Effects of Reverse Micellar Structure on the Particle Charging Capabilities of the Span Surfactant Series

Michor, Edward L.; Ponto, Benjamin S.; Berg, John C.

doi:10.1021/acs.langmuir.6b02959

Cited by 10 publications

(8 citation statements)

References 32 publications

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“…As the reverse micelles can stabilize charges in apolar media 22,25,30,39,40 , two properties of the suspension depend on surfactant concentration: the microparticle charge and medium conductivity. These properties depend mainly on the local surfactant concentration; that is, the microparticle charge is limited by the amount of surfactant adsorbed, Cad, while the medium conductivity, σ, is limited by the amount of surfactant in the medium, Cd.…”

Section: Resultsmentioning

confidence: 99%

“…To control a particle using an electric field, easily modified electric and dielectric properties of the particle and surrounding medium are desirable. Surfactants can modify the medium conductivity [21][22][23][24] and charge microparticles suspended in apolar liquids [24][25][26][27][28][29][30][31][32] . Although not fully understood, the modification of electrical properties of apolar colloids by surfactant addition is of great importance in industry as it is used to control the electrical properties of ink in printing processes 21 .…”

Section: Introductionmentioning

confidence: 99%

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Surfactant concentration modulates the motion and placement of microparticles in an inhomogeneous electric field

2020

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This study examined the effects of surfactants on the motion and positioning of microparticles in an inhomogeneous electric field. The microparticles were suspended in oil with a surfactant and the electric field was generated using sawtooth-patterned electrodes. The microparticles were trapped, oscillated, or attached to the electrodes. The proportion of microparticles in each state was defined by the concentration of surfactant and the voltage applied to the electrodes. Based on the trajectory of the microparticles in the electric field, a newly developed physical model in which the surfactant was adsorbed on the microparticles allowed the microparticles to be charged by contact with the electrodes, with either positive or negative charges, while the non-adsorbed surfactant micellizing in the oil contributed to charge relaxation. A simulation based on this model showed that the charging and charge relaxation, as modulated by the surfactant concentration, can explain the trajectories and proportion of the trapped, oscillating, and attached microparticles. These results will be useful for the development of novel self-assembly and transport technologies and colloids sensitive to electricity.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Surfactant concentration modulates the motion and placement of microparticles in an inhomogeneous electric field

2020

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“…The surfactant affects the size of the reverse micelle particles formed (Michor et al 2016). In the present work, the surfactant evaluated.…”

Section: Effect Of Surfactant On Forward Extractionmentioning

confidence: 99%

Influence of different parameters on reverse micelle extraction combined with acetone precipitation to purify sn-1,3 extracellular lipase from Aspergillus niger GZUF36

et al. 2019

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There are few reports on the feasibility of combined reverse micelle extraction and acetone precipitation to obtain electrophoretic pure enzymes. We aimed to purify a sn-1,3 extracellular lipase from a novel Aspergillus niger GZUF36 through this combination in this work. This lipase preliminarily purified by controlling the volume ratio (1:2.5) of crude enzyme solution and acetone. Then, we studied effects of different parameters on reverse micelle extraction. The suitable surfactant, pH, salt and cosolvent and extraction time for forward extraction were 125 mM cetyl trimethylammonium bromide (CTAB), 9.0, 0.075 M NaCl, 10% n-hexanol and 30 min, respectively. Under these conditions, the forward extraction rate reached 90.3% ± 3.2%. The suitable salt, pH, extraction time and short chain alcohol for backward extraction were consecutively 1.5 M KCl, 6.5, 60 min and 10% ethanol. Adding 10% ethanol shows a significant advantage of improvement the extraction rate. Under these optimal conditions, the total extraction rate and purification factor of lipase reached 76.8% and 10.14, respectively. SDS-PAGE showed that molecular weight of the pure protein was 42.7 kDa and TLC exhibited sn-1,3 selectivity of this lipase. LC-MS/MS analysis revealed that the lipase had 297 amino acid residues and was likely to glycosylate. Through the study of different parameters, it demonstrated that the new and simple combination of reverse micelle extraction using CTAB as surfactant and n-hexanol as cosolvent for forward extraction and adding ethanol for backward extraction and acetone precipitation is a promising method to get almost an electrophoretically pure sn-1,3 lipase.

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“…Various types of organic molecules, such as self-assembled aggregates [2,19,20], weakly-coordinating ions [14,21], dendrimers [3], or macromolecules [22], are often employed to stabilize ions in non-polar solvents. One advantage of such species is that they are potentially amenable to analysis by nuclear magnetic resonance (NMR) spectroscopy, using techniques that make use of the nuclear Overhauser effect to study cross-relaxation or field gradients to study diffusion [12,[23][24][25][26][27].…”

Section: Introductionmentioning

confidence: 99%

The extent of counterion dissociation at the interface of cationic diblock copolymer nanoparticles in non-polar solvents

Smith

Meurs

Armes

2020

Journal of Colloid and Interface Science

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Hypothesis Diblock copolymer nanoparticles prepared in non-polar solvents that are sterically stabilized but possess ionic functionality from the inclusion of cationic comonomers in the stabilizer shell are known to exhibit complex electrokinetic behavior (Chem. Sci. 9 (2018) 922-934). For example, core-shell nanoparticles with cationic comonomers located solely within the shell layer have lower magnitude electrophoretic mobilities than nanoparticles containing the same cationic comonomers located within the core, and nanoparticles prepared using a minor fraction of steric stabilizer chains containing cationic comonomer repeat units have comparable electrophoretic mobilities to nanoparticles prepared with this cationic comonomer solely located within the core. We hypothesize that these observations can be explained in terms of the strength of the Coulombic interaction between counterions and the nanoparticle interface.Experiments The highly-fluorinated anionic counterion associated with these cationic nanoparticles is studied by 19 F nuclear magnetic resonance (NMR) spectroscopy in n-dodecane. This revealed only one type of 19 F environment for a soluble macromolecular cation (the oil-soluble steric stabilizer chains used to prepare the nanoparticles), whereas two distinct environments were observed for the sterically-stabilized cationic nanoparticles. Both 19 F diffusion NMR and 19 F-13 C heteronuclear single quantum correlation (HSQC) measurements support the existence of two environments for this counterion.Findings The existence of two distinct 19 F environments for the highly-fluorinated anion associated with the sterically-stabilized nanoparticles demonstrates the presence of spectroscopically distinguishable populations of ion pairs and of fully dissociated free anions. 19 F NMR spectra recorded for sterically-stabilized nanoparticles with a fully ionic shell (all stabilizer chains containing the cationic comonomer) and those with a partly ionic shell (10% of stabilizer chains containing the cationic comonomer) reveal a higher proportion of dissociated anions in the partly ionic case. This suggests a stronger Coulombic interaction between counterions and the cationic interface when the shell is fully ionic, which accounts for the observed reduction in the magnitude of the electrophoretic mobility.

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Effects of Reverse Micellar Structure on the Particle Charging Capabilities of the Span Surfactant Series

Cited by 10 publications

References 32 publications

Surfactant concentration modulates the motion and placement of microparticles in an inhomogeneous electric field

Surfactant concentration modulates the motion and placement of microparticles in an inhomogeneous electric field

Influence of different parameters on reverse micelle extraction combined with acetone precipitation to purify sn-1,3 extracellular lipase from Aspergillus niger GZUF36

The extent of counterion dissociation at the interface of cationic diblock copolymer nanoparticles in non-polar solvents

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