On the Effect of pH, Temperature, and Surfactant Structure on Bovine Serum Albumin–Cationic/Anionic/Nonionic Surfactants Interactions in Cacodylate Buffer–Fluorescence Quenching Studies Supported by UV Spectrophotometry and CD Spectroscopy

Due to the fact that surfactant molecules are known to alter the structure (and consequently the function) of a protein, protein–surfactant interactions are very important in the biological, pharmaceutical, and cosmetic industries. Although there are numerous studies on the interactions of albumins with surfactants, the investigations are often performed at fixed environmental conditions and limited to separate surface-active agents and consequently do not present an appropriate comparison between their different types and structures. In the present paper, the interactions between selected cationic, anionic, and nonionic surfactants, namely hexadecylpyridinium chloride (CPC), hexadecyltrimethylammonium bromide (CTAB), sodium dodecyl sulfate (SDS), polyethylene glycol sorbitan monolaurate, monopalmitate, and monooleate (TWEEN 20, TWEEN 40, and TWEEN 80, respectively) with bovine serum albumin (BSA) were studied qualitatively and quantitatively in an aqueous solution (10 mM cacodylate buffer; pH 5.0 and 7.0) by steady-state fluorescence spectroscopy supported by UV spectrophotometry and CD spectroscopy. Since in the case of all studied systems, the fluorescence intensity of BSA decreased regularly and significantly under the action of the surfactants added, the fluorescence quenching mechanism was analyzed thoroughly with the use of the Stern–Volmer equation (and its modification) and attributed to the formation of BSA–surfactant complexes. The binding efficiency and mode of interactions were evaluated among others by the determination, comparison, and discussion of the values of binding (association) constants of the newly formed complexes and the corresponding thermodynamic parameters (ΔG, ΔH, ΔS). Furthermore, the influence of the structure of the chosen surfactants (charge of hydrophilic head and length of hydrophobic chain) as well as different environmental conditions (pH, temperature) on the binding mode and the strength of the interaction has been investigated and elucidated.

Study of the stability of lipid nanoemulsions with oleic acid

This work presents the results of a study on the effect of ionic surfactant cetriltrimethylammonium chloride (CTAB) on the size and ζ-potential of lipid nanoemulsions composed of oleic acid, prepared by temperature phase inversion method and stabilized by nonionic surfactants — Tween 60, Span 60

Solid lipid nanoparticles with stearic acid stabilized with yttrium stearate

In this work, we studied the effect of yttrium stearate on the physicochemical properties of dispersions of solid lipid nanoparticles composed of stearic acid stabilized with nonionic surfactants (Tween 60, Span 60). The results showed that an increase in the concentration of yttrium stearate leads to increasing kinetic stability and decreasing the average size of the aggregates. Along with this, the average size of single particles remains practically unchanged and amounts to 35±5 nm.

Nonylphenol Ethoxylate Surfactants Modified by Carboxyl Groups for Foam EOR at High-Salinity Conditions

High mineralization of water complicates the use of foam in reservoir conditions. Anionic–nonionic surfactants are one of the best candidates for these conditions since they have both high surface activity and salt tolerance. One of the ways to obtain anionic–nonionic surfactants is to modify nonionic surfactants by an anionic group. The type of the group and its chemical structure can strongly affect the properties of the surfactant. In this work, widely-produced nonionic surfactant nonylphenol (12) ethoxylate (NP12EO) was modified by new types of carboxylic groups through the implementation of maleic (NP12EO-MA) and succinic (NP12EO-SA) anhydrides with different saturation levels. The main objectives of this work were to compare synthesized surfactants with nonionic precursor and to reveal the influence of unsaturated bonds in the carboxyl group on the properties of the foam. NaCl concentration up to 20 wt% was used to simulate high mineralization conditions, as well as to assess the effect of unsaturated bonds on foam properties. Synthesized anionic–nonionic surfactants retained surfactant solubility and long-term stability in high-salinity water, but have better foaming ability, as well as higher apparent viscosity, in porous media. The presence of an unsaturated bond in NP12EO-MA surfactant lowers foaming ability at high mineralization.

Recent patents and a market overview on green or bio-based solvents for chromatographic analysis: a review

Green solvents (GSs) in chromatography originate from green chemistry. Therefore, using GSs in liquid chromatographic analysis to separate drugs and chemicals is an emerging approach to reduce hazardous chemicals in nature. The Orbit Intelligence database was used to conduct a strategic patent search for peer-reviewed patents on GSs as a mobile phase for chromatographic analysis. This article reported numerous approaches for encouraging GSs such as ethanol, butanol, esters, polyethylene glycol, supercritical fluids and nonionic surfactants to analyze drugs or compounds. The main aim of this article is to explore the patented GSs for chromatographic analysis and forecasting of the GSs that encourage industries to shift from hazardous to GSs.