What Is The Nanoparticle

Published Date: 02 Nov 2017

Figure1"A particle having one or more dimensions of the order of 100nm or less". http://www.nanodic.com/Nanomaterial/Nanoparticle.htm. Bulk property of a material in nano-sized structure which differ significantly from the actual material.This is achieved by altering the size of building blocks can control the internal and surface chemistry,electrical conductivity, magnetic properties and many more(Monosson Emily March 20, 2010). There is no international definition of a nanoparticle, but one given above is in the new PAS71 document developed in the UK. Webhttp://www.malvern.com/labeng/industry/nanotechnology/nanoparticles_definition.htm

"Novel properties that differentiate nanoparticles from the bulk material typically develop at a critical length scale of under 100nm". This makes the size of particles or the extent of its character the largely vital feature of nanoparticles.

What is so unique about them about a nanoparticle?400px-Mesoporous_Silica_Nanoparticle.jpg

There are not any stringent parametersseparatingthe nanoparticles from the non-nanoparticles. "The dimension at which materials exhibit dissimilar properties to the bulk material is solely dependent on the nature of the material and can unquestionably be claimed for many materials much larger in size than 100nm."(Monosson Emily March 20, 2010).

How do you manufacture nanoparticles?

Most of these nanomaterials are manufactured straight from the dry powders. The most come miss conception that these powders will preserve their nature of state when they are stored. The truth is they will swiftly form clumps through a solid bonding mechanism in no time. Whether these aggregates/clumps are unfavourable will depend completely on the purposeof the nanomaterial. To preserve the properties associated with the nanoparticles they need to be maintained disconnected, they must be primed and stored in a liquid medium calculated to aid adequate interparticle repugnance forces to avert aggregation (Monosson Emily March 20, 2010).

Nanoparticles can also be described as being submicronic (< 1 μm) colloidal substances commonly, but not essentially, made of polymeric molecules (biologically degradable or not). Depending on the process adapted for the preparation of the nanoparticles, nanospheres or nanocapsules can be yielded. "Unlike nanospheres (matrix systems in which the drug is dispersed throughout the particles), nanocapsules are vesicular systems in which the drug is confined to an aqueous or oily cavity surrounded by a single polymeric membrane. Nanocapsules may, thus, be considered as a ‘reservoir’ system" (Briggeret.al December 2012)

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If premeditated suitably, nanoparticles may potentiate as a drug vehicle capable to target tumor tissues or cells, to an appreciable extent, whilst shielding the drug from untimely inactivation through its transport.

In today’s time there is en-number categories of nanoparticles are made and are available.

Carbon-based nanomaterials: fullerenes (that is, cage-like carbon structures);

single-walled carbon nanotubes (SWNT) in the form of a tube (or they appear as a cage-like);

buckyballs (60 carbons in the shape of a sphere).

Metal-based nanomaterials which consist of quantum dots, metal oxides and pure metal nanoparticles.

Quantum dots are structures that minute that their features are susceptible to the removal of a single electron. (Silicon and germanium or cadmium and selenium are a few examples to be named)

Metals can also exist as single ions or larger bulkier structures gold or silver nanoparticles.

Dendrimers are branched polymers which can be manufactured in such a way that they can carry other molecules within themselves (Monosson March 20, 2010).

Diverse kinds of nanoparticles have been developed for application in cancer diagnosis/therapy: inorganic [iron oxide based (magnetic) and other inorganic nanoparticles (Table 1)] and organic nanoparticles (Table 2) (based on information reviewed in Cuenca et al., 2006; Couvreur and; Alexiou et al., 2006).

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The table 1 explains the inorganic nanoparticles as magnetic, metallic, nanoshells and ceramic kind. It has briefly illustrated its properties advantages and the application. Below in table 2 it elaborates the organic nanoparticles(Tang et.al 2007 June).

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Nanoparticles: Cancer Diagnostics and Therapy

The role of nanotechnology- nanoparticles in cancer identification and cancer therapy is solely revolving around; the mean and engineering of <100nm particles of inorganic and/or organic origin. By good feature of their nanosize, these particles are very much capable to explicitly target tumor tissue. Earlier studies of nanotechnology focused basically on the liposomes, gelatin, and micelle based particles to progress the mechanisms of drug delivery and reduce the drugs side effects. It’s only the recent development in design and engineering has led to the discovery of the various kinds (as mentioned above) of nanoparticles. They are extensively explored for numerous applications in the field of biomedical sciences. They have found place in cancer imaging, drug delivery, tissue repair, detoxification of biological fluids, and hyperthermia. Above all the approval from the FDA; based on the preclinical and clinical studies have proven them safe. The formulations are successfully approved for use in clinical imaging and drug delivery (Tang et.al 2007 June).

Nanoparticles exhibit inimitable physico-chemical properties with respect to precise tumor targeting. This is largely based on the favoreduptake and accumulation of nanoparticles of ≤100nm in the tumors. The reason being; it’s enhanced permeability and retention effects produced by their hyper permeable vasculature and insufficient lymphatic drainage.  Currently the area of research pertaining to nanoparticles and cancer is to use its enhanced specificity; to design and develop nanoparticles for cancer imaging (MRI, optical imaging) and but obvious cancer therapy. Efforts are put in the direction to now make it possible to custom design their functional properties for targeting specific cancers and metastases (Tang et.al 2007 June).

Cancer Diagnosis and Imaging via Magnetic Nanoparticles

The figure besides illustrates for applications of inorganic nanomaterials in various imaging modalities. CT denotes computed tomography, MRI magnetic resonance imaging, PET positron emission tomography, SPECT single photon emission computed tomography, GN gold nanocage, QDs quantum dot, QRs, quantum rod, CNTs carbon nanotubes, MSN mesoporous silica nanoparticles, and Au gold nanoparticles.(Yang October 2012)

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Magnetic nanoparticles conjugated to targeting ligands are used to identifycirculatedcancerous metastatic cells in existence of magnetic field and examine disease eminence due course of the treatment (Alexiou et al., 2006).

The commercially available water suspensions of polymer-coated ferromagnetic nanoparticles have superior magnetic vulnerability (Superparamagnetic contrastagents) than the traditional MRI contrast agents like gadolinium (Alexiou et al., 2006). Their incidenceradicallyweakens the MRI signal and creates a negative intensification effects on images generated.

MRI-enhancing/improving contrast molecules include superparamagnetic iron oxide (SPIO, >50nm) and ultra small superparamagnetic iron oxide (USPIO, <50nm) particles (Couvreur and Vauthier, 2006). Impounding of SPIO nanoparticles throug the RES produces high contrast imaging of splenic/hepatic tumorsor metastic cells. USPIO nanoparticles are circulated for much longer in the blood and have wide tissue deliverydue to their capability to keep away from RES confiscation. They are more over preferredfor detecting/identifyingmetastases in lymph nodes (LN).(Corot et al. 2006).

Nanoparticles in cancer therapy, drug delivery and MRI

Unlikethe conventional drugs used in cancer treatment the nanoparticles preferentially amassin tumorsdue to their improvedpermeability and withholdingeffects, leading to MRI signal loss. Magnetic nanoparticles are purposefully designed in such a way that they can help cancer-specific MRI enhancement, for example,by detecting/identifying changes in MRI contrast due to telomerase activity of cancer cells or apoptosis (cell shrinkage and membrane blebbing) to determinecurative responses in vivo (Cuenca et al., 2006).

In a latest preclinical study, precise tumoral amassing of intravenously injected magnetic nanoparticles labelled with a near-infrared dye and covalently concurrent to small interfering RNA (siRNA) was established by in vivo MRI and optical imaging; explicit silencing of an apoptosis inhibitor protein was achieved, leading to improvedtumor apoptosis and necrosis as seen in figure 4 (Medarova et al., 2007).

"Magnetic targeting uses a strong, high-gradient external magnetic field to capture and concentrate nanoparticles in target areas, facilitating delivery to tissues with poor accessibility" (Alexiou et al., 2006).

Efficient release of magnetic nanoparticles depends on physical parametes of (field strength, gradient, magnetic properties), hydrodynamicand physiological parameters accountability of blood flow rate, ferrofluid concentration, infusion route, circulation time and tissue depth to target site, reversibility, strength of drug/carrier binding, tumor volume parameters. A most important challenge is providing adequately physically powerful magnetic fields to centre particles on minute areas whereas counteracting linear blood-flow rates. Magnetic targeting is further viable with generously proportioned particles (~1μm) that can better endure flow

dynamics and in regions of slower blood flow or those acquiescent to close organization with magnets(Tang et.al 2007 June).

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Advantages of Nanoparticles: (Grill, et.al 2009, Gelperina, et.al 2005, Susa, et al 2009, Sajja, et. al 2009).

The nanoparticles have longer shelf-stability, high carrier capacity. They have an ability to incorporate hydrophilic and hydrophobic drug molecules; they can be administered via different routes, they have longer clearance timealso. They possess the ability to sustain the release of drug, to be utilized for imaging studies. They have increased the bioavailability of drugs; it deliversat cellular and nuclear level, more and more development for launching the protein later. They also have the ability to prevent the multi-drug resistance mediated efflux of chemotherapeutic agents and above all product life extension.

An ideal example is the nanorods to identify/detect cancer; it has numerous reason to be favoured over flow cytometry, in which uses a fluorescent molecule thatbind to cancer cells. Low costing, use of low sample size required by nanorods is capable of helping to determine an earlier diagnosis. All the more it needs less invasive procedures in comparison to other methods (nanorods use blood samples not biopsy). The added advantage of this is that scientists can use conventional microscopes and light sources to view the samples versus other methods that utilize expensive microscopes or lasers contributes to the overall cost savings of nanorods(Tang et.al 2007 June).

Disadvantages of nanoparticles: (Mainardes et al 2005,  Jong et.al 2008, Varde et.al 2004)

a)Involves higher manufacturing costs which may in turn lead to increase in the cost of formulationb) Involves use of harsh toxic solvents in the preparation processc) May trigger immune response and allergic reactionsd) Extensive use of poly(vinyl alcohol) as stabilizer may have toxicity  issues(Tang et.al 2007 June).

Careful contemplation must do regarding the disposal techniques for nanoparticles used in manufacturing or other processes. It is imperative that particular disposal methods are practiced to stop destructiveparticles from ending up in the water supply or in the general environment, where they would be nearly impossible to track.

Another most concerning points would be the thought of mass poisoning. If the coatings contain toxic nanoparticles which are capable of transgressing the blood-brain barrier, they then run the risk of creating mass poisoning.

Ethical Issues related to the use of nanoparticles:

Nanotechnology offers and appreciable level of positive drastic technological advances, but the ethical issues related to the same should be encountered wisely. The most dreadful fact put forth is the sustainedprologueof nanoparticles would lead to an highly advanced engineered human population which would in a short period dominate and become hyper-intelligent and far more powerful as to compared to the current average human. The further most common threat would be realised by the community that it can be sustained or afforded by the finically well to do class. Consequently this would lead to a formation of hierarchy in the human population which in turn would, leave the individualswe are now as the underclass citizens.

With the use of nanotechnology we are using particles that are so diminutiveand can pass through almost all membranes. We must consider the fact that this is something we can neither perceive nor control, at the moment. Another problem is that the implications of nanotechnology are revolutionary - but the consequences could be severe. Jobs will be under threat as an explosion of new technology

Conclusion

The major highlight in the assay has been nanotechnology-nanoparticles; applications of nanoparticles in the imaging, detection and elimination of cancer cells; the advantages and disadvantages of their use; and the ethical issues of using nanotechnology-nanoparticlesin medicine. We have focused on nanoparticals as drug molecules, as carriers and many more.

We recognize the shortcomings related to the continuous use of nanoparticles. For example, due to their small size they can cross almost anydevelopedmembrane, and would be enormouslycomplicatedto trace. However we anticipatethat the nanoparticles can be developed so that they only attach to the cancer cells and any unboundexcessnanoparticles will be engineered to exit, rather than linger in the body. We hope that the work of scientists will continue to advancenanotechnology in medicine and that the advances in this area ofmedicine will fulfilthe potential that nanotechnology has to offer.