Hofmeister anion effects on surfactant self-assembly and the formation of mesoporous solids

Leontidis, Epameinondas

doi:10.1016/s1359-0294(02)00010-9

Cited by 382 publications

(385 citation statements)

References 66 publications

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“…[1][2][3][4] Specific ion adsorption at the surface of the ocean is reflected in the distinct composition of marine aerosols [5][6][7][8] and its significant impact on the chemistry of the atmospheric boundary layer. 5,[9][10][11][12][13][14] Enzyme activities, 15 protein binding, 16 and self-assembly processes in general [17][18][19][20][21][22] also show pronounced specific ion effects (SIE). Controlling the self-aggregation of nanoparticles and biopolymers via SIE is a tantalizing goal that calls for a deeper understanding of structural, Coulombic, and non-electrostatic effects at low, intermediate, and high concentrations.…”

Section: Introductionmentioning

confidence: 99%

Hofmeister effects in micromolar electrolyte solutions

Enami

Mishra

Hoffmann

et al. 2012

The Journal of Chemical Physics

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Ions induce both specific (Hofmeister) and non-specific (Coulomb) effects at aqueous interfaces. More than a century after their discovery, the origin of specific ion effects (SIE) still eludes explanation because the causal electrostatic and non-electrostatic interactions are neither local nor separable. Since direct Coulomb effects essentially vanish below ∼10 μM (i.e., at >50 nm average ion separations in water), we decided to investigate whether SIE operate at, hitherto unexplored, lower concentrations. Herein, we report the detection of SIE above ∼0.1 μM in experiments where relative iodide/bromide populations, χ = I − /Br − , were determined on the surface of aqueous (NaI + NaBr) jets by online electrospray mass spectrometry in the presence of variable XCl (X = H, Na, K, Cs, NH 4 , and N(C 4 H 9 ) 4 ) and NaY (Y = OH, Cl, NO 3 , and ClO 4 ) concentrations. We found that (1) all tested electrolytes begin to affect χ below ∼1 μM and (2) I − and Br − are preferentially suppressed by co-ions closely matching their interfacial affinities. We infer that these phenomena, by falling outside the reach of even the longest ranged electrostatic interactions, are dynamical in nature.

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Section: Introductionmentioning

confidence: 99%

Hofmeister effects in micromolar electrolyte solutions

Enami

Mishra

Hoffmann

et al. 2012

The Journal of Chemical Physics

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“…Interestingly, the method sensitivity is strongly dependent on the species of ammonium salts used together with NH 3 ·H 2 O for preparing the buffer solutions. Six ammonium salts including NH 4 51 and therefore lead to enhanced aggregation of the P-AuNPs. However, the Hofmeister effect of SCN − was so strong that it induced significant blank response of the P-AuNP probe, thus NH 4 NO 3 −NH 3 ·H 2 O buffer was selected in the following experiments.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Colorimetric Au Nanoparticle Probe for Speciation Test of Arsenite and Arsenate Inspired by Selective Interaction between Phosphonium Ionic Liquid and Arsenite

Tan

Liu

Yin

et al. 2014

ACS Appl. Mater. Interfaces

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The exposure of millions of people to unsafe levels of arsenite (As III ) and arsenate (As V ) in drinking waters calls for the development of low-cost methods for on-site monitoring these two arsenic species in waters. Herein, for the first time, tetradecyl (trihexyl) phosphonium chloride ionic liquid was found to selectively bind with As III via extended Xray absorption fine structure (EXAFS) analysis. Based on the finding, an As III -specific probe was developed by modifying gold nanoparticles with the ionic liquid. Futhermore, Hofmeister effect was primarily observed to significantly affect the sensitivity of gold nanoparticle probe. With the colorimetric probe, we developed a protocol for naked eye speciation test of As III and As V at levels below the World Health Organization (WHO) guideline of 10 μg L −1 . This method featured with high tolerance to common coexisting ions such as 10 mM PO 4 3− , and was validated by assaying certified reference and environmental water samples. KEYWORDS: arsenic, ionic liquid, interaction, gold nanoparticle, Hofmeister effect, visual test ■ INTRODUCTIONArsenic shows various adverse health effects including carcinogenic disease relative to skin, lung, and kidney. 1−3 More than 140 million people worldwide are exposed to superfluous arsenic, mainly by drinking ground waters polluted by inorganic arsenic that are more toxic than the organic ones. 4,5 Although As III and As V are coexisting and undergo mutual transformation in groundwater, As III is usually the main form and more toxic than As V . 6 Consequently, monitoring of inorganic arsenic species in waters is of prior interest in arsenic detection. Numerous instrumental methods have been developed to quantify trace arsenic, 7−10 but the requirement of bulk equipment and strict laboratory conditions restricts their application in field analysis. On the contrary, the colorimetric or visual methods are quite suitable for field determination. Because of their poor sensitivity, however, traditional visual probes are incapable of detecting As III and As V at 10 μg L −1 level, which is the arsenic guideline value in drinking water required by the World Health Organization (WHO) and U.S. Environmental Protection Agency (EPA). Additionally, the fairly poor tolerance to interferences of these probes restricts their application in real sample analysis. 11−13 Several arsenic testing field kits are able to semiquantify 10 or 50 μg L −1 As, but most of them fail to meet the requirements of an ideal test kit for As. 14−16 Gold nanoparticles (AuNPs) are widely used as optical probes in colorimetric detection in recent years, 17−19 because of their higher extinction coefficient in the visible region and thus higher sensitivity in comparison to the organic probes. Since the pioneering work of the Mirkin group, 20 AuNPs have served as optical probes for sensing cations, anions, small organic compounds, and biological molecules, 21−23 with Hg 2+ as one of the most attractive target analytes. 24−31 Surprisingly, studies on the u...

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“…The water-structure-breaking ions have weak electric fields and a loose hydration shell, which can be easily removed. Therefore, chaotropic ions disrupt the "icebergs" of water molecules in bulk water and increase the concentration of free water molecules that can form hydrogen bonds with the PEO chains of nonionic surfactants (Schott, 1997;Leontidis, 2002).…”

Section: Coexistence Curves Of the C 10 E 4 /Buffer Systemsmentioning

confidence: 99%

Influence of salts on the coexistence curve and protein partitioning in nonionic aqueous two-phase micellar systems

Lopes

Santos-Ebinuma

Pessoa

et al. 2014

Braz. J. Chem. Eng.

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-Aqueous two-phase micellar systems (ATPMS) can be exploited in separation science for the extraction/purification of desired biomolecules. Prior to phase separation the surfactant solution reaches a cloud point temperature, which is influenced by the presence of electrolytes. In this work, we provide an investigation on the cloud point behavior of the nonionic surfactant C 10 E 4 in the presence of NaCl, Li 2 SO 4 and KI. We also investigated the salts' influence on a model protein partitioning. NaCl and Li 2 SO 4 promoted a depression of the cloud point. The order of salts and the concentration that decreased the cloud point was: Li 2 SO 4 0.5 M > NaCl 0.5 M ≈ Li 2 SO 4 0.2 M. On the other hand, 0.5 M KI dislocated the curve to higher cloud point values. For our model protein, glucose-6-phosphate dehydrogenase (G6PD), partitioning experiments with 0.5 M NaCl or 0.2 M Li 2 SO 4 at 13.85 °C showed similar results, with K G6PD ~ 0.46. The lowest partition coefficient was obtained in the presence of 0.5 M KI (K G6PD = 0.12), with major recovery of the enzyme in the micelle-dilute phase (%Recovery = 90%). Our results show that choosing the correct salt to add to ATPMS may be useful to attain the desired partitioning conditions at more extreme temperatures. Furthermore, this system can be effective to separate a target biomolecule from fermented broth contaminants.

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Hofmeister anion effects on surfactant self-assembly and the formation of mesoporous solids

Cited by 382 publications

References 66 publications

Hofmeister effects in micromolar electrolyte solutions

Hofmeister effects in micromolar electrolyte solutions

Colorimetric Au Nanoparticle Probe for Speciation Test of Arsenite and Arsenate Inspired by Selective Interaction between Phosphonium Ionic Liquid and Arsenite

Influence of salts on the coexistence curve and protein partitioning in nonionic aqueous two-phase micellar systems

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