Unraveling How Membrane Nanostructure Changes Impact the Eye Irritation of Nonionic Alkyl Ethoxylate Surfactants.

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, CE) 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.

Impacts of chain and head lengths of nonionic alkyl ethoxylate surfactants on cytotoxicity to human corneal and skin cells in agri-spraying processes.

Hypothesis: Nonionic surfactants are widely used as co-formulants in agrochemical sprays. During spraying, they may come into direct contact with humans and animals, causing irritation in different tissues. However, how the molecular structures of these surfactants affect their toxicity towards human eye and skin at the cellular level has not been well characterised.

Contrasting impacts of mixed nonionic surfactant micelles on plant growth in the delivery of fungicide and herbicide.

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.

What happens when pesticides are solubilised in binary ionic/zwitterionic-nonionic mixed micelles?

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 (CE), anionic sodium dodecylsulphate (SDS), cationic dodecyltrimethylammonium bromide (DTAB) and zwitterionic dodecylphosphocholine (CPC) as model adjuvant systems to solubilise 3 pesticides, Cyprodinil (CP), Azoxystrobin (AZ) and Difenoconazole (DF), representing different structural features.

How does substrate hydrophobicity affect the morphological features of reconstituted wax films and their interactions with nonionic surfactant and pesticide?

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.

How does solubilisation of plant waxes into nonionic surfactant micelles affect pesticide release?

Hypothesis: Nonionic surfactants are used as adjuvants in agri-sprays to stabilise pesticides, but what happens when pesticide-loaded micelles are brought into direct contact with plant leaves? As pesticide solubilisation dehydrates the micellar shell and increases the effective hydrophobicity of the surfactant, we hypothesise that these micelles would uptake plant waxes and alter the amount of pesticide solubilized as a result of the re-equilibrating process.

Experiments: The solubility of the pesticide cyprodinil (CP) and its effect on the shape of hexaethylene glycol monododecyl ether (CE) micelles were studied using changes in cloud point, nuclear magnetic resonance (NMR), cryogenic transmission electron microscopy (Cryo-TEM) and small-angle neutron scattering (SANS). Similarly, the solubility of wheat leaf waxes was examined, as was the effect of adding leaf waxes to pre-dissolved cyprodinil in micellar CE.

What happens when pesticides are solubilized in nonionic surfactant micelles.

Nonionic surfactants have been widely used in agri-sprays to enhance the solubility and mobility of pesticides, but what happens when pesticides become solubilized into surfactant micelles remains poorly characterized. To facilitate physical characterisations, we used the nonionic surfactant hexaethylene glycol monododecyl ether (CE) as a model system to solubilize 4 pesticides including Cyprodinil (CP), Diuron (DN), Azoxystrobin (AZ) and Difenoconazole (DF). The investigation focused on the influence of solubilizate and temperature in driving changes to the micellar nanostructures.

Influence of molecular structure on the size, shape, and nanostructure of nonionic C(n)E(m) surfactant micelles.

Nonionic alkyl ethoxylates (C(n)E(m)) have been extensively studied for their adsorption, aggregation, and solubilization individually and in small groups. In this work, we report a more systematic study of the effects of alkyl chain (tail) and ethoxylate (head) length on the size, shape, and extent of intermixing within the C(n)E(m) micelles in aqueous solution. Data from small angle neutron scattering (SANS) and nuclear magnetic resonance (NMR) were combined to undertake the structural characterization of micelles formed from the two separate series of surfactants C(n)E6 (n = 10, 12, 14) and C12E(m) (m = 5, 6, 8, 10, 12).

Thermoresponsive copolymer nanofilms for controlling cell adhesion, growth, and detachment.

This study reports the development and use of a novel thermoresponsive polymeric nanofilm for controlling cell adhesion and growth at 37 °C, and then cell detachment for cell recovery by subsequent temperature drop to the ambient temperature, without enzymatic cleavage or mechanical scraping. A copolymer, poly(N-isopropylacrylamide-co-hydroxypropyl methacrylate-co-3-(trimethoxysilyl)propyl methacrylate) (abbreviated PNIPAAm copolymer), was synthesized by free radical polymerization. The thermoresponses of the copolymer in aqueous solution were demonstrated by dynamic light scattering (DLS) through detecting the sensitive changes of copolymer aggregation against temperature.