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1 BIO-NANOROBOTICS&ITS MEDICAL APPLICATIONS Submitted byT.Anton Bright R.ArumugamBE-II Year,ECE BE-II year,
[email protected],
[email protected]:9842815400Mobile: 9791992571 2 BIO-NANOROBOTICS “ Living organisms are naturally-existing, fabulously complex systems of molecular nanotechnology. Abstract: This paper focuses on the state of the art in thefield of Bio -Nano robotics by describingvarious molecular level systems and associateddesign and control issues. Nano-robots arecontrollable machines at the nano (10 -9 ) meter ormolecular scale that are composed of nano-scalecomponents. With the modern scientificcapabilities, it has become possible to attemptthe creation of nanorobotic devices and interfacethem with the macro world for control. There arecountless such machines that exist in nature andthere is an opportunity to build more of them bymimicking nature. Even if the field of nanorobotics is fundamentally different than thatof macro robots due to the differences in scaleand material, there are many similarities indesign and control techniques that eventuallycould be projected and applied. A roadmaptowards the progression of this field is proposedand some design concept and philosophies areillustrated. Two types of control mechanisms aregiven with examples and further hybridmechanisms are proposed. There are manyapplications for nanorobotic systems and itsbiggest impact would be in the area of medicine. Introduction:Nanotechnology , is the study of the controllingof matter on anatomicandmolecularscale. Generally nanotechnology deals with structuresof the size 100nanometersor smaller in at leastone dimension, and involves developingmaterials or devices within that size. A Bionanorobot ( bio-nanorobot implies nanorobots made up of bio components ) is essentially acontrollable machine at the nano meter ormolecular scale that is composed of nano-scalecomponents. Nano robots would constitute anypassive or active structure (nano scale) capableof actuation, sensing, signaling, informationprocessing, intelligence, swarm behavior at nanoscale. Nano Devices and Components Protein based molecular machines o ATP Synthase – a true nanorotary motor o The Kinesin,Myosin,Dyneinand Flagella molecular motors DNA based molecular machines o THE DNA tweezers Inorganic (chemical) molecularmachines o The Rotaxenes o The Catenanes o Other inorganic molecularmachines Other Protein based motors underdevelopment o VPLM(Viral Protein linearMotors ) o SCPM(Synthetic ContractilePolymer Motors ) The ATPase Motor ATP Synthase is the process within themitochondria of a cell by which a rotary engineuses the potential difference across the bilipidlayer to power a chemical transformation of ADP into ATP. The process, though as complicated as it sounds,can be simplified into a few steps and twopieces. Mitochondria, the powerhouses of cells,exist in a fluid within the human body. Theyhave a wall (a bilipid layer ) which boundsthem on all sides. Because of a difference insodium and potassium ion concentrations apotential can be created. The potential can evenbe altered to a desired value by changing the ionconcentrations. This process is one which usesthat difference in potential to the cells'advantage. 3 The positive ions try to move to a lowerpotential, and the negative ions try to move to ahigher one, thus creating a force which is usedto spin the rotor. As shown in one of the moviesbelow, as the rotor spins the bottom sectionopens and closes special sections which do theactual work. When they open they take in ADP(Adenosine Di-Phosphate), and a phosphategroup. As the rotor continues to turn the sectioncloses and the phosphate is chemically bound tothe ADP to form ATP (Adenosine Tri-Phosphate).ATP is what your body uses (especially inmuscle cells) to store energy and the process of breaking it up into ADP and phosphate is whatreleases that energy. More technically, thediphosphate state is at a lower energy, so whenthe body breaks off the extra phosphate groupin ATP it releases energy which the body canthen use. The rotor combines an extraphosphate group with the lower energy ADPusing the cell wall's potential as the drivingforce... Kinesin and Myosin Kinesins are a large family of proteins withdiverse structures. Mammalian cells have atleast40 different kinesin genes. Kinesin are referredto as kinesin related proteins (KRPs) or kinesinI. Kinesin I has a structure somewhat analogousto but distinct from that of myosin. There are 2copies each of a heavy chain and a light chain.Each heavy chain includes a globular ATP-binding motor domain at the N-terminus.Stalk domais of the heavy chain interact in an a-helical coiled coil that extends from the heavychain neck to the tail.The coiled coil isinterrupted by a few hinge regions that giveflexibility to the otherwise stiff stalk domain.N-termini of the two light chains associate withthe two heavy chains near the tail. The diagramabove is over simplified. Light chains at the N-terminus include a series of hydrophobic heptadrepeats that are predicted to interact with similarrepeats in heavy chains near the tail region, in a4-helix coiled coil.C-terminal tail domains of kinesin light chains include several tetratrico peptide repeats (TPRs). The 34 amino acid TPRs mediateprotein-protein interactions. Kinesin light chainTPR repeats are involved in binding of kinesinsto cargo . C terminal domains of heavy chainsmay also participate in binding some kinesins tocargo. 4 The Flagella Motors Escherichia coli and similar organisms areequipped with a set of rotary motors only 45 nmin diameter. Each motor drives a long, thin,helical filament that extends several cell bodylengths out into the external medium. In additionto rotary engines andPropellers , E. coli‟s standard accessories include particle counters, rate meters, and gearboxesetrain system, complete with tracks, loadingdocks and a control system. Since motorproteins are a thousand times smaller than anyman-made motor, they aim to utilize them in asynthetic environment as engines powering thenanotrains a static wheel, Inorganic (chemical) based motors: Rotaxanes are organic compounds consisting of a dumbbell-shaped component that incorporatesone or more recognition sites in its rod section and is terminated by bulky „stoppers‟, encircled by one or more ring components. The possibilityof manufacturing specific forms of rotaxane andcreating molecular motors capable of guidedrotary motion and the possibility of fueling sucha motor bylight, electrons and chemical energyhas been proposed [Schalley e, 2001].Molecular shuttles have been reported using α -cyclodextrin – a parent of rotaxanes andcatenanes [Harada, 2001]. A light-drivenmonodirectional rotor made of helical alkene,with rotation around a central carbon-carboncovalent bond due to chirality has beenreported [Koumura et al, 1999]. DNA-Based Molecular Nanomachines, Jointsand Actuators DNA is small, relatively simple andhomogeneous, and its structure and function iswell understood. The predictable self-assembling nature of the double helix makes itan attractive candidate for engineerednanostructures. This property has been exploitedto build several complex geometric structures,including knots, cubes and various polyhedral[Seeman, 1998]. A dynamic device providingatomic displacements of 2-6 nm was proposed in[Mao et al, 1999], wherein the chemicallyinduced transition between the B and Z DNAmorphologies acts as a moving nanoscaledevice. A method for localized element-specificmotion control was seen in the reversibletransition between four stranded topoisomericDNA motifs (PX and JX2) thereby producingrotary motion [Yan et al, 2002]. A veryimportant, though simple DNA machine thatresembles a pair of tweezers has beensuccessfully created [Seeman1998], whoseactuation (opening and closing) is also fueled byadding additional DNA fuel strands. Power sources for nanorobots: The powering of the nanorobots can be done bymetabolising local glucose and oxygen forenergy. In a clinical environment, another optionwould be externally supplied acoustic energy.Other sources of energy within the body can alsobe used to supply the necessary energy for thedevices. They will have simple onboardcomputers capable of performing around 1000or fewer computations per second. This isbecause their computing needs are simple.Communication with the device can be achievedby broadcast-type acoustic signalling. A navigational network may be installed in thebody, with station keeping navigational elementsproviding high positional accuracy to all passingnanorobots that interrogate them, wanting toknow their location. This will enable thephysician to keep track of the various devices inthe body. These nanorobots will be able todistinguish between different cell types bychecking their surface antigens (they aredifferent for each type of cell). This isaccomplished by the use of chemotactic sensorskeyed to the specific antigens on the target cells.When the task of the nanorobots is completed,they can be retrieved by allowing them to exfusethemselves via the usual human excretorychannels. They can also be removed by activescavenger systems. This feature is design-dependent.
