This document discusses a project to characterize magnetic nanoparticles for use in biomedical applications. The objectives are to: 1. Characterize the magnetic nanoparticles and study their AC susceptibility, size distribution, magnetic properties, and relaxation to determine parameters like magnetic moment and blocking temperature. 2. Develop a system to detect biological targets using magnetic nanoparticles and improve the system's sensitivity. 3. Validate the magnetic immunoassay technique by comparing results to conventional methods and analyzing outcomes for biological targets.

1. Roll No: 08085707
Registration No: 1834
Session: 2007-08
Department of Materials Science &
Engineering
Rajshahi University

2. Project Objectives
 Detail characterization of the magnetic markers/nanoparticles,
which will be used for Biomedical Application.
 Detailed Study of AC susceptibility χ , Size distribution, M-H
curves, magnetic relaxation, magnetic moment m.
Analyzing the experimental results, try to obtain the values of the
key parameters, dh, mB, EB for the markers.
 Develop the measurement system and the detection principle
for biological target.
 Improvement of the System Sensitivity.

3. Magnetic Nanomaterials
• Magnetic nanomaterials are minute parts of magnetic materials
with typical size well below 10-7m(smaller than 100 nm).
• They are present in different materials found in nature such as
rocks, living organisms, ceramics, and corrosion products, but
they are also artificially made and used as the active component
of ferrofluids, permanent magnets, soft magnetic materials,
biomedical materials, and catalysts.
• Their diverse applications in geology, physics, chemistry, biology,
and medicine render the study of their properties of great
importance to both science and technology.
• Nanomaterials have chemical, physical and bioactive
characteristics, which are different from those of larger entities of
the same materials.

6. Magnetic Marker
Practical Marker used in
the experiment
AFM imaging of Fe3O4
magnetic nanoparticles.
Scanning field, 10 × 10
μm

7.  Superparamagnetic nanoparticles are currently used as contrast agent
in magnetic resonance imaging (MRI) and other biological applications.
They are originally ferromagnetic substances, which have lost their
permanent magnetism due to their small size.
 The magnetization of such nanoparticles follows an external magnetic
field without any hysteresis and they are better known as
“superparamagnetic” due to their large magnetic susceptibility.
 These nanoparticles consist of a coated iron oxide core (magnetite,
maghemite or other insoluble ferrites) characterized by a large magnetic
moment in the presence of a static external magnetic field. They are
classified into two main groups according to their size
SPIOs ≥ 50 nm USPIOs ≤ 50 nm
Super Paramagnetic Nanoparticles

8.  For biomedical applications, those nanomaterials enter
the body and contact with tissues and cells directly, thus
it is necessary for exploring their biocompatibility.
 Nanomaterials are used as vectors for the applications in
drug delivery, gene delivery, or as biosensors, where a
direct contact with blood occurs.

9. Characteristics of Magnetic Marker
• Magnetic immunoassays utilizing magnetic markers and
magnetic sensors. In this method, an antibody is labeled
with the magnetic marker made of magnetic nanoparticles
and the binding reaction is detected by measuring the
magnetic signal from the marker.
• The magnetic properties are determined by measuring the
magnetization curve, the magnetic relaxation, and the ac
susceptibility. Comprehensive comparisons are made
between the experimental results and the theoretical ones
predicted from the Brownian relaxation. From the
comparison, the distributions of the particle parameters,
such as magnetic moment, relaxation time, and particle size,
are estimated.

11. H=0 H ≠ 0 H=0
Néel relaxation
H = 0
Brownian relaxation
2. Neel mechanism
Rotation of the
magnetization vector
within the particles.
3. Brownian Mechanism
Mechanical rotation
of the magnetic particle
Intrinsic superparamagnetism
(the particle magnetic moments
aligns with external field)
Extrinsic superparamagnetism
(the particle itself aligns with
field)
H
What is Brownian and Neel Relaxation?

13. Introduction of Immunoassay
 An immunoassay is a test that uses antibody and antigen
complexes as a means of generating a measurable result.
 An antibody: antigen complex is also known as an immuno-
complex.
 “Immuno” refers to an immune response that causes the
body to generate antibodies,
and
 “Assay” refers to a test. Thus, an immunoassay is a test that
utilizes immunocomplexing when antibodies and antigens
are brought together.
“Immuno”& “assay”

14. The immunoassay methodologies are:
 noncompetitive and competitive immunoassays,
and
 homogeneous and heterogeneous immunoassays
Labeled material
 All immunoassays require the use of labeled material in order to
measure the amount of antigen or antibody present.
 A label is a molecule that will react as part
of the assay, so a change in signal can be measured in the blood:
reagent solution.
CATEGORIES OF IMMUNOASSAY METHODOLOGIES
Immunoassay

15. There are several different methods used
in immunoassay tests
 Immunoprecipitation
 Particle immunoassays
 Immunonephelometry
 Radioimmunoassay (RIA)
 Enzyme (EIA)
 Fluorescent immunoassay (FIA)
 Chemiluminescent immunoassays
 Magnetic Immunoassay
 Liquid Phase Immunoassay.
Conventional Immunoassays

16. Fig. Radioimmunoassay Technique. Fig. ELISA Technique.
Conventional Immunoassays Methods

17. The antibody-enzyme conjugate is
added to the reaction mixture.
The antibody part of the conjugate
binds to any antigen molecules that
were bound previously, creating an
antibody-antigen-antibody
"sandwich".
After washing away any unbound
conjugate, the substrate solution is
added.
Conventional Immunoassay Disadvantages
Need washing process for B/F separation
A typical radioimmunoassay is performed by the simultaneous preparation of a series
of standard and unknown mixtures in test tubes, each containing identical
concentrations of labeled antigen and specific antibody. After an appropriate reaction
time the antibody-bound (B) and free (F) fractions of the labeled antigen are
separated by one of a variety of techniques.

18. Detecting antibody
Capturing antibody
Signal
Magnetic Marker
Antigen
Signal
MR/Flux Sensor
•Disease-related
protein
•Cancer cell
•Pathogenic
bacteria
•DNA
Magnetic Marker
Detecting antibody
Capturing antibody
Signal
Magnetic Immunoassay
High sensitivity: Detection with highly sensitive SQUID
High speed: Detection without B/F (Bound/Free) separation
High linearity: No saturation of signal
 No washing process is needed
 Signal from free marker is zero due
to Brownian rotation

19. Merits of Magnetic Method
• One of the merits of this magnetic method is that we can
perform immunoassay in the liquid phase. This function
can be realized by utilizing magnetic relaxation
phenomena caused by Brownian rotation of the magnetic
markers in a solution.
• Using the phenomena, we can distinguish bound markers
from unbound (free) ones without using the so called
bound/free (BF) separation process. Since the time
consuming process of the BF separation can be
eliminated, we can expect a high-speed immunoassay
with the magnetic method.

20. Liquid Phase Immunoassay
1. Susceptibility
2. Relaxation
3. Remanence
The method will be chosen
depends on the magnetic
properties of the marker
Validity of the
Immunoassay
experiment
Biological Targets
Outcome of
Project
Compare with
conventional
methods
Future Work

21. Excitation
Field
MR/Flux Gate Sensor
Sample
MagnetizationSignal
Sample
Rotation
No SignalSignal
(1) magnetization(2) Brownian
relaxation
Excitation
Bex=40 mT
reaction
cellrotation
Sensor
Bs
(3) detection
Bound markers Free markers
Polymer
(dp=3.3 mm )
target
(biotin)
(1) magnetization(2) Brownian
relaxation
Excitation
Bex=40 mT
reaction
cellrotation
Sensor
Bs
(3) detection
Bound markers Free markers
Polymer
(dp=3.3 mm )
target
(biotin)
Detection Principle

22. Magneto Resistive (MR) Sensor
Fig. 4.1 MR sensor (Honeywell)
Magneto Resistive
Wheatstone Bridge
Elements.
Fig. 4.2 Noise characteristics
curve.

27. Conclusion
• Radiation is very harmful for our body. We can use
nanomaterials to detect biological target instead of
radiation.
• The main objective of this project paper is to use
nanomaterials in biomedical application. In Bangladesh if
we can use this technology in various diagnosis and
diagnostic centre which will be beneficial for us.
• Cancer is known to be one of the main causes of death in
the developed world. Nanotechnology through the use of
drug delivery systems participates in the struggle against
cancer.