Engineering carbon encapsulated nanomagnets towards their use for magnetic fluid hyperthermia [Elektronische Ressource] / von Arthur Westphal Taylor

Arthur Weir

Sujets

• Gesundheit

Informations

• Publié par: technische_universitat_dresden
• Publié le: 01 janvier 2010
• Nombre de lectures: 32
• Langue: English
• Poids de l'ouvrage: 6 Mo

Extrait

Engineering Carbon Encapsulated Nanomagnets
towards Their Use for Magnetic Fluid Hyperthermia


DISSERTATION

Zur Erlangung des akademischen Grades

Doctor rerum naturalium
(Dr. rer. nat.)

vorgelegt

der Fakultät Mathematik und Naturwissenschaften
der Technischen Universität Dresden

von

M. Sc. Arthur Westphal Taylor

geboren am 10. Juni 1981 in Florianópolis, Brasilien

Eingereicht am 23. August 2010
Verteidigt am 17. Dezember 2010

Gutachter: Prof. Dr. Petra Schwille
Prof. Dr. Rüdiger Klingeler

Die Dissertation wurde in der Zeit von Juli 2007 bis
Juli 2010 im Labor der Klinik und Poliklinik für Urologie der Medizinischen Fakultät Carl
Gustav Carus und in dem Leibniz-Institut für Festkörper- und Werkstoffforschung
Dresden angefertigt. III

TABLE OF CONTENTS

TABLE OF CONTENTS.......................................................................................III
ABSTRACT............................................................................................................VII
1. INTRODUCTION ................................................................................................1
1.1 THE BIOLOGICAL AND CLINICAL FOUNDATIONS OF HYPERTHERMIA........................1
1.1.1 The Basis of Tumour Heat Sensitivity ...............................................................................1
1.1.2 Hyperthermia as an Enhancer of Radiotherapy and Chemotherapy.....................................4
1.1.3 Heat Dosage and Thermotolerance.....................................................................................5
1.1.4 An Overview of Heating Methods in Clinical Practice........................................................7
1.2 MAGNETICALLY MEDIATED HYPERTHERMIA..................................................................9
1.2.1 Thermoseeds and Nanoparticles for Magnetic Hyperthermia ...............................................9
1.2.2 Physical Principles of Magnetic Nanoparticle Heating ......................................................11
1.2.3 Clinical Limits of Magnetic Fluid Hyperthermia..............................................................15
1.3 NANOPARTICLES ENGINEERED FOR MAGNETIC FLUID HYPERTHERMIA.................16
1.4 OBJECTIVES .........................................................................................................................18
2. MATERIALS AND METHODS......................................................................... 21
2.1 CARBON ENCAPSULATED IRON NANOPARTICLES.........................................................21
2.2 METHODS FOR PHYSICAL CHARACTERISATION .............................................................21
2.2.1 Transmission Electron Microscopy ...................................................................................21
2.2.2 Raman Analyses.............................................................................................................21
2.2.3 X-Ray Diffraction...........................................................................................................22
2.2.4 Magnetic Measurements...................................................................................................22
2.2.5 Specific Absorption Rate..................................................................................................22
2.2.6 Surface Analysis..............................................................................................................23
2.3 SURFACE FUNCTIONALISATION........................................................................................24
2.3.1 Acidic Treatments ...........................................................................................................24
2.3.2 Chemical Conjugation via Diimide-activated Amidation ..................................................24
2.4 DRUG CONJUGATION AND PLATINUM MEASUREMENTS..............................................25
2.4.1 Aquation of Cisplatin .....................................................................................................25
2.4.2 Drug Loading and Release ..............................................................................................25 2.4.3 Quantification of Platinum ..............................................................................................26
2.5 CELL CULTURE AND BIOLOGICAL ASSAYS .....................................................................27
2.5.1 Cell Culture ....................................................................................................................27
2.5.2 Toxicity Studies...............................................................................................................28
2.5.3 Thermotherapy Studies ....................................................................................................29
2.5.4 Cell Cycle Measurement...................................................................................................30
2.5.5 Imaging Techniques .........................................................................................................31
3. FEASIBILITY STUDY OF TWO CARBON ENCAPSULATED IRON
NANOSTRUCTURES FOR MAGNETIC FLUID HYPERTHERMIA..............33
3.1 PHYSICAL PROPERTIES33
3.2 SPECIFIC ABSORPTION RATE ............................................................................................37
3.3 IRON RELEASE AND CYTOTOXICITY ...............................................................................38
3.4 IMPLICATIONS ON THE POTENTIAL USE FOR THERMOTHERAPY................................43
4. SURFACE FUNCTIONALISATION OF CARBON ENCAPSULATED
NANOSPHERES....................................................................................................45
4.1 EFFECT OF ACIDIC TREATMENTS ON MAGNETIC AND SURFACE PROPERTIES.........45
4.1.1 Assessment of Suitable Conditions for Surface Oxidation.................................................45
4.1.2 Optimisation of the Oxidation Treatments.......................................................................49
4.2 FUNCTIONALISATION VIA DIIMIDE-ACTIVATED-AMIDATION....................................52
4.3 FLUORESCENT LABELLING OF NANOMAGNETS ............................................................57
4.4 FLUORESCENT IMAGING OF NANOMAGNETS IN CELLS...............................................60
5. DRUG CONJUGATION: FEASIBILITY AND IN VITRO EFFECTS IN
COMBINATION WITH HYPERTHERMIA.......................................................65
5.1 EXPLORING CARBOXYLIC FUNCTIONALITIES FOR DRUG CONJUGATION.................65
5.2 IN VITRO EFFECTS OF THERMOTHERAPY USING DRUG LOADED IRON
NANOPARTICLES.......................................................................................................................71
5.3 RELATIONSHIP BETWEEN IN VITRO STUDIES AND CLINICAL CONDITIONS...............73
6. APPLICATION TO THREE-DIMENSIONAL TUMOUR MODELS ...........75
6.1 ESTABLISHMENT OF MULTICELLULAR TUMOUR SPHEROIDS.......................................75
6.2 EFFECTS OF THERMOTHERAPY ON THE METABOLIC ACTIVITY OF SPHEROIDS.......80
6.3 ETHERMOTHERAPY INDUCED WITH NANOMAGNETS ..............................82
7. CONCLUSIONS .................................................................................................87 V
LIST OF ABBREVIATIONS..................................................................................89
LIST OF PUBLICATIONS..................................................................................... 91
REFERENCES .......................................................................................................93 VII

ABSTRACT

Magnetic fluid hyperthermia is a potential therapy for achieving interstitial hyperthermia
and is currently under clinical trials. This approach is based on the instillation of magnetic
nanoparticles at the tumour site, which dissipate heat when exposed to an alternating
magnetic field. This procedure leads to a local increase of temperature and induction of
tumour death or regression. Nanoparticles of metallic iron are potential heating agents for
this therapy, but rely on the presence of a protecting coat that avoids reactions with their
environment. In this work, iron nanospheres and iron nanowires with a graphite coat are
explored for this purpose. From these two nanostructures, the nanospheres are shown to
have a greater potential in terms of heat dissipation. The graphite shell is further
investigated as an interface for conjugation with other molecules of relevance such as
drugs and fluorescent probes. The effect of acidic treatments on the magnetic and surface
properties of the nanospheres is systematically studied and a suitable method to generate
carboxylic functionalities on the nanoparticle surface alongside with a good preservation
of the magnetic properties is developed. These carboxylic groups are shown to work as a
bridge for conjugation with a model molecule, methylamine, as well as with a fluorescent
dye, allowing the detection of the nanoparticles in cells by means of optical methods. The
carboxylic functionalities are further explored for the conjugation with the anti-cancer
drug cisplatin, where the amount of drug loaded per particle is found to be dependent on
the density of free carboxylic groups.