Nanotechnology is defined as the technology which includes study and manufacture of devices and structures in nanometer range. These nanosized objects like nanoparticles have novel properties and functions. Cell specific targeting can be achieved by attaching drugs to individually designed nanocarriers. The small size, improved solubility, modified surface and multi utility of nanoparticles open many doors in new biomedical applications.
Today nanotechnology is involved in every field of science. In medical science nanotechnology is useful for disease diagnosis and its treatment. The nanotechnology is applied in manufacture of devices which structure is in nanometer scale. Nanotechnology used for tracking changes inside the body and treatment according to the changes. So it is the great achievement by the scientists. Nanotechnology based drug delivery systems uses nanoparticles (between 1-100nm) or nanomedicines or nanocarriers. So nanoparticles transformed the process of treatment and diagnosis of diseases. Nanoparticles can change or copy the biological processes. Nanoparticle is a small unit which behaves as an object when it is transported. It increases the capability and decreases side effect of medicines. These nanoparticles remain other organs healthy by decreasing the exposure of drugs. It enhances drug distribution to target site by delivering a concentrate dose of drug. Nanoparticles have high potency of converting the poorly soluble drugs into good deliverable drugs. Scientists are interested in nanoparticles because of their important properties like reactivity and solubility.
The most widely used polymers for nanoparticles are polylactic acid (PLA), polygly colic acid (PGA). During the 1980s and 1990s many drug delivery options were developed to minimize its side effects and improve the efficiency of drugs. In early stage nanoparticles were mainly obtained from polyalkylcyanoacrylate. The primary challenge for nanoparticles was reduced by the factor that there was a size limit for the particles for crossing the intestinal cavity to the lymphatic system through the oral delivery. The surface of nanoparticles is designed to get affinity towards specific cells.
Another class of nanosized particles used in drug delivery applications is liposome. These are prepared from lipids and used as potential drug carriers. They protect the drugs in their core.
The conjugation of drugs to the nanocarrier and the way of its targeting is most important for a targeted therapy. A drug may be adsorbed or covalently attached to the nanocarriers surface or it can be encapsulated into it. The covalent linking leads over other ways of attaching because it controls the drug molecules connected to the nanocarrier.
Once the drug-nanocarrier conjugates reach the diseased tissues, the drugs are released. The changes in physiological environment such as temperature, pH or via an enzymatic activity also controls release of drugs from nanocarriers.
Undesirable effects of nanoparticles strongly depend on their hydrodynamic size, shape, amount, surface chemistry, the route of administration, reaction of the immune system (especially a route of the uptake by macrophages and granulocytes) and residence time in the bloodstream.
Uses of nanoparticles
Nanomedicine uses atomic sized particles to target drug delivery for particular cells in the human. Due to their small size, nanoscale particles can properly communicate with biomolecules on both the surface of cells and inside the cells. When they entered into the body they can possibly identify sick area and then convey treatment. Nanoparticles can directly sedate the diseased cells in the body.
A wide variety of drugs are delivered by using nanoparticles via a number of routes. Nanoparticles are used to deliver hydrophobic drugs, hydrophilic drugs, proteins, vaccines, biological macromolecules etc. They are used for targeted delivery to the brain, lymphatic system, arterial walls, lungs, liver and spleen. The major contribution of nanomedicine is in the treatment of cancer. They target the drug to the tumor as well as reduce multidrug resistance (MDR). So nanotechnology provides an alternative way to traditional way of therapy and decreases chance of multidrug resistance. Nanoparticles made from synthetic and natural polymers have gained the major attention due to their stability and easily surface modification. The first nanoparticle was Abraxane approved by US FDA in 2005, which is used in the treatment of head and neck cancer, lung cancer, metastatic breast cancer and anal cancer.
Sometimes these nanoparticles may destroy the patient’s lifetime. But at the same time nano materials enhance the life time of the drugs and save patient’s life. Nanocrystalline zirconium oxide (zirconia) is hard and its bio consumption is safe. Hence it used as preferred option material as carriers. Nanocrystalline silicon carbide is used in heart valves preferably due to its low weight and high quality.
Another important application is to carry the drug molecules in targeting brain disorders by crossing Blood Brain Barrier (BBB), main obstacle to transportation of the drug to the brain. It is useful in treating various Central Nervous System (CNS) disorders. A poorly distributed drug to the brain can be loaded on a nanocarrier system which interacts with the BBB and produces higher drug concentrations in brain cells.
Nanomaterials are manipulated to create a new drug delivery system which solves the problem of poor water solubility of most anticancer drugs. So nanomaterials increase the efficiency of drugs. The poorly soluble anticancer drugs require the addition of solvents for easy absorption into cancer cells. These solvents not only diminish the potency of the drugs but make them toxic. Curcumin, cooking spice turmeric has anticancer properties. Since its solubility is very poor this reduces its efficiency. This problem is solved by encapsulating curcumin in a polymeric nanoparticle called as nanocurcumin. The mechanism of action of nanocurcumin on pancreatic cancer cells like that of free curcumin.
Delivery of drugs via nanoparticles need near about 1,000 times fewer dose than the dose of the free drug required for tumor growth suppression. Reduced dose is an important factor for limiting toxic effect.
Nanomaterials enhance the life time of the inserted materials. Since nanocrystals of zirconium oxide (zirconia) is hard and its bioconsumption is safe. Hence it exhibits an appealing option material for inserts. Similarly nanocrystalline silicon carbide is a hopeful material for duplicate heart valves essentially due to its low weight and high quality. Nanotechnology could moreover be used as a piece of reducing environmental pollution.
Titanium dioxide and zinc oxide are discovered as nanoparticles in sunscreen’s application. Iron oxide in nanosize is also present in a few lipsticks as a pigment.
Nanoparticle involved drug delivery systems hold great potency to overcome from some of the obstacles to efficiently target a wide variety of cells. This reflects an exciting possibility to overcome problems of drug resistance in target cells and to facilitate the movement of drugs across barriers. The challenge, however, remains the precise characterization of molecular targets and ensuring that these molecules only affect targeted organs.
Furthermore, it is important to understand the role of the drugs once delivered to the nucleus and other sensitive cells organelles. Nanomedicine is the best way which involves nanotechnologies making a better and healthier human life.