Experimental and theoretical approach to nonequivalent adsorption of novel dicephalic ammonium surfactants at the air/solution interface.
ABSTRACT The interfacial behavior of novel dicephalic cationic surfactants, N,N-bis[3,3'-(trimethylammonio)propyl]alkylamide dibromides and N,N-bis[3,3'-(trimethylammonio)propyl]alkylamide dimethylsulfates, was analyzed both experimentally and theoretically in comparison to their linear standards, 3-[(trimethylammonio)propyl]dodecanamide bromide and 3-[(trimethylammonio)propyl]dodecanamide methylsulfate. Adsorption of the studied double head-single tail surfactants depends strongly upon their structure, making them less surface active in comparison to the single head-single tail structures having the same alkyl chain length. Surface tension isotherms of aqueous solutions of the studied dicephalic derivatives were measured using the pendant drop shape analysis method and interpreted with the so-called surface quasi-two-dimensional electrolyte (STDE) model of ionic surfactant adsorption. The model is based on the assumption that the surfactant ions and counterions (bromide and methylsulfate ions in the studied case) undergo nonequivalent adsorption within the Stern layer, and it allows for accounting for the formation of surfactant ion-counterion associates in the case of multivalent surfactant headgroup ions. As a result, good agreement between theory and experiment was obtained. Additionally, the presence of surfactant-counterion complexes was successfully confirmed by both measurements of the concentration of free bromide ions in solution and molecular modeling simulations. The results of the present study may prove useful in the potential application of the investigated dicephalic cationic surfactants.
- SourceAvailable from: Michał Sowa[Show abstract] [Hide abstract]
ABSTRACT: The present study has been focused on determination and evaluation of three different preparation techniques i.e., solvent-diffusion, hot homogenization-ultrasonification and microemulsification, applied in fabrication of biocompatible phosphatidylcholine solid lipid nanoparticles ((PC)-SLNs), containing Polawax National Formulary (NF) in the internal lipid phase. The fabricated lipid nanoparticles were loaded with the newly synthesized flavonoid cocrystals i.e., baicalein-nicotinamide (1:1) (BaiNam), myricetin-piracetam (1:1) (MyrPac) and myricetin-caffeine (1:1) (MyrCaf) cocrystals in relation to the starting flavonoids, differing in solubility and physical state. The assessment of all studied drugs entrapment and availability in aqueous SLN dispersions has been carried out; the size along with size distribution of lipid nanoparticles loaded with the studied flavonoids cocrystals and flavonoids was determined by the DLS technique, while the structural changes–by FT-IR spectroscopy and X-Ray powder diffraction (XRPD) of the lipid nanomatrices. XRPD and FT-IR analyses confirmed that parent flavonoids as well as their cocrystals are present in the nanoparticles fabricated with solvent-diffusion method as physical mixtures with the lipid and their crystalline structures at least partially conserved. Summarizing, we designed and fabricated the biocompatible SLN-type nanocarriers of enhanced physical stability and availability for the flavonoids delivery - a vast group of naturally occurring polyphenolic compounds, considered as active pharmaceutical ingredients.Colloids and Surfaces A Physicochemical and Engineering Aspects 01/2014; · 2.11 Impact Factor
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ABSTRACT: There is great clinical interest in developing novel nanocarriers for hydrophobic cyanine dyes used as photosensitizing agents in photodynamic therapy (PDT). In the present study we have employed nanoemulsion-templated oil-core multilayer nanocapsules as robust nanocarriers for a cyanine-type photosensitizer IR-786. These nanoproducts were fabricated via layer-by-layer (LbL) adsorption of oppositely charged polyelectrolytes (PEs), i.e., anionic PSS and cationic PDADMAC on nanoemulsion liquid cores created by dicephalic or bulky saccharide-derived cationic surfactants. All nanocapsules, with different thicknesses of the PE shell and average size <200 nm (measured by DLS) demonstrated good capacity for IR-786 encapsulation. The nanocarriers were visualized by SEM and AFM and their photo-induced anticancer effect and cellular internalization in human breast carcinoma MCF-7/WT cells were determined. Biological response of the cell culture, expressed as dark and photocytotoxicity as well as fluorescence of drug molecules loaded in the multilayer vehicles, analyzed by the FACS and CLSM techniques, have indicated that the delivered IR-786 did not aggregate inside the cells and could, therefore, act as an effective third-generation photosensitizing agent. In vitro biological experiments demonstrated that the properties of studied nanostructures depended upon the PE type and the envelope thickness as well as on the surfactant architecture in the nanoemulsion-based templates employed for the nanocapsule fabrication. Similarity of results obtained for stored (three weeks in the dark at room temperature) and freshly-prepared nanocapsules, attests to viability of this stable, promising drug delivery system for poorly water-soluble cyanines useful in PDT.European journal of pharmaceutical sciences: official journal of the European Federation for Pharmaceutical Sciences 07/2012; 47(2):406-20. · 2.61 Impact Factor
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ABSTRACT: The colloidal and biological properties of the two single-chain surfactants N-benzyl-N,N-dimethyl-N-(1-dodecyl)ammonium bromide (PH12) and N-cyclohexylmethyl-N,N-dimethyl-N-(1-dodecyl)ammonium bromide (CH12) and their two dimeric counterparts N,N'-(1,3-phenylenebis(methylene))bis(N,N-dimethyl-N-(1-dodecyl)ammonium dibromide (12PH12) and N,N'-(cyclohexane-1,3-diylbis(methylene))bis(N,N-dimethyl-N-(1-dodecyl)ammonium dibromide (12CH12) were investigated. The thermodynamic functions of the self-aggregation process were estimated by using calorimetric measurements and the micellization enthalpy values, ΔHM, were examined considering the different enthalpic contributions to ΔHM. In the investigation of the structure-property relationship, it was found that the surfactant structure does not influence practically the foamability of the surfactants, but it plays a key role in their solubilization capacity, antimicrobial activity and biodegradability.Colloids and surfaces B: Biointerfaces 10/2013; 114C:247-254. · 3.55 Impact Factor