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Magnetic nanostructured materials for advanced bio-applications
KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
2008 (English)Licentiate thesis, comprehensive summary (Other scientific)
Abstract [en]

In the recent years, nanostructured magnetic materials and their use in biomedical and biotechnological applications have received a lot of attention. In this thesis, we developed tailored magnetic nanoparticles for advanced bio-applications, such as direct detection of antibodies in biological samples and stimuli responsive drug delivery system.

For sensitive and selective detection of biomolecules, thermally blocked iron oxide nanoparticles with specific magnetic properties are synthesized by thermal hydrolysis to achieve a narrow size distribution just above the superparamagnetic limit.  The prepared nanoparticles were characterized and functionalized with biomolecules for use in a successful biosensor system. We have demonstrated the applicability of this type of nanoparticles for the detection of Brucella antibodies as model compound in serum samples and very low detection limits were achieved (0.05 mg/mL).

The second part is concerning an in-depth investigation of the evolution of the thermally blocked magnetic nanoparticles. In this study, the formation of the nanoparticles at different stages during the synthesis was investigated by high resolution electron microscopy and correlated to their magnetic properties.  At early stage of the high temperature synthesis, small nuclei of 3.5 nm are formed and the particles size increases successively until they reach a size of 17-20 nm. The small particles first exhibit superparamagnetic behavior at the early stage of synthesis and then transform to thermally blocked behavior as their size increases and passes the superparamagnetic limit.

The last section of the Thesis is related to the development of novel drug delivery system based on magnetically controlled release rate. The system consists of hydrogel of Pluronic FP127 incorporating superparamagnetic iron oxide nanoparticles to form a ferrogel. The sol to gel formation of the hydrogel could be tailored to be solid at body temperature and thus have the ability to be injected inside living biological tissues.

In order to evaluate the drug loading and release, the hydrophobic drug indomethacin was selected as a model compound. The drug could be loaded in the ferrogel owning to the oil in water micellar structure. We have studied the release rate from the ferrogel in the absence and presence of magnetic field. We have demonstrated that the drug release rate can be significantly enhanced by use of external magnetic field decreasing the half time of the release to more than 50% (from 3200 to 1500 min) upon the application of the external magnetic field.

This makes the developed ferrogel a very promising drug delivery system that does not require surgical implant procedure for medical treatment and gives the possibility of enhancing the rate of release by external magnetic field.

Place, publisher, year, edition, pages
Stockholm: KTH , 2008. , vii, 59 p.
Series
Trita-ICT/MAP AVH, ISSN 1653-7610 ; 2008:15
National Category
Materials Chemistry
Identifiers
URN: urn:nbn:se:kth:diva-9569ISBN: 978-91-7415-184-8 (print)OAI: oai:DiVA.org:kth-9569DiVA: diva2:117509
Presentation
2008-12-08, N1, KTH-Electrum 3, Isafjordsgatan 28 A/D, Kista, 14:00 (English)
Opponent
Supervisors
Note
QC 20101110Available from: 2008-11-21 Created: 2008-11-14 Last updated: 2010-11-10Bibliographically approved
List of papers
1. Tailored Magnetic Nanoparticles for Direct and Sensitive Detection of Biomolecules in Biological Samples
Open this publication in new window or tab >>Tailored Magnetic Nanoparticles for Direct and Sensitive Detection of Biomolecules in Biological Samples
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2008 (English)In: Nano letters (Print), ISSN 1530-6984, E-ISSN 1530-6992, Vol. 8, no 10, 3423-3428 p.Article in journal (Refereed) Published
Abstract [en]

We developed nanoparticles with tailored magnetic properties for sensitive detection of biomolecules directly in biological samples in a single step. Thermally blocked nanoparticles obtained by thermal hydrolysis are mixed with sample solutions and the variation of the magnetic relaxation due to surface binding is used to detect the presence of biomolecules. The binding events significantly increase the hydrodynamic volume of nanoparticles, thus changing their Brownian relaxation frequency which is measured by a specifically developed AC-susceptometer.

The system was tested for the presence of Brucella antibodies in serum samples from infected cows and the surface of the nanoparticles was functionalized with lipopolysaccarides (LPS) from Brucella abortus. The hydrodynamic volume of functionalized particles increased by 25-35% as a result of the binding of the antibodies, as measured by changes in the susceptibility in an alternating magnetic field. The method has shown high sensitivity, with detection limit of 7 nmol·L-1 in serum without any pre-treatment of the biological samples.

The detection method is very sensitive, cost-efficient and versatile, giving a direct indication if the animal is infected or not, making it suitable for point-of care applications. The functionalization of tailored magnetic nanoparticles can be modified to suit numerous homogenous assays for a wide range of applications.

Keyword
BRUCELLA-ABORTUS, RELAXATION, ANTIBODIES, PARTICLES
National Category
Natural Sciences
Identifiers
urn:nbn:se:kth:diva-9231 (URN)10.1021/nl8022498 (DOI)000259906800064 ()2-s2.0-56149116406 (Scopus ID)
Note

QC 20101001

Available from: 2008-10-10 Created: 2008-10-10 Last updated: 2017-12-11Bibliographically approved
2. Evolution of Structural and Magnetic Properties of Magnetite Nanoparticles for Biomedical Applications
Open this publication in new window or tab >>Evolution of Structural and Magnetic Properties of Magnetite Nanoparticles for Biomedical Applications
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2010 (English)In: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 10, no 5, 2278-2284 p.Article in journal (Refereed) Published
Abstract [en]

We have investigated the evolution of microstructure and magnetic properties of thermally blocked magnetite nanoparticles, aimed for immunoassay applications, during their synthesis. High-resolution transmission electron microscopy (HRTEM) investigations of the size, size distribution, morphology, and crystal structure of particles reveal that particles at an early stage of the reaction process are either single crystals or polycrystals containing planar faults and they grow via a combination of reactant (monomer) consumption and oriented attachment at specific crystallographic surfaces because of the strong dipolar character of the < 111 > surfaces of magnetite. At a later stage of the synthesis reaction, the magnetic attraction strives to align contacting particles with their < 111 > axis of easy magnetization in parallel and this may also be an active driving force for crystal growth. At latter stages, the crystal growth is dominated by Ostwald ripening leading to smoother crystalline particles with a mean diameter of 16.7 +/- 3.5 nm and a narrow size distribution. The magnetic properties of the particles measured using static and dynamic magnetic fields are consistent with the evolution of particle size and structure and show the transition from superparamagnetic to thermally blocked behavior needed for magnetic relaxation-based immunoassay applications.

Keyword
IMPERFECT ORIENTED ATTACHMENT, MAGNETOTACTIC BACTERIA, NANOCRYSTALLINE ZNS, DEFECT GENERATION, GROWTH-KINETICS, CRYSTAL-GROWTH, PARTICLES, ORGANIZATION, ACCRETION, DYNAMICS
National Category
Materials Chemistry
Identifiers
urn:nbn:se:kth:diva-9567 (URN)10.1021/cg901602w (DOI)000277273900040 ()2-s2.0-77952053462 (Scopus ID)
Note
QC 20101110 Uppdaterad från manuskript till artikel (20101110).Available from: 2008-11-14 Created: 2008-11-14 Last updated: 2017-12-14Bibliographically approved
3. Injectable Superparamagnetic Ferrogels for Controlled Release of Hydrophobic Drugs
Open this publication in new window or tab >>Injectable Superparamagnetic Ferrogels for Controlled Release of Hydrophobic Drugs
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2009 (English)In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 21, no 13, 1354-1357 p.Article in journal (Refereed) Published
Abstract [en]

A ferrogel for magnetically controlled release of drugs is prepared by integration of superparamagnetic iron oxide nanoparticles and Pluronic F127 gels. The hydrophobic drug indomethacin is loaded in the ferrogel owing to the oil-in-water micellar structure. The characteristic solgel transition property renders the ferrogel an injectable drug carrier that will be, in principle, free from surgical implant procedure.

Keyword
BLOCK-COPOLYMER SOLUTIONS, PLURONIC F-127 GELS, MAGNETIC NANOPARTICLES, AQUEOUS-SOLUTION, IN-VITRO, BEHAVIOR, DELIVERY, HYDROGELS, SOLUBILIZATION, NANOCRYSTALS
National Category
Materials Chemistry
Identifiers
urn:nbn:se:kth:diva-12104 (URN)10.1002/adma.200800764 (DOI)000265432700008 ()2-s2.0-66149153430 (Scopus ID)
Note
QC 20100722Available from: 2010-03-04 Created: 2010-03-04 Last updated: 2017-12-12Bibliographically approved

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