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Dear Colleagues,

Surfactants are a unique class of chemical compounds with specific physicochemical properties. Due to their amphiphilic nature, they can be soluble both in polar and nonpolar liquids, form micelles and adsorb at different interfaces, changing the properties of a given system. As a result of these properties, surfactants are widespread in petroleum processing, biological systems, health and personal care products, cosmetics and food and crop protection. Due to the very large scale of their applications, surfactants are present in large amounts in different compartments of the environment. On the one hand, they are irreplaceable in everyday life, and on the other hand, they can be a huge problem in relation to their retention in the environment. Hence, at present, the use of surfactants is directed towards the use of compounds of natural origin (good biodegrability) or those whose properties are superior to commonly used surfactants. In this respect, so-called natural surfactants play the most important role. In this context, such compounds perfectly fit into the policy of sustainable development. Although many surfactants have been studied, many others (especially those based on renewable resources) have not. This Special Issue aims to provide a comprehensive overview of the latest discoveries in synthesis, physicochemical properties of surfactants based on natural and renewable resources and their applications. Papers dealing with the biodegrability and retention of such surfactants in the environment and their application in everyday life, medicine and the cosmetic, household, energy and petroleum industries are especially welcome.

Dr. Joanna Krawczyk
Guest Editor

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Keywords

adsorption
aggregation
wettability of different solids
surfactants based on renewable resources
synthesis of surfactants
retention of surfactants in the environment
biodegrability
antimicrobial properties
self-cleaning
surface coatings

Published Papers (2 papers)

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Research

12 pages, 5803 KiB

Open AccessArticle

Influence of the Antimicrobial LL-37 Peptide on Legionella dumoffii Phospholipids Adsorbed at the Air–Liquid Interface

by Katarzyna Pastuszak, Bożena Kowalczyk, Jacek Tarasiuk, Małgorzata Jurak and Marta Palusińska-Szysz

Sustainability 2023, 15(8), 6670; https://0-doi-org.brum.beds.ac.uk/10.3390/su15086670 - 14 Apr 2023

Cited by 2 | Viewed by 929

Abstract

Legionella dumoffii is an intracellular pathogen of freshwater protozoans capable of infecting and multiplying in mammalian cells, causing a severe respiratory disease called Legionnaires’ disease. The pathomechanism of infection development is very complex and depends on many factors, including the structure and properties of macromolecules that build the components of the L. dumoffii cell envelope. Phospholipids (PLs) forming biological membranes have a significant impact on the integrity of the membrane as well as on the interactions with the host cells. L. dumoffii changes its lipid profile under the influence of external factors, which allows it to adapt to the living environment. One of the factors altering the PL composition is the presence of exogenous choline. The aim of this study was to determine the physicochemical properties of the model bacterial membranes adsorbed at the air–liquid interface (Langmuir monolayers). They were composed of phospholipids isolated from L. dumoffii cultured with (PL+choline) and without (PL−choline) choline. Moreover, the effect of the human cathelicidin (LL-37 peptide) added to the subphase on these monolayers was analyzed in terms of phospholipid–peptide interactions. The results indicated that the monolayers of PL+choline were slightly more condensed than PL−choline. In the presence of LL-37, the elasticity of both monolayers increased; thus, their molecular packing and ordering decreased. The disturbing effect was related to the peptide’s antibacterial activity. Full article

(This article belongs to the Special Issue Green Surfactants and Sustainability)

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18 pages, 2190 KiB

Open AccessArticle

Thermodynamic Studies of the Micellar Properties of a Surfactant Used for Membrane Protein Solubilization and Stabilization

by Joanna Krawczyk

Sustainability 2023, 15(8), 6618; https://0-doi-org.brum.beds.ac.uk/10.3390/su15086618 - 13 Apr 2023

Cited by 1 | Viewed by 965

Abstract

The effect of temperature on the micellar properties of the alkylglucoside surfactant n-octyl-β-D-thioglucopyranoside (OTG) used for membrane protein solubilization has been investigated. Critical micelle concentration (CMC), apparent (

ϕ_{V}

) and partial (

{\bar{V}}_{M}

) molar volume [...] Read more.

ϕ_{V}

) and partial (

{\bar{V}}_{M}

) molar volume changes of the studied surfactant, as well as thermodynamic functions (the standard Gibbs free energy (

Δ G_{m i c}^{o}

), the standard enthalpy (

Δ H_{m i c}^{o}

) and entropy (

Δ S_{m i c}^{o}

)) of the OTG micellization process were determined. The above-mentioned parameters were calculated on the basis of the results obtained from measurements of surface tension, density and viscosity of the aqueous solutions of n-octyl-β-D-thioglucopyranoside, as well as pyrene (Py) and 8-anilinonaphthalene-1-sulfonic acid (ANS) fluorescence intensity in aqueous solutions of OTG and dynamic light scattering of aqueous solutions of OTG. Basing on the obtained results it is stated that critical micelle concentration of OTG is much lower compared to that of the earlier studied n-octyl-β-D-glucopyranoside (OGP). The standard Gibbs free energy changes indicate that the tendency of OTG molecules to form aggregates increases with temperature increase. However, this increase is not so evident as in the case of some other sugar-based surfactants. The small temperature effect on the aggregation properties of OTG in water is probably connected with the presence and strength of the hydrogen bonds between the water molecules and sugar units, or the type of linkage between the hydrophobic and hydrophilic parts of the studied surfactant. In addition, the presence of S-linkage in the OTG molecule despite its high enzymatic stability also causes the hydrophobicity increase of the studied surfactant (compared to OGP), which directly influences its micellization process. Full article

(This article belongs to the Special Issue Green Surfactants and Sustainability)

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