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14 pages, 1417 KiB  
Article
Surface and Antimicrobial Properties of Ester-Based Gemini Surfactants
by Iwona Kowalczyk, Adrianna Szulc, Anna Koziróg, Anna Komasa and Bogumił Brycki
Molecules 2025, 30(12), 2648; https://doi.org/10.3390/molecules30122648 - 19 Jun 2025
Viewed by 448
Abstract
Cationic surfactants, accounting for approximately 7% of the global surfactant market, are widely used in applications such as fabric softeners, biocides, and corrosion inhibitors. Recently, gemini surfactants—comprising two amphiphilic units linked by a spacer—have attracted significant interest due to their superior surface activity, [...] Read more.
Cationic surfactants, accounting for approximately 7% of the global surfactant market, are widely used in applications such as fabric softeners, biocides, and corrosion inhibitors. Recently, gemini surfactants—comprising two amphiphilic units linked by a spacer—have attracted significant interest due to their superior surface activity, lower critical micelle concentrations, and strong antimicrobial properties. However, their poor biodegradability, resulting from their complex molecular structure, has raised environmental concerns. To address this, researchers have developed ester-based gemini surfactants incorporating biodegradable bonds. This study aimed to investigate the relationship between the structure of ester-based gemini surfactants (hydrophobic chain length and spacer type) and their antimicrobial activity against bacteria and fungi. Three series of compounds featuring different functional groups in the spacer were synthesized, along with a trimeric surfactant for comparative purposes. The results demonstrated that both the hydrophobic chain length and the presence of additional cationic groups significantly influence the CMC and antimicrobial performance. Quantum mechanical calculations were also performed to search for correlations between electronic properties and chemical reactivity of compounds. These findings highlight that ester-based gemini surfactants combine high surface and antimicrobial activity with the potential for improved biodegradability, making them promising candidates for use in environmentally friendly applications. Full article
(This article belongs to the Section Organic Chemistry)
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18 pages, 8695 KiB  
Article
Ordered Mesoporous Silica Prepared with Biodegradable Gemini Surfactants as Templates for Environmental Applications
by Sarvarjon Kurbonov, Martin Pisárčik, Miloš Lukáč, Zsolt Czigány, Zoltán Kovács, István Tolnai, Manfred Kriechbaum, Vasyl Ryukhtin, Viktor Petrenko, Mikhail V. Avdeev, Qiang Tian, Ana-Maria Lacrămă and László Almásy
Materials 2025, 18(4), 773; https://doi.org/10.3390/ma18040773 - 10 Feb 2025
Viewed by 1014
Abstract
Mesoporous silica sieves have been prepared through sol–gel synthesis using diester gemini surfactants as pore templates, aiming to obtain new materials with potential use for water remediation. A series of mesoporous spherical silica particles of submicron size have been prepared in an alkali-catalyzed [...] Read more.
Mesoporous silica sieves have been prepared through sol–gel synthesis using diester gemini surfactants as pore templates, aiming to obtain new materials with potential use for water remediation. A series of mesoporous spherical silica particles of submicron size have been prepared in an alkali-catalyzed reaction, using a tetraethyl orthosilicate precursor and bis-quaternary ammonium gemini surfactants with diester spacers of varied lengths as pore-forming agents. The effect of the spacer length on the particle morphology was studied using nitrogen porosimetry, small-angle X-ray scattering (SAXS), ultra-small-angle neutron scattering, scanning, and transmission electron microscopy (SEM, TEM). The results revealed that for all spacer lengths, a long-range hexagonal pore ordering developed in the materials. The silica particles were nearly spherical, with sizes below 1 micrometer, and a weak dependence of the mean particle size on the spacer length could be observed. The template removal procedure had a strong influence on the porosity: calcination caused a moderate shrinkage of the pores while retaining the hexagonal structure, whereas treatment with acidified ethanol resulted in only partial removal of the surfactants; however, the hexagonal structure was severely destroyed. The applicability of the obtained calcined materials as adsorbents for heavy metal ions from water was studied with the example of Pb(II). A high sorption capacity of 110 mg/g was obtained in batch experiments, at pH 5 and 4 h contact time. Full article
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23 pages, 2979 KiB  
Article
Impact of Alkyl Spacer and Side Chain on Antimicrobial Activity of Monocationic and Dicationic Imidazolium Surface-Active Ionic Liquids: Experimental and Theoretical Insights
by Marta Wojcieszak, Sylwia Zięba, Alina T. Dubis, Maciej Karolak, Łukasz Pałkowski, Agnieszka Marcinkowska, Andrzej Skrzypczak, Alicja Putowska and Katarzyna Materna
Molecules 2024, 29(23), 5743; https://doi.org/10.3390/molecules29235743 - 5 Dec 2024
Cited by 3 | Viewed by 1432
Abstract
This study investigates a series of surface-active ionic liquids (SAILs), including both imidazolium monocationic and dicationic compounds. These compounds are promising candidates, as they combine unique surface properties with antimicrobial activity, aligning with modern trends in chemistry. The research encompasses synthesis, thermal analysis, [...] Read more.
This study investigates a series of surface-active ionic liquids (SAILs), including both imidazolium monocationic and dicationic compounds. These compounds are promising candidates, as they combine unique surface properties with antimicrobial activity, aligning with modern trends in chemistry. The research encompasses synthesis, thermal analysis, and topographical assessment, focusing on the impact of the amphiphilic cationic moiety, alkyl chain length, and the spatial relationship between the imidazolium ring and the phenyl substituent on the compounds’ physicochemical behavior. An added value of this work lies in the integration of theoretical calculations related to their behavior in solution and at the air–water interface, revealing spontaneous adsorption (negative Gibbs free energy of adsorption values, ΔG0ads). The results indicate that dicationic imidazolium SAILs have a greater tendency to form micelles but are less effective at reducing surface tension compared to their monocationic counterparts. Topography analyses of SAILs with 12 carbon atoms further highlight these differences. Notably, the dicationic SAIL with 12 carbon atoms in the spacer exhibited an impressive MIC of 0.007 mmol L−1 against Candida albicans, consistent with findings showing that dicationic SAILs outperformed conventional antifungal agents, such as amphotericin B and fluconazole, at equivalent concentrations. Overall, the synthesized SAILs demonstrate superior surface activity compared to commercial surfactants and show potential as disinfectant agents. Full article
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16 pages, 2887 KiB  
Article
Influence of Linear Diamine Counterions on the Self-Assembly of Glycine-, Alanine-, Valine-, and Leucine-Based Amphiphiles
by Margarita Angel Alvarez, Nathan Black, Saylor Estelle Blanco, Katelyn Ruth Reid, Eugene J. Billiot, Fereshteh H. Billiot and Kevin F. Morris
Molecules 2024, 29(18), 4436; https://doi.org/10.3390/molecules29184436 - 18 Sep 2024
Viewed by 959
Abstract
Electrical conductimetry and dynamic light scattering (DLS) were used to investigate the aggregation behaviors of four amino acid-based surfactants (AABSs; undecanoyl-glycine, undecanoyl-l-alanine, undecanoyl-l-valine, undecanoyl-l-leucine) in the presence of five linear diamine counterions (1,2-diaminoethane, 1,3-diaminopropane, [...] Read more.
Electrical conductimetry and dynamic light scattering (DLS) were used to investigate the aggregation behaviors of four amino acid-based surfactants (AABSs; undecanoyl-glycine, undecanoyl-l-alanine, undecanoyl-l-valine, undecanoyl-l-leucine) in the presence of five linear diamine counterions (1,2-diaminoethane, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane). Electrical conductimetry was used to measure the CMCs for each system, which ranged from 5.1 to 22.5 mM. With respect to counterions, the obtained CMCs decreased with increases in the interamine spacer length; this was attributed to the improved torsional binding flexibility in longer counterions. Strong linear correlations (mean R2 = 0.9443) were observed between the CMCs and predicted surfactant partition coefficients (logP; water/octanol), suggesting that micellization is primarily driven by the AABS’s hydrophobicity for these systems. However, significant deviations in this linear relationship were observed for systems containing 1,2-diaminoethane, 1,4-diaminobutane, and 1,6-diaminohexane (p = 0.0774), suggesting altered binding dynamics for these counterions. pH measurements during the CMC determination experiments indicated the full deprotonation of the AABSs but did not give clear insights into the counterion protonation states, thus yielding an inconclusive evaluation of their charge stabilization effects during binding. However, DLS measurements revealed that the micellar size remained largely independent of the counterion length for counterions longer than 1,2-diaminoethane, with hydrodynamic diameters ranging from 2.2 to 2.8 nm. This was explained by the formation of charge-stabilized noncovalent dimers, with each counterion bearing a full +2 charge. Conductimetry-based estimates of the degrees of counterion binding (β) and free energies of micellization (ΔG°M) revealed that bulky AABSs exhibit preferential binding to counterions with an even number of methylene groups. It is proposed that when these counterions form noncovalent dimers, perturbations in their natural geometries result in the formation of a binding pocket that accommodates the AABS steric bulk. While the direct application of these systems remains to be seen, this study provides valuable insights into the structure–property relationships that govern AABS aggregation. Full article
(This article belongs to the Special Issue Amphiphilic Molecules, Interfaces and Colloids)
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13 pages, 6837 KiB  
Article
Cationic Serine-Based Gemini Surfactant:Monoolein Aggregates as Viable and Efficacious Agents for DNA Complexation and Compaction: A Cytotoxicity and Physicochemical Assessment
by Isabel S. Oliveira, Sandra G. Silva, Andreia C. Gomes, M. Elisabete C. D. Real Oliveira, M. Luísa C. do Vale and Eduardo F. Marques
J. Funct. Biomater. 2024, 15(8), 224; https://doi.org/10.3390/jfb15080224 - 13 Aug 2024
Viewed by 1706
Abstract
Cationic gemini surfactants have emerged as potential gene delivery agents as they can co-assemble with DNA due to a strong electrostatic association. Commonly, DNA complexation is enhanced by the inclusion of a helper lipid (HL), which also plays a key role in transfection [...] Read more.
Cationic gemini surfactants have emerged as potential gene delivery agents as they can co-assemble with DNA due to a strong electrostatic association. Commonly, DNA complexation is enhanced by the inclusion of a helper lipid (HL), which also plays a key role in transfection efficiency. The formation of lipoplexes, used as non-viral vectors for transfection, through electrostatic and hydrophobic interactions is affected by various physicochemical parameters, such as cationic surfactant:HL molar ratio, (+/−) charge ratio, and the morphological structure of the lipoplexes. Herein, we investigated the DNA complexation ability of mixtures of serine-based gemini surfactants, (nSer)2N5, and monoolein (MO) as a helper lipid. The micelle-forming serine surfactants contain long lipophilic chains (12 to 18 C atoms) and a five CH2 spacer, both linked to the nitrogen atoms of the serine residues by amine linkages. The (nSer)2N5:MO aggregates are non-cytotoxic up to 35–90 µM, depending on surfactant and surfactant/MO mixing ratio, and in general, higher MO content and longer surfactant chain length tend to promote higher cell viability. All systems efficaciously complex DNA, but the (18Ser)2N5:MO one clearly stands as the best-performing one. Incorporating MO into the serine surfactant system affects the morphology and size distribution of the formed mixed aggregates. In the low concentration regime, gemini–MO systems aggregate in the form of vesicles, while at high concentrations the formation of a lamellar liquid crystalline phase is observed. This suggests that lipoplexes might share a similar bilayer-based structure. Full article
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10 pages, 2093 KiB  
Article
Structural Characteristics, Electronic Properties, and Coupling Behavior of 12-4-12, 12-3-12, 12-2-12 Cationic Surfactants: A First-Principles Computational Investigation and Experimental Raman Spectroscopy
by Shiru Lin, Daisy Woodring, Richard D. Sheardy and Nasrin Mirsaleh-Kohan
Molecules 2024, 29(12), 2880; https://doi.org/10.3390/molecules29122880 - 17 Jun 2024
Viewed by 1113
Abstract
In this study, we present a comprehensive first-principles computational investigation focused on the structural characteristics, electronic properties, and coupling integrations of three cationic Gemini surfactants: 12-4-12, 12-3-12, and 12-2-12 ((CH3(CH2)11)(CH3)2-N+-(CH2 [...] Read more.
In this study, we present a comprehensive first-principles computational investigation focused on the structural characteristics, electronic properties, and coupling integrations of three cationic Gemini surfactants: 12-4-12, 12-3-12, and 12-2-12 ((CH3(CH2)11)(CH3)2-N+-(CH2)n-N+(CH3(CH2)11)(CH3)2, where n = 2, 3, or 4). By employing Density Functional Theory (DFT) computations, we aimed to gain insights into the fundamental aspects of these surfactant molecules, and the intermolecular interactions among these surfactant molecules. We examined different conformers of each surfactant, including parallel, wing, and bent conformers, and compared their relative stability and properties. We elucidated that the complex structural characteristics, electronic properties, and molecular arrangements of the surfactants vary according to the number of carbon atoms in the central spacer. We also conducted experimental Raman spectroscopy on the three surfactants to compare the results with our computational findings. Furthermore, we computed the coupling behaviors of different conformers of 12-4-12 surfactants in order to gain insights into their coupling mechanism. Full article
(This article belongs to the Special Issue Computational Studies of Novel Function Materials—2nd Edition)
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21 pages, 6771 KiB  
Article
Synthesis and Aggregation Behavior of Hexameric Quaternary Ammonium Salt Surfactant Tz-6C12QC
by Jianjian Jiao, Chi Ma, Linlin Zhang, Fan Li, Tianxu Gao, Lei Wang and Lee Tin Sin
Polymers 2023, 15(22), 4396; https://doi.org/10.3390/polym15224396 - 13 Nov 2023
Cited by 1 | Viewed by 1656
Abstract
A hexameric quaternary ammonium salt surfactant Tz-6C12QC featuring a rigid triazine spacer and six ammonium groups was synthesized. The molecular structure and aggregation behavior of Tz-6C12QC were characterized by nuclear magnetic resonance spectroscopy, surface tension, conductivity, dynamic light scattering, [...] Read more.
A hexameric quaternary ammonium salt surfactant Tz-6C12QC featuring a rigid triazine spacer and six ammonium groups was synthesized. The molecular structure and aggregation behavior of Tz-6C12QC were characterized by nuclear magnetic resonance spectroscopy, surface tension, conductivity, dynamic light scattering, and transmission electron microscopy, etc. Dissipative particle dynamics (DPD) simulation was employed to investigate the self-assembly behavior of Tz-6C12QC at different concentrations. The rheological behavior of the polyacrylamide/Tz-6C12QC system was characterized by shear rheology. The results indicated that Tz-6C12QC exhibited superior surface activity and lower surface tension compared to conventional surfactants. Rheology analysis revealed that Tz-6C12QC had a significant viscosity reduction effect on polyacrylamide. DLS and TEM indicated that, as the concentration of Tz-6C12QC increased, monomer associations, spherical aggregations, vesicles, tubular micelles, and bilayer vesicles were sequentially formed in the solution. This study presents a synthetic approach for polysurfactants with a rigid spacer and sheds light on the self-assembly process of micelles. Full article
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13 pages, 2939 KiB  
Article
Synthesis, Photophysical Properties, and Toxicity of o-Xylene-Bridged Porphyrin Dimers
by Kseniya A. Zhdanova, Andrey A. Zaytsev, Margarita A. Gradova, Oleg V. Gradov, Anton V. Lobanov, Alexander S. Novikov and Natal’ya A. Bragina
Inorganics 2023, 11(10), 415; https://doi.org/10.3390/inorganics11100415 - 19 Oct 2023
Viewed by 2697
Abstract
In this work, a number of new porphyrin dimers coupled with spacers based on α,α’-dibromo-o-xylene were synthesized and characterized by 1H, 13C NMR, 1H-1H COSY NMR, UV-vis-spectroscopy, and MALDI-TOF mass spectrometry. The initial A3B-type hydroxy-substituted porphyrins [...] Read more.
In this work, a number of new porphyrin dimers coupled with spacers based on α,α’-dibromo-o-xylene were synthesized and characterized by 1H, 13C NMR, 1H-1H COSY NMR, UV-vis-spectroscopy, and MALDI-TOF mass spectrometry. The initial A3B-type hydroxy-substituted porphyrins form dimer structures with high yields of 80–85%, while the use of amino-substituted porphyrins as starting compounds leads to the heterocyclization and formation of N-heterocycle fused porphyrins. For porphyrin dimers, photophysical properties and quantum yields of singlet oxygen were investigated. The peripheral alkoxy-substituents increase fluorescence quantum yield in comparison with the unsubstituted compounds. Also, it was found that dimers are characterized by lower singlet oxygen quantum yields compared to the corresponding monomers. Model aggregation experiments in micellar systems demonstrate stabilization of the photoactive monomolecular form of all the porphyrins, using nonionic surfactant Triton X-100. Cytotoxicity of received dimers shows high inhibition against HEK293T cells in the absence of light. Full article
(This article belongs to the Special Issue 10th Anniversary of Inorganics: Coordination Chemistry)
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25 pages, 3952 KiB  
Article
Arginine Gemini-Based Surfactants for Antimicrobial and Antibiofilm Applications: Molecular Interactions, Skin-Related Anti-Enzymatic Activity and Cytotoxicity
by Francisco Fábio Oliveira de Sousa, Aurora Pinazo, Zakaria Hafidi, María Teresa García, Elena Bautista, Maria del Carmen Moran and Lourdes Pérez
Molecules 2023, 28(18), 6570; https://doi.org/10.3390/molecules28186570 - 11 Sep 2023
Cited by 6 | Viewed by 2754
Abstract
The antimicrobial and antibiofilm properties of arginine-based surfactants have been evaluated. These two biological properties depend on both the alkyl chain length and the spacer chain nature. These gemini surfactants exhibit good activity against a wide range of bacteria, including some problematic resistant [...] Read more.
The antimicrobial and antibiofilm properties of arginine-based surfactants have been evaluated. These two biological properties depend on both the alkyl chain length and the spacer chain nature. These gemini surfactants exhibit good activity against a wide range of bacteria, including some problematic resistant microorganisms such us methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa. Moreover, surfactants with a C10 alkyl chain and C3 spacer inhibit the (MRSA) and Pseudomonas aeruginosa biofilm formation at concentrations as low as 8 µg/mL and are able to eradicate established biofilms of these two bacteria at 32 µg/mL. The inhibitory activities of the surfactants over key enzymes enrolled in the skin repairing processes (collagenase, elastase and hyaluronidase) were evaluated. They exhibited moderate anti-collagenase activity while the activity of hyaluronidase was boosted by the presence of these surfactants. These biological properties render these gemini arginine-based surfactants as perfect promising candidates for pharmaceutical and biological properties. Full article
(This article belongs to the Special Issue Gemini Surfactants for Medical and Non-medical Applications)
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30 pages, 8899 KiB  
Article
Synthesis, Properties, and Biomedical Application of Dicationic Gemini Surfactants with Dodecane Spacer and Carbamate Fragments
by Leysan Vasileva, Gulnara Gaynanova, Farida Valeeva, Elvira Romanova, Rais Pavlov, Denis Kuznetsov, Grigory Belyaev, Irina Zueva, Anna Lyubina, Alexandra Voloshina, Konstantin Petrov and Lucia Zakharova
Int. J. Mol. Sci. 2023, 24(15), 12312; https://doi.org/10.3390/ijms241512312 - 1 Aug 2023
Cited by 13 | Viewed by 2378
Abstract
A synthesis procedure and aggregation properties of a new homologous series of dicationic gemini surfactants with a dodecane spacer and two carbamate fragments (N,N′-dialkyl-N,N′-bis(2-(ethylcarbamoyloxy)ethyl)-N,N′-dimethyldodecan-1,6-diammonium dibromide, n-12-n(Et), where n = 10, 12, 14) were comprehensively described. The critical micelle concentrations of gemini surfactants were [...] Read more.
A synthesis procedure and aggregation properties of a new homologous series of dicationic gemini surfactants with a dodecane spacer and two carbamate fragments (N,N′-dialkyl-N,N′-bis(2-(ethylcarbamoyloxy)ethyl)-N,N′-dimethyldodecan-1,6-diammonium dibromide, n-12-n(Et), where n = 10, 12, 14) were comprehensively described. The critical micelle concentrations of gemini surfactants were obtained using tensiometry, conductometry, spectrophotometry, and fluorimetry. The thermodynamic parameters of adsorption and micellization, i.e., maximum surface excess (Гmax), the surface area per surfactant molecule (Amin), degree of counterion binding (β), and Gibbs free energy of micellization (∆Gmic), were calculated. Functional activity of the surfactants, including the solubilizing capacity toward Orange OT and indomethacin, incorporation into the lipid bilayer, minimum inhibitory concentration, and minimum bactericidal and fungicidal concentrations, was determined. Synthesized gemini surfactants were further used for the modification of liposomes dual-loaded with α-tocopherol and donepezil hydrochloride for intranasal treatment of Alzheimer’s disease. The obtained liposomes have high stability (more than 5 months), a significant positive charge (approximately + 40 mV), and a high degree of encapsulation efficiency toward rhodamine B, α-tocopherol, and donepezil hydrochloride. Korsmeyer-Peppas, Higuchi, and first-order kinetic models were used to process the in vitro release curves of donepezil hydrochloride. Intranasal administration of liposomes loaded with α-tocopherol and donepezil hydrochloride for 21 days prevented memory impairment and decreased the number of Aβ plaques by 37.6%, 40.5%, and 72.6% in the entorhinal cortex, DG, and CA1 areas of the hippocampus of the brain of transgenic mice with Alzheimer’s disease model (APP/PS1) compared with untreated animals. Full article
(This article belongs to the Special Issue New Prospects of Colloid Chemistry – Molecular Perspectives)
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30 pages, 10106 KiB  
Article
Perspectives on Corrosion Inhibition Features of Novel Synthesized Gemini-Fluorinated Cationic Surfactants Bearing Varied Spacers for Acid Pickling of X60-Steel: Practical, and In Silico Calculations
by Kamal Shalabi, Hany M. Abd El-Lateef, Mohamed M. Hammouda, Amany M. A. Osman, Ahmed H. Tantawy and Mohamed A. Abo-Riya
Materials 2023, 16(14), 5192; https://doi.org/10.3390/ma16145192 - 24 Jul 2023
Cited by 10 | Viewed by 1744
Abstract
Through our present study, three novel Gemini-fluorinated cationic surfactants bearing different spacers (FSG6-2, FSG6-4, and FSG6-6) were synthesized, and their structures were explained via different spectroscopic instruments such as 1H, 13C, and 19F NMR spectra. The surface activity of the [...] Read more.
Through our present study, three novel Gemini-fluorinated cationic surfactants bearing different spacers (FSG6-2, FSG6-4, and FSG6-6) were synthesized, and their structures were explained via different spectroscopic instruments such as 1H, 13C, and 19F NMR spectra. The surface activity of the as-prepared surfactants was examined. The inhibiting influence of FSG6 molecules on the X60 steel corrosion in the pickling solution (HCl) was examined by diverse methods comprising electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), and X-ray photoelectron spectroscopy (XPS) experimentations, and computational calculations. The inhibition effectiveness of FSG6 surfactants followed the order of 93.37% (FSG6-2) < 96.74% (FSG6-4) < 98.37% (FSG6-6) at 2.0 × 10−4 M. The FSG6 surfactants function as mixed-type inhibitors, according to PDP investigations. The H2O molecules that adsorbed on the steel interface were substituted with surfactant molecules, and the surfactant’s inhibitory activity is likely caused by the improvement in an adsorptive layer on the steel substrate, as specified by the EIS results. The Langmuir isotherm describes the absorption of FSG6 molecules on the metal surface. The XPS investigations validate the steel interface’s extremely protective nature. The mechanism of interaction between FSG6 molecules with an X60-steel employing the DFT calculations and MC simulations methods was also examined and discussed. Full article
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12 pages, 1145 KiB  
Article
Self-Aggregation, Antimicrobial Activity and Cytotoxicity of Ester-Bonded Gemini Quaternary Ammonium Salts: The Role of the Spacer
by Yaqin Liang, Hui Li, Jiahui Ji, Jiayu Wang and Yujie Ji
Molecules 2023, 28(14), 5469; https://doi.org/10.3390/molecules28145469 - 17 Jul 2023
Cited by 5 | Viewed by 1662
Abstract
Five ester-bonded gemini quaternary ammonium surfactants C12-En-C12 (n = 2, 4, 6), with a flexible spacer group, and C12-Bm-C12 (m = 1, 2), with rigid benzene spacers, were synthesized via a two-step reaction [...] Read more.
Five ester-bonded gemini quaternary ammonium surfactants C12-En-C12 (n = 2, 4, 6), with a flexible spacer group, and C12-Bm-C12 (m = 1, 2), with rigid benzene spacers, were synthesized via a two-step reaction and analyzed. Furthermore, the effects of the spacer structure, spacer length and polymerization degree on the self-aggregation, antimicrobial activity and cytotoxicity of C12-En-C12 and C12-Bm-C12 and their corresponding monomer N-dodecyl-N,N,N-trimethyl ammonium chloride DTAC were investigated. The results showed that C12-En-C12 and C12-Bm-C12 had markedly lower critical micellar concentration (CMC) values and lower surface tension than DTAC. Moreover, the CMC values of C12-En-C12 and C12-Bm-C12 decreased with increasing spacer length. In the case of equivalent chain length, the rigidity and steric hindrance of phenylene and 1,4-benzenediyl resulted in larger CMC values for C12-Bm-C12 than for C12-En-C12. The antibacterial ability of C12-En-C12 and C12-Bm-C12 was assessed using Escherichia coli (E. coli) and Staphylococcus albus (S. aureus) based on minimum inhibitory concentrations (MICs). Furthermore, C12-En-C12 and C12-Bm-C12 exhibited higher antimicrobial activity than DTAC and had stronger function toward S. aureus than E. coli. The antimicrobial activity was enhanced by increasing the spacer chain length and decreased with the increased rigidity of the spacers. The cytotoxic effects of C12-En-C12 and C12-Bm-C12 in cultured Hela cells were evaluated by the standard CCK8 method based on half-maximal inhibitory concentration (IC50). The cytotoxicity of C12-En-C12 and C12-Bm-C12 was significantly lower than alkanediyl-α,ω-bis(dimethyldodecylammonium) bromide surfactants and DTAC. The spacer structure and the spacer length could induce significant cytotoxic effects on Hela cells. These findings indicate that the five ester-bonded GQASs have stronger antibacterial activity and lower toxicity profile, and thus can be used in the pharmaceutical industry. Full article
(This article belongs to the Special Issue Gemini Surfactants for Medical and Non-medical Applications)
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17 pages, 161680 KiB  
Article
DFT Calculation and MD Simulation Studies on Gemini Surfactant Corrosion Inhibitor in Acetic Acid Media
by Mohd Sofi Numin, Khairulazhar Jumbri, Kok Eng Kee, Almila Hassan, Noorazlenawati Borhan and Juan Matmin
Polymers 2023, 15(9), 2155; https://doi.org/10.3390/polym15092155 - 30 Apr 2023
Cited by 12 | Viewed by 3266
Abstract
Gemini surfactant corrosion inhibitor (CI) is one type of CI mainly used in mitigating corrosion in the complex system of oil/gas production industries. Computer modeling methods such as density functional theory (DFT) calculation and molecular dynamic (MD) simulation are required to develop new [...] Read more.
Gemini surfactant corrosion inhibitor (CI) is one type of CI mainly used in mitigating corrosion in the complex system of oil/gas production industries. Computer modeling methods such as density functional theory (DFT) calculation and molecular dynamic (MD) simulation are required to develop new CI molecules focusing on their application condition as a prediction or screening process before the physical empirical assessment. In this work, the adsorption inhibition efficiencies of two monomer surfactants (2B and H) and their respective Gemini structures with the addition of different spacers (alkyl, benzene, ester, ether, and ketone) are investigated using DFT calculation and MD simulation method in 3% sodium chloride (NaCl), and 1500 ppm acetic acid solutions. In DFT calculation, 2B-benzene molecules are assumed to have the most promising inhibition efficiency based on their high reactivity and electron-donating ability at their electron-rich benzene ring region based on the lowest bandgap energy (0.765 eV) and highest HOMO energy value (−2.879 eV), respectively. DFT calculation results correlate with the adsorption energy calculated from MD simulation, where 2B-benzene is also assumed to work better as a CI molecule with the most adsorption strength towards Fe (110) metal with the highest negative adsorption energy value (−1837.33 kJ/mol at temperature 323 K). Further, diffusion coefficient and molecular aggregation analysis in different CI concentrations through MD simulation reveals that only a small amount of Gemini surfactant CI is needed in the inhibition application compared to its respective monomer. Computer simulation methods successfully predict and screen the Gemini surfactant CI molecules that can work better as a corrosion inhibitor in acetic acid media. The amount of Gemini surfactant CI that needs to be used is also predicted. The future planning or way forward from this study will be the development of the most promising Gemini surfactant CI based on the results from DFT calculation and MD simulations. Full article
(This article belongs to the Collection Polymer Applications in Environmental Science)
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17 pages, 3985 KiB  
Article
Chemico-Physical Properties of Some 1,1′-Bis-alkyl-2,2′-hexane-1,6-diyl-bispyridinium Chlorides Hydrogenated and Partially Fluorinated for Gene Delivery
by Michele Massa, Mirko Rivara, Thelma A. Pertinhez, Carlotta Compari, Gaetano Donofrio, Luigi Cristofolini, Davide Orsi, Valentina Franceschi and Emilia Fisicaro
Molecules 2023, 28(8), 3585; https://doi.org/10.3390/molecules28083585 - 20 Apr 2023
Cited by 1 | Viewed by 1707
Abstract
The development of very efficient and safe non-viral vectors, constituted mainly by cationic lipids bearing multiple charges, is a landmark for in vivo gene-based medicine. To understand the effect of the hydrophobic chain’s length, we here report the synthesis, and the chemico-physical and [...] Read more.
The development of very efficient and safe non-viral vectors, constituted mainly by cationic lipids bearing multiple charges, is a landmark for in vivo gene-based medicine. To understand the effect of the hydrophobic chain’s length, we here report the synthesis, and the chemico-physical and biological characterization, of a new term of the homologous series of hydrogenated gemini bispyridinium surfactants, the 1,1′-bis-dodecyl-2,2′-hexane-1,6-diyl-bispyridinium chloride (GP12_6). Moreover, we have collected and compared the thermodynamic micellization parameters (cmc, changes in enthalpy, free energy, and entropy of micellization) obtained by isothermal titration calorimetry (ITC) experiments for hydrogenated surfactants GP12_6 and GP16_6, and for the partially fluorinated ones, FGPn (where n is the spacer length). The data obtained for GP12_6 by EMSA, MTT, transient transfection assays, and AFM imaging show that in this class of compounds, the gene delivery ability strictly depends on the spacer length but barely on the hydrophobic tail length. CD spectra have been shown to be a useful tool to verify the formation of lipoplexes due to the presence of a “tail” in the 288–320 nm region attributed to a chiroptical feature named ψ-phase. Ellipsometric measurements suggest that FGP6 and FGP8 (showing a very interesting gene delivery activity, when formulated with DOPE) act in a very similar way, and dissimilar from FGP4, exactly as in the case of transfection, and confirm the hypothesis suggested by previously obtained thermodynamic data about the requirement of a proper length of the spacer to allow the molecule to form a sort of molecular tong able to intercalate DNA. Full article
(This article belongs to the Special Issue 2D Materials for Biomedical Applications)
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15 pages, 4099 KiB  
Article
Characterization of Micelle Formation by the Single Amino Acid-Based Surfactants Undecanoic L-Isoleucine and Undecanoic L-Norleucine in the Presence of Diamine Counterions with Varying Chain Lengths
by Amber Maynard-Benson, Mariya Alekisch, Alyssa Wall, Eugene J. Billiot, Fereshteh H. Billiot and Kevin F. Morris
Colloids Interfaces 2023, 7(2), 28; https://doi.org/10.3390/colloids7020028 - 4 Apr 2023
Cited by 4 | Viewed by 3692
Abstract
The binding of linear diamine counterions with different methylene chain lengths to the amino-acid-based surfactants undecanoic L-isoleucine (und-IL) and undecanoic L-norleucine (und-NL) was investigated with NMR spectroscopy. The counterions studied were 1,2-ethylenediamine, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, and 1,6-diaminohexane. These counterions were all linear diamines [...] Read more.
The binding of linear diamine counterions with different methylene chain lengths to the amino-acid-based surfactants undecanoic L-isoleucine (und-IL) and undecanoic L-norleucine (und-NL) was investigated with NMR spectroscopy. The counterions studied were 1,2-ethylenediamine, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, and 1,6-diaminohexane. These counterions were all linear diamines with varying spacer chain lengths between the two amine functional groups. The sodium counterion was studied as well. Results showed that when the length of the counterion methylene chain was increased, the surfactants’ critical micelle concentrations (CMC) decreased. This decrease was attributed to diamines with longer methylene chains binding to multiple surfactant monomers below the CMC and thus acting as templating agents for the formation of micelles. The entropic hydrophobic effect and differences in diamine counterion charge also contributed to the size of the micelles and the surfactants’ CMCs in the solution. NMR diffusion measurements showed that the micelles formed by both surfactants were largest when 1,4-diaminobutane counterions were present in the solution. This amine also had the largest mole fraction of micelle-bound counterions. Finally, the und-NL micelles were larger than the und-IL micelles when 1,4-diaminobutane counterions were bound to the micelle surface. A model was proposed in which this surfactant formed non-spherical aggregates with both the surfactant molecules’ hydrocarbon chains and n-butyl amino acid side chains pointing toward the micelle core. The und-IL micelles, in contrast, were smaller and likely spherically shaped. Full article
(This article belongs to the Special Issue Progress in Surfactants with Low Environmental Impact)
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