Title

Magnetic Colloidal Collective Behavior for Single-Cell Manipulation and Biomolecule Detection

DGIST Authors

Ali Abbas ; CheolGi Kim ; Seonki Hong

Advisor

김철기

Co-Advisor(s)

Seonki Hong

Issued Date

2026

Awarded Date

2026-02-01

Type

Thesis

Description

Magnetic colloids; Flowless micropump; Micromagnetic pattern; Exosome-functionalized magnetic beads; Magnetophoretic biosensing

Table Of Contents

List of Contents
Abstract i
List of contents ii
List of tables iv
List of figures v
Ⅰ. Introduction 1
1.1 Magnetic Colloids 1
1.1.1 Introduction to magnetic colloids 1
1.1.2 Properties of magnetic colloids 3
1.1.3 Magnetic colloids surface chemistry applications 5
1.2 Strategies for Magnetic Colloids Manipulation 6
1.2.1 Magnetic colloids manipulation through magnetic nanowires 6
1.2.2 Magnetic colloids manipulation via micromagnetic patterns 9
1.3 Magnetic Colloids for Bio-Application 14
1.3.1 Magnetic colloids for nucleic acid separation 14
1.3.2 Magnetic colloids for protein separation 15
1.3.3 Magnetic colloids for cell manipulation and separation 17
1.3.4 Mimicking natural synchronization phenomena 20
1.4 Necessity of this study 24
1.5 Thesis objectives and outline 25
II. Experimental Methods 28
2.1 The micromagnet pattern's fabrication 28
2.2 Fabrication of nonmagnetic (SU-8) guiding wall 30
2.3 Experimental set-up 30
2.3.1 Magnetic colloids functionalization with exosomes 31
2.3.2 Magnetophoretic disk-shaped pattern with target antibodies 32
2.4 Experimental set-up 34
III. Theoretical Background 35
3.1 Types of magnetophoresis 36
3.1.1 Positive magnetophoresis 37
3.1.2 Negative magnetophoresis 38
3.1.3 Positive magnetophoresis for magnetic colloids 40
3.1.4 Magnetophoretic patterns for magnetic colloids manipulation 41
3.1.5 Sigmoidal Logistic Model for the Magnetic Beads Oscillation and Sticking
Fraction Analysis 43
3.1.6 Biological and Physical Interpretation 44
3.1.7 MATLAB Implementation 45
3.1.8 Modeling of Oscillation and Sticking Dynamics of Exosome-Functionalized Magnetic
Beads 45
3.1.9 Oscillation Amplitude Model 46
3.2 Analysis using magnetic simulations 50
3.2.1 Micromagnetic simulation (Mumax3) 50
3.2.2 Equation-based MATLAB code 51
3.3 Limitations of micromagnetic thin-film devices for particle manipulation 53
3.4 Strategies to overcome limitations for magnetic colloids manipulation 54
3.5 Breaking through the restricted use of magnetophoretic circuits 55
IV. Results and Discussion 57
4.1 Magnetic colloids' collective behavior for nonlabelled cell manipulation 57
4.1.1 Direct manipulation of a single cell by magnetic colloidal flow 61
4.1.2 Non-magnetic guiding wall for direct label-free manipulation 64
4.1.3 Indirect manipulation of microcargo by local magnetic colloidal flow 68
4.2 Magnetic colloids for the biomolecule’s detection 78
4.2.1 Detection principle of biomarkers utilizing magnetic colloids 80
4.2.2 Magnetic colloids functionalization for exosome detection 83
4.2.3 Oscillation and sticking of exosome functionalized magnetic colloids 93
4.2.4 Magnetic colloids functionalization for the PEG/Biotin analysis 99
4.2.5 Exosome-Ab-magnetic beads binding and unbinding force analysis 102
V. Conclusion and Summary 107
5.1 Magnetic colloids collective behavior for manipulating nonlabelled cells 107
5.2 Magnetic colloids trajectories for the detection of biomolecules 108
VI. Future Plans 109
6.1 Integrated Micromagnetic Lab-On-Chip Devices for Bio-applications 109
6.1.1 Background and Purpose of Research 109
6.1.2 Research Plan 110
6.1.3 Multiplexed Proteins or Biomolecules Detection Array 110
6.1.4 Protein Folding/Unfolding and Polymer Analysis 111
6.1.5 Single-cell Membrane Elasticity and Deformation Analysis 112
6.1.6 Study on the friction force of endothelial cells and other proteins 113
6.2 Expected Results and Impacts 114
6.3 Position within the Field 115
References 117
Summary in Korean (요 약 문) 125
List of Publications 127
List of Patents 129

URI

https://scholar.dgist.ac.kr/handle/20.500.11750/59645
http://dgist.dcollection.net/common/orgView/200000942333

DOI

10.22677/THESIS.200000942333

Degree

Doctor

Department

Department of Physics and Chemistry

Publisher

DGIST

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