Super paramagnetic iron oxide nanoparticles (SPIONs):

development, surface modification and applications in chemotherapy

RIYAS BC.Department of Biochemistry and Molecular Biology

“Cancer is the name given to a collection of related diseases. In all types of cancer, some of the body’s cells begin to divide without stopping and spread into surrounding tissues”

• Cancer affects about 7 million people worldwide, and that number is projected to grow to 15 million by 2020. Most of those patients are treated with chemotherapy and/or radiation, which are often effective but can have debilitating side effects because it's difficult to target tumour tissue.

Types Of Treatment

The types of treatment that you receive will depend on the type of cancer you have and how advanced it is. The main types of cancer treatment include:

SurgeryRadiation TherapyChemotherapyImmunotherapyHormone TherapyStem Cell Transplant

• Applications of magnetic nanoparticles in biomedicine introduces the basic concepts of superparamagnetism and then presents the following applications in biomedicine :

• Drug delivery• Articial hyperthermia treatments of tumours• Contrast enhancement agents for magnetic resonance

imaging applications (MRI).

Super paramagnetic Iron Oxide Nano Particles(SPIONs)

• Super paramagnetic iron oxide nanoparticles (SPIONs) are small synthetic maghemite (γ-Fe2O3) or magnetite (Fe3O4) particles with a core diameter ranging from 10 nm to 20 nm.

• Their magnetization is zero, in the absence of an external magnetic field and they can be magnetized by an external magnetic source. This property provides additional stability for magnetic nanoparticles in solutions

http://www.sigmaaldrich.com/technical-documents/articles/technology-spotlights/iron-oxide-nanoparticles-characteristics-an applications.html

Advantages

Super paramagnetism

Long blood retention time.

Biodegradability

Less toxicity.

Large surface area to accommodate large number of functional groups.

High contrast than gadolinium Diethylene triaminopenta acetic acid

(Gd-DTPA) which is using in MRI.

Synthesis• Iron-oxide (IO) nanoparticles were synthesized by co-

precipitation method .The synthesis was carried out by coprecipitation of ferrous and ferric ion salts in aqueous solution by adding base at room temperature with flowing N2 gas

World Journal of Nano Science and Engineering, 2012, 2, 196-200 (http://www.SciRP.org/journal/wjnse)

Methods of Characterisation•XRD Analysis

IOP PUBLISHING Nanotechnology 23 (2012) 215602

FIG:TEM images of 20 nm diameter SPIONs.

•TEM Analysis

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Figure 1. Representative TEM images of (a) one-pot-synthesized dextran-coated iron oxide nanoparticles (DIO) with an iron oxide core measuring 6:5 1:2 nm, (b) uncoated iron oxide nanoparticles (obtained after step 1 of the two-step synthesis) with a core diameter of 17:7 6:6 nm and (c) two-step DIO with a core diameter of 18:0 4:1 nm. Scale bar D 50 nm. The histograms included below each image indicate the population size distributions for three batches of each, respectively

Nanotechnology 23 (2012) 215-602

•TEM Analysis

Tumour Targeting

•It relies on the enhanced permeability and retention effect(EPR).• Passive targeting is limited however because not all tumours exhibit the EPR effect and the degree of permeability of the tumour vasculature is not homogenous across the whole site .•This limitation will overcome by active targeting.

•Active targeting is achieved by modifying an NP through the attachment of targeting ligands to the NP surface.

•Ligands that recognize biological structures unique to or over expressed in cancer cells can then preferentially accumulate at tumour sites.

Passive Targeting Active Targeting

EPR effect(enhanced permeability and retention effect) The extravasation of particulate materials in to the tumor tissue and their

retention is called Enhanced Permeation and Retention (EPR) effect.

Tumour Targeting

Cytotoxicity Study

Figure 3. Dextran and PEG coating reduced iron oxide nanoparticle cytotoxicity, as measured by a Live/Dead assay. PAEC were incubated with 0, 0.1, 0.25 and 0.5 mg/mL of 5 and 30 nm bare and coated nanoparticles for 24 h. (A) Selected fluorescent images in which green = live cells and red = dead cells; and (B) Quantification of dead cell number by Image J. * p < 0.01, # p < 0.05.

Int. J. Mol. Sci. 2012, 13, 5554-5570; doi:10.3390/ijms13055554

Coating of SPIONs

IO nanoparticles without any surface coating are not stable in aqueous media and readily aggregate and precipitate. For in vivo applications, the particles often form aggregates in blood and are sequestered by macrophages.Therefore, the surface of IO nanoparticles should be coated with a variety of different moieties that can eliminate or minimize their aggregation under physiological conditions.

Coating of SPIONs is essential, because• It reduces the aggregation tendency of the uncoated

particles, thus improving their dispersibility and colloidal stability.

• Protects their surface from oxidation.• provides a surface for conjugation of drug molecules

and targeting ligands.• Increases the blood circulation time by avoiding

clearance by the reticuloendothelial system(RES). • Makes the particles biocompatible and minimizes

nonspecific interactions, thus reducing toxicity.• Increases their internalization efficiency by target cells.

a, A whole range of delivery agents are possible but the main components typically include a nanocarrier, a targeting moiety conjugated to the nanocarrier, and a cargo (such as the desired chemotherapeutic drugs). b, Schematic diagram of the drug conjugation and entrapment processes. The chemotherapeutics could be bound to the nanocarrier, as in the use of polymer–drug conjugates, dendrimers and some particulate carriers, or they could be entrapped inside the nanocarrier.

NanoCarriers

• Novel approach of delivering drug-loaded SPIONs by encapsulating them within cationic liposomes has been proposed by Yang et al.

• Chlorotoxin(Cltx) is a 36-amino acid peptide that can specifically bind to matrix metalloproteinase-2 (MMP-2) on the surface of cells. MMP-2 is over expressed in gliomas and other related cancers and degrades the extracellular matrix during cancer invasion (Soroceanu et al 1998; Deshane et al 2003;Veiseh et al 2007).

• Sun and colleagues (2008) conjugated Cltx to IO nanoparticles with covalently bound bifunctional PEG polymer and showed that internalization of the Cltx- conjugated IO nanoparticles by 9L glioma cells was 10-fold higher than that of the nontargeted nanoparticles after 2hrs incubation.

www.dovepress.com Dovepress Dovepress .Superparamagnetic iron oxide nanoparticles International Journal of Nanomedicine 2012:7

Delivering drug-loaded SPIONs

• Methotrexate (MTX) is an analogue of FA, which can exhibit both a targeting role as FA and a therapeutic effect in cancer cells that overexpress folate receptor on their surface. Kohler and colleagues (2005) conjugated MTX to IO nanoparticles (through amidation between the carboxylic acid end groups on MTX and the amine groups on the particle surface). Their results showed that cells expressing the human folate receptor internalized a higher level of MTX-IO nanoparticles than negative control cells

•Deng and colleagues fabricated a magnetic liposome structure for pancreatic cancer therapy . Here, ultra-small SPIONs were incorporated into a liposome containing doxorubicin . The surface of the liposome was coated with anti-mesothelin antibodies which are over expressed in pancreatic cancer cells and subsequently poly(ethylene glycol) to give stealth properties. The novel formulation was tested on PANC-1 cells.

A tissue distribution assay further proved that magnetic liposomes were capable of selectively accumulating inside the tumour xenograft.

Mechanism of Drug Delivery• At physiological pH-value doxorubicin is retained in the liposomes,

whereas drug release is achieved by lowering the pH to 5.5 (approximately 25% release at 25 °C or 30% at 37 °C within two h). The DXR release of liposome which were loaded via a sulfate gradient showed a maximum of 3% at pH 5.5.

2013

Guided and Enhanced Drug Delivery

Solid tumor

Apply magnetic field to concentrate particles

Modulate field to release drug from particles

Inject NMPs IV,NMP will circulate through the blood stream

Other options for targeting:1 - Direct injection into tumor site2 - Coating NMP with antibodies to target tumor

Magnetic Targeting

(a) A schematic drawing to illustrate in vivo magnetic tumor targeting.

MRI Contrast Enhancement

•Iron oxide NPs was used for the first time in clinic to image liver tumor and metastases .•Many SPIONs are in the first stage of clinical trials or experimental study and several formulations have been approved for clinical use for medical imaging and therapeutic applications.•Lumiren® for bowel imaging •Feridex IV® as a liver and spleen imaging agent. •Combidex® for lymph node metastases imaging and•Ferumoxytol® for iron replacement therapy.

Journal of Nanomedicine Research Volume 1 Issue 1 - 2014

In vivo MRI of the mouse liver before and 2 h after injection of dextran coated iron oxide nanoparticles.

Schematic diagram of cell target delivery and hyperthermia of tumors under the influence of alternating magnetic field: iron nanospheres (A), iron@Au core-shell nanosphere (B), iron@Au core-shell nanorods (C) and cancer cells (D).

Hyperthermia•“Hyperthermia, also called thermal therapy or thermotherapy, is a type of cancer treatment in which body tissue is exposed to high temperatures (up to 113°F). •Heating Tumour above 42ºC

Fig: Magnetite cationic liposomes (MCLs) can be used for intracellular hyperthermia

Internalisation• Intravenously

vascular endothelium is the primary barrier, in order to reach their target site. Hanini et al evaluated the interaction between human endothelial cells and SPIONs using confocal microscopy.

Human umbilical vein endothelial cells were incubated with labeled SPIONs at a concentration of 10 µg/mL. The Iron Oxide nanoparticles were efficiently internalized by the human umbilical vein endothelial cells.

Elimination Eliminated through kidney, because this route involves minimal

intracellular catabolism, reducing the probability of generating reactive oxygen species and hence associated toxicity. Renal excretion represents the safest route of elimination for SPIONs.

It can be removed from the circulation by either via uptake by the RES(Reticulo Endothelial System) (200 nm)

Draw Backs SPIONsThere are still many obstacles for successfully delivering drug using tumour-targeted IO nanoparticles in vivoFunctional group modification of the drugs during conjugation may change their chemical properties. Quick release of conjugated or encapsulated drugs from IO nanoparticles in the blood before entering into tumour mass. Drugs usually released in the endosome or lysosome but not in the cytoplasm within targeting cells. Embedding part of the ligand binding site in IO nanoparticles may decrease the targeting ability.

IO nanoparticles combined with other nanoparticles such as biodegradable and biocompatible polymeric micelles may overcome some of the above obstacles.

The days are not far off when we will walk into a clinic, the doctor will inject SPIO nanoparticles, the disease will be detected, treated with nanoparticles and we can walk out of the room in a few hours.

References Xiang-Hong Peng,Ximei Qian,Hui Mao,Andrew Y Wang,Zhuo (Georgia)

Chen,Shuming Nie,Dong M Shin; Targeted magnetic iron oxide nanoparticles for tumor imaging and therapy; International Journal of Nanomedicine;2008:3(3) 311–321.

Clare Hoskins, Institute of Science and Technology in Medicine, Keele University;The Use of Iron Oxide Nanoparticles for Pancreatic Cancer Therapy;Journal of Nanomedicine Research;Volume 1 Issue 1;sep 24 2014.

Richard A. Revia ,Miqin Zhang; Magnetite nanoparticles for cancer diagnosis, treatment, and treatment monitoring: recent advances;Elesevier; Materials Today September 2015.

Joshua E. Rosena, Lorena Chana, Dar-Bin Shieh, DDS, DMScb, Frank X. Gu; Iron oxide nanoparticles for targeted cancer imaging and diagnostics; ElesevierNanomedicine: Nanotechnology, Biology, and Medicine 8 (2012) 275–290.

Thank You