose/métodos , Ouro
13.
Anal Methods ; 14(18): 1782-1787, 2022 05 13.
Artigo em Inglês | MEDLINE | ID: mdl-35475508

RESUMO

Pressure-assisted electrokinetic injection (PAEKI) was applied for stacking of positively charged biogenic amines (BAs) to improve the sensitivity of capillary electrophoresis (CE). It is well known that the essential step for PAEKI is finding a stationary state of the running buffer such that the movement of the running buffer due to electroosmotic flow (EOF) is counterbalanced by external pressure in the opposite direction of the EOF under a given electric field. In order to find the balance point systematically and integrally, we studied the velocity of the whole BGE in the capillary by the impetus of opposite direction pressure (-0.1 to -0.6 psi), and the velocity of EOF with different voltages. According to the two sets of linear data, the EOF of CE coupled with PAEKI could be counterbalanced at the opposite direction pressure (-0.1 psi) and voltage (7.8 kV). In this study, the injection time was extended up to 0.35 min for all BAs and 0.70 min for the direct ultraviolet (UV) detection of BAs. Compared with hydrodynamic injection (HDI), the enrichment factors for sample injection times of 0.35 min and 0.70 min were 480-fold and 970-fold, respectively. The limits of detection (LODs) (S/N = 3) of indirect and direct UV detection were respectively 8.7-24.3 nmol L-1 and 0.4-4.5 nmol L-1, which reaches the sensitivity of high-performance liquid chromatography-mass spectrophotometry (HPLC-MS). With appropriate sample dilution, PAEKI can be used in the analysis of BAs in chicken.


Assuntos
Eletro-Osmose , Eletroforese Capilar , Aminas Biogênicas , Eletro-Osmose/métodos , Eletroforese Capilar/métodos , Limite de Detecção
14.
ACS Nano ; 16(5): 7701-7712, 2022 05 24.
Artigo em Inglês | MEDLINE | ID: mdl-35435659

RESUMO

The voltage-dependent transport through biological and artificial nanopores is being used in many applications such as DNA or protein sequencing and sensing. The primary approach to determine the transport has been to measure the temporal ion current fluctuations caused by solutes when applying external voltages. Crossing the nanoscale confinement in the presence of an applied electric field primarily relies on two factors, i.e., the electrophoretic drag and electroosmosis. The electroosmotic flow (EOF) is a voltage-dependent ion-associated flow of solvent molecules, i.e., usually water, and depends on many factors, such as pH, temperature, pore diameter, and also the concentration of ions. The exact interplay between these factors is so far poorly understood. In this joint experimental and computational study, we have investigated the dependence of the EOF on the concentration of the buffer salt by probing the transport of α-cyclodextrin molecules through the ΔCymA channel. For five different KCl concentrations in the range between 0.125 and 2 M, we performed applied-field molecular dynamics simulations and analyzed the ionic flow and the EOF across the ΔCymA pore. To our surprise, the concentration-dependent net ionic flux changes non-monotonically and nonlinearly and the EOF is seen to follow the same pattern. On the basis of these findings, we were able to correlate the concentration-dependent EOF with experimental kinetic constants for the translocation of α-cyclodextrin through the ΔCymA nanopore. Overall, the results further improve our understanding of the EOF-mediated transport through nanopores and show that the EOF needs to seriously be taken into consideration when analyzing the permeation of (neutral) substrates through nanopores.


Assuntos
Nanoporos , alfa-Ciclodextrinas , Eletro-Osmose/métodos , DNA/química , Eletroforese , Íons
15.
J Am Chem Soc ; 144(7): 3063-3073, 2022 02 23.
Artigo em Inglês | MEDLINE | ID: mdl-35143193

RESUMO

Protein sequencing, as well as protein fingerprinting, has gained tremendous attention in the electrical sensing realm of solid-state nanopores and is challenging due to fast translocations and the use of high molar electrolytes. Despite providing an appreciable signal-to-noise ratio, high electrolyte concentrations can have adverse effects on the native protein structure. Herein, we present a thorough investigation of low electrolyte sensing conditions across a broad pH and voltage range generating conductive pulses (CPs) irrespective of protein net charge. We used Cas9 as the model protein and demonstrated that unfolding is noncooperative, represented by the gradual elongation or stretching of the protein, and sensitive to both the applied voltage and pH (i.e., charge state). The magnitude of unfolding and the isoelectric point (pI) of Cas9 was found to be correlated and a critical factor in our experiments. Electroosmotic flow (EOF) was always aligned with the transit direction, whereas electrophoretic force (EPF) was either reinforcing (pH < pI) or opposing (pH > pI) the protein's movement, which led to slower translocations at higher pH values. Further exploration of higher pH values led to slowing down of protein with > 30% of the population being slower than 0.5 ms. Our results would be critical for protein sensing at very low electrolytes and to retard their translocation speed without resorting to high-bandwidth equipment.


Assuntos
Proteína 9 Associada à CRISPR/metabolismo , Nanoporos , Eletro-Osmose/instrumentação , Eletro-Osmose/métodos , Concentração de Íons de Hidrogênio , Ponto Isoelétrico , Conformação Proteica , Desdobramento de Proteína
16.
Electrophoresis ; 43(5-6): 717-723, 2022 03.
Artigo em Inglês | MEDLINE | ID: mdl-34657307

RESUMO

Recent studies have demonstrated the strong influences of fluid rheological properties on insulator-based dielectrophoresis (iDEP) in single-constriction microchannels. However, it is yet to be understood how iDEP in non-Newtonian fluids depends on the geometry of insulating structures. We report in this work an experimental study of fluid rheological effects on streaming DEP in a post-array microchannel that presents multiple contractions and expansions. The iDEP focusing and trapping of particles in a viscoelastic polyethylene oxide solution are comparable to those in a Newtonian buffer, which is consistent with the observations in a single-constriction microchannel. Similarly, the insignificant iDEP effects in a shear-thinning xanthan gum solution also agree with those in the single-constriction channel except that gel-like structures are observed to only form in the post-array microchannel under large DC electric fields. In contrast, the iDEP effects in both viscoelastic and shear-thinning polyacrylamide solution are significantly weaker than in the single-constriction channel. Moreover, instabilities occur in the electroosmotic flow and appear to be only dependent on the DC electric field. These phenomena may be associated with the dynamics of polymers as they are electrokinetically advected around and through the posts.


Assuntos
Técnicas Analíticas Microfluídicas , Eletricidade , Eletro-Osmose/métodos , Eletroforese/métodos , Técnicas Analíticas Microfluídicas/métodos , Reologia
17.
Electrophoresis ; 43(12): 1259-1262, 2022 06.
Artigo em Inglês | MEDLINE | ID: mdl-34755360

RESUMO

We describe an improved method for determining the electroosmotic mobility and zeta potential of surfaces based on a current-monitoring method. This technique eliminates the requirement for measurements of channel dimensions and sample conductivities, leading to a simple high precision measurement. The zeta potential of PDMS is measured for native surfaces and surfaces treated with a nonionic surfactant in low-conductivity electrolytes.


Assuntos
Técnicas Analíticas Microfluídicas , Microfluídica , Eletrólitos , Eletro-Osmose/métodos , Técnicas Analíticas Microfluídicas/métodos
18.
Anal Chem ; 92(21): 14558-14567, 2020 11 03.
Artigo em Inglês | MEDLINE | ID: mdl-32961052

RESUMO

There are many processes that actively alter the concentrations of solutes in the extracellular space. Enzymatic reactions, either by soluble enzymes or membrane-bound ectoenzymes, and uptake or clearance are two such processes. Investigations of ectoenzymatic reactions in vivo is challenging, particularly in the brain. Studies using microdialysis have revealed some qualitative information about what enzymes may be present, but microdialysis is a sampling technique so it is not designed to control conditions such as a substrate concentration outside the probe. Micropush-pull perfusion has been used to determine which nitric oxide synthase enzymes are active in discrete regions of the rat retina. Ectopeptidases are a particularly important class of ectoenzymes. As far as it is known, the extracellular activity of active peptides in the brain is controlled by ectopeptidases. To understand ectopeptidase activity, we developed a physical probe and an accompanying method. The probe has a two-channel source that supplies substrate or substrate plus inhibitor using electroosmotic perfusion (EOP). It also has a microdialysis probe to collect products and unreacted substrate. The method provides quantitative estimates of substrate-to-product conversion and the influence of inhibitors on this process. The quantitative estimates are made possible by including a d-amino acid-containing peptide analog of the substrate in the substrate-containing solution infused. Quantitative analysis of substrate, substrate analog, and products is carried out by quantitative, online capillary liquid chromatography-tandem mass spectrometry. The electroosmotic perfusion-microdialysis probe and associated method were used to determine the effect of the selective inhibitor HFI-419 on insulin-regulated aminopeptidase (EC 3.4.11.3) in the rat neocortex.


Assuntos
Aminopeptidases/metabolismo , Eletro-Osmose/métodos , Encefalina Leucina/metabolismo , Insulina/metabolismo , Lasers , Microdiálise/métodos , Animais , Hidrólise , Neocórtex/metabolismo , Perfusão , Ratos
19.
Electrophoresis ; 41(13-14): 1225-1229, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32310305

RESUMO

Ideal-filter CE (IFCE) is a method for the selection of affinity binders for protein targets from oligonucleotide libraries, for example, random-sequence oligonucleotide libraries and DNA-encoded libraries, in a single step of partitioning. In IFCE, protein-oligonucleotide complexes and unbound oligonucleotides move in the opposite directions, facilitating very high efficiency of their partitioning. For any given protein target and oligonucleotide library, protein-oligonucleotide complexes and unbound oligonucleotides move in the opposite directions only for a limited range of EOF mobilities, which, in turn, corresponds to a limited range of pH and ionic strength values of the running buffer. Rational design of IFCE-based partitioning requires a priori knowledge of this range of pH and ionic strength values, and here we introduce an approach to predict this range for a given type of the running buffer. The approach involves measuring EOF mobilities for a relatively wide range of pH and ionic strength (I) values and finding an empirical predictor function that related the EOF mobility with pH and ionic strength. In this work, we developed a predictor function for a running buffer (Tris-HCl) that is commonly used in CE-based partitioning of affinity binders for protein targets. This predictor function can be immediately used for the rational design of IFCE-based partitioning in this running buffer, while the described approach will be used to develop predictor functions for other types of running buffer if needed.


Assuntos
Eletro-Osmose/métodos , Eletroforese Capilar/métodos , Modelos Químicos , Concentração de Íons de Hidrogênio , Oligonucleotídeos/química , Oligonucleotídeos/metabolismo , Concentração Osmolar , Ligação Proteica , Proteínas/química , Proteínas/metabolismo
20.
J Ocul Pharmacol Ther ; 36(4): 247-256, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32155098

RESUMO

Purpose: The objectives were to investigate the effect of transscleral iontophoresis of macromolecules in vitro and in vivo, to study the importance of electroosmosis on macromolecules of low charge to mass ratio, and to evaluate transscleral iontophoresis efficacy in a choroidal neovascularization (CNV) animal model. Methods: Through in vitro transport experiments, the permeability coefficients of macromolecules [eg, immunoglobulin G (IgG), dextran 70 kDa] were determined under different conditions. The effect of ionic strength formulations and iontophoretic conditions was studied on the distribution of IgG and bevacizumab into the eye in vivo. Magnetic resonance imaging (MRI) was utilized to evaluate in vivo real time distribution of gadolinium-labeled albumin (Galbumin) following iontophoresis. The efficacy between no treatment, intravitreal injection (IVT), and iontophoresis of bevacizumab on a CNV model of subretinal injection of adeno-associated virus encoding human VEGF-165 was investigated. Results: The permeability data suggested a significant effect of ionic strength on the iontophoretic transport of macromolecules. Transscleral iontophoresis of IgG at 4 mA with a low ionic strength formulation was about 600 times greater than passive diffusion and 14-fold over a conventional formulation in vitro. Approximately 0.6 mg of bevacizumab can be delivered into the rabbit eye in vivo with a 20-min treatment of iontophoresis. MRI showed that Galbumin was in the posterior tissues after iontophoresis. In the CNV model, the iontophoresis and IVT methods of bevacizumab delayed retinal neovascularization by 4 and 8 weeks, respectively. Conclusions: Transscleral iontophoresis is capable of delivering macromolecule drugs through the conjunctiva and sclera, eventually exposing the retina/choroid to the drugs.


Assuntos
Bevacizumab/farmacocinética , Neovascularização de Coroide/tratamento farmacológico , Sistemas de Liberação de Medicamentos/métodos , Iontoforese/métodos , Substâncias Macromoleculares/farmacocinética , Inibidores da Angiogênese/administração & dosagem , Inibidores da Angiogênese/farmacocinética , Inibidores da Angiogênese/uso terapêutico , Animais , Bevacizumab/administração & dosagem , Bevacizumab/uso terapêutico , Transporte Biológico , Túnica Conjuntiva/efeitos dos fármacos , Túnica Conjuntiva/metabolismo , Eletro-Osmose/métodos , Imunoglobulina G/efeitos dos fármacos , Imunoglobulina G/metabolismo , Injeções Intravítreas , Substâncias Macromoleculares/administração & dosagem , Imageamento por Ressonância Magnética/métodos , Modelos Animais , Permeabilidade/efeitos dos fármacos , Coelhos , Esclera/efeitos dos fármacos , Esclera/metabolismo
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