Nanotechnology is set to revolutionize the healthcare, agriculture, textile and energy sectors. While the 19th century saw great advances in textiles and 20th century, in the transport system ; 21st century is set to be revolutionized by nanotechnology products that are applicable in the entire spectrum of human activity. And already several products are in the market.
The word 'nano' means 'dwarf' in Greek language and refers to dimensions on the order of magnitude of 10- 9 that focuses on special properties. For example in biological system the first level organization is nanoscale structure where all the fundamental properties and functions are defined systematically.
Nanotechnology is a method primarily of molecular engineering for the creation of materials and machines, which is likely to enable us to snap together the fundamental building blocks of nature inexpensively. Manufacturing at nano level enables us to work at atomic level and fabricate new generation products that are cleaner, stronger, lighter and more precise.
Nanobiotechnology
This technology uses a vast array of microbes or micro-organisms with a vast diversity. The microbes are the workshops in nature. These organisms have been playing a vital role in the maintenance of eco systems and environment. It is only in the last century the utilization of microbes has reached the zenith for the exploitation of their genetic potential that revolutionized genetic engineering technology. Microbes do play a vital role in almost all the activities of human being ranging from food,medical and health energy, environment, biodiversity, metal leaching of toxic and oil wastes, besides contributing to a range of product to replace chemicals with bioinsecticides, bioviricides and bioweedicides.
Micro-organisms are continuously exposed to stressful situations and their ability to resist these biotic and abiotic stresses is essential for their survival. The ability of microbes to grow in high metal concentrations results from specific mechanisms or resistance. These mechanisms are efflux system, alteration of solubility and toxicity by changes in redox state of metal ion, extracellular complexation or precipitation of metal and the lack of specific metal transport systems. These metal-microbe interactions have an important role in several biotechnological applications including the fields of bioremediation and bioleaching.
The contribution of microbiology to nanotechnology is indeed very important. Metal-microbe interaction studies have led to the synthesis of microbial derived nanocrystallites like cadmium sulphidee, lead and gold by the Agarkar Research Institute, Pune. Dr. Pakniker Group have synthesized cadmium sulphideee nanocrystallite of 2 to 2.5 nm size range by an yeast strain of Schiozosaccharomyces pombe. Similarly, 2-5 nm size range of lead sulphide of 5 to 8 nm size range of gold and silver crystallites were synthesized. Bhabha Atomic Research Centre has developed nano silver material by extracellular products.
Application in medicine and health sectors
Proteins, nucleic acids , DNA/RNA, lipids, polysaccharides are all examples of .materials that are building blocks of life due to their inherent nanoscale size configurations.
Their applications are
?Genetic diagnostic tools and therapy through DNA biochips, intracellular sensors for monitoring cells in the body.
?New formulations for drug delivery to exactly deliver the drug to the targeted cells that are even inaccessible.
Novel rejection resistant artificial organs attain higher performance due to their contact surface nanostructure that is biocompatible with the human body.
The growing incidence of multi drug - resistant bacteria has become an acute problem through the indiscriminate use of antibiotics that has finally led to the renewed interest of the antimicrobial properties of silver.
Silver ions have received great attention due to their attractive physico chemical properties. The surface plasma resonance and large effective scattering of individual silver non's make them the ideal candidates for molecular labelling also.
Mode of action
Silver ions rapidly kill the microbes in a variety ways like blocking the cell respiration pathway, interference with the components microbial electron transport system that has effect with bacterial signal transduction, binding to DNA and inhibition of DNA replication. Silver ions bind at molecular level the effect of which does not wear off'; cannot be neutralized by sweat or detergents and continues to work as long as the product exists.
With their rich history in medicine and advances in sciences using nanotechnology to improve the therapeutic properties of the noble metals could lead to new and improved medicines and medical devices.
?Gastrointestinal diseases cause heartburn, acid digestion and bowel disorder. Many gastrointestinal disorders exhibit both infection and inflammation and represent the potential targets for silver nano crystal. Inflammatory Bowel Disease (IBD) comprises ulcerative colitis and Crohn's Disease which cause inflammation and ulcers in lining of the rectum and colon that affect half a million people in U.S.A that led led that country to spend $ 500 million in 2006 to treat the condition according to IMS health.
About half the people diagnosed have mild symptoms. The first line treatment for mild to moderate disease is aminosalicylates (5-ASAs) which do not work in all and is not well tolerated in many. Silver nanos have tremendous potential in this aspects.
Silver nano particles are used in antimicrobial coatings, medical devices including bioinert and absorbable materials and lubricant coatings.
Nanoships to defect SNP's (Single nucleotide polymorphism) and STR's (Repeats) as genetic markers in clinical medicine.
Gene expression systems and on-chip amplification of gene expression of study the drug reactions in individuals.
Medical
In the medical field, application is found in miniature analyticaldevices for diagnostics like lab-on-a-chip system although biochips or lab-on-a-chip system are microfluidic devices. These are often discussed in the context of nanotechnology.
Molecular diagnostics involves detection of analytical molecules for example gold nanocrystals are also magnetic nanoparticles used as markers for the substances like proteins and DNA.
The detection methods is based on several systems such as fluorescence spectroscopy, magnetic field measuring, electron microscopy. The optical colour changes is suitable for self diagnosis for the patients. Molecular diagnostics is the fastest segment of the in vitro diagnostic industry that reached 5 billion by 2008.
Drug delivery
Controlled and targeted drug delivery systems can be developed provided the nanoscale, transportable vehicles are formulated. Transport system can be developed from nanoscale cage molecules. The goal is to carry the active drug selectively to the targeted cells by means of nanoparticles with specific function al sites. Nanoparticles penetrates the cell membrane and overcome the physiological barriers in the organism. Nanoscale suspension improves the solubility and bioavailability of drugs.
The most prominent application of nanos is tissue and cell specific drug delivery unlike liposomes, dedrimers, metal and semiconductor nanos made of biopolymers such as bacterial spores, viruses that are natural, uniform in size and other precise control for the surface displayed targeting groups and other components.
Anti VEGF antibodies on gold/ silver nanos increase the ability of these antibodies to induce apoptosis in chronic lymphocytic leukaemia Bcells.
Range of medical products
?Products
?Silver in nanoform
?Antimicrobial dressings - gauze, cotton and catheters.
?Anti-infection powders/ bacteriocides
?Nanoemulsions against bacteria (E Coli, Salmonella, Anthrax) Viruses (Herpes, HIV 1) and Fungi (Candida albicans).
Preventive medicine
Human monoclonal antibodies against the GP 120 of HIV I coupled to Nano silver kill the virus before entry into the cell (CD 24. T4)
Therapeutics
?Ulcerative Colitis (UC) is the first area of focus that causes inflammation and ulcer lining of the colon and rectum at present it is being treated by aminosalicylates (5-ASA) as the first line of treatment. But the drug is not well tolerated. Silvernano's play a significant role and has tremendous potential in the treatment.
?Silvernano's coupled to tumour markers of cancer cause apoptosis (cell death).
?The wide-spread infection by clostridium difficile associated disease has created a good market. The current treatment with powerful antibiotics like metronidazole and vancomycin kill the vegetative form and not the spores that are implicated in reinfection inresilvernano treat the infection as well as prevent its recurrence.
Clostridium Difficile Associated Disease (CDAD) is an important and growing medical problem. The frequency of condition has doubled in USA since 2000 due to increased use of fluroquinolone antibiotics and proton pump inhibitors which are treated with powerful antibiotics like metronidazole and vancomycin that kill only the vegetative form and the recurrence occurs with spore form. Silvernanos are able to kill both the forms that makes it a leader both in prevention, as well as treatment.
Nanotechnology has the potential to revolutionize the scientific world by aiding scientists to manipulate matter at atomic or molecular scale. From the moment of the creation of the universe to the first signs of life on the earth, self organization has existed.
Nature has evolved many bioorganic molecules that form complex structures with complex dynamic behaviour called a living cell. These living cells assemble and form further complex structure culminating in intelligent life forms like humans and animals. When living cell is wounded, the body reacts immediately by sending white blood cells to ward off the infections by killing the germs and red blood cells and proteins to form a seal cover over the wound and also supply nutrients to the cell to make new cells to replace damaged cells. This is custom process made for specific applications. When materials are built from a bottom-up approach, a molecule at a time, it is possible to incorporate feature at will. This concept of self assembly with nanotechnology has potential ranging from biology to material science.
Nanoparticles exhibit properties that is strength, electrical conductivity elasticity, colour etc. Since the efficacy of any drug depends on bioavailability and residence time, nanomaterials have extensive application in diagnosis as contrasting agents in ultrasonography, MRI imaging and delivery of drugs by virtue of long resident time and treatment by penetration through cell wall into cytoplasm as well as nucleus by virtue of accessibility overcoming the blood barrier and thus leads to stimulate innate repair mechanism.
Quantum dots of nanoparticals that glow when exposed to U V light, shines brighter and longer than the presently used fluorescent dyes to track proteins. Since a single protein in the living cell can be tracked it is easier to detect cancer at the early stage by utilizing the biomarkers. The bio marks PSA (Prostatic Specific Antigen) in a drop of blood gives immediate result. Calcium selenlde quantum dots can penetrate the cells of malignant tumor to identify location size and proceed to destroy the same.
In photo dynamic therapy, gold coated nanoshells (120 nm diameters) conjugated to anti bodies / peptides that attached to cancer cells. When tumour is irradiated by infra-red laser , gold gets heated killing each cancer cell. Nanoscale materials can be used to develop synthetic bone and coating artificial joints. Nanosilver is used in antimicrobial coatings wound dressing and cathetores.
Nanoemulsive technology
During the SARS epidemic in May 2003, WHO recommended that the cabin or quarters occupied as SARS patients be disinfected with sodium hypochilorite bleach and Formation 1 or Chilorometaxylenol. Technologies were developed along this line to deliver one of the ingredients at any extremely low concentration to create powerful hospital grade disinfectant that is non-hazardous and environmentally safe. One regular product line employing unique nanoemulsive technology as a means for disinfecting infectious agents has been developed. It is to be noted that these are disinfectant agents only.
This nanoemulsive technology can be effectively utilized to preventing the spread of a broad range of organisms namely E Coli, Salmonella Listeria, Staplhylococci streptococci pseudomonas MRSA, VRE, Norwalk-like virus, influenza A, hepatitis B and C and Vaccinia.
Another product range can be to utilize the non-emulsive technology as a spray, smeared on clothing, vehicles people or anything that has been exposed to slow a deadly substances. It can be ru6bed on skin , eaten or put into beverages like orange juice or used in hot water in the tub.
The working principle is that nanobubbles contain energy that is stored as surface tension. The energy is released when bubbles coalesce thus zapping the containment.
Thus the potential of products and services from nanotechnology is immense that makes it a billions dollar industry. The genetic potential of microbes is limitless and the only limit is the human ingenuity to conceive and exploit the potential.
Dr. A. P. J. Abdul Kalam, former President of India has been stressing this aspect on many an occasions. Clustering of research centres,educational institutions and intense interaction with industry can create a new dawn for the development of nano biotechnology in India.
In all sectors of industry, manufacturing of nano products through microbial production is the latest and economical route compared to the traditional methods. Since nanotechnology is a part of any nation's future, development and commercialization has to be accelerated for the progress of the society.
The author is founder, former Director of Institute of Genetics, Hospital for Genetic Diseases, Osmania University