Nanoparticles are used in medicine at various stages, including design, manufacture and administration and monitoring of drugs. Apart, nanoparticles are also useful in diagnosis and therapy. Nanoparticles, no matter whether they are of micro or macro size, exhibit properties like strength, electrical conductivity, elasticity and colour.
Benefits of nanomedicines are:
● For the detection of cancer by specific markers in the blood using molecules of prostate specific antigen (PSA)
● For the identification of location and size of prostate cancer and malignant tumour by cadmium salenide
● Gold nanoparticles of 13-20 nm diameter functionalised with a defined number of antibodies that are specific to a particular protein can be detected in blood
Nanoparticles can assist in diagnosis as contrasting agents in ultra sonography, magnetic resonance imaging (MRI) images as well as delivery by virtue of long residence time in the treatment due to their penetration inside the cell, including the nucleus and access event to even brain, crossing the blood-brain barrier, besides stimulating the natural repair process. Tracking of proteins has become easy by virtue of their intensity of colour, where exposed to UV light as compared to fluorescent dyes in vitro as well as in vivo.
We can track a single protein in the living cell. The colour of nanoparticles depends on particle size 2 nm glow bright green and 5 nm particles appear dark red. Different proteins can be detected. The photodynamic therapy involves gold coated nanoshells (120 nm) that have conjugated antibodies or peptides that make them get attached to cancer cells. When the tumour is irradiated by infrared laser gold gets heated thereby killing all the cancerous cells. Similarly, folic acid is used in the dendrimers for target delivery system.
Nanometre sized particles of pharmaceuticals are used to manufacture drugs like antiemetics cholesterol lowering drugs, aneroxia, cachexia and during renal transplantation.
In ovarian cancer, a liposome is used to encapsulate the drug to prevent detection and destruction by immune system. Biocompatible and biodegradable scaffolding of nanostructured polymer is seeded with cells taken from patient. The cells regenerate fast and the scaffold dissolves slowly peptide amphiphiles assist in cell growth and in the treatment of bone injuries.
Silver kills microbes and nanocrystalline silver is used as an anti microbial coating on wound dressings and catheters.
Due to the unusual properties of high reactivity due to large mobility due to size may lead to toxicity and studies have to be done on long term toxicity.
(The author is former director of Institute of Genetics & Hospital for Genetic Diseases)