Preparation of Highly Concentrated Uniform-Sized Silver Nanoparticles via Use of Thermoresponsive Zwitterionic Surfactants.

Despite the popular use of citrate for the reduction of silver ions, this process suffers from slow crystal growth and broad size distribution. The rapid and effective synthesis of highly concentrated and stable spherical silver nanoparticles (AgNPs) confined in the surfactant-rich phase of thermoresponsive 3-(alkyldimethylammonio)-propyl sulfate surfactants obtained after reaction with citrate ions at high temperature is described. The present approach using the zwitterionic surfactant offers an alternative rapid approach for production of AgNPs and an in situ phase separation step that serves to "extract" and concentrate the AgNPs in the surfactant-rich phase.

Shape- and Size-Controlled Fabrication of Gold Nano-Urchins via Use of a Mixed Sodium Borohydride and Ascorbic Acid Reductant System.

Urchin-shaped gold nanoparticles (AuNUs) are anisotropic nanomaterials with unique chemical and physical properties of interest for a variety of applications. However, synthesizing AuNUs with controlled sizes and shapes remains challenging. We demonstrate that a combination of sodium borohydride (NaBH) and ascorbic acid (AA) as reducing agents can produce an aqueous dispersion of AuNUs after just 9 min at room temperature (25 °C).

Nanoparticle induced formation of self-assembled zwitterionic surfactant microdomains which mimic microemulsions for the fabrication and dispersion of silver nanoparticles.

The effective synthesis of highly concentrated and stable spherical silver nanoparticles (Ag-NPs) enclosed within microdomains formed by the Ag-NP induced self-assembly of zwitterionic surfactants is described. In this paper, the rapid and efficient synthesis of dispersed and stable Ag-NPs in zwitterionic surfactants, such as 3-(nonyldimethylammonio)- or 3-(decyldimethyl-ammonio)-propyl sulfate (C- or C-APSO) that self-assemble in the presence of the Ag-NPs to form microdomains akin to microemulsions (ME) without the need of any organic solvent, co-surfactant or polymer is presented. Essentially all (>99.

Rapid Micelle-Mediated Size-Controlled Fabrication of Calcium Sulfate Nanorods Using Silver Nanoparticles.

Calcium sulfate nanorods (CS-NRs) are valuable materials utilized in various applications, particularly in the medical field. In this work, the size-controlled synthesis of CS-NRs was carried out on the basis of the micelle-mediated phase separation phenomenon. A nonionic surfactant, Triton X-114, was employed for the thermoresponsive phase separation of a homogeneous solution to a surfactant-rich phase.

Synthesis and evaluation of a diethylammonio-propylsulfate amphoteric ionic column for the high-performance liquid chromatography-mass spectrometric separation and detection of amino acids.

A diethylammonio-propylsulfate amphoteric ionic resin was synthesized and employed as the stationary phase for high-performance liquid chromatography-mass spectrometry (LC-MS) separation and detection of amino acids. The influence of experimental conditions such as mobile phase composition, column length and temperature upon the amino acid separations was evaluated. However, temperature, addition of water-miscible organic solvent to the mobile phase and mobile phase gradients were not effective at improving the separations.

One-pot synthesis with in situ preconcentration of spherical monodispersed gold nanoparticles using thermoresponsive 3-(alkyldimethylammonio)-propyl sulfate zwitterionic surfactants.

Homogeneous solutions of thermoresponsive zwitterionic 3-(alkyldimethylammonio)-propyl sulfate surfactants at elevated temperatures were employed for the synthesis of gold nanoparticles (AuNPs) by the citrate reduction method. Upon cooling at completion of the reaction, the mixture phase separates with the monodispersed AuNPs condensed and concentrated in the small volume surfactant-rich phase.

Fluorescence method using on-line sodium cholate coacervate surfactant mediated extraction for the flow injections analysis of Rhodamine B.

An on-line surfactant mediated extraction method in a flow injection analysis format with fluorescence detection was developed for the determination of Rhodamine B (RhB) in food condiments. The sample was extracted using the phase separation behavior exhibited by the bile salt surfactant, sodium cholate (NaC), upon addition of sodium dodecylsulfate (SDS) in the presence of acid at room temperature. The RhB in the sample was incorporated into the NaC/SDS coacervate phase which was then collected on a glass-wool packed mini column from which it was subsequently eluted using a 1.

"Turn-on" fluorescent polymeric microparticle sensors for the determination of ammonia and amines in the vapor state.

Cross-linked acrylic ester microparticles (EG50OH) with absorbed fluorescent probe molecules, such as fluorescein and acridine orange were successfully fabricated and employed as "turn-on" fluorescent sensors for the detection and determination of ammonia and organic amine vapor concentrations. Using EG50OH microparticles that had fluorescein (fluorescein fluorescent microparticle, FL-FMP sensor) incorporated as the fluorescent probe molecule (with lambda(ex) = 450 nm; lambda(em) = 528 nm), the detection limit achieved for ammonia vapor was 0.73 ppm, the response being linearly dependent on concentration over the range of 1.

Cloud point extraction with surfactant derivatization as an enrichment step prior to gas chromatographic or gas chromatography-mass spectrometric analysis.

Cloud point extraction (CPE) using Triton X-114 was successfully applied as an extractive preconcentration step prior to gas chromatographic-mass spectrometric analysis. No liquid chromatographic or back-extraction steps were required to remove the target analyte(s) from the surfactant-rich extractant phase. Instead a post-extraction derivatization step is employed in which the surfactant of the surfactant-rich phase is reacted with N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) prior to injection into the gas chromatograph.

Evaluation of the potential of chitosan hydrogels to extract polar organic species from nonpolar organic solvents: application to the extraction of aminopyridines from hexane.

The extraction of a series of aminopyridines (APs) utilizing chitosan hydrogels in hexane was investigated. The chitosan hydrogel was prepared using glutaraldehyde as a cross-linking agent. Experiments were carried out to determine the maximum extraction efficiency, distribution coefficient, sorption capacity, and adsorption and desorption mechanisms.