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Hu X, Liao M, Shen K, Ding K, Campana M, van der Kamp S, McInnes EF, Padia F, Lu JR. Unraveling How Membrane Nanostructure Changes Impact the Eye Irritation of Nonionic Alkyl Ethoxylate Surfactants. ACS APPLIED MATERIALS & INTERFACES 2023; 15:59087-59098. [PMID: 38078441 PMCID: PMC10739585 DOI: 10.1021/acsami.3c14794] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Revised: 11/28/2023] [Accepted: 11/29/2023] [Indexed: 12/22/2023]
Abstract
Nonionic surfactants used in agri-spraying processes may cause varying degrees of corneal irritation when they come in direct contact with farmers' eyes, and the exact irritations are thought to be determined by how surfactants interact with corneal cell membranes. However, how nonionic surfactants interact with cell membranes at the molecular and nano levels remains largely unexplored. In this study, the interactions between nonionic surfactants (alkyl ethoxylate, C12Em) and lipid membranes were examined by membrane permeability measurement, quartz crystal microbalance with dissipation, dual polarization interferometry, confocal laser scanning microscopy, and neutron reflection, aiming to reveal complementary structural features at the molecular and nano levels. Apart from the extremely hydrophobic surfactant C12E2, all nonionic surfactants studied could penetrate the model cell membrane composed of a phosphocholine lipid bilayer. Nonionic surfactants with intermediate amphiphilicity (C12E6) rapidly fused into the lipid membrane and stimulated the formation of pores across the lipid bilayer, consistent with the cytoplasm leakage and fast cell necrosis observed from the cytotoxicity study of corneal cells. In comparison, while hydrophobic and hydrophilic surfactants [those with long and short ethoxylates (C12E4,12,23)] could cause mild structural alteration to the outer lipid layer of the membrane, these structural changes were insufficient to elicit large cytoplasmic leakage rapidly and instead cell death occurred over longer periods of time due to changes in the membrane permeability. These results reveal the strong link of surfactant-lipid membrane interactions to surfactant cytotoxicity and the association with amphiphilicity of nonionic surfactants.
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Affiliation(s)
- Xuzhi Hu
- Biological
Physics Group, Department of Physics and Astronomy, School of Natural
Sciences, University of Manchester, Oxford Road, Manchester M13 9PL, U.K.
| | - Mingrui Liao
- Biological
Physics Group, Department of Physics and Astronomy, School of Natural
Sciences, University of Manchester, Oxford Road, Manchester M13 9PL, U.K.
| | - Kangcheng Shen
- Biological
Physics Group, Department of Physics and Astronomy, School of Natural
Sciences, University of Manchester, Oxford Road, Manchester M13 9PL, U.K.
| | - Ke Ding
- Biological
Physics Group, Department of Physics and Astronomy, School of Natural
Sciences, University of Manchester, Oxford Road, Manchester M13 9PL, U.K.
| | - Mario Campana
- Rutherford
Appleton Laboratory, STFC ISIS Facility, Didcot OX11 0QX, U.K.
| | - Sophie van der Kamp
- Jealott’s
Hill International Research Centre, Syngenta, Bracknell, Berkshire RG42
6EY, U.K.
| | - Elizabeth F. McInnes
- Jealott’s
Hill International Research Centre, Syngenta, Bracknell, Berkshire RG42
6EY, U.K.
| | - Faheem Padia
- Jealott’s
Hill International Research Centre, Syngenta, Bracknell, Berkshire RG42
6EY, U.K.
| | - Jian R. Lu
- Biological
Physics Group, Department of Physics and Astronomy, School of Natural
Sciences, University of Manchester, Oxford Road, Manchester M13 9PL, U.K.
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Tan H, Bi Y, Zhang S, Wang S. Growth of alfalfa in the presence of metabolites from a dark septate endophyte strain Alternaria sp. 17463 cultured with a nonionic surfactant and emulsifier. J Appl Microbiol 2023; 134:lxad226. [PMID: 37793812 DOI: 10.1093/jambio/lxad226] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2023] [Revised: 09/18/2023] [Accepted: 10/03/2023] [Indexed: 10/06/2023]
Abstract
AIM Dark septate endophytes (DSE) were widely used in the agriculture and ecological restoration. The objective of this work was to assess the effect of culture media nonionic surfactant and emulsifier on the biomass and metabolites of DSE strain Alternaria sp. 17463. METHODS AND RESULTS Changes in the composition of DSE metabolites following the addition of Tween 80 during liquid culture of a DSE fungus were analyzed and used in growth tests of alfalfa.Shaking flask fermentation was carried out and the surfactant was fed to the fungus during the fermentation. The residual sugar content and pH declined significantly in the medium and the biomass of DSE increased by 7.27% over controls with no surfactant. Metabolomic analysis showed that adding the surfactant significantly increased the content of 63 metabolites (P < 0.05). These include lipids and lipid-like molecules, organooxygen compounds, amino acids and organic acids, and flavonoids. Enrichment analysis of metabolic pathways indicates that surfactant addition promoted carbohydrate metabolism and amino acid synthesis. A plant hydroponic experiment indicated that these changes in metabolites altered the root structure of alfalfa seedlings. They also promoted significant increases in root length and root surface area, and increased alfalfa total biomass by 50.2%. CONCLUSIONS The addition of the surfactant promoted sugar utilization by the DSE fungus and increased the synthesis of lipids and amino acids, resulting in the ability of the fungal metabolites to change root structure and promote plant growth.
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Affiliation(s)
- Hai Tan
- Shaanxi Provincial Key Laboratory of Geological Support for Coal Green Exploitation, Xi'an University of Science and Technology, Xi'an 710054, China
- College of Geology and Environment, Xi'an University of Science and Technology, Xi'an 710054, China
- Institute of Ecological Environment Restoration in Mine Areas of West China, Xi'an University of Science and Technology, Xi'an 710054, China
| | - Yinli Bi
- Shaanxi Provincial Key Laboratory of Geological Support for Coal Green Exploitation, Xi'an University of Science and Technology, Xi'an 710054, China
- College of Geology and Environment, Xi'an University of Science and Technology, Xi'an 710054, China
- Institute of Ecological Environment Restoration in Mine Areas of West China, Xi'an University of Science and Technology, Xi'an 710054, China
| | - Shishuang Zhang
- Shaanxi Provincial Key Laboratory of Geological Support for Coal Green Exploitation, Xi'an University of Science and Technology, Xi'an 710054, China
- Institute of Ecological Environment Restoration in Mine Areas of West China, Xi'an University of Science and Technology, Xi'an 710054, China
| | - Shuhui Wang
- Institute of Ecological Environment Restoration in Mine Areas of West China, Xi'an University of Science and Technology, Xi'an 710054, China
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Bao Z, Wu Y, Song R, Gao Y, Zhang S, Zhao K, Wu T, Zhang C, Du F. The simple strategy to improve pesticide bioavailability and minimize environmental risk by effective and ecofriendly surfactants. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 851:158169. [PMID: 35995160 DOI: 10.1016/j.scitotenv.2022.158169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Revised: 08/16/2022] [Accepted: 08/16/2022] [Indexed: 06/15/2023]
Abstract
Low pesticide efficiency has caused serious environmental pollution and economic loss, which are closely related to each link in the targeted delivery of pesticides. However, the existing strategies for improving pesticide utilization rate are not comprehensive, and the regulation of foliar absorption and biological activity has been neglected. As surfactants are the most important agricultural synergists, the impact, wetting, adhesion, and leaf retention behaviors of pyraclostrobin (PYR) droplets containing the surfactant Triton X (TX) series on hydrophobic scallion leaf surfaces were studied. The results showed that TX-102 can sufficiently reduce the splash and roll of droplets when they impact inclined leaves, owing to its low dynamic surface tension. Moderate wetting ability and high adhesion also maximizes leaf retention of the TX-102-added PYR solution sprayed on scallion leaves. Furthermore, TX-102 improved the permeation and absorption of PYR in scallion leaves through the synergistic effects of opening the stomata and dissolving the waxy layer. The synergistic bioactivity of TX-102 against pathogenic fungi Alternaria porri and its safety to non-target organism zebrafish have also been demonstrated. Our study provides a more comprehensive theoretical rationale for screening adjuvants to improve the effectiveness and bioavailability of pesticides and reduce the risk of pesticides entering the environment.
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Affiliation(s)
- Zhenping Bao
- Department of Applied Chemistry, College of Science, China Agricultural University, Beijing 100193, China.
| | - Yanling Wu
- Department of Applied Chemistry, College of Science, China Agricultural University, Beijing 100193, China.
| | - Ridan Song
- Department of Applied Chemistry, College of Science, China Agricultural University, Beijing 100193, China.
| | - Yuxia Gao
- Department of Applied Chemistry, College of Science, China Agricultural University, Beijing 100193, China.
| | - Songhao Zhang
- Department of Applied Chemistry, College of Science, China Agricultural University, Beijing 100193, China.
| | - Kefei Zhao
- Department of Applied Chemistry, College of Science, China Agricultural University, Beijing 100193, China.
| | - Tianyue Wu
- Department of Applied Chemistry, College of Science, China Agricultural University, Beijing 100193, China.
| | - Chenhui Zhang
- Department of Applied Chemistry, College of Science, China Agricultural University, Beijing 100193, China.
| | - Fengpei Du
- Department of Applied Chemistry, College of Science, China Agricultural University, Beijing 100193, China.
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Hu X, Carter J, Ge T, Liao M, Margaret Stephens A, Mclnnes EF, Padia F, Lu JR. Impacts of chain and head lengths of nonionic alkyl ethoxylate surfactants on cytotoxicity to human corneal and skin cells in agri-spraying processes*. J Colloid Interface Sci 2022; 628:162-173. [DOI: 10.1016/j.jcis.2022.08.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 07/19/2022] [Accepted: 08/03/2022] [Indexed: 10/15/2022]
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Hu X, Gong H, Liu H, Wang X, Wang W, Liao M, Li Z, Ma K, Li P, Rogers S, Schweins R, Liu X, Padia F, Bell G, Lu JR. Contrasting impacts of mixed nonionic surfactant micelles on plant growth in the delivery of fungicide and herbicide. J Colloid Interface Sci 2022; 618:78-87. [PMID: 35334364 DOI: 10.1016/j.jcis.2022.03.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Revised: 02/13/2022] [Accepted: 03/01/2022] [Indexed: 10/18/2022]
Abstract
HYPOTHESIS Nonionic alkyl ethoxylate surfactants are widely used in agrochemicals to facilitate the permeation of systemic herbicides and fungicides across the plant waxy film. Industrial grade surfactants are often highly mixed and how the mixing affects their interactions with pesticides and wax films remains largely unexplored. A better understanding could enable design of mixed nonionic surfactants for herbicides and fungicides to maximize their efficiency and reduce wastage whilst controlling their impact on plant wax films. EXPERIMENT In this study, nonionic surfactants with general structure n-oxyethylene glycol monododecyl ether (C12En) were used to form surfactant mixtures with the same average ethoxylate numbers but different hydrophilic-lipophilic balance (HLB) values. Their mixed micellar systems were then used to solubilize a herbicide diuron (DN) and a fungicide cyprodinil (CP), followed by plant wax solubilization upon contact with wax films. These processes were monitored by 1H NMR and SANS. FINDING Pesticide solubilization made surfactant micelles effectively more hydrophobic but subsequent wax dissolution caused pesticide release and the restoration of the micellar amphiphilicity. Nonionic surfactants with lower HLBs form larger nanoaggregates, show enhanced wettability, and have better ability to solubilize and permeate pesticides across the wax film, but may cause significant damage to plant growth. These observations help explain why herbicides applied on weeds would benefit from surfactants with lower HLB values while fungicides require surfactants with HLBs to balance between delivery efficiency and potential phytotoxicity risks.
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Affiliation(s)
- Xuzhi Hu
- Biological Physics Group, Department of Physics and Astronomy, School of Natural Sciences, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Haoning Gong
- Biological Physics Group, Department of Physics and Astronomy, School of Natural Sciences, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Huayang Liu
- Biological Physics Group, Department of Physics and Astronomy, School of Natural Sciences, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Xi Wang
- Department of Materials, School of Natural Sciences, the University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Weimiao Wang
- Department of Materials, School of Natural Sciences, the University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Mingrui Liao
- Biological Physics Group, Department of Physics and Astronomy, School of Natural Sciences, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Zongyi Li
- Biological Physics Group, Department of Physics and Astronomy, School of Natural Sciences, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Kun Ma
- STFC ISIS Facility, Rutherford Appleton Laboratory, Didcot, OX11 0QX, UK
| | - Peixun Li
- STFC ISIS Facility, Rutherford Appleton Laboratory, Didcot, OX11 0QX, UK
| | - Sarah Rogers
- STFC ISIS Facility, Rutherford Appleton Laboratory, Didcot, OX11 0QX, UK
| | - Ralf Schweins
- Large Scale Structures Group, Institut Laue-Langevin, CS 20 156, 38042 Grenoble CEDEX 9, France
| | - Xuqing Liu
- Department of Materials, School of Natural Sciences, the University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Faheem Padia
- Syngenta, Jealott's Hill International Research Centre, Bracknell, Berkshire RG42 6EY, UK
| | - Gordon Bell
- Syngenta, Jealott's Hill International Research Centre, Bracknell, Berkshire RG42 6EY, UK
| | - Jian R Lu
- Biological Physics Group, Department of Physics and Astronomy, School of Natural Sciences, University of Manchester, Oxford Road, Manchester M13 9PL, UK.
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6
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Liu H, Fa K, Hu X, Li Z, Ma K, Liao M, Zhang L, Schweins R, Maestro A, Li P, Webster JRP, Petkov J, Thomas RK, Lu JR. How do chain lengths of acyl-l-carnitines affect their surface adsorption and solution aggregation? J Colloid Interface Sci 2021; 609:491-502. [PMID: 34863541 DOI: 10.1016/j.jcis.2021.11.056] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Revised: 11/10/2021] [Accepted: 11/11/2021] [Indexed: 11/26/2022]
Abstract
HYPOTHESIS l-carnitines in our body systems can be readily converted into acyl-l-carnitines which have a prominent place in cellular energy generation by supporting the transport of long-chain fatty acids into mitochondria. As biocompatible surfactants, acyl-l-carnitines have potential to be useful in technical, personal care and healthcare applications. However, the lack of understanding of the effects of their molecular structures on their physical properties has constrained their potential use. EXPERIMENTS This work reports the study of the influence of the acyl chain lengths of acyl-l-carnitines (CnLC) on solubility, surface adsorption and aggregation. Critical micellar concentrations (CMCs) of CnLC were determined by surface tension measurements. Neutron reflection (NR) was used to further examine the structure and composition of the adsorbed CnLC layer. The structural changes of the micellar aggregates under different concentrations of CnLC, pH and ionic strength were determined by dynamic light scattering (DLS) and small angle neutron scattering (SANS). FINDINGS C12LC is fully soluble over a wide temperature and concentration range. There is however a strong decline of solubility with increasing acyl chain length. The adsorption and aggregation behavior of C14LC was therefore studied at 30 °C and C16LC at 45 °C. The solubility boundaries displayed distinct hysteresis with respect to heating and cooling. The CMCs of C12LC, C14LC and C16LC at pH 7 were 1.1 ± 0.1, 0.10 ± 0.02 and 0.010 ± 0.005 mM, respectively, with the limiting values of the area per molecule at the CMC being 45.4 ± 2, 47.5 ± 2 and 48.8 ± 2 Å2 and the thicknesses of the adsorbed CnLC layers at the air/water interface increasing from 21.5 ± 2 to 22.6 ± 2 to 24.2 ± 2 Å, respectively. All three surfactants formed core-shell spherical micelles with comparable dimensional parameters apart from an increase in core radius with acyl chain length. This study outlines the effects of acyl chain length on the physicochemical properties of CnLCs under different environmental conditions, serving as a useful basis for developing their potential applications.
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Affiliation(s)
- Huayang Liu
- Biological Physics Laboratory, Department of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Ke Fa
- Biological Physics Laboratory, Department of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Xuzhi Hu
- Biological Physics Laboratory, Department of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Zongyi Li
- Biological Physics Laboratory, Department of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Kun Ma
- ISIS Neutron Facility, Rutherford Appleton Laboratory, STFC, Chilton, Didcot, Oxon OX11 0QX, UK
| | - Mingrui Liao
- Biological Physics Laboratory, Department of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Lin Zhang
- Biological Physics Laboratory, Department of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Ralf Schweins
- Institut Laue-Langevin, 71 Avenue des Martyrs, CS20156, 38042 Grenoble Cedex 9, France
| | - Armando Maestro
- Institut Laue-Langevin, 71 Avenue des Martyrs, CS20156, 38042 Grenoble Cedex 9, France
| | - Peixun Li
- ISIS Neutron Facility, Rutherford Appleton Laboratory, STFC, Chilton, Didcot, Oxon OX11 0QX, UK
| | - John R P Webster
- ISIS Neutron Facility, Rutherford Appleton Laboratory, STFC, Chilton, Didcot, Oxon OX11 0QX, UK
| | - Jordan Petkov
- Biological Physics Laboratory, Department of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK; Arxada, Hexagon Tower, Delaunays Road, Blackley, Manchester M9 8ZS, UK.
| | - Robert K Thomas
- Physical and Theoretical Chemistry, University of Oxford, South Parks, Oxford OX1 3QZ, UK
| | - Jian Ren Lu
- Biological Physics Laboratory, Department of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK.
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7
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Gong H, Hu X, Liao M, Fa K, Ciumac D, Clifton LA, Sani MA, King SM, Maestro A, Separovic F, Waigh TA, Xu H, McBain AJ, Lu JR. Structural Disruptions of the Outer Membranes of Gram-Negative Bacteria by Rationally Designed Amphiphilic Antimicrobial Peptides. ACS APPLIED MATERIALS & INTERFACES 2021; 13:16062-16074. [PMID: 33797891 DOI: 10.1021/acsami.1c01643] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Gram-negative bacteria are covered by both an inner cytoplasmic membrane (IM) and an outer membrane (OM). Antimicrobial peptides (AMPs) must first permeate through the OM and cell wall before attacking the IM to cause cytoplasmic leakage and kill the bacteria. The bacterial OM is an asymmetric bilayer with the outer leaflet primarily composed of lipopolysaccharides (LPSs) and the inner leaflet composed of phospholipids (PLs). Two cationic α-helical AMPs were designed to target Gram-negative bacteria, a full peptide G(IIKK)3I-NH2 (G3), and a hydrophobic lipopeptide C8-G(IIKK)2I-NH2 (C8G2, with C8 denoting the octanoyl chain). LPS dominates OM functions as the first line of defense against antibiotics, thereby reducing drug susceptibility. This work explores how the two AMPs interact with LPS through several carefully chosen OM models that facilitated measurements from solid-state nuclear magnetic resonance (ss-NMR), small-angle neutron scattering (SANS), and neutron reflectivity (NR). The results revealed that G3 molecules bound preferably to the LPS head region and functioned as bridge molecules to reassemble the dislocated lipids into bilayer stacks. In contrast, C8G2 lipopeptides could quickly penetrate into the central region of the OM to cause direct removal of some membrane lipids. Different structural disruptions implicated different antimicrobial efficacies from these AMPs. The demonstration of the structural features underlying different susceptibilities of the OM to AMPs offers a useful route for the future development of strain-specific AMPs against antimicrobial-resistant pathogens.
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Affiliation(s)
- Haoning Gong
- Biological Physics Laboratory, Department of Physics and Astronomy, Faculty of Science and Engineering, The University of Manchester, Oxford Road, Manchester M13 9PL, UK
- Division of Pharmacy and Optometry, Faculty of Biology, Medicine and Health, The University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Xuzhi Hu
- Biological Physics Laboratory, Department of Physics and Astronomy, Faculty of Science and Engineering, The University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Mingrui Liao
- Biological Physics Laboratory, Department of Physics and Astronomy, Faculty of Science and Engineering, The University of Manchester, Oxford Road, Manchester M13 9PL, UK
- Division of Pharmacy and Optometry, Faculty of Biology, Medicine and Health, The University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Ke Fa
- Biological Physics Laboratory, Department of Physics and Astronomy, Faculty of Science and Engineering, The University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Daniela Ciumac
- Biological Physics Laboratory, Department of Physics and Astronomy, Faculty of Science and Engineering, The University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Luke A Clifton
- ISIS Pulsed Neutron & Muon Source, STFC Rutherford Appleton Laboratory, Harwell Campus, Didcot OX11 0QX, UK
| | - Marc-Antoine Sani
- School of Chemistry, Bio21 Institute, University of Melbourne, Melbourne, VIC 3010, Australia
| | - Stephen M King
- ISIS Pulsed Neutron & Muon Source, STFC Rutherford Appleton Laboratory, Harwell Campus, Didcot OX11 0QX, UK
| | - Armando Maestro
- Institute Laue Langevin, 71 Avenue des Martyrs, CS-20156, 38042 Grenoble, France
| | - Frances Separovic
- School of Chemistry, Bio21 Institute, University of Melbourne, Melbourne, VIC 3010, Australia
| | - Thomas A Waigh
- Biological Physics Laboratory, Department of Physics and Astronomy, Faculty of Science and Engineering, The University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Hai Xu
- State Key Laboratory of Heavy Oil Processing and the Centre for Bioengineering and Biotechnology, China University of Petroleum (East China), 66 Changjiang West Road, Qingdao 266580, China
| | - Andrew J McBain
- Division of Pharmacy and Optometry, Faculty of Biology, Medicine and Health, The University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Jian Ren Lu
- Biological Physics Laboratory, Department of Physics and Astronomy, Faculty of Science and Engineering, The University of Manchester, Oxford Road, Manchester M13 9PL, UK
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Hu X, Gong H, Hollowell P, Liao M, Li Z, Ruane S, Liu H, Pambou E, Mahmoudi N, Dalgliesh RM, Padia F, Bell G, Lu JR. What happens when pesticides are solubilised in binary ionic/zwitterionic-nonionic mixed micelles? J Colloid Interface Sci 2021; 586:190-199. [PMID: 33162043 DOI: 10.1016/j.jcis.2020.10.083] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Revised: 10/20/2020] [Accepted: 10/21/2020] [Indexed: 10/23/2022]
Abstract
HYPOTHESIS Surfactants have been widely used as adjuvants in agri-sprays to enhance the solubility of pesticides in foliar spray deposits and their mobility through leaf cuticles. Previously, we have characterised pesticide solubilisation in nonionic surfactant micelles, but what happens when pesticides become solubilised in anionic, cationic and zwitterionic and their mixtures with nonionic surfactants remain poorly characterised. EXPERIMENTS To facilitate characterisations by SANS and NMR, we used nonionic surfactant hexaethylene glycol monododecyl ether (C12E6), anionic sodium dodecylsulphate (SDS), cationic dodecyltrimethylammonium bromide (DTAB) and zwitterionic dodecylphosphocholine (C12PC) as model adjuvant systems to solubilise 3 pesticides, Cyprodinil (CP), Azoxystrobin (AZ) and Difenoconazole (DF), representing different structural features. The investigation focused on the influence of solubilisates in driving changes to the micellar nanostructures in the absence or presence of electrolytes. NMR and NOESY were applied to investigate the solubility and location of each pesticide in the micelles. SANS was used to reveal subtle changes to the micellar structures due to pesticide solubilisation with and without electrolytes. FINDINGS Unlike nonionic surfactants, the ionic and zwitterionic surfactant micellar structures remain unchanged upon pesticide solubilisation. Electrolytes slightly elongate the ionic surfactant micelles but have no effect on nonionic and zwitterionic surfactants. Pesticide solubilisation could alter the structures of the binary mixtures of ionic/zwitterionic and ionic/nonionic micelles by causing elongation, shell shrinkage and dehydration, with the exact alteration being determined by the molar ratio in the mixture.
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Affiliation(s)
- Xuzhi Hu
- Biological Physics Group, School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Haoning Gong
- Biological Physics Group, School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Peter Hollowell
- Biological Physics Group, School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Mingrui Liao
- Biological Physics Group, School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Zongyi Li
- Biological Physics Group, School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Sean Ruane
- Biological Physics Group, School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Huayang Liu
- Biological Physics Group, School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Elias Pambou
- Biological Physics Group, School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Najet Mahmoudi
- STFC ISIS Facility, Rutherford Appleton Laboratory, Didcot OX11 0QX, UK
| | | | - Faheem Padia
- Syngenta, Jealott's Hill International Research Centre, Bracknell, Berkshire RG42 6EY, UK
| | - Gordon Bell
- Syngenta, Jealott's Hill International Research Centre, Bracknell, Berkshire RG42 6EY, UK
| | - Jian R Lu
- Biological Physics Group, School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK.
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9
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Liu H, Hu X, Li Z, Fa K, Gong H, Ma K, Liao M, Li P, Webster JRP, Petkov JT, Thomas RK, Ren Lu J. Surface adsorption and solution aggregation of a novel lauroyl-l-carnitine surfactant. J Colloid Interface Sci 2021; 591:106-114. [PMID: 33592522 DOI: 10.1016/j.jcis.2021.01.106] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Revised: 01/18/2021] [Accepted: 01/31/2021] [Indexed: 11/19/2022]
Abstract
HYPOTHESIS l-carnitine plays a crucial role in the cellular production of energy by transporting fatty acids into mitochondria. Acylated l-carnitines are amphiphilic and if appropriate physical properties were demonstrated, they could replace many currently used surfactants with improved biocompatibility and health benefits. EXPERIMENTS This work evaluated the surface adsorption of lauroyl-l-carnitine (C12LC) and its aggregation behavior. The size and shape of the aggregates of C12LC surfactant were studied at different temperatures, concentrations, pH and ionic strength by dynamic light scattering (DLS) and small-angle neutron scattering (SANS). Surface tension measurements were carried out to determine the critical micellar concentration (CMC) of C12LC. Combining with the Gibbs equation, the surface excess at different concentrations could be determined. Neutron reflection (NR) was used to determine the structure of the adsorbed layer at the air/water interface with the help of isotopic contrast variations. FINDINGS At pH 7, the limiting area per molecule (ACMC) of the zwitterionic C12LC adsorbed layer at the air/water interface was found to be 46 Å2 from surface tension and neutron reflection, smaller than the values of C12PC, C12E5, DTAB, C12C4betaine and C12C8betaine but close to that of SDS. A pronounced surface tension minimum at pH 2 at the low ionic strength was linked to a minimum value of area per molecule of about 30 Å2, indicating the competitive adsorption from traces of lauric acid produced by hydrolysis of C12LC. As the concentration increased, area per molecule reached a plateau of 37-39 Å2, indicating the dissolution of the more surface-active lauric acid into the micelles of C12LC. DLS and SANS showed that the size and shape of micelles had little response to temperature, concentration, ionic strength or pH. The SANS profiles measured under 3 isotopic contrasts could be well fitted by the core-shell model, giving a spherical core radius of 15.7 Å and a shell thickness of 10.5 Å. The decrease of pH led to more protonated carboxyl groups and more positively charged micelles, but the micellar structures remained unchanged, in spite of their stronger interaction. These features make C12LC potentially attractive as a solubilizing agent.
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Affiliation(s)
- Huayang Liu
- Biological Physics Laboratory, School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Xuzhi Hu
- Biological Physics Laboratory, School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Zongyi Li
- Biological Physics Laboratory, School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Ke Fa
- Biological Physics Laboratory, School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Haoning Gong
- Biological Physics Laboratory, School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Kun Ma
- ISIS Neutron Facility, Rutherford Appleton Laboratory, STFC, Chilton, Didcot, Oxon OX11 0QX, UK
| | - Mingrui Liao
- Biological Physics Laboratory, School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Peixun Li
- ISIS Neutron Facility, Rutherford Appleton Laboratory, STFC, Chilton, Didcot, Oxon OX11 0QX, UK
| | - John R P Webster
- ISIS Neutron Facility, Rutherford Appleton Laboratory, STFC, Chilton, Didcot, Oxon OX11 0QX, UK
| | - Jordan T Petkov
- Arch UK Biocides Ltd, Lonza, Hexagon Tower, Delaunays Road, Blackley, Manchester M9 8ZS, UK
| | - Robert K Thomas
- Physical and Theoretical Chemistry, University of Oxford, South Parks, Oxford OX1 3QZ, UK
| | - Jian Ren Lu
- Biological Physics Laboratory, School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK.
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10
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Shao Y, Jin X, Li C, Zheng Y. An effective non-equivalent ion exchange method for building an advanced Z-scheme WO 3/Bi 2WO 6 photocatalyst. NEW J CHEM 2021. [DOI: 10.1039/d1nj03770f] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
X-ray diffraction (XRD) patterns of (a) WO3, Bi2WO6 and (b) WBs composites.
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Affiliation(s)
- Yiliang Shao
- School of Petrochemical Engineering, Lanzhou University of Technology, Lanzhou 730050, P. R. China
| | - Xingzhi Jin
- School of Petrochemical Engineering, Lanzhou University of Technology, Lanzhou 730050, P. R. China
| | - Chunlei Li
- School of Petrochemical Engineering, Lanzhou University of Technology, Lanzhou 730050, P. R. China
| | - Yi Zheng
- School of Petrochemical Engineering, Lanzhou University of Technology, Lanzhou 730050, P. R. China
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11
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Hu X, Pambou E, Gong H, Liao M, Hollowell P, Liu H, Wang W, Bawn C, Cooper J, Campana M, Ma K, Li P, Webster JRP, Padia F, Bell G, Lu JR. How does substrate hydrophobicity affect the morphological features of reconstituted wax films and their interactions with nonionic surfactant and pesticide? J Colloid Interface Sci 2020; 575:245-253. [PMID: 32361410 DOI: 10.1016/j.jcis.2020.04.043] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 04/08/2020] [Accepted: 04/09/2020] [Indexed: 01/19/2023]
Abstract
HYPOTHESIS Surfactants are widely used in agri-sprays to improve pesticide efficiency, but the mechanism underlying their interactions with the surface wax film on plants remains poorly understood. To facilitate physical characterisations, we have reconstituted wheat cuticular wax films onto an optically flat silicon substrate with and without octadecyltrimethoxysilane modification to control surface hydrophobicity. EXPERIMENTS Imaging techniques including scanning electron microscopy (SEM) unravelled morphological features of the reconstituted wax films similar to those on leaves, showing little impact from the different substrates used. Neutron reflection (NR) established that reconstituted wax films were comprised of an underlying wax film decorated with top surface wax protrusions, a common feature irrespective of substrate hydrophobicity and highly consistent with what was observed from natural wax films. NR measurements, with the help of isotopic H/D substitutions to modify the scattering contributions of the wax and solvent, revealed different wax regimes within the wax films, illustrating the impact of surface hydrophilicity on the nanostructures within the wax films. FINDINGS It was observed from both spectroscopic ellipsometry and NR measurements that wax films formed on the hydrophobic substrate were more robust and durable against attack by nonionic surfactant C12E6 solubilised with pesticide Cyprodinil (CP) than films coated on the bare hydrophilic silica. Thus, the former could be a more feasible model for studying the wax-surfactant-pesticide interactions.
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Affiliation(s)
- Xuzhi Hu
- Biological Physics Group, School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Elias Pambou
- Biological Physics Group, School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Haoning Gong
- Biological Physics Group, School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Mingrui Liao
- Biological Physics Group, School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Peter Hollowell
- Biological Physics Group, School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Huayang Liu
- Biological Physics Group, School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Weimiao Wang
- Department of Materials and National Graphene Institute, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Carlo Bawn
- School of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Jos Cooper
- STFC ISIS Facility, Rutherford Appleton Laboratory, Didcot OX11 0QX, UK
| | - Mario Campana
- STFC ISIS Facility, Rutherford Appleton Laboratory, Didcot OX11 0QX, UK
| | - Kun Ma
- STFC ISIS Facility, Rutherford Appleton Laboratory, Didcot OX11 0QX, UK
| | - Peixun Li
- STFC ISIS Facility, Rutherford Appleton Laboratory, Didcot OX11 0QX, UK
| | - John R P Webster
- STFC ISIS Facility, Rutherford Appleton Laboratory, Didcot OX11 0QX, UK
| | - Faheem Padia
- Syngenta, Jealott's Hill International Research Centre, Bracknell, Berkshire RG42 6EY, UK
| | - Gordon Bell
- Syngenta, Jealott's Hill International Research Centre, Bracknell, Berkshire RG42 6EY, UK
| | - Jian R Lu
- Biological Physics Group, School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK.
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