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- Wadsäter, Maria, et al.
(författare)
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Structural effects of the dispersing agent polysorbate 80 on liquid crystalline nanoparticles of soy phosphatidylcholine and glycerol dioleate
- 2015
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Ingår i: Soft Matter. - : Royal Society of Chemistry. - 1744-683X .- 1744-6848. ; 11:6, s. 1140-1150
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Tidskriftsartikel (refereegranskat)abstract
- Well-defined, stable and highly structured I-2 (Fd (3) over barm) liquid crystalline nanoparticles (LCNP) of 50/50 (wt/wt) soy phosphatidylcholine (SPC)/glycerol dioleate (GDO), can be formed by using a low fraction (5-10 wt%) of the dispersing polymeric surfactant polyoxyethylene (20) sorbitan monooleate (polysorbate 80 or P80). In the present study we used small angle neutron scattering (SANS) and deuterated P80 (d-P80) to determine the location and concentration of P80 within the LCNP and small angle X-ray scattering (SAXS) to reveal the internal structure. SANS data suggests that some d-P80 already penetrates the particle core at 5%. However, the content of d-P80 is still low enough not to significantly change the internal Fd (3) over barm structure of the LCNP. At higher fractions of P80 a phase separation occurs, in which a SPC and P80 rich phase is formed at the particle surface. The surface layer becomes gradually richer in both solvent and d-P80 when the surfactant concentration is increased from 5 to 15%, while the core of the particle is enriched by GDO, resulting in loss of internal structure and reduced hydration. We have used neutron reflectometry to reveal the location of the stabiliser within the adsorbed layer on an anionic silica and cationic (aminopropyltriethoxysilane (APTES) silanized) surface. d-P80 is enriched closest to the supporting surface and slightly more so for the cationic APTES surface. The results are relevant not only for the capability of LCNPs as drug delivery vehicles but also as means of preparing functional surface coatings.
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| 2. |
- Yanez, Marianna, et al.
(författare)
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On the formation of dendrimer/nucleolipids surface films for directed self-assembly.
- 2015
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Ingår i: Soft Matter. - : Royal Society of Chemistry (RSC). - 1744-6848 .- 1744-683X. ; 11:10, s. 1973-1990
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Tidskriftsartikel (refereegranskat)abstract
- We describe the formation and structure of nucleolipid/dendrimer multilayer films controlled by non-covalent interactions to obtain biomaterials that exhibit molecular recognition of nucleic acids. Layers of cationic poly(amidoamine) (PAMAM) dendrimers of generation 4 and the anionic nucleolipids 1,2-dilauroyl-sn-glycero-3-phosphatidylnucleosides (DLPNs) based on uridine (DLPU) and adenosine (DLPA) were first formed at the silica-water interface. The PAMAM/DLPN layers were then exposed to short oligonucleotides, polynucleotides and single stranded DNA (ssDNA). The interfacial properties were characterized using quartz crystal microbalance with dissipation monitoring, attenuated total reflection Fourier transform infrared spectroscopy and neutron reflectometry. Both types of DLPN were found to adsorb as aggregates to preadsorbed PAMAM monolayers with a similar interfacial structure and composition before rinsing with pure aqueous solution. Nucleic acids were found to interact with PAMAM/DLPA layers due to base pairing interactions, while the PAMAM/DLPU layers did not have the same capability. This was attributed to the structure of the DLPA layer, which is formed by aggregates that extend from the interface towards the bulk after rinsing with pure solvent, while the DLPU layer forms compact structures. In complementary experiments using a different protocol, premixed PAMAM/DLPN samples adsorbed to hydrophilic silica only when the mixtures contained positively charged aggregates, which is rationalized in terms of electrostatic forces. The PAMAM/DLPA layers formed from the adsorption of these mixtures also bind ssDNA although in this case the adsorption is mediated by the opposite charges of the film and the nucleic acid rather than specific base pairing. The observed molecular recognition of nucleic acids by dendrimers functionalized via non-covalent interactions with nucleolipids is discussed in terms of biomedical applications such as gene vectors and biosensors.
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