Monday, May 23, 2011

Cancer nanotechnology: current scenario

 Cancer is one of the leading causes of mortality worldwide. Every year, a large number of patients suffering from cancer die. This number is continuously rising with an estimation of about 12 million deaths from cancer by 2030. The current treatment given to cancer patients primarily includes chemotherapy (where anticancer drugs are used to kill the cancer cells) and radiation therapy (where radiations are focused on the infected areas to kill the cancer cells). However, both the therapies are associated with severe toxicities due to their inability to differentiate between cancer cells and normal cells. Hence, to overcome this, many laboratories are trying to develop an arsenal based on nanotechnology to fight against this dreadful disease. In this article, the nanotechnologies used for treating cancer have been discussed briefly.

Why nanotechnology?

Over the past few years, many pharmaceutical companies, institutions and R&D laboratories all over the world are trying to develop nanotechnology based drug delivery systems. Nanotechnology, as defined, is the creation and application of devices, drugs or any materials that are in the size range of 1-100 nm in size. This extremely small size of such appliances offers several advantages in drug delivery while treating diseases like cancer. The major advantage is the ability of such systems to penetrate the biological membranes with ease and become available at the target site. As a result, nanotechnology has found very wide applications in drug delivery systems.

Current cancer nanotechnologies

Nanobiosensors have found to have diagnostic applications in cancer. A biosensor is basically made up of several components including sensitive biological element, a transducer and a detector with the help of which they detect the analyte. Typically when such a device is in nano dimensions, they are termed as nanobiosensors. Many different types of nanobiosensors have been produced which are claimed to be of use in early cancer detection. The cancer specific ligand or antibody present in such sensors selectively captures cancer cells thereby producing signals, which are ultimately detected by the detector. Such devices are projected to be of utmost importance for cancer diagnostics in future.

Liposomes have been used to deliver drugs in various cancer indications. With its help, the concentrations of anticancer agents at the target site have found to increase and thereby better efficacy and bioavailability can be expected from such systems. For instance, many anticancer drugs like Doxorubicin and Docetaxel have been used using liposomes as the drug delivery system. One of the most important advantages of liposomes as a carrier system is that they are made up of lipids which are biocompatible and non toxic to the human body.

Dendrimers are a class of macromolecules, which are repeatedly branched. They have found their applications in many fields including engineering, medicine, nanobiotechnology, to name a few. More than 5000 patents and publications have been reported on this novel class of molecules regarding their synthesis and potential applications. They have been projected to be a potential MRI contrast agent that can be utilised for diagnosis and treatment in cancer therapy. One of the research groups at the University of Michigan have successfully synthesised dendrimer-based MRI contrasting agent, which successfully targeted tumors in animal models.

Nanoparticles, including polymeric nanoparticles and lipid nanoparticles are used in research for their applications in drug delivery for cancer. Many biodegradable polymeric nanoparticles like PLGA (poly lactide co glycolic acid) and PEG (poly ethylene glycol) have been utilised as drug delivery carriers for anticancer agents. Being biodegradable they are non-toxic and can be degraded within the human body to release the drug. With the help of such polymeric nanoparticulate systems, sustained release of drugs have obtained a reduction in the associated toxicities. A large number of anticancer agents like Docetaxel, Doxorubicin, Cisplatin, Doxorubicin have been successfully encapsulated in such carrier systems. In addition, such polymeric nanoparticles have also shown to simultaneously encapsulate two drugs, thereby aiding in dual drug delivery and better efficacy. Such systems also help in better targeting of the drugs at the infected areas, thereby minimising toxicities.

Besides this, many different types of quantum dots, nanoshells, nanocantilevers, nanowires, nanotubes and fullerenes have been synthesised, characterised and researched for their potential applications. Quantum dots-based nanobiosensors have been developed. Nanoshells have also found applications in cancer treatment. Hollow Gold NanoShells (HGNS) have shown to be of use in photothermal therapy wherein such systems, after they reach the infected areas, are irradiated due to which they get heated and kill the cancer cells. Such systems have shown great promise for future cancer treatments.

Currently, many scientists are also trying to combine and integrate different systems in one system. For instance, many scholars at Nanobios laboratory at Indian Institute of Technology Bombay, are trying to encapsulate one or two anticancer drugs in a polymeric system to which gold nanoshells are attached. Such systems may be given intravenously directly to the infected areas. After reaching the target site, they can be irradiated as a result of which gold nanoshells get heated up and kill the cancer cells. Also due to the heat generated, polymeric particles may get degraded or thermoresponsive polymeric system may release the anticancer agents encapsulated within it. Such systems seem to be a great breakthrough in cancer therapy where radiation therapy and chemotherapy is combined into one system. Such systems are also projected to reduce the side effects and associated toxicities due to the conventional radiation therapy or chemotherapy.

To conclude, we can say that current cancer nanotechnologies have shown great promise for their practical applications in the diagnosis and treatment of cancer. However, plenty of research is still required especially focusing upon their toxicities and efficacy.

Source: ExpressPharma

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