Preface ...................................................... XVII
List of Contributors .......................................... XXI
Part One Biosensing and Diagnosis .............................. 7
1 Nanomaterials-Based Magnetic Relaxation Switch Biosensors .... 3
Tom Lowery
1.1 Introduction ............................................ 3
1.2 Superparamagnetic Nanoparticles ......................... 4
1.3 Agglomeration-Based Sensing ............................. 6
1.4 T2 Sensitivity of MRSW Particles ........................ 8
1.4.1 Fundamentals of T2 Relaxation .................... 8
1.4.2 Detecting T2 Relaxation ......................... 11
1.4.3 Theoretical Model for T2 and Nanoparticle
Size ............................................ 14
1.5 Kinetics of Magnetic Relaxation Switch Biosensors ...... 18
1.6 Demonstrations of Magnetic Relaxation Switch
Biosensors ............................................. 20
1.6.1 Detecting Nucleic Acids ......................... 21
1.6.2 Detecting Proteins .............................. 24
1.6.3 Detecting Enzymes ............................... 25
1.6.4 Detecting Viruses ............................... 29
1.6.5 Detecting Small Molecules ....................... 30
1.6.6 Detecting Ions .................................. 32
1.6.7 Detecting Cells ................................. 34
1.7 Methods Development .................................... 36
1.7.1 Reagent Synthesis, Preparation, and
Characterization ................................ 36
1.7.2 Measurement and Sensitivity Enhancement
Methods ......................................... 38
1.8 Micro-NMR of Magnetic Relaxation Switch Biosensors ..... 42
Acknowledgments ........................................ 46
References ............................................. 47
2 Multiplexed Detection with Magnetic Nanoparticles ........... 55
Robert Wilson
2.1 Introduction ........................................... 55
2.2 Magnetism and Magnetic Particles ....................... 56
2.2.1 Separating and Mixing Magnetic Particles ........ 58
2.3 Planar Arrays .......................................... 58
2.4 Rotating Discs ......................................... 63
2.5 Diagnostic Devices ..................................... 64
2.6 Bio-Barcode Assays Based on Magnetic Microspheres ...... 66
2.7 Spectrally Encoded Suspension Arrays of Magnetic
Microspheres ........................................... 66
2.7.1 Magnetically Encoded Suspension Arrays .......... 70
2.8 Summary and Conclusions ................................ 72
References ............................................. 72
3 Magnetophoretic Biosensing and Separation Using Magnetic
Nanomaterials ............................................... 77
Joo H. Kang, Young Ki Hahn, Kyu Sung Kim, and Je-Kyun Park
3.1 Introduction ........................................... 77
3.2 Theory ................................................. 79
3.2.1 Magnetic Properties of a Material ............... 79
3.2.2 Magnetophoresis ................................. 80
3.2.3 High-Gradient Magnetic Separation ............... 81
3.3 Magnetophoresis in Microfluidic Devices ................ 83
3.3.1 Design and Microfabrication Processes ........... 83
3.3.2 Experimental Set-Up ............................. 85
3.3.3 Measurement and Analysis ........................ 88
3.4 Magnetophoretic Biosensing ............................. 88
3.4.1 Magnetophoretic Sandwich Immunoassay ............ 89
3.4.2 Highly Sensitive Biosensors Using HGMS .......... 92
3.4.3 Disease Diagnosis Using Magnetophoretic Assay
Systems ......................................... 93
3.4.4 Multiplexed Magnetophoretic Immunoassay ......... 97
3.5 Magnetophoretic Separation ............................ 102
3.5.1 Cell Separation and Analysis ................... 102
3.5.2 Separation of Nanomaterials .................... 104
3.5.3 Isomagnetophoresis (IMP) ....................... 107
3.6 Concluding Remarks .................................... 111
Acknowledgments ....................................... 112
References ............................................ 112
4 Magnetic Nanomaterials as MRI Contrast Agents .............. 779
Yurii К. Gun'ко and Dermot F. Brougham
4.1 Introduction .......................................... 119
4.2 Classification of Magnetic Nanomaterials Used for
MRI Applications ...................................... 121
4.2.1 Magnetic Oxide-Based Nanoparticles ............. 122
4.2.2 Magnetic Metal- and Alloy-Based Nanoparticles
as Contrast Agents ............................. 125
4.2.3 Rare Earth Metal-Loaded Nanoparticulate
Contrast Agents ................................ 226
4.3 Coating and Surface Functionalization of Magnetic
Nanoparticles ......................................... 129
4.3.1 Surface Modification with Monomeric
Stabilizers .................................... 129
4.3.2 Modification Using Polymeric Stabilizers ....... 130
4.3.3 Modification Using Inorganic Coatings .......... 133
4.3.4 Vectorization of Magnetic Nanomaterials for
Targeted Imaging ............................... 137
4.4 Properties and Characterization of Magnetic
Nanoparticle Suspensions .............................. 138
4.4.1 Characterizing the Suspensions ................. 139
4.4.1.1 Nanoparticle Size: Transmission
Electron Microscopy ................... 139
4.4.1.2 Magnetic Properties: Magnetometry ..... 139
4.4.1.3 Hydrodynamic Size: Photon
Correlation Spectroscopy .............. 140
4.4.1.4 Magnetic Resonance Properties:
Nuclear Magnetic Resonance
Dispersion ............................ 141
4.4.2 NMR Relaxation in the Presence of
Superparamagnetic Nanoparticles ................ 141
4.4.3 SPM Theory Applied to Suspensions of
Nanoparticle Clusters .......................... 143
4.4.4 General Application of Relaxation Time
Measurements ................................... 144
4.5 Application of Magnetic Nanomaterials in MRI .......... 145
4.5.1 Current Clinical Applications .................. 145
4.5.1.1 Gastrointestinal Tract and Bowel
Imaging ............................... 145
4.5.1.2 Liver and Spleen Imaging .............. 146
4.5.1.3 Lymph Node Imaging .................... 147
4.5.1.4 Bone Marrow Imaging ................... 148
4.5.1.5 Brain Imaging ......................... 149
4.5.1.6 Blood Pool Imaging and MR
Angiography ........................... 151
4.5.1.7 Atherosclerosis Imaging ............... 152
4.5.2 Potential Clinical Applications ................ 152
4.5.2.1 Cellular Labeling and Tracking ........ 152
4.5.2.2 Molecular Imaging ..................... 154
4.6 Summary and Future Outlook ............................ 159
4.6.1 Improved Imaging Methods ....................... 160
4.6.2 Improved Imaging Hardware ...................... 161
4.6.3 Improved Contrast Agents ....................... 161
References ............................................ 164
Part Two Diagnosis and Therapy ............................... 187
5 Magnetic Nanomaterials for In Vivo and In Vitro Cancer
Diagnostics ................................................ 189
Kelly Y. Kim
5.1 Introduction .......................................... 189
5.2 Physico-Chemical Properties of Magnetic
Nanoparticles ......................................... 190
5.3 Surface Coating for Improved Biocompatibility and
Bioavailability ....................................... 191
5.4 MRI for In Vivo Diagnostics ........................... 194
5.4.1 Principles of MRI .............................. 194
5.4.2 SPIOs as MRI Contrast Agents ................... 195
5.4.3 Specific Targeting of Tumors for Imaging ....... 195
5.5 MRI for the Monitoring of Treatment ................... 196
5.6 Application of Magnetic Nanoparticles in In Vitro
Diagnostics ........................................... 197
5.6.1 Magnetic Nanoparticle-Based Improvements on
Immunoassays ................................... 198
5.6.1.1 Electrochemical Immunoassays .......... 198
5.6.1.2 Immunoassays Using Magnetic
Luminescent Nanoparticles (MLNPs) ..... 199
5.6.2 Magnetic Relaxation Switch (MRSw) Biosensors
for Multi-Sample Analysis ...................... 199
5.6.3 DNA Sequence Detection by Brownian Relaxation
Frequency Measurement .......................... 201
5.7 Detection of Circulating Tumor Cells .................. 202
5.8 Aptamers as an Alternative to Antibodies .............. 203
5.9 Conclusions ........................................... 204
References ................................................. 205
6 Magnetic Nanoparticles for Cancer Imaging and Therapy ...... 209
Arutselvan Natarajan, Rajeswari Sundrarajan, and Sally
J. DeNardo
6.1 Introduction .......................................... 209
6.2 Synthesis and Surface Modifications of MNPs for
Biological Applications ............................... 211
6.2.1 Fabrication of the Magnetic Nanoparticle
Core ........................................... 211
6.2.2 Surface Coatings and Chemistry ................. 211
6.2.3 Physico-Chemical Characterization of MNPs ...... 212
6.2.4 Plasma Stability and Pharmacokinetic Profile
of the MNPs .................................... 212
6.3 Development of MNPs as Cancer Diagnosis and
Imaging Agents ........................................ 214
6.3.1 MNPs Used in MR Imaging for Cancer Diagnosis ... 214
6.3.2 MNPs Used in Optical Imaging for Cancer
Diagnosis ...................................... 219
6.3.3 Ligand-Directed MNPs for Cancer Imaging ........ 225
6.3.3.1 Antibody-Directed MNPs ................ 225
6.3.3.2 Antibody Fragment-Directed MNPs ....... 226
6.3.4 Radioimmunonanoparticles ....................... 228
6.3.5 Annexin 5-Directed MNPs ........................ 230
6.3.6 Chemotherapeutic Drugs Loaded with MNPs for
Cancer Therapy ................................. 230
6.3.7 Lymph Node-Targeting MNPs ...................... 231
6.3.8 Other Novel MNPs for Cancer Targeting .......... 231
6.4 MNPs Applied to Cancer Therapy ........................ 232
6.4.1 MNPs Utilized in Targeted Therapy for Cancer ... 232
6.4.1.1 Brain Tumor Therapy ................... 232
6.4.1.2 Breast Cancer Therapy ................. 234
6.4.1.3 MNPs in Hyperthermia and Thermal
Ablation .............................. 237
6.4.1.4 MNPs-Directed Toxicity ................ 240
6.5 Summary ............................................... 242
References ............................................ 244
7 Core-Shell Magnetic Nanomaterials in Medical Diagnosis
and Therapy ................................................ 259
Marites P. Melancon and Chun Li
7.1 Introduction .......................................... 259
7.2 Synthesis ............................................. 260
7.2.1 Formation of the Magnetic Core ................. 260
7.2.1.1 Coprecipitation from Solution ......... 260
7.2.1.2 Thermal Decomposition ................. 261
7.2.1.3 Microemulsions ........................ 262
7.2.1.4 Pyrolysis ............................. 262
7.2.2 Formation of the Core-Shell Structure .......... 263
7.2.2.1 Inorganic Core with Organic Shell ..... 263
7.2.2.2 Inorganic Core with Inorganic Shell ... 264
7.3 Applications: Magnetic Resonance Imaging .............. 270
7.4 Applications: Hyperthermia and Thermal Ablation ....... 273
7.4.1 Passive Targeting .............................. 275
7.4.1.1 Dextran-Coated Magnetite .............. 275
7.4.1.2 Aminosilan-Coated Magnetic
Particles ............................. 275
7.4.1.3 Magnetic Cationic Liposomes ........... 276
7.4.2 Active Targeting ............................... 277
7.4.2.1 Antibodies ............................ 277
7.4.2.2 Peptides .............................. 277
7.4.2.3 Folic Acid ............................ 278
7.4.3 Laser-Induced Hyperthermia/Thermal Ablation
Therapy ........................................ 278
7.5 Application: Drug Delivery ............................ 279
7.6 Summary and Perspectives .............................. 281
Acknowledgments ............................................ 282
References ................................................. 282
Part Three Tissue Engineering ................................ 297
8 The Use of Magnetic Particles in Tissue Engineering ........ 293
Sarah H. Cartmell and Jon Dobson
8.1 Introduction .......................................... 293
8.1.1 Mechanotransduction ............................ 293
8.1.2 Cell Seeding: Scaffolds and 3-D Structures ..... 296
8.2 Magnetic Particle Technology Used in Various Tissue
Types ................................................. 297
8.2.1 Bone and Cartilage ............................. 297
8.2.2 Blood Vessels and Cardiac Structure ............ 299
8.2.3 Skin ........................................... 300
8.2.4 Lung ........................................... 301
8.2.5 Eye ............................................ 301
8.2.6 Liver .......................................... 302
8.2.7 Nervous Tissue ................................. 302
8.2.8 Stem Cell Targeting ............................ 303
8.2.9 Use of Magnetic Particles to Create Acellular
Scaffolds ...................................... 303
8.3 Summary and Concluding Remarks ........................ 303
References ............................................ 304
Part Four Environmental Applications ......................... 309
9 Magnetic Nanomaterials for Environmental Applications ...... 377
Marvin C. Warner, Cynthia L. Warner, R. Shane Addleman,
and Wassana Yantasee
9.1 Introduction .......................................... 311
9.1.1 The Aim of the Chapter ......................... 311
9.1.2 The Role of Nanomaterials in Environmental
Detection ...................................... 311
9.2 Synthesis and Functionalization of Magnetic
Nanoparticles ......................................... 313
9.2.1 Synthetic Strategies for Magnetic Metal Oxide
Nanoparticles .................................. 313
9.2.1.1 Coprecipitation ....................... 314
9.2.1.2 Thermal Decomposition ................. 315
9.2.1.3 Other Synthetic Methods ............... 317
9.2.2 Functionalization of Magnetic Nanoparticles .... 317
9.2.2.1 Organic Ligand Modification ........... 318
9.2.2.2 Stabilization with Polymers ........... 319
9.2.2.3 Inorganic Stabilization with Silica
or Carbon ............................. 319
9.2.2.4 Less Common Methods of Passivation .... 324
9.3 Magnetic Nanoparticles for the Separation and
Detection of Analytes ................................. 324
9.3.1 Chemical Separations with Functionalized
Magnetic Nanoparticles ......................... 324
9.3.2 High Magnetic Field Gradient Separation and
Preconcentration ............................... 327
9.3.3 Electrochemical Detection Enhanced by
Magnetic Nanomaterials for Preconcentration .... 330
9.3.4 Analyte Detection Using Magnetic
Nanoparticles through Nonelectrochemical
Methods ........................................ 334
9.4 Summary and Future Perspective ........................ 336
Acknowledgments ....................................... 337
References ............................................ 337
Part Five Biofunctionalization and Characterization .......... 345
10 Magnetic Core-Polymer Shell Nanoparticles: Synthesis and
Biomedical Applications .................................... 347
Koon Gee Neoh, Lihan Tan, and En-Tang Kang
10.1 Introduction .......................................... 347
10.2 Synthesis of Magnetic Nanoparticles ................... 348
10.2.1 Primary Synthesis Methods ...................... 348
10.2.2 Effect of Synthesis Conditions on Particle
Size and Surface Properties .................... 349
10.3 Magnetic Nanoparticles with Polymeric Shell ........... 350
10.3.1 Coating with Polymer During MNP Synthesis ...... 350
10.3.1.1 Dextran-Coated MNPs via the
Coprecipitation Method ................ 350
10.3.1.2 Starch-Coated MNPs via the
Coprecipitation Method ................ 352
10.3.1.3 PEG-Coated MNPs via the
Coprecipitation Method ................ 353
10.3.1.4 MPEG-COOH-Coated MNPs via the High-
Temperature Decomposition Method ...... 354
10.3.1.5 Triethylene Glycol-Coated MNPs via
the High-Temperature Decomposition
Method ................................ 356
10.3.1.6 4-Methylcatechol-Coated MNPs via
High Temperature Decomposition
Method ................................ 356
10.3.2 Modification of Preformed MNPs ................. 357
10.3.2.1 Physical Adsorption of Polymer onto
Preformed MNPs ........................ 357
10.3.2.2 Grafting of Polymer on Preformed
MNPs .................................. 359
10.4 Encapsulation of Magnetic Nanoparticles in
a Polymeric Matrix .................................... 371
10.4.1 Nanospheres for Imaging ........................ 372
10.4.1.1 PLGA and PLLA Coating ................. 372
10.4.1.2 PEG-PEI, CrossHnked Poly(Maleic
Anhydride-alt-1-Tetradecene) and
Lipid Micelles Coating ................ 373
10.4.1.3 Iodinated Polymer Coating ............. 374
10.1.4.1 Poly(Styrene-co-Acrylic Acid)
Coating ............................... 375
10.4.2 Nanospheres with Targeting and Recognition
Capability ..................................... 375
10.4.2.1 Polypyrrole Coating with FA as the
Targeting Ligand ...................... 376
10.4.2.2 PPY Coating with Herceptin as the
Targeting Ligand ...................... 377
10.4.2.3 PLGA Coating with Arginine Peptide
as the Targeting Ligand ............... 379
10.4.2.4 Phospholipid Coating with Antibodies as
the Targeting Ligand ......................... 379
10.4.2.5 Poly(MMA-co-EGDMA) Coating with BSA
Surface-1 mprintation ................. 380
10.4.3 Nanospheres as Drug/Gene Delivery System ....... 380
10.4.3.1 PLGA Loaded with Taxol ................ 381
10.4.3.2 PLLA and PCL Loaded with Tamoxifen .... 381
10.4.3.3 Chitosan Loaded with Cefradine ........ 382
10.4.3.4 PECA or PCL Loaded with Cisplatin or
Gemcitabine ........................... 382
10.4.3.5 Poly(Alkylcyanoacrylate) Loaded with
Tegafur or 5-Fluorouracil ............. 384
10.4.3.6 PHDCA-PEI Loaded with Doxorubicin ..... 386
10.4.3.7 PLGA Loaded with QDs, DOX, and
Functionalized with FA ................ 386
10.4.3.8 PEI and Transferrin-Mediated Gene
Delivery .............................. 388
10.4.3.9 Polyamidoamine (РАМАМ) Dendrimer-
Mediated Gene Delivery ................ 389
10.5 Future Perspectives ................................... 389
References ............................................ 392
11 Magnetosomes: Bacterial Biosynthesis of Magnetic
Nanoparticles and Potential Biomedical Applications ........ 399
Sarah S. Staniland
11.1 Introduction .......................................... 399
11.2 Magnetic Nanoparticles for Medical Applications ....... 400
11.2.1 Introduction ................................... 400
11.2.2 Requirements and Specifications for
Biomedical Applications ........................ 401
11.2.2.1 Safety Aspects ........................ 401
11.2.2.2 Magnetic Properties ................... 402
11.2.2.3 Particle Size and Shape ............... 402
11.2.2.4 Particle Coatings ..................... 402
11.2.3 General Synthetic Methods ...................... 403
11.2.3.1 Precipitation ......................... 403
11.2.3.2 Thermal Decomposition ................. 405
11.3 What Is Biomineralization? Biogenic Inorganic
Materials ............................................. 405
11.4 Magnetosomes: Biomineralization in Magnetic
Bacteria .............................................. 407
11.4.1 Bacteria Characterization ...................... 409
11.4.2 Magnetosome Characterization ................... 412
11.4.3 Magnetosome Formation .......................... 415
11.4.3.1 Proteomics ............................ 416
11.4.3.2 Genetics .............................. 417
11.4.3.3 Mechanism ............................. 418
11.5 Progress and Applications of Novel Biomedical
Magnetosome Materials ................................. 419
11.6 The Future for Biomedical Magnetosomes ................ 422
References ................................................. 424
12 Approaches to Synthesis and Characterization of Spherical
and Anisometric Metal Oxide Magnetic Nanomaterials ......... 431
Lorenza Suber and Davide Peddis
12.1 Introduction .......................................... 431
12.2 Magnetism in Nanostructured Metal Oxides .............. 433
12.2.1 Magnetism in Condensed Matter .................. 433
12.2.2 Magnetic Anisotropy Energy ..................... 435
12.2.3 Magnetism in Small Particles: An Experimental
Approach ....................................... 436
12.2.3.1 Zero Field-Cooled and Field-Cooled
Magnetization ......................... 438
12.2.3.2 Thermoremanent Magnetization .......... 439
12.2.4 Magnetic Metal Oxides .......................... 440
12.3 Synthesis Methods for Spherical and Anisometric Iron
Oxide Nanomaterials ................................... 442
12.3.1 Synthesis of Spherical and Anisometric
Nanoparticles .................................. 443
12.3.1.1 Metal Salt Precipitation in Water ..... 443
12.3.1.2 Sol-Gel ............................... 445
12.3.1.3 Microemulsions ........................ 447
12.3.1.4 Autocombustion Method ................. 448
12.3.1.5 Surfactant-Assisted Hydrothermal
Treatment ............................. 448
12.3.1.6 Surfactant-Assisted Ultrasound
Irradiation ........................... 449
12.3.2 Ferrofluids .................................... 449
12.3.2.1 Surfactant-Assisted Dehydration ....... 450
12.3.2.2 Hydrophobic-Hydrophilic Phase
Transfer .............................. 450
12.3.3 Core-Shell Spherical and Anisometric
Particles ...................................... 451
12.3.3.1 Core-Shell Fluorescent Magnetic Iron
Oxide-Silica Particles ................ 452
12.3.3.2 Synthesis of Anisometric Iron Oxide
Nanocapsules .......................... 453
12.3.4 Maghemite and Magnetite Nanotubes .............. 455
12.3.4.1 Solid Nanotube Template ............... 455
12.3.4.2 Soluble Nanotube Template ............. 456
12.4 Correlations between Synthesis and Magnetic Behavior
in Iron Oxide Nanomaterials ........................... 457
12.4.1 Spherical and Anisometric Iron Oxide
Particles ...................................... 457
12.4.1.1 Spherical Magnetite (Fe3O4)
Nanoparticles ......................... 457
12.4.1.2 Stable Iron Oxide Spherical
Nanoparticle Dispersions
(Ferrofluids) ......................... 459
12.4.1.3 Surfactant Effect ..................... 461
12.4.1.4 Anisometric Maghemite (γ-Fe2O3)
Particles ............................. 462
12.4.2 Core-Shell Nanoparticles ....................... 463
12.4.2.1 γ-Fe2O3/Silica Core Coated with Gold
Nanoshell ............................. 464
12.4.2.2 Effect of Particle Size and Particle
Size Distribution on the Magnetic
Properties of Magnetite/PDMS
Nanoparticles ......................... 466
12.4.3 Nanocomposites ................................. 468
12.4.3.1 Magnetic Properties of Cobalt
Ferrite-Silica Nanocomposites
Prepared by a Sol-Gel Autocombustion
Technique ............................. 468
12.4.3.2 Ordered Mesoporous γ-Fe2O3/SiO2
Nanocomposites ........................ 472
12.4.3.3 Fe3O4/Polymethylmethacrylate .......... 473
12.4.4 Iron Oxide Nanowires and Nanotubes ............. 474
12.4.4.1 Fe3O4 Nanowires ....................... 475
12.4.4.2 Fe3O4 Nanowires and γ-Fe2O3
Nanotubes ............................. 475
12.5 Conclusions and Perspectives .......................... 479
List of Abbreviations ................................. 480
References ............................................ 480
13 Approaches to the Synthesis and Characterization of
Spherical and Anisotropic Magnetic Alloy Nanomaterials ......489
Matthew S. Wellons and Charles M. Lukehart
13.1 Introduction .......................................... 489
13.2 Magnetic Noble Metal Alloy Nanoparticles .............. 490
13.3 Magnetic Early Transition Metal Alloy Nanoparticles ... 500
13.4 Summary and Future Perspectives ....................... 502
References ............................................ 502
14 Approaches to the Biofunctionalization of Spherical and
Anisotropic Iron Oxide Nanomaterials ....................... 507
Christopher J. Thode and Mary Elizabeth Williams
14.1 Introduction ..................................... 507
14.2 Magnetic Nanoparticle Synthesis .................. 508
14.3 Nanoparticle Functionalization ................... 509
14.4 Conclusions ...................................... 533
References ............................................ 533
15 Characterization of Magnetic Nanoparticles Using Magnetic
Force Microscopy ........................................... 551
Gunjan Agarwal
15.1 Introduction .......................................... 551
15.2 Development of MFM .................................... 551
15.3 Comparison of MFM to Other Techniques ................. 553
15.4 Physical Principals of MFM ............................ 555
15.4.1 Static Mode .................................... 555
15.4.2 Dynamic Mode ................................... 556
15.4.3 Forces Due to Magnetic Interaction ............. 559
15.5 Noise in MFM .......................................... 560
15.5.1 Thermal Noise .................................. 560
15.5.2 Magnetic Versus Topographic Signals ............ 561
15.6 MFM Cantilevers and Probes ............................ 562
15.6.1 Wire Probes .................................... 563
15.6.2 Thin-Film-Coated Si Probes ..................... 563
15.6.3 FIB Probes ..................................... 564
15.6.4 CNT Probes ..................................... 565
15.7 Probe Calibration ..................................... 565
15.7.1 Quantitative Calibration of the Magnetic
Force Microscope Probe ......................... 566
15.7.2 Calibration Samples ............................ 567
15.8 Resolution in MFM ..................................... 568
15.8.1 Lateral Resolution ............................. 568
15.8.2 Vertical Resolution ............................ 569
15.9 MFM for Magnetic Nanoparticles ........................ 569
15.9.1 Ferromagnetic Nanoparticles .................... 570
15.9.2 Superparamagnetic or Paramagnetic
Nanoparticles .................................. 571
15.10 The Application of MFM in the Life Sciences .......... 576
15.11 Limitations in MFM ................................... 577
15.12 Recent Developments in MFM ........................... 578
15.12.1 Non-Optical Methods for Cantilever
Detection ..................................... 578
15.12.2 Application of External Magnetic Fields ....... 579
15.12.3 Technique Developments for MFM ................ 579
15.13 Summary and Future Perspectives ...................... 580
References ............................................ 580
16 Cobalt Nanomaterials: Synthesis and Characterization ....... 587
Zhihua Zhang, Tiejun Zhou, Meihua Lu, Allen Wei Choong
Poh, and Seidikkurippu N. Piramanayagam
16.1 Introduction .......................................... 587
16.2 The Characterization of Co Nanoparticles .............. 588
16.2.1 Shape, Size, and Microstructure ................ 588
16.2.1.1 Transmission Electron Microscopy ...... 588
16.2.1.2 Scanning Electron Microscopy .......... 590
16.2.2 Magnetic Properties ............................ 593
16.2.3 Morphology ..................................... 594
16.2.4 Elemental and Chemical Analysis ................ 596
16.2.4.1 Auger Electron Spectroscopy ........... 596
16.2.4.2 X-Ray Photoelectron Spectroscopy
(XPS) ................................. 596
16.2.5 Fourier Transform Infrared (FTIR)
Spectroscopy ................................... 597
16.2.6 The Crystal Structure: X-Ray Diffraction
(XRD) .......................................... 598
16.3 Synthesis of Cobalt-Based Nanoparticles ............... 598
16.3.1 Introduction ................................... 598
16.3.2 Stabilization of Nanomaterials ................. 599
16.3.3 Synthesis of Cobalt Nanomaterials .............. 601
16.3.3.1 Physical Methods ...................... 601
16.3.3.2 Chemical Vapor Deposition ............. 602
16.3.3.3 Liquid-Phase Chemical Precipitation ... 603
16.3.4 Summary and Outlook ............................ 612
16.4 Magnetic Properties of Co Nanoparticles ............... 612
16.4.1 Introduction ................................... 612
16.4.2 Finite Size Effects ............................ 613
16.4.2.1 Size-Dependent Crystalline
Structure ............................. 613
16.4.2.2 Size-Dependent Magnetic Domain
Structure and the Reversal of Co
Nanoparticles ......................... 614
16.4.2.3 Thermal-Activation Effect on the
Moment and Coercivity ................. 615
16.4.2.4 Superparamagnetism in Co
Nanoparticle System and its Direct
Investigation ......................... 616
16.4.3 Surface Effects of Co Nanoparticles ............ 618
16.4.3.1 Moment Enhancement of Surface Atoms ... 618
16.4.3.2 Anisotropy Enhancement of Co
Nanoparticles ......................... 619
16.4.3.3 Exchange Bias Between the Core and
the Oxidized Surface in Co
Nanoparticles ......................... 620
16.4.4 Summary ........................................ 622
16.5 Summary and Outlook ................................... 621
References ............................................ 621
Index ......................................................... 633
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