W/O Microemulsions as Dendrimer Nanocarriers: An EPR Study

Rokach, Shifra; Ottaviani, M. Francesca; Shames, Alexander I.; Nir, I.; Aserin, Abraham; Garti, Nissim

doi:10.1021/jp307616b

Cited by 16 publications

(6 citation statements)

References 46 publications

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“…When the film was formed, both the microviscosity and the order significantly increased because the structure became more organized because of gellan adhesion at the ME droplet surface. A similar effect was already found in previous studies dealing on interactions of ME with polymeric structures . The increased order and microviscosity of surfactant aggregates when interacting with the amphiphilic polymer in the film arise from the polymer-surfactant head interactions that squeeze the surfactants, leading to a more packed and ordered aggregate structure.…”

Section: Resultssupporting

confidence: 85%

“…A similar effect was already found in previous studies dealing on interactions of ME with polymeric structures. 38 The increased order and microviscosity of surfactant aggregates when interacting with the amphiphilic polymer in the film arise from the polymer-surfactant head interactions that squeeze the surfactants, leading to a more packed and ordered aggregate structure. After dissolution of the film, the microviscosity values decreased returning back to the values of the originally formed ME droplets (τ = 2.80 ns for the ME solution before and after film dissolution, instead of τ = 4.80 ns for the film).…”

Section: Resultsmentioning

confidence: 99%

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Structural Characterization of Reconstituted Bioactive-Loaded Nanodomains after Embedding in Films Using Electron Paramagnetic Resonance and Self-Diffusion Nuclear Magnetic Resonance Techniques

et al. 2019

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Pharmaceutical applications of microemulsions (MEs) as drug delivery vehicles are recently gaining scientific and practical interests. Most MEs are able to solubilize bioactive molecules, but, at present, they cannot guarantee either controlled release of the drugs or significant advantage in the bioavailability of the bioactives. This study proposes to incorporate the modified ME structures, or nanodomains, into a natural polymeric film, to be used as a stable and capacious reservoir of drug-loaded nanodomains. These nanodomainloaded films may release the nanodroplets along with the drug molecules in a slow and controlled way. Gellan gum, an anionic polysaccharide, was used in aqueous solution as the film former, and curcumin, hydrophobic polyphenol, served as the guest molecule in the loaded systems. Films were prepared by using empty and curcumin-loaded MEs. It is imperative to verify the persistence of the ME structure upon the dissolution of the film mimicking its behavior when in contact with a human physiological aqueous environment via reaching the cell membranes. For this purpose, the films were dissolved, and the reconstituted ME structure was compared with the ME structure before film formation. Characterization of these structures, before and after dissolution, was achieved using electron paramagnetic resonance (EPR) and self-diffusion nuclear magnetic resonance (SD-NMR) techniques. Specific spin probes were inserted in the system, and a computer-aided analysis of the EPR spectra was performed to provide information on nanodomain microstructure assemblies. In addition, the SD-NMR profile of each component was analyzed to extract information on the diffusivity of the ME components before film formation and after ME reconstitution. The EPR and SD-NMR results were in good agreement to each other. The most important finding was that, after film dissolution, the ME nanodomains were reversibly and spontaneously reformed. It was also found that the film did not perturb the ME-nanodomain structure embedded in it. The film remained transparent and the bioactive curcumin was easily solubilized into the ME-droplet/water interface even after film dissolution. The combined techniques confirmed that the film constituted by bioactive-loaded MEs can serve as novel drug delivery vehicles.

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Section: Resultssupporting

confidence: 85%

Section: Resultsmentioning

confidence: 99%

Structural Characterization of Reconstituted Bioactive-Loaded Nanodomains after Embedding in Films Using Electron Paramagnetic Resonance and Self-Diffusion Nuclear Magnetic Resonance Techniques

et al. 2019

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“…The location of 5-DSA in the interface of empty and PPI-G2-loaded MEs is schematically illustrated in Figure . Opposite results were obtained when PPI-G2 was added to AOT-based MEs . The interaction of PC with PPI-G2, in PC-based MEs, prevents the probe from penetrating and locating near the surfactant’s polar heads.…”

Section: Resultsmentioning

confidence: 95%

“…Opposite results were obtained when PPI-G2 was added to AOT-based MEs. 66 The interaction of PC with PPI-G2, in PC-based MEs, prevents the probe from penetrating and locating near the surfactant's polar heads. Furthermore, as discussed in Section 3.2, increasing PPI-G2 concentration attracts more water molecules at the expense of PC and butanol headgroups' hydration; thus the hydrophobic probe is pushed more inside the lipid layer and the micropolarity is lower.…”

Section: Me At Increasing Ppi-g2 Concentrations Figure 6bmentioning

confidence: 99%

Behavior of PPI-G2 Dendrimer in a Microemulsion

et al. 2017

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Dendrimer nanostructures are of eminent interest in biomedical applications because of their uniform and well-defined molecular size and shape, and their ability to cross cell membranes and reduce the risk of premature clearance from the human body. Dendrimers perform as gene and drug carriers and have also shown significant therapeutic properties for treating cancer and neurodegenerative diseases. A complex drug delivery system, based on a dendrimer solubilized in the aqueous core of a water-in-oil (W/O) microemulsion (ME) along with the drug may combine the advantages of both dendrimers and MEs to provide better control of drug release. We propose a new microemulsion composed of drug-permitted surfactants and dendrimer that can be used as a potential controlled drug delivery nanosystem. The influence of second generation poly(propyleneimine) (PPI-G2) dendrimer; solubilized in (W/O) ME with a capacity of up to 25 wt% PPI-G2 at various pHs; and their interactions with the surfactant phosphatidylcholine (PC), cosurfactant (butanol), and water was studied. SAXS and EPR measurements indicated that increasing PPI-G2 concentration reduces droplet curvature and increases droplet size thus increasing macro-(SAXS) and micro-(EPR) order degree. Furthermore, SD-NMR and ATR-FTIR show stronger interactions between PPI-G2 and water molecules at the expense of PC and butanol headgroups hydration, which increases microviscosity (EPR). PPI-G2's effect is somewhat opposite to the increasing water phase effect, thus reducing the amount of free water (DSC) and slowing the mobility of all ME components (SD-NMR).

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“…Among the available tools for studying nanoparticle–cell interactions, electron paramagnetic resonance (EPR) spectroscopy has excelled in providing on-site structural and dynamical information. The spin-probe/spin-label-based EPR technique has already been demonstrated to be a powerful tool in characterizing the interactions of dendrimers with model membranes and cells [10,13,14,15,16,17,18,19,20,21,22,23,24], and has even been used in living systems [25]. Importantly, EPR spectroscopy shares many of the features of magnetic resonance imaging (MRI), including the underlying principles, and exhibits superior detection sensitivity.…”

Section: Introductionmentioning

confidence: 99%

Exploring the Interactions of Ruthenium (II) Carbosilane Metallodendrimers and Precursors with Model Cell Membranes through a Dual Spin-Label Spin-Probe Technique Using EPR

et al. 2019

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Dendrimers exhibit unique interactions with cell membranes, arising from their nanometric size and high surface area. To a great extent, these interactions define their biological activity and can be reported in situ by spin-labelling techniques. Schiff-base carbosilane ruthenium (II) metallodendrimers are promising antitumor agents with a mechanism of action yet to explore. In order to study their in situ interactions with model cell membranes occurring at a molecular level, namely cetyltrimethylammonium bromide micelles (CTAB) and lecithin liposomes (LEC), electron paramagnetic resonance (EPR) was selected. Both a spin probe, 4-(N,N-dimethyl-N-dodecyl)ammonium-2,2,6,6-tetramethylpiperidine-1-oxyl bromide (CAT12), able to enter the model membranes, and a spin label, 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) covalently attached at newly synthesized heterofunctional dendrimers, were used to provide complementary information on the dendrimer–membrane interactions. The computer-aided EPR analysis demonstrated a good agreement between the results obtained for the spin probe and spin label experiments. Both points of view suggested the partial insertion of the dendrimer surface groups into the surfactant aggregates, mainly CTAB micelles, and the occurrence of both polar and hydrophobic interactions, while dendrimer–LEC interactions involved more polar interactions between surface groups. We found out that subtle changes in the dendrimer structure greatly modified their interacting abilities and, subsequently, their anticancer activity.

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W/O Microemulsions as Dendrimer Nanocarriers: An EPR Study

Cited by 16 publications

References 46 publications

Structural Characterization of Reconstituted Bioactive-Loaded Nanodomains after Embedding in Films Using Electron Paramagnetic Resonance and Self-Diffusion Nuclear Magnetic Resonance Techniques

Structural Characterization of Reconstituted Bioactive-Loaded Nanodomains after Embedding in Films Using Electron Paramagnetic Resonance and Self-Diffusion Nuclear Magnetic Resonance Techniques

Behavior of PPI-G2 Dendrimer in a Microemulsion

Exploring the Interactions of Ruthenium (II) Carbosilane Metallodendrimers and Precursors with Model Cell Membranes through a Dual Spin-Label Spin-Probe Technique Using EPR

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