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Dos Santos Silva Araújo L, Lazzara G, Chiappisi L. Thermoresponsive behavior of cyclodextrin inclusion complexes with weakly anionic alkyl ethoxy carboxylates. SOFT MATTER 2023; 19:1523-1530. [PMID: 36727568 DOI: 10.1039/d2sm01621d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
This study investigates the temperature responsive behavior of inclusion complexes formed by weakly anionic alkyl ethoxy carboxylates and α (αCD) and β-cyclodextrins (βCD). Small-angle neutron scattering (SANS) was performed to probe the structural behaviour at the 1-100 nanometer scale of the hierarchical assemblies at different temperatures. The phase transitions and thermodynamics were systematically monitored as a function of the degree of ionization of the surfactant by differential scanning calorimetry (DSC). Herein, we investigate the effect of the surfactant degree of ionization on the thermoresponsive properties of the inclusion complex supramolecular assemblies. Inclusion complexes formed with the ionized surfactant spontaneously assemble into multilayered structures, which soften with increasing temperature. We also found that the presence of charges is not only required to impart order to the supramolecular assemblies, but also induced in-plane crystallization of the inclusion complexes. Finally, the use of a weakly anionic surfactant allows us to probe the interplay between the charge density and temperature on the assembly of surfactant-cyclodextrin inclusion complexes. This study helps to improve the design of multi-responsive supramolecular systems based on cyclodextrins.
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Affiliation(s)
- Larissa Dos Santos Silva Araújo
- Dipartimento di Fisica e Chimica, Università degli Studi di Palermo, Viale delle Scienze pad 17, 90128, Palermo, Italy
- Institut Max von Laue-Paul Langevin, 71 avenue des Martyrs, 38042, Grenoble, France.
| | - Giuseppe Lazzara
- Dipartimento di Fisica e Chimica, Università degli Studi di Palermo, Viale delle Scienze pad 17, 90128, Palermo, Italy
| | - Leonardo Chiappisi
- Institut Max von Laue-Paul Langevin, 71 avenue des Martyrs, 38042, Grenoble, France.
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Dos Santos Silva Araújo L, Watson L, Traore DAK, Lazzara G, Chiappisi L. Hierarchical assembly of pH-responsive surfactant-cyclodextrin complexes. SOFT MATTER 2022; 18:6529-6537. [PMID: 35894255 DOI: 10.1039/d2sm00807f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
In this work, the inclusion complexes of alkyl ethoxy carboxylates with α-cyclodextrin (αCD) and β-cyclodextrin (βCD) were investigated. The thermodynamics of the complexation process was probed by isothermal titration calorimetry (ITC) and volumetry as a function of the degree of ionization of the surfactant. The complexation process was shown to be an enthalpically driven pH-independent process. For both types of cyclodextrins, the complexes were found to spontaneously self-assemble into highly-ordered supramolecular aggregates probed by small-angle neutron scattering and electron and optical microscopy. Herein, we report the formation of thin platelets for nonionized surfactant systems and equally spaced multilayered hollow cylinders for ionized systems in a hierarchical self-assembly process. In addition, the analysis allowed unveiling the effect of the number of ethylene oxides in the surfactants and the CD cavity size on the morphology of the aggregates. Finally, this study also highlights the importance of examining the tuning parameters' influence on the short and long-range interactions involved in the control of the assembly process.
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Affiliation(s)
- Larissa Dos Santos Silva Araújo
- Dipartimento di Fisica e Chimica, Università degli Studi di Palermo, Viale delle Scienze pad 17, 90128, Palermo, Italy
- Institut Max von Laue - Paul Langevin, 71 Avenue des Martyrs, 38042, Grenoble, France.
| | - Leah Watson
- Institut Max von Laue - Paul Langevin, 71 Avenue des Martyrs, 38042, Grenoble, France.
| | - Daouda A K Traore
- Institut Max von Laue - Paul Langevin, 71 Avenue des Martyrs, 38042, Grenoble, France.
- School of Life Sciences, Keele University, Staffordshire ST5 5BG, UK
| | - Giuseppe Lazzara
- Dipartimento di Fisica e Chimica, Università degli Studi di Palermo, Viale delle Scienze pad 17, 90128, Palermo, Italy
| | - Leonardo Chiappisi
- Institut Max von Laue - Paul Langevin, 71 Avenue des Martyrs, 38042, Grenoble, France.
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Dos Santos Silva Araújo L, Lazzara G, Chiappisi L. Cyclodextrin/surfactant inclusion complexes: An integrated view of their thermodynamic and structural properties. Adv Colloid Interface Sci 2021; 289:102375. [PMID: 33592397 DOI: 10.1016/j.cis.2021.102375] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Revised: 01/25/2021] [Accepted: 01/27/2021] [Indexed: 12/14/2022]
Abstract
Cyclodextrins (CDs) play an important role in self-assembly systems of amphiphiles. The structure of CDs provides distinguished physicochemical properties, including the ability to form host-guest complexes. The complexation affects the properties of guest molecules and can produce supramolecular aggregates with desirable characteristics for fundamental and practical applications. Surfactants are particularly attractive host molecules due to their wide variety, availability, responsiveness to different stimuli, and high relevance in different fields, e.g. medical, cosmetic, pharmaceutical, and food industries. The tendency of organization in higher-order supramolecular aggregates arises the interest in applying such versatile complexes in the development of novel materials. In this review, we provide a comprehensive overview of the thermodynamics aspects of surfactants and CDs inclusion complexes formation in aqueous environment, emphasizing the assessment of the interactions, thermodynamic driving forces, and structural aspects. Also, the most common analytical techniques used to gather deep insight into the aspects of CDs complexes are discussed and the perspectives for the surfactant-cyclodextrin complexes are pointed out.
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Affiliation(s)
- Larissa Dos Santos Silva Araújo
- Dipartimento di Fisica e Chimica, Università degli Studi di Palermo, Viale delle Scienze pad 17, 90128 Palermo, Italy; Institut Max von Laue - Paul Langevin, 71 avenue des Martyrs, 38042 Grenoble, France
| | - Giuseppe Lazzara
- Dipartimento di Fisica e Chimica, Università degli Studi di Palermo, Viale delle Scienze pad 17, 90128 Palermo, Italy.
| | - Leonardo Chiappisi
- Institut Max von Laue - Paul Langevin, 71 avenue des Martyrs, 38042 Grenoble, France.
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In Vitro Cytotoxicity and In Vivo Antitumor Efficacy of Tetrazolato-Bridged Dinuclear Platinum(II) Complexes with a Bulky Substituent at Tetrazole C5. INORGANICS 2019. [DOI: 10.3390/inorganics7010005] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Tetrazolato-bridged dinuclear platinum(II) complexes ([{cis-Pt(NH3)2}2(μ-OH)(μ-5-R-tetrazolato-N2,N3)]2+; tetrazolato-bridged complexes) are a promising source of next-generation platinum-based drugs. β-Cyclodextrin (β-CD) forms inclusion complexes with bulky organic compounds or substituents, changing their polarity and molecular dimensions. Here, we determined by 1H-NMR spectroscopy, the stability constants for inclusion complexes formed between β-CD and tetrazolato-bridged complexes with a bulky, lipophilic substituent at tetrazole C5 (complexes 1–3, phenyl, n-nonyl, and adamantyl substitution, respectively). We then determined the in vitro cytotoxicity and in vivo antitumor efficacy of complexes 1–3 against the Colon-26 colorectal cancer cell line in the absence or presence of equimolar β-CD. Compared with the platinum-based anticancer drug oxaliplatin (1R,2R-diaminocyclohexane)oxalatoplatinum(II)), complex 2 had similar cytotoxicity, complex 3 was moderately cytotoxic, and complex 1 was the least cytotoxic. The cytotoxicity of the complexes decreased in the presence of β-CD. When we examined the in vivo antitumor efficacy of complexes 1–3 (10 mg/kg) against homografted Colon-26 colorectal tumors in male BALB/c mice, they showed a relatively low tumor growth inhibition compared with oxaliplatin. However, in the presence of β-CD, complex 3 had higher in vivo antitumor efficacy than oxaliplatin, suggesting a new direction for future research into tetrazolato-bridged complexes with high in vivo antitumor activity.
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Hu X, Zou C. Pentaerythrityl tetra-β-cyclodextrin: Synthesis, characterization and application in multiple responses hydrogel. Colloids Surf A Physicochem Eng Asp 2017. [DOI: 10.1016/j.colsurfa.2017.06.023] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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Displacement of Drugs From Cyclodextrin Complexes by Bile Salts: A Suggestion of an Intestinal Drug-Solubilizing Capacity From an In Vitro Model. J Pharm Sci 2016; 105:2640-2647. [DOI: 10.1002/jps.24678] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Revised: 07/13/2015] [Accepted: 09/15/2015] [Indexed: 11/07/2022]
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Use of liquid crystals for imaging different inclusion abilities of α-cyclodextrin and β-cyclodextrin toward cetyltrimethyl ammonium bromide. Chem Phys Lett 2015. [DOI: 10.1016/j.cplett.2015.08.021] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Ghosh P, Das T, Maity A, Mondal S, Purkayastha P. Incorporation of Coumarin 6 in cyclodextrins: microcrystals to lamellar composites. RSC Adv 2015. [DOI: 10.1039/c4ra13706j] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Coumarin 6 precipitates in water as microcrystals resulting in a considerable loss in fluorescence yield that can be considerably revived using cyclodextrin.
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Affiliation(s)
- Prasun Ghosh
- Indian Institute of Science Education and Research (IISER) Kolkata
- Mohanpur Campus
- Mohanpur 741 246
- India
| | - Tarasankar Das
- Indian Institute of Science Education and Research (IISER) Kolkata
- Mohanpur Campus
- Mohanpur 741 246
- India
| | - Arnab Maity
- Indian Institute of Science Education and Research (IISER) Kolkata
- Mohanpur Campus
- Mohanpur 741 246
- India
| | - Somen Mondal
- Indian Institute of Science Education and Research (IISER) Kolkata
- Mohanpur Campus
- Mohanpur 741 246
- India
| | - Pradipta Purkayastha
- Indian Institute of Science Education and Research (IISER) Kolkata
- Mohanpur Campus
- Mohanpur 741 246
- India
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Tsianou M, Fajalia AI. Cyclodextrins and surfactants in aqueous solution above the critical micelle concentration: where are the cyclodextrins located? LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:13754-64. [PMID: 25126838 DOI: 10.1021/la5013999] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Cyclodextrins (CDs) are known to bind surfactant molecules below the surfactant critical micelle concentration (CMC); however, interactions of CDs with surfactant micelles (above the CMC) are not well understood. In particular, direct structural evidence of the location of CDs in the different subphases found in micellar solutions is lacking. We have utilized small-angle neutron scattering (SANS) with contrast matching to probe the localization of α-cyclodextrin (α-CD) and 2-hydroxypropyl-β-cyclodextrin (HPβ-CD) in sodium dodecyl sulfate (SDS) micelles in aqueous (D2O) solutions. SANS data from solutions containing either hydrogenated or deuterated surfactants were analyzed by considering three different scenarios pertaining to the localization of cyclodextrin, either all in solution or some in the micelle shell or some in the micelle core, and were simultaneously fitted using the core-shell prolate ellipsoid form factor and the Hansen-Hayter-based structure factor. The scenario that considered a fraction of CD to localize in the micelle core well described the SANS data from both hydrogenated and deuterated SDS-CD-D2O solutions, while the other two scenarios did not. Among the various structural and interaction parameters obtained from this analysis, it emerged that the micelle core consisted of up to ∼10% HPβ-CD or ∼16% α-CD with respect to the total number of molecules (surfactants and CDs) present in the micelle at 25 mM SDS, and up to 14% HPβ-CD or 28% α-CD at 50 mM SDS. This is the first study that provides direct evidence on the location of cyclodextrin in the core of surfactant micelles. An improved understanding of CD interactions with surfactants and lipids would enable better strategies for drug encapsulation and delivery with CDs.
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Affiliation(s)
- Marina Tsianou
- Department of Chemical & Biological Engineering, University at Buffalo, The State University of New York (SUNY) , Buffalo, New York 14260-4200, United States
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Benkő M, Király LA, Puskás S, Király Z. Complexation of β-cyclodextrin with a gemini surfactant studied by isothermal titration microcalorimetry and surface tensiometry. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:6756-6762. [PMID: 24846443 DOI: 10.1021/la501386j] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We report on the inclusion complex formation of β-cyclodextrin (βCD) with a cocogem surfactant (counterion-coupled gemini surfactant; (bis(4-(2-alkyl)benzenesulfonate)-Jeffamine salt, abbreviated as ABSJ), studied by isothermal titration calorimetry (ITC) and surface tension (SFT) measurements. We measured the critical micelle concentration (cmc) of ABSJ in water by the two experimental techniques in the temperature range 283-343 K, and determined the thermodynamic parameters of the complex formation directly by ITC and indirectly by the SFT. The stoichiometry (N), the binding constant (K), and the enthalpy of complexation were determined, and the Gibbs free energy and the entropy term were calculated from the experimental data. A novel method is presented for the determination of N and K by using surface tensiometry.
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Affiliation(s)
- Mária Benkő
- Department of Physical Chemistry and Materials Science, University of Szeged , Aradi Vt. 1, H-6720 Szeged, Hungary
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Silva OF, Correa NM, Silber JJ, de Rossi RH, Fernández MA. Supramolecular assemblies obtained by mixing different cyclodextrins and AOT or BHDC reverse micelles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:3354-3362. [PMID: 24597759 DOI: 10.1021/la404584q] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
In this contribution we show the effect of the surfactant polar head and the external solvent on the incorporation of different cyclodextrins (CDs) {α-CD, β-CD, γ-CD, decenylsuccinyl-β-CD (Mod-β-CD), and hydroxypropyl-β-CD (hp-β-CD)} in different reverse micelles (RMs) {benzene/sodium 1,4-bis(2-ethylhexyl) sulfosuccinate(AOT)/water, and benzene/benzyl-n-hexadecyldimethylammonium chloride (BHDC)/water} and compare them with previous results obtained in n-heptane/AOT/water RMs. To investigate the different systems, we have used UV-vis spectrophotometry, induced circular dichroism spectroscopy (ICD), and the achiral molecular probe methyl orange (MO). The results show dramatic differences changing the external solvent and the surfactant, which are explained by considering the differences in the RMs interface composition, the water-surfactant interaction, and the CDs' location in the different media investigated. None of the CDs were incorporated into the benzene/AOT/water RMs at any [H2O]/[surfactant] ratio studied (W0) whereas it was previously shown that Mod-β-CD and hp-β-CD could be included in n-heptane/AOT/water RMs. However, all of the CDs are incorporated in benzene/BHDC/water RMs at W0 > 10 and hp-β-CD is dissolved even at W0 = 0. Different from what was found in n-heptane/AOT RMs, in BHDC RMs MO showed ICD signals with two different CDs: Mod-β-CD and hp-β-CD. The results are explained by considering the known difference in the interfacial water structure for AOT and BHDC RMs and the electron-rich region on the secondary hydroxyl (wider side of the CDs), which helps to solubilize all CDs in BHDC. This study shows that chiral cyclodextrin could be available for a guest in an organic medium such as the RMs. Therefore we have created a potentially powerful nanoreactor with two different confined regions in the same aggregate: the polar core of the RMs and the chiral hydrophobic cavity of cyclodextrin.
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Affiliation(s)
- O Fernando Silva
- Instituto de Investigaciones en Físico-Química de Córdoba, INFIQC-CONICET, Facultad de Ciencias Químicas, Departamento de Química Orgánica, Universidad Nacional de Córdoba, Ciudad Universitaria , X5000HUA Córdoba, Argentina
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Valente AJM, Söderman O. The formation of host-guest complexes between surfactants and cyclodextrins. Adv Colloid Interface Sci 2014; 205:156-76. [PMID: 24011696 DOI: 10.1016/j.cis.2013.08.001] [Citation(s) in RCA: 133] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2013] [Revised: 08/01/2013] [Accepted: 08/01/2013] [Indexed: 11/15/2022]
Abstract
Cyclodextrins are able to act as host molecules in supramolecular chemistry with applications ranging from pharmaceutics to detergency. Among guest molecules surfactants play an important role with both fundamental and practical applications. The formation of cyclodextrin/surfactant host-guest compounds leads to an increase in the critical micelle concentration and in the solubility of surfactants. The possibility of changing the balance between several intermolecular forces, and thus allowing the study of, e.g., dehydration and steric hindrance effects upon association, makes surfactants ideal guest molecules for fundamental studies. Therefore, these systems allow for obtaining a deep insight into the host-guest association mechanism. In this paper, we review the influence on the thermodynamic properties of CD-surfactant association by highlighting the effect of different surfactant architectures (single tail, double-tailed, gemini and bolaform), with special emphasis on cationic surfactants. This is complemented with an assessment of the most common analytical techniques used to follow the association process. The applied methods for computation of the association stoichiometry and stability constants are also reviewed and discussed; this is an important point since there are significant discrepancies and scattered data for similar systems in the literature. In general, the surfactant-cyclodextrin association is treated without reference to the kinetics of the process. However, there are several examples where the kinetics of the process can be investigated, in particular those where volumes of the CD cavity and surfactant (either the tail or in special cases the head group) are similar in magnitude. This will also be critically reviewed.
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Affiliation(s)
- Artur J M Valente
- Department of Chemistry, University of Coimbra, 3004-535 Coimbra, Portugal.
| | - Olle Söderman
- Division of Physical Chemistry, Center for Chemistry and Chemical Engineering, Lund University, Lund, Sweden
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da Silva MA, Weinzaepfel E, Afifi H, Eriksson J, Grillo I, Valero M, Dreiss CA. Tuning the viscoelasticity of nonionic wormlike micelles with β-cyclodextrin derivatives: a highly discriminative process. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:7697-7708. [PMID: 23682968 DOI: 10.1021/la4015338] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We report the influence of five β-cyclodextrin (β-CD) derivatives, namely: randomly methylated β-cyclodextrin (MBCD), heptakis (2,6-di-O-methyl)-β-cyclodextrin (DIMEB), heptakis (2,3,6-tri-O-methyl)-β-cyclodextrin (TRIMEB), 2-hydroxyethyl-β-cyclodextrin (HEBCD) and 2-hydroxypropyl-β-cyclodextrin (HPBCD), on the self-assembly of mixtures of nonionic surfactants: polyoxyethylene cholesteryl ether (ChEO10) and monocaprylin (MCL). Mixtures of ChEO10/MCL in water form highly viscoelastic wormlike micelle solutions (WLM) over a range of concentrations; herein, the composition was fixed at 10 wt % ChEO10/3 wt % MCL. The addition of methylated β-CDs (MBCD, DIMEB, TRIMEB) induced a substantial disruption of the solid-like viscoelastic behavior, as shown from a loss of the Maxwell behavior, a large reduction in G' and G″ in oscillatory frequency-sweep measurements, and a drop of the viscosity. The disruption increased with the degree of substitution, following: MBCD < DIMEB < TRIMEB. Cryo-TEM images confirmed a loss of the WLM networks, revealing short rods and disc-like aggregates, which were corroborated by small-angle neutron scattering (SANS) measurements. Critical aggregation concentrations (CAC), measured by fluorescence spectroscopy, increased in the presence of DIMEB for both ChEO10 and MCL, suggesting the existence of interactions between methylated β-CDs and both surfactants involved in WLM formation. Instead, hydroxyl-β-CDs had a very different effect on the WLM. HPBCD only slightly reduced the solid-like behavior, without suppressing it. Quite remarkably, the addition of HEBCD reinforced the solid-like characteristics and increased the viscosity 10-fold. Cryo-TEM images confirmed the subsistence of WLM in ChEO10/MCL/HEBCD solutions, while SANS data revealed a slight elongation and thickening of the worms, and an increase of associated water molecules. CAC data showed that HPBCD had little effect on either surfactant, while HEBCD strongly affected the CAC of MCL and only slightly affected the ChEO10. For both DIMEB and HEBCD, time-resolved SANS measurements showed that morphology changes underlying these macroscopic changes occur in less than 100 ms.
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Affiliation(s)
- Marcelo A da Silva
- Institute of Pharmaceutical Science, King's College London, Franklin-Wilkins Building, 150 Stamford Street, London SE1 9NH, United Kingdom
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Liu X, Meng L. Chiral adsorption of phenylalanine by α-, β-cyclodextrin modified layered double hydroxides. KOREAN J CHEM ENG 2013. [DOI: 10.1007/s11814-012-0217-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Characterization of β-cyclodextrins and isosorbide diesters self-assemblies: Towards new renewable surfactants. Colloids Surf A Physicochem Eng Asp 2012. [DOI: 10.1016/j.colsurfa.2012.09.033] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Carlstedt J, Lundberg D, Dias RS, Lindman B. Condensation and decondensation of DNA by cationic surfactant, spermine, or cationic surfactant-cyclodextrin mixtures: macroscopic phase behavior, aggregate properties, and dissolution mechanisms. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:7976-7989. [PMID: 22546152 DOI: 10.1021/la300266h] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The macroscopic phase behavior and other physicochemical properties of dilute aqueous mixtures of DNA and the cationic surfactant hexadecyltrimethylammounium bromide (CTAB), DNA and the polyamine spermine, or DNA, CTAB, and (2-hydroxypropyl)-β-cyclodextrin (2HPβCD) were investigated. When DNA is mixed with CTAB we found, with increasing surfactant concentration, (1) free DNA coexisting with surfactant unimers, (2) free DNA coexisting with aggregates of condensed DNA and CTAB, (3) a miscibility gap where macroscopic phase separation is observed, and (4) positively overcharged aggregates of condensed DNA and CTAB. The presence of a clear solution beyond the miscibility gap cannot be ascribed to self-screening by the charges from the DNA and/or the surfactant; instead, hydrophobic interactions among the surfactants are instrumental for the observed behavior. It is difficult to judge whether the overcharged mixed aggregates represent an equilibrium situation or not. If the excess surfactant was not initially present, but added to a preformed precipitate, redissolution was, in consistency with previous reports, not observed; thus, kinetic effects have major influence on the behavior. Mixtures of DNA and spermine also displayed a miscibility gap; however, positively overcharged aggregates were not identified, and redissolution with excess spermine can be explained by electrostatics. When 2HPβCD was added to a DNA-CTAB precipitate, redissolution was observed, and when it was added to the overcharged aggregates, the behavior was essentially a reversal of that of the DNA-CTAB system. This is attributed to an effectively quantitative formation of 1:1 2HPβCD-surfactant inclusion complexes, which results in a gradual decrease in the concentration of effectively available surfactant with increasing 2HPβCD concentration.
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Affiliation(s)
- Jonas Carlstedt
- Physical Chemistry, Center for Chemistry and Chemical Engineering, Lund University, Lund, Sweden.
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Carlstedt J, Bilalov A, Olsson U. Aqueous phase behavior of polyelectrolytes with amphiphilic counterions modulated by cyclodextrin: the role of polyion flexibility. Phys Chem Chem Phys 2012; 14:9574-7. [DOI: 10.1039/c2cp41353a] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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