Experimental mapping of a pH gradient from a positively charged micellar interface to bulk solution

Lacerda, Caroline Dutra; Andrade, Mauro; Pessoa, Phillipe de Santana; Prado, Fernanda Manso; Pires, Paulo Augusto Rodrigues; Pinatto-Botelho, Marcos F.; Wodtke, Felipe; Santos, Alcindo A. Dos; Dias, Luís Gustavo; Lima, Filipe da Silva; Chaimovich, Hernán; Cuccovia, Iolanda Midea

doi:10.1016/j.colsurfa.2020.125770

Cited by 9 publications

(8 citation statements)

References 34 publications

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“…At the same time, more anions are attracted by the Au NTs, which positively charged and weakened the electrostatic repulsion. On the other hand, when Na 2 CO 3 is added, it changes the alkalinity in the solution, which may also negatively affect the shape of the micelles, , resulting in a worsening of the final purification effect. As shown in Figure S8, as the pH increases, the alkalinity in the solution also increases accordingly, and a too high alkalinity reduces the yield of the product significantly.…”

Section: Resultsmentioning

confidence: 99%

Highly Pure Gold Nanotriangles with almost 100% Yield for Surface-Enhanced Raman Scattering

Sun

Zeng

Luo

et al. 2022

ACS Appl. Nano Mater.

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Gold nanotriangle (Au NT), a unique anisotropicshaped plasmonic nanostructure with distinctive optical, electrical, and catalytic characteristics, has been utilized in a variety of hightechnological applications. However, the basic and practical applications of Au NTs are often hindered by size and yield (less than 60%) and engineering a facile and manageable approach to acquire Au NTs with high yields is still challenging. Herein, a simple and rapid seed-mediated method to prepare high-purity Au NTs (up to 97.4%) is proposed by precisely controlling the reaction kinetics. Importantly, there are two key factors to achieve high-yield Au NTs (70%) during the two-growth synthesis: (1) the high concentration of hexadecyltrimethylammonium chloride (CTAC) that can provide a greater binding force on the ⟨111⟩ facet of Au seed and (2) the selective adsorption of potassium iodide (KI) on the ⟨111⟩ facet. Additionally, Au NTs with a wide range of sizes from 58 to 137 nm with a high uniformity can be tailored by a small window parameter regulation. Additionally, it is found that the addition of optimized salts can induce the rapid precipitation of Au NTs to form self-assembled microfibers and the efficient purification of Au NTs with a yield of about 97.4%. Furthermore, the finite difference time domain (FDTD) simulation shows that anisotropic electromagnetic field enhancements and hot spot excitation modes can be generated in different assembling models of Au NTs. Finally, we construct macroscopic two-dimensional (2D) ordered monolayer films of Au NTs through volatilizing self-assembly. As a proof of concept, the ordered Au NT arrays exhibit both high surface-enhanced Raman spectroscopy (SERS) sensitivity and detecting stability compared to random assembling structures and Au NPs. Therefore, we believe that our proposed rapid synthesis and high-yield purification approach of Au NTs would pave a way to prepare designed nanomaterials for a variety of basic and high-technological practical applications.

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Section: Resultsmentioning

confidence: 99%

Highly Pure Gold Nanotriangles with almost 100% Yield for Surface-Enhanced Raman Scattering

Sun

Zeng

Luo

et al. 2022

ACS Appl. Nano Mater.

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“…Notably, physical properties, such as pH and polarity, in the microenvironment of the micellar interface are different than those in bulk solution; and this property is also preserved in surfactant-layer-anchored nanoparticle surfaces. 33–35 Recently, we have shown that the catalytic ability of a cetyltrimethylammonium bromide (CTAB)-functionalized cationic gold nanoparticle (GNP) can be up- and downregulated by exploiting multivalent interactions between GNPs and adenosine-based nucleotides. 35 The alteration of the local surface pH of the GNPs due to the assembly of these differently charged nucleotides was the key reason for this modulatory catalytic behavior.…”

Section: Resultsmentioning

confidence: 99%

Perpetuating enzymatically induced spatiotemporal pH and catalytic heterogeneity of a hydrogel by nanoparticles

et al. 2022

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“…Surfactant aggregates are valuable not only in themselves as reaction media but also as reduced models of biomembranes and polypeptides in water. − The surfactant molecules aggregate and form an interface with water. Their formation is possible because the surfactant molecules have a hydrophilic “head” pointing toward the aqueous solution and a hydrophobic “tail” that escapes water and forms the “dry” core of an aggregate.…”

Section: Introductionmentioning

confidence: 99%

“…A generally accepted concept interprets the totality of micelles’ Stern layers in solution as a pseudophase. , The pseudophase is the location where molecules and ions are adsorbed. Hence, its electrical charge and potential govern the association of different ions with the micelles, − protolytic reactions on the micellar surface, ,,,− acceleration/deceleration of the rates of chemical reactions, − ,, the behavior of surfactant foams, etc . Let us consider the methods used to estimate the interfacial electric potential.…”

Section: Introductionmentioning

confidence: 99%

Estimation of Nanoparticle’s Surface Electrostatic Potential in Solution Using Acid–Base Molecular Probes I: In Silico Implementation for Surfactant Micelles

et al. 2023

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Surface electrostatic potential Ψ is a key characteristic of colloid particles. Since the surface of the particles adsorbs various compounds and facilitates chemical reactions between them, Ψ largely affects the properties of adsorbed reactants and governs the flow of chemical reactions occurring between them. One of the most popular methods for estimating Ψ in hydrophilic colloids, such as micellar surfactant solutions and related systems, is the application of molecular probes, predominantly acid−base indicator dyes. The Ψ value is calculated from the difference of the probe's indices of the apparent acidity constant between the examined colloid solution and, usually, some other colloid solution with noncharged particles. Here, we show how to implement this method in silico using alchemical free energy calculations within the framework of molecular dynamics simulations. The proposed implementation is tested on surfactant micelles and is shown to predict experimental Ψ values with quantitative accuracy depending on the kind of surfactant. The sources of errors in the method are discussed, and recommendations for its application are given.

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Experimental mapping of a pH gradient from a positively charged micellar interface to bulk solution

Cited by 9 publications

References 34 publications

Highly Pure Gold Nanotriangles with almost 100% Yield for Surface-Enhanced Raman Scattering

Highly Pure Gold Nanotriangles with almost 100% Yield for Surface-Enhanced Raman Scattering

Perpetuating enzymatically induced spatiotemporal pH and catalytic heterogeneity of a hydrogel by nanoparticles

Estimation of Nanoparticle’s Surface Electrostatic Potential in Solution Using Acid–Base Molecular Probes I: In Silico Implementation for Surfactant Micelles

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