Magnetic sepertion,detection & targeting

1. NAST-734: NANOMAGNETIC MATERIALS AND DEVICES
UNIT –V
NANOBIOMAGNETISM
PRESENTED BY,
MUGILAN N
M.TECH NAST 2nd year
Reg no:16305012
COURSE INSTRUCTOR;
Dr. K. Vijayarangamuthu (DST-INSPIRE)
ASSISTANT PROFESSOR
Centre for Nano Sciences & Technology
Madanjeet School of Green Energy Technologies

2. INTRODUCTION
MAGNETIC SEPARATION
• Magnetic separation is used in many fields and industries. The main use in
manufacturing is using the magnetic properties of a substance to separate
magnetic materials from nonmagnetic materials or materials with strong
magnetic fields from materials with low magnetic fields.
• This is useful for separating crushed ore at various stages of the mining, iron
production, mineral processing and metallurgy industries; the process is also
used to remove materials with magnetic properties in the processing of
food.
• Another field where magnetic separation is used in microbiology where new
techniques are being developed on a regular basis. Some of the applications
include diagnostic microbiology, isolating rare cells, studying nano cells in
biological processes.
• Biological samples are particularly complicated samples with matrix
interference. Therefore, prior to the analysis of trace biological targets, it is
imperative for the isolation, separation and purification of raw samples.

3.  Magnetic separation technique is a batch-scale technique based on
functionalized magnetic materials. Magnetic materials are adsorbents
particularly suitable for biological macromolecules due to their large
surface area, good biocompatibility, easy functionalization and
convenient manipulation.
 In a typical process of magnetic separation, magnetic materials, which
exhibit affinity toward the isolated structure, are mixed with a sample
containing target compounds. Within a period of incubation, target
compounds bind to the magnetic particles.
 The whole magnetic complex is subsequently separated from the
sample using an extra magnetic field. After washing out the
contaminants, the isolated target compounds can be eluted and used for
further work.
 Magnetic separation techniques have several advantages in
comparison with standard separation techniques used in various areas of
biosciences.

4. Magnetic separation is usually gentle and nondestructive to biological
analytic such as proteins or peptides, and even large protein complexes
which tend to be broke up in process of traditional column
chromatography may remain active.
Besides, magnetic separation can be easily and directly used for raw
biological samples with several simple steps. Target analysts captured to
magnetic materials can be easily and selectively removed from the
sample.
magnetic separation technique is able to facilitate or accelerate many
separation and purification procedures and efficiently combine with the
majority of other procedures used in biological analysis.

6. STRATEGIES OF MAGNETIC SEPARATION TECHNIQUES
 There are two main ways for performing magnetic separation of
biological analytics.
 In the first case, no special modification for the target is needed when to deal
with those exhibiting sufficient intrinsic magnetic moments involving some
paramagnetic or ferromagnetic biomolecules or cells, such as ferritin,
hemoglobin and deoxygenated erythrocytes (in plasma).
In all other cases, when coping with diamagnetic molecules and
supramolecular structures, suitable magnetic modifications should be
performed in order to attach magnetic labels to targets or immobilize targets
to magnetic carriers or adsorbents.
The linkage of magnetic labels to the targets is often mediated by affinity
ligands or other types of interactions.

7. DIRECT AND INDIRECT MODES
Generally, magnetic separation can be performed in direct or indirect modes. In
the direct mode, magnetic affinity particles which possess appropriate affinity
ligands and exhibit affinity toward target compound(s), are applied directly to
sample.
After incubation, the target compounds or cells are binded to the magnetic
affinity particles, and stable magnetic complexes are formed.
In the indirect mode, free affinity ligands such as appropriate antibodies are
firstly added to the solution or suspension to enable the interaction with target
compounds.
After the excess unbound affinity ligand is removed from the solution, the
resulting labeled complex is captured by appropriate affinity magnetic particles.

8. In both methods, the resulting complex of magnetic particles with the target
structure is washed and recovered using an appropriate magnetic separator.
The two methods perform equally well.Generally, the direct mode is faster
and more easily controlled and requires fewer antibodies, while the indirect
mode is more efficient especially for the affinity ligands with poor affinity to
target compounds or cells.
However, the indirect mode usually needs excess antibodies or excess
magnetic particles, so the removal of free antibodies may be more difficult.
The magnetic force acting on a magnetic carrier is given by

9. Fig- A Schematic of Magnetic Separation in Biological Samples

11. MAGNETIC TARGETING
 Magnetic targeting is used when a therapy has limited ability to be chemically
targeted to specific types of cells or tissues due to high nonspecific binding.
 The force felt by a magnetic moment in a gradient field is:
 Early detection and targeted therapy are two major challenges in the battle
against cancer.
 Novel imaging contrast agents and targeting approaches are greatly needed to
improve the sensitivity and specificity of cancer theranostic agents.
 A novel approach has been implemented using a magnetic micromesh and
biocompatible fluorescent magnetic nanoparticles (FMN) to magnetically
enhance cancertargeting in living subjects.

12.  This approach enables magnetic targeting of systemically administered
individual FMN, containing a single 8 nm superparamagnetic iron oxide
core.
 Using a human glio-blastoma mouse model, Nanoparticles can be
magnetically retained in both the tumor neo vasculature and surrounding
tumor tissues.
 Magnetic accumulation of nanoparticles within the neo vasculature was
observable by fluorescence intra vital microscopy in real time.
 Finally, such magnetically enhanced cancer targeting augments the
biological functions of molecules linked to the nanoparticle surface.

13. Process of Magnetic Targeting
 First the physician injects an aqueous solution containing the nanoparticle
medication combination through a catheter into an artery of the patient.
 Next, the external magnetic field is applied so that the particles are carried
through the blood stream to the target destination and held there.
 The field is strongest at the pole tip of the magnet, i.e., close to the skin
surface.

15. Characterization of Magnetic-targeted Carriers
 When MNPs are allowed to move in a carrier, driven by thermal
agitation (Brownian motion) and their mutual interactions
(magnetostatic), they tend to form well- defined shapes such as chains
and loops, or more complicated structures such as branching points
and labyrinths, whose statistical morphology can be characterized as a
fractal.
 The aggregation mechanism and the resulting fractal morphology
depend on internal parameters (particle size distribution, magnetic
moment, particle shape, interparticle interactions, particle–carrier
interactions, particle density) and external conditions (temperature,
applied field).

16. MEDICALAPPLICATION OF MAGNETIC TARGETING
 Magnetic NPs can be used in a wide variety of biomedical applications, ranging from
contrast agents for MRI to the destruction of cancer cells via hyperthermia treatment.
 Most of these promising applications require well-defined and controllable interactions
between the MNPs and living cells.
MAGNETIC DELIVERY OF CANCER TREATMENT
 Chemotherapy is a balancing act between efficacy and toxicity and a number of strategies
have been developed that aim to resolve this dilemma.
 Chemotherapy via a regional artery administers a more concentrated dose of the active
agent directly into the tumor while limiting systemic drug concentration.
 The site-specific delivery of anti-tumor agents (Figure 2) tries to reduce the negative side
effects of systemic chemotherapy (intravenous application), and may be able to overcome
the multiple drug-resistant phenotype.

17. MAGNETIC DETECTION
• Magnetic sorting techniques have high potential for real-time detection and
monitoring of bacterial, viral and other pathogenic contamination .
Integrated structures utilizing nanolithography can perform sorting and
quantitative analysis in a single device.
• Magnetic transducers have low interference, low background signal, do not
require sample pre-treatment,and can be small enough to be portable.
• Magnetoresistive techniques have an advantage over techniques that use, for
example, MFM or AFM tips to manipulate magnetic beads attached to
molecules, in that they are much
faster and have the potential to detect more than one molecule at a time.
• Spin-valve and other magnetoresistive devices detect the stray field
from a magnetic micro- or nanobead.
• Lithographically fabricated microcircuits may be used to manipulate the
magnetic particles.
• Detection limits in the 100Nm can be achieved, and detection of
single particles is theoretically possible.

19.  Detection of multiple species on a single chip is possible by fixing a
probe molecule (often DNA) to a polymer layer covering the sensor.
 The analyte DNA is a single strand complementary to the
probe DNA and is labeled (often with biotin).
 Magnetic microspheres
functionalized with streptavidin (which attaches to biotin) are then
introduced.
 the microspheres bind to the biotin, which is present only on the
successfully trapped DNA.
 The signal measured by sensor can be used to quantify the amount of
analyte present.
 The response to the sensor is determined by the in-plane
component of the stray fields induced by the magnetized microspheres.
 Concentrations as low as 3.2 pglml have been detected .
 The introduction of tunneling magnetoresistance (TMR) sensing elements and
smaller magnetic markers will increase the sensitivity of the method.

20. REFERENCES
Book:
D.J. Sellmyer, Ralph Skomski-Advanced Magnetic Nanostructures-Springer (2005)
Research papers and notes:
http://onlinelibrary.wiley.com/doi/10.1002/cyto.990110203/abstract http://epsc.wustl.edu/geochronology/frantz.htm
http://www.lps.ens.fr/~vincent/courdea/PDF/marko.pdf http://scitation.aip.org/content/aip/journal/rsi/71/12/10.1063/1.1326056
http://scitation.aip.org/docserver/fulltext/aip/journal/rsi/71/12/1.1326056.pdf?expires=14103683
36&id=id&accname=2100920&checksum=88AC1ABE35C9CBBF630EAFC6D882E291
http://www.bourbaphy.fr/croquette.pdf http://www.nat.vu.nl/~wiedemey/Magnetic%20tweezers.pdf
http://pubs.rsc.org/en/content/articlepdf/2014/ib/c3ib40185e
http://nynkedekkerlab.tudelft.nl/wp-content/uploads/dekker_springer_handbook_single- molecule_biophysics_2009_Chapter13.pdf
http://onlinelibrary.wiley.com/doi/10.1002/cyto.990110203/pdf
http://nmmiweb.mgh.harvard.edu/CAMIS/?page_id=542 http://pubs.acs.org/doi/pdf/10.1021/nn301670a
http://circres.ahajournals.org/content/106/10/1570.full.pdf+html
http://www.cemag.es/Resources/files/Santander04/Pankhurst1.pdf