Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Biocompatible microemulsions: formulation, encapsulation of bioactive compounds and their potential applications
Örebro University, School of Science and Technology.
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Place, publisher, year, edition, pages
Örebro: Örebro universitet , 2014. , 82 p.
Series
Örebro Studies in Chemistry, ISSN 1651-4270 ; 14
Keyword [en]
biocompatible microemulsions, encapsulation, pharmaceuticals, methylxanthine, agrochemicals, pyrethrinsfood, squalene, octyl gallate, gallic acid, EPR, DLS, SAXS
National Category
Chemical Sciences
Research subject
Chemistry
Identifiers
URN: urn:nbn:se:oru:diva-35059ISBN: 978-91-7529-029-4 (print)OAI: oai:DiVA.org:oru-35059DiVA: diva2:717555
Public defence
2014-06-09, Hörsalen, Musikhögskolan, Örebro universitet, Fakultetsgatan 1, 702 81, 09:00 (English)
Opponent
Supervisors
Available from: 2014-05-15 Created: 2014-05-15 Last updated: 2017-10-17Bibliographically approved
List of papers
1. Surfactant-rich biocompatible microemulsions as effective carriers of methylxanthine drugs
Open this publication in new window or tab >>Surfactant-rich biocompatible microemulsions as effective carriers of methylxanthine drugs
2014 (English)In: Colloids and Surfaces A: Physicochemical and Engineering Aspects, ISSN 0927-7757, E-ISSN 1873-4359, Vol. 442, 80-87 p.Article in journal (Refereed) Published
Abstract [en]

Under the perspective of their potential pharmaceutical applications, new surfactant-rich biocompatible microemulsions were prepared and structurally characterized to be used as novel carriers of theophylline and theobromine. The existence of single phase regions was investigated in pseudo-ternary phase diagrams of three different microemulsion systems: (1) isopropyl palmitate/Triton X-100/water + propylene glycol, (2) Miglyol 818/Triton X-100/water + propylene glycol and (3) isopropyl palmitate/Triton X-100 + Span 20/water + propylene glycol. Electrical conductivity measurements indicated the formation of water-in-oil (w/o) structures. Interfacial properties of the microemulsions were studied by electron paramagnetic resonance (EPR) spectroscopy employing the nitroxide spin probe 5-doxylstearic acid (5-DSA). The determined order parameter and wobbling angle showed that the system composition influences the membrane flexibility whereas drug incorporation resulted in more flexible membranes. Particle size measurements were performed using dynamic light scattering (DLS) showing that addition of the drugs resulted in the formulation of larger aqueous droplets. To evaluate the ability of the proposed microemulsions to serve as carriers of bioactive compounds for topical administration, in vitro permeation studies were carried out using the Franz type diffusion cells and a model membrane. The nature of the oil and the surfactant used for the construction of the microemulsions affected the phase behavior, the size and also the interfacial properties of both free and loaded systems. Drug permeation studies revealed the effectiveness of the proposed formulations as carriers of theophylline and theobromine. (C) 2013 Elsevier B.V. All rights reserved.

Keyword
microemulsions, drug carrier, dynamic light scattering, electron paramagnetic resonance, spectroscopy, theophylline, theobromine
National Category
Chemical Sciences
Research subject
Chemistry
Identifiers
urn:nbn:se:oru:diva-35079 (URN)10.1016/j.colsurfa.2013.05.055 (DOI)000331687000012 ()
Available from: 2014-05-19 Created: 2014-05-19 Last updated: 2017-12-05Bibliographically approved
2. Highly water dilutable microemulsions: a structural study
Open this publication in new window or tab >>Highly water dilutable microemulsions: a structural study
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Highly aqueous dilutable microemulsions based on biocompatible materials were developed and structurally investigated. Phase diagrams were constructed for systems consisting of non-ionic Tweens (20, 40 and blends of them), R-(+)-limonene, ethanol, water and propylene glycol. The obtained phase diagrams reveal the formation of fully aqueous dilutable microemulsions along certain dilution lines in the surfactant-rich region. Two phase transitions of the investigated systems were detected by conductivity measurements, from w/o to bicontinuous and to the o/w, without phase separation. Interfacial properties and the dynamic structure of the surfactant’s monolayer were studied by electron paramagnetic resonance spectroscopy. It was observed that the mobility of the spin probe and the rigidity of the membrane are affected by increasing aqueous content and by the type of surfactant. DLS measurements were performed in (o/w) microemulsions for different aqueous content, and oil droplet diameters in the range of 8.2 to 17.4 nm were observed.

Keyword
biocompatible microemulsions, limonene, tweens, epr, dls, electrical conductivity
National Category
Chemical Sciences
Research subject
Chemistry
Identifiers
urn:nbn:se:oru:diva-35080 (URN)
Available from: 2014-05-19 Created: 2014-05-19 Last updated: 2017-10-17Bibliographically approved
3. Biocompatible nanodispersions as delivery systems of food additives: a structural study
Open this publication in new window or tab >>Biocompatible nanodispersions as delivery systems of food additives: a structural study
Show others...
2013 (English)In: Food Research International, ISSN 0963-9969, E-ISSN 1873-7145, Vol. 54, no 2, 1448-1454 p.Article in journal (Refereed) Published
Abstract [en]

Nanodispersions based on food grade biocompatible materials were developed and structurally characterized to be used as carriers of bioactive compounds with specific nutritional value. The main idea was to formulate concentrated solutions of specific food components at the nanoscale to be consumed either on their own or as integrating parts of classic foods, upon aqueous dilution. For this purpose microemulsions consisting of (R)-(+)-limonene/ethanol/Tween 40/water/propylene glycol were formulated in the presence and in the absence of squalene, gallic acid and octyl gallate. The limits of the single-phase region as described by pseudo-ternary phase diagrams were related to the nature of the food additive. The more extended monophasic region was obtained when octyl gallate was added in the system. Interfacial properties of the microemulsions were studied by electron paramagnetic resonance (EPR) spectroscopy employing the nitroxide spin probe 5-doxylstearic acid (5-DSA). In general guest molecules decreased the flexibility of the surfactant monolayer as manifested from the calculation of rotational correlation time (T-R) and order parameter S of 5-DSA. Particle size measurements were performed using dynamic light scattering (DLS) and oil droplet diameters in the range of 11.7 to 17.4 nm were observed. The addition of squalene resulted in the formulation of larger oily droplets whereas octyl gallate formed smaller ones. Finally SAXS experiments provided qualitative information of o/w microemulsions showing squalene solubilization in the dispersed oily phase, octyl gallate localization on the membrane and gallic acid solubilization in the continuous aqueous phase. (C) 2013 Elsevier Ltd. All rights reserved.

Keyword
O/w microemulsions, Squalene, Gallic acid, EPR, DLS, SAXS
National Category
Natural Sciences
Research subject
Culinary Arts and Meal Science
Identifiers
urn:nbn:se:oru:diva-33759 (URN)10.1016/j.foodres.2013.08.010 (DOI)000329766300013 ()
Note

Funding Agencies:

Greek Secretary of Research Technology  

VIORYL SA, Greece 

STSM, COST, Action 

Available from: 2014-02-14 Created: 2014-02-14 Last updated: 2017-12-06Bibliographically approved
4. Biocompatible nanodispersions as potential formulations of natural pyrethrins: a structural and efficacy study
Open this publication in new window or tab >>Biocompatible nanodispersions as potential formulations of natural pyrethrins: a structural and efficacy study
Show others...
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Biocompatible nanodispersions of the micro- and nanoemulsion type based on lemon oil terpenes, polysorbates, water and glycerol were used for the formulation of pyrethrins, natural insecticides derived from the extract of chrysanthemum flower. The proposed pyrethrin containing water-in-oil (w/o) microemulsions could be diluted with aqueous phase to obtain kinetically stable oil-in-water (o/w) nanoemulsions ready to use in sprayers for plant protection. Structural characteristics of the micro- and nanoemulsions were evaluated by Electron Paramagnetic Resonance (EPR) spectroscopy, Dynamic Light Scattering (DLS), Small Angle X-Ray Scattering (SAXS) and electrical conductivity. Dynamic properties of the surfactants’ monolayer as evidenced by EPR measurements were affected by the water content, the nature of the surfactant and also the presence of the biocide in both w/o microemulsions and o/w nanoemulsions. DLS and SAXS experiments of the nanoemulsions indicated the existence of two populations of oil droplets dispersed in the aqueous phase, globular droplets of 36-37 nm in diameter and also larger droplets with diameters >150 nm. In addition, all the applied techniques for structural determination revealed participation of the biocide in the nanostructure. The insecticidal effect of the natural pyrethrin nanodispersions was evaluated in laboratory bioassays upon a target-insect pest, the cotton aphid Aphis gossypii Glover (Hemiptera: Aphididae) in eggplant and was found increased compared to the natural pyrethin emulsion. 

National Category
Chemical Sciences
Research subject
Chemistry
Identifiers
urn:nbn:se:oru:diva-35082 (URN)
Note

This work was financed by the Greek Secretary of Research &Technology and VIORYL SA, Greece, within the frame of the commonresearch project “Cooperation”, 09- ΣΥΝ -42-699 and the STSM,COST, Action CM 1101 scientific programme on Colloidal Aspects ofNanoscience for Innovative Processes and Materials.

Available from: 2014-05-19 Created: 2014-05-19 Last updated: 2017-10-17Bibliographically approved
5. Biocompatible nanodispersions as media for encapsulatingbioactive substances with phytoprotective activity
Open this publication in new window or tab >>Biocompatible nanodispersions as media for encapsulatingbioactive substances with phytoprotective activity
2013 (English)Patent (Other (popular science, discussion, etc.))
National Category
Chemical Sciences
Research subject
Chemistry
Identifiers
urn:nbn:se:oru:diva-35083 (URN)
Patent
OBI, 20130100305
Available from: 2014-05-19 Created: 2014-05-19 Last updated: 2017-10-17Bibliographically approved

Open Access in DiVA

Introductory chapter(13710 kB)55 downloads
File information
File name FULLTEXT02.pdfFile size 13710 kBChecksum SHA-512
54357437254a65ce964337cb8002e0a3a3f9c046bd8f2d28c31b55f0dac7bc74e7313776c027bc70d314834f82c961ab3b466290fb853df99a468bc493789179
Type fulltextMimetype application/pdf
Cover(126 kB)20 downloads
File information
File name COVER01.pdfFile size 126 kBChecksum SHA-512
36de24974be7855ff654ed10a2fde063355cee479629ccedebd6c83633d0296e332d67d238de8f000e92c8b13a7aa50b30e9d8ca0366aeeefc3e10929d9f1eb8
Type coverMimetype application/pdf
Spikblad(313 kB)8 downloads
File information
File name SPIKBLAD01.pdfFile size 313 kBChecksum SHA-512
62824e75067bbffef7b0db91138fbef32229a467a6bb6843ada0e701c7165ee1bf107be9f8b228d7d327e9c37761e35684b6eb52e35fe830c9b927cdcee6df13
Type spikbladMimetype application/pdf

By organisation
School of Science and Technology
Chemical Sciences

Search outside of DiVA

GoogleGoogle Scholar
Total: 55 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 265 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf