Application of Nanotechnology Tomedicine from Marine Resources

GHOSE Mrinal K，HU Ning

(1.Environmental Science ＆Engineering，West Bengal University of Technology，Kolkata 700064，India;2.Wuhan University of Science and Technology，Wuhan 430081，China)

Nanobiotechnology and bionanotechnology refer to materials and processes at the nanometer scale that are based on biological，biometric or biologically-inspired molecules and nanotechnological devices used to control biological processes，e.g.in medicine［1］.Nanomaterials are the base components for the nanotechnology and are at the leading edge of this field.Nanotechnology studies materials with morphological features materials with morphological features on the nano-scale and specially that have special properties stemming from their nanoscale dimension.The nanometer length scale is creating possibilities of novel materials that can be used for the construction of devices and systems to generate services to mankind.The unique size dependant properties of nanomateials make them superior and indispensible in many areas of human activity.Nanotechnology with chemistry，biology and quantum mechanics:Nanotechnology is considered to be rather new，but it is by no means the only field concerned with atoms and molecules.

The nanometer length scale is creating possibilities of novel materials that can be used for the construction of devices and systems to generate services to mankind.The unique size dependant properties of nanomateials make them superior and indispensable in many areas of human activity.In different way，the disciplines of physics，chemistry and biology have long dealt with atoms and molecules，their behavior their manipulation;and quantum mechanics is already firmly established as the science of the absolutely small.

Biology is considered to provide living proof of principle of nanotechnology.Biological structure at macromolecular and supramolecular scales are apparently assembled using the principles of self-assembly so eagerly sought by the nanotechnologist，and these structures，mostly protein-based，often combine extraordinary lightness with extraordinary strength.

India has a vast coastline of about 6 800 km.and its Exclusive Economic Zone(EEZ)extends upto 370 km from the coast.The pioneering researches conducted by the Central Marine Fisheries Research Institute has shown that there are numerous species of organism belonging to sponges，gorgonids，corals，echinoderms，sea-anemones.The liver oil from fish provides excellent sources of vitamins X and D;insulin has been extracted from whales and tuna fish;and the red alga Digenia simplex has been shown to contain an anthelminthic.The objective of this paper is to discuss the applications of nanotechnology to medicine from marine resources

1 Applications of Nanotechnology to Medicine

Nanomedicine involves utilization of nanotechnology for the benefit of human health and well being.The use of nanotechnology in various sectors of therapeutics has revolutionized the field of medicine where nanoparticles of dimensions ranging between 1～100 nm are designed and used for diagnostics，therapeutics and as biomedical tools for research［1］.It is now possible to provide therapy at a molecular level with the help of these tools，thus treating the disease and assisting in study of the pathogenesis of disease.Conventional drugs suffer from major limitations of adverse effects occurring as a result of non specificity of drug action and lack of efficacy due to improper or ineffective dosage formulation(e.g.，cancer chemotherapy and ant diabetic agents).Designing of drugs with greater degree of cell specificity improves efficacy and minimizes adverse effects.Diagnostic methods with greater degree of sensitivity aid in early detection of the disease and provide better prognosis.Nanotechnology is being applied extensively to provide targeted drug therapy，diagnostics，tissue regeneration，cell culture，biosensors and other tools in the field of molecular biology.Various nanotechnology platforms like fullerenes，nano tubes，quantum dots，nanopores，dendrimers，liposomes，magnetic nanoprobes and radio controlled nanoparticles are being developed

Usually water soluble drugs are loaded in aqueous compartment and lipid soluble drugs are incorporated in the liposome membrane［2］.The major limitation of liposome is its rapid degradation and clearance by the liver macrophages［3］，thus reducing the duration of action of the drug it carries.This can be reduced to a certain extent with the advent of stealth liposomes where the liposomes are coated with materials like polyoxyethylene［4］which prevents opsonisation of the liposome and their uptake by macrophages［5］.Other ways of prolonging the circulation time of liposomes are incorporation of substances like cholesterol［6］，polyvinylpyrollidone polyacrylamide lipids［7］and high transition temperature phospholipids distearoyl phosphatidylcholine［8-9］.

Antibody directed enzyme prodrug therapy(ADEPT)consists of liposomes conjugated with an enzyme to activate a prodrug and an antibody directed to a tumour antigen(enzyme linked immunoliposomes).These are administered prior to administration of a prodrug.The antibody directs the enzyme to the target tissue where it activates the prodrug selectively and converts it to its active form.This way，action of the drug is avoided in other normal tissues，thus minimizing the toxicity of drug［10-12］.Such studies are being tried with epirubicin and doxorubicin［11-13］.Ligand bearing liposome's are conjugated with specific legends which are directed towards target structures.In ovarian cancer，over expression of folate receptors by the tumor tissue occurs.The liposomal drug can be conjugated with folate so as to direct the molecule to the tumour［14］.This method is also being tried in the treatment of leishmaniasis where liposomal hamycin conjugated with mannose human serum albumin are targeted towards human macrophages［15］.Asialofeutin conjugation is being tried to target liver cells for gene therapy［16］.The targeted liposomal preparations are found to have a better efficacy than non targeted liposome.

The applications of nanotechnology to medicine are in nano surgery，a development of microsurgery.Although complicated operations still require to be carried out in the traditional way，the diminished invasiveness implied by microsurgical techniques makes them very attractive.The ultimate development in nanotechnology is considered to be quasiautonomous robots that can be released into the blood，through which they will travel to the site needing intervention，nanotechnology offers the tools to investigate airborne particles-nano photonics(integrated optics)for detecting and qualifying them，atomic force microscopy for auxiliary structural investigations，and so on.Medical science will of course be heavily involved in these investigations，which will impact not only human cell ultra structure and effects on the immune system，but should also contribute to solving the riddle of allergy.It is now known that several marine organisms contain many bioactive chemical compounds with various pharmacological properties.Many marine organisms have provided useful drugs.The liver oil from fish provides excellent sources of vitamins X and D;insulin has been extracted from whales and tuna fish;and the red alga Digenia simplex has been shown to contain an anthelminthic.An outstanding example of the potential，the biotechnological application offers is that of marine pharmaceuticals and drugs.Cardiotonic polypeptides have been extracted from sea anemones，adrenergic compound from sponges，potential anti tumor compound from Caribbean gorgonians and soft corals.Antiviral and anti tumor despeptides have been obtained from a Caribbean tunicate of the family Didemnidae，which inhibits the growth of DNA and RNA viruses as well as L1210 marine leukemic cells.

2 Bioactive Compounds

There are indications that tunicates may be an abundant source of bioactive compounds.Cardio vascular active substances have been isolated from sponges，N-methylated histamines and histamines from Verongia fistularis，asystolic nucleoside from Dasychalnia cyathnia and the nucleosids spongosine from Cryptotethya crypta.These provide a few examples.

The fact remains that it is uneconomical to extract and purify material from organisms that have to be captured in large quantities from various remote areas.This necessitates the need for culture of these organisms.Further there is a lack of knowledge concerning the basic chemistry of many of the marine natural products which has limited these sources for the development of useful drugs.Genetic engineering can change this situation dramatically by revealing the vast and diverse genetic composition of marine life for pharmacological application.Marine biofouling is highly destructive to vessels and under water and floating structures used for marine aquaculture.The ability of bacterial to find，attach，adhere and elaborate specific primary films are the crucial stages in biofouling.If these factor involved are understood，it is possible to manipulate them by employing biotechnology techniques.Two approaches are being tested to elucidate the molecular basis of fouling.Many powerful chemical toxins have been isolated from various toxic organisms.They have specific functional groups in the molecule and show strong toxic physiological activity.Many toxins have potential applications as a drug or pharmaceutical agent.Even when the direct use as drug is not feasible，because of potent or harmful side effects，these toxins still serve as models for synthesis or providing suitable derivatives which improves their suitability as drugs.One is to identify the genes involved in each of this process using recombinant DNA technology.The other is the use of transposing mutagenesis，when a transposing mutant deficient in the expression of adhesion gene is discovered it could be easy for further elucidation of the factors involved in microbial adhesion and then it might be possible to manipulate these factors at a genetic and biochemical level.This has also implication in aquaculture by enhancing spat settlement of cultivable mollusks.

3 Marine Pharmacology

A dramatic example of biotechnology applications is that of marine pharmaceuticals.Extracts from a tunicate belonging to the family of Didemnidae，inhibit growth of DNA and RNA virus as well as leukemic cells.Marine toxins besides being pharmacological chemicals，also serve as models for development of new synthetic chemicals.The strategy to be undertaken in marine pharmacology would be initial screening of marine organism for bioactive agents.The most useful bioactive compound can be tested and characterized.Then a two prolonged strategy could be undertaken.One for evolving techniques for mass culture of the organism and the other for using recombinant DNA technique to identify and clone genes responsible for synthesizing the bioactive.

4 Marine Pollution Control and Management

This is more important because natural organisms cannot produce enzymes necessary fortrans formation of the original compounds so the intermediates are produced which can enter into common metabolic pathways and metabolized completely.Synthetic compounds are relatively resistant to biodegradation compared to natural products.This creates special problems for waste management and environmental protection.Groups of microorganism useful in treating specific types of man made compounds have been complied and are known.Selective use of microorganisms，including actinomycets，fungi，bacteria，phototrophic microorganisms，anaerobic bacteria and oligotrophic bacteria are known in certain application such as waste water treatment for biological removal of nitrogen via sequential nitrification and denitrification.The treatment of selected industrial wastes in reactors using controlled mixed cultures is in use in Japan.Various methods of genetic engineering will certainly prove to be of use for this.

The engineering of microorganisms to be added to wastes that are to be discharged into the marine environment has to be found out.Pollutants entering the marine environment can interfere with the integrity of the ecosystems.The pollutants include synthetic organic compounds，chlorinated chemicals，dredged spoils，litter，artificial radionuclide，trace metals and fossil fuel compounds.Toxaphene，a group of about 200 compounds produced by chlorination of wood waste products and comphors under ultraviolet light contains carcinogenic and mutagenic chemicals.These may be more persistent in the environment than DDT and its degradation products.The modifications of genetic information resident in microorganisms can be used for pollution control.The enzyme concentration may be amplified either by selection of constitutive mutants，increase in the number of copies of the gene for the enzyme or both，so that enzymatic degradation can be made.Rearrangement of regulatory mechanisms controlling the expression of specific genes in response to specific stimuli may also prove to be useful.

Another useful modification is the introduction of new enzymatic functions into organisms not having them.The alteration of the characteristics，such as substrate specificity，kinetic instant and pH optimum，of specific enzymes can also be made use of.These modifications can be achieved by undertaking invitro modifications via transposing mutagenesis or other transposing mediated gene manipulation，genetic exchange via，transduction，transformation，or conjugation，protoplast fusion，specific site mutagenesis，and specialized selection procedures to enrich for mutants.The engineering of microorganisms capable of flourishing in the marine optimized proliferation and maintenance of selected populations has to be considered.The need for algaecides and antifouling agents is so great that discoveries of such compounds with these activities will produce marketable success.

5 Marine Aquaculture

The pathology and diseases of organisms under marine aquaculture have to be studied and their control using genetic engineering techniques as well as immunological methods found out.The post-harvest technologies to increase the quality and value of the final food products have to be improved.Another very important area which needs our attention is the transportation of eeds of the organisms from the hatchery to the farm or field for marine aquaculture.Today the transportation of seeds present a risk of mortality which is very high.Coelenterates，alcyonarians，sea-urchins，molluscs，pearl and edible oysters，clams，seaweeds and algae，sea greases，etc.in our coastal waters，screening of these for their bioactivity and isolation and characterization of the chemical compounds responsible for these activities is the first step needed.Already some researches have been conducted by Central Marine Fisheries Research Institute(CMFRI)，Central Institute of Fisheries Technology(CIFT)，National Institute of Oceanography(NIO)，Central Drug Research Institute(CDRI)and Indian Drugs and Pharmaceuticals Private Limited(IDPL)，but it is only peripheral.The other biotechnological strategies needed in marine aquaculture activities are the farm engineering and harvesting technology which have to be designed and perfected for production of maximum yield.

Chromosomal manipulation techniques may be utilized and perfected to improve fish production in marine aquaculture.Fish nutrition is another aspect which has to be considered from the point of view of marine aquaculture.The feed for the organisms to be reared has to be carefully compounded with due regard for increased growth rate and breeding so that their culture is profitable.By far the importance of the applications of genetic engineering techniques is greatest to marine biotechnological field.It will also provide an untapped gene pool representing transport system for minerals，metal concentration，novel photosynthetic systems，and marine pheromones，i.e.，communicator substances produced by marine organisms as well as the hydrogen sulphide utilizing and microbial mediated ecosystems.With the advent of the tools of genetic engineering，the potential of the sea as a significant source of protein food can be assessed.The stock assessment and the migration of fish can be known so that we will know when and where to fish at a particular period.The management and stock breeding can be made with more precision using these biotechnologies for fish and shellfish in a more profitable way so as to provide food and returns for our country.

6 Conclusion

From these，it is seen that there are immense potential for biotechnology in marine sciences.The greatest need of today is for exploitation of biologically active compounds and the hither to untapped food resource.India has a vast coastline of about 8 000 km.and itsExclusive Economic Zone(EEZ)extends upto 370 km from the coast.The pioneering researches conducted by the Central Marine Fisheries Research Institute has shown that there are numerous species of organism belonging to sponges，gorgonids，corals，echinoderms，sea-anemones，Medical science will of course be heavily involved through the application of nanotechnology，which will impact not only human cell ultra structure and effects on the immune system，but should also contribute to solving the riddle of allergy.

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