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Matthews L, Ruscigno S, Rogers SE, Bartlett P, Johnson AJ, Sochon R, Briscoe WH. Fracto-eutectogels: SDS fractal dendrites via counterion condensation in a deep eutectic solvent. Phys Chem Chem Phys 2021; 23:11672-11683. [PMID: 33978002 DOI: 10.1039/d1cp01370j] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Glyceline, a deep eutectic solvent comprising glycerol and choline chloride, is a green nonaqueous solvent with potential industrial applications. Molecular mechanisms of surfactant self-assembly in deep eutectic solvents are expected to differ from those in their constituent polar components and are not well understood. Here we report the observation of self-assembled SDS fractal dendrites with dimensions up to ∼mm in glyceline at SDS concentrations as low as cSDS ∼ 0.1 wt%. The prevalence of these dendritic fractal aggregates led to the formation of a gel phase at SDS concentrations above ≥1.9 wt% (the critical gelation concentration cCGC). The gel microscopic structure was visualised using polarised light microscopy (PLM); rheology measurements confirmed the formation of a colloidal gel, where the first normal stress difference was negative and the elastic modulus was dominant. Detailed nano-structural characterisation by small-angle neutron scattering (SANS) further confirmed the presence of fractal aggregates. Such SDS aggregation or gelation has not been observed in water at such low surfactant concentrations, whereas SDS has been reported to form lamellar aggregates in glycerol (a component of glyceline). We attribute the formation of the SDS fractal dendrites to the condensation of counterions (i.e. the choline ions) around the SDS aggregates - a diffusion-controlled process, leading to the aggregate morphology observed. These unprecedented results shed light on the molecular mechanisms of surfactant self-assembly in deep eutectic solvents, important to their application in industrial formulation.
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Affiliation(s)
- Lauren Matthews
- School of Chemistry, University of Bristol, Cantock's Close, Bristol, BS8 1TS, UK. and Bristol Centre for Functional Nanomaterials, HH Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, UK
| | - Silvia Ruscigno
- School of Chemistry, University of Bristol, Cantock's Close, Bristol, BS8 1TS, UK.
| | - Sarah E Rogers
- ISIS Muon and Neutron Source, Rutherford Appleton Laboratory, Harwell Oxford, Didcot, OX11 0QX, UK
| | - Paul Bartlett
- School of Chemistry, University of Bristol, Cantock's Close, Bristol, BS8 1TS, UK.
| | | | - Robert Sochon
- GlaxoSmithKline, St George's Avenue, Weybridge, KT13 0DE, UK
| | - Wuge H Briscoe
- School of Chemistry, University of Bristol, Cantock's Close, Bristol, BS8 1TS, UK.
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De Leo V, Milano F, Paiano A, Bramato R, Giotta L, Comparelli R, Ruscigno S, Agostiano A, Bucci C, Catucci L. Luminescent CdSe@ZnS nanocrystals embedded in liposomes: a cytotoxicity study in HeLa cells. Toxicol Res (Camb) 2017; 6:947-957. [PMID: 30090555 PMCID: PMC6062261 DOI: 10.1039/c7tx00172j] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Accepted: 09/14/2017] [Indexed: 11/21/2022] Open
Abstract
The use of fluorescent nanocrystals (NCs) as probes for bioimaging applications has emerged as an advantageous alternative to conventional organic fluorescent dyes. Therefore their toxicological evaluation and intracellular delivery are currently a primary field of research. In this work, hydrophobic and highly fluorescent CdSe@ZnS NCs were encapsulated into the lipid bilayer of liposomes by the micelle-to-vesicle transition (MVT) method. The obtained aqueous NC-liposome suspensions preserved the spectroscopic characteristics of the native NCs. A systematic study of the in vitro toxicological effect on HeLa cells of these red emitting NC-liposomes was then carried out and compared to that of empty liposomes. By using liposomes of different phospholipid composition, we evaluated the effect of the lipid carrier on the cytotoxicity towards HeLa cells. Surprisingly, a cell proliferation and death study along with the MTT test on HeLa cells treated with NC-liposomes have shown that the toxic effects of NCs, at concentrations up to 20 nM, are negligible compared to those of the lipid carrier, especially when this is constituted by the cationic phospholipid DOTAP. In particular, obtained data suggest that DOTAP has a dose- and time-dependent toxic effect on HeLa cells. In contrast, the addition of PEG to the liposomes does not alter significantly the viability of the cells. In addition, the ability of NC-liposomes to penetrate the HeLa cells was assessed by fluorescence and confocal microscopy investigation. Captured images show that NC-liposomes are internalized into cells through the endocytic pathway, enter early endosomes and reach lysosomes in 1 h. Interestingly, red emitting NCs co-localized with endosomes and were positioned at the limiting membrane of the organelles. The overall results suggest that the fluorescent system as a whole, NCs and their carrier, should be considered for the development of fully safe biological applications of CdSe@ZnS NCs, and provide essential indications to define the optimal experimental conditions to use the proposed system as an optical probe for future in vivo experiments.
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Affiliation(s)
- Vincenzo De Leo
- Chemistry Department , University of Bari "Aldo Moro" , Via Orabona 4 , 70125 Bari , Italy .
- CNR-IPCF , Institute for Chemical and Physical processes , Via Orabona 4 , 70125 Bari , Italy
| | - Francesco Milano
- CNR-IPCF , Institute for Chemical and Physical processes , Via Orabona 4 , 70125 Bari , Italy
| | - Aurora Paiano
- Department of Biological and Environmental Sciences and Technologies (DiSTeBA) , University of Salento , Via Provinciale Lecce-Monteroni n. 165 , 73100 Lecce , Italy .
| | - Roberta Bramato
- Department of Biological and Environmental Sciences and Technologies (DiSTeBA) , University of Salento , Via Provinciale Lecce-Monteroni n. 165 , 73100 Lecce , Italy .
| | - Livia Giotta
- Department of Biological and Environmental Sciences and Technologies (DiSTeBA) , University of Salento , Via Provinciale Lecce-Monteroni n. 165 , 73100 Lecce , Italy .
| | - Roberto Comparelli
- CNR-IPCF , Institute for Chemical and Physical processes , Via Orabona 4 , 70125 Bari , Italy
| | - Silvia Ruscigno
- Chemistry Department , University of Bari "Aldo Moro" , Via Orabona 4 , 70125 Bari , Italy .
| | - Angela Agostiano
- Chemistry Department , University of Bari "Aldo Moro" , Via Orabona 4 , 70125 Bari , Italy .
- CNR-IPCF , Institute for Chemical and Physical processes , Via Orabona 4 , 70125 Bari , Italy
| | - Cecilia Bucci
- Department of Biological and Environmental Sciences and Technologies (DiSTeBA) , University of Salento , Via Provinciale Lecce-Monteroni n. 165 , 73100 Lecce , Italy .
| | - Lucia Catucci
- Chemistry Department , University of Bari "Aldo Moro" , Via Orabona 4 , 70125 Bari , Italy .
- CNR-IPCF , Institute for Chemical and Physical processes , Via Orabona 4 , 70125 Bari , Italy
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