ARTICLE IN PRESS - Nanomedicine

1 EDITORIALN anotechnology, Nanomedicine and nanosurgeryAn exciting revolution in health care and med-ical technology looms large on the horizon. Yet theagents of change will be microscopically small,future products of a new discipline known asnanotechnology. Nanotechnology is the engineer-ing of molecularly precise or smallereand, ultimately, the application of nano-technology to medicine. It is the preservationand improvement of human health, using molecu-lar tools and molecular knowledge of the humanbody. Present-day Nanomedicine exploits carefullystructured nanoparticles such as dendrimers,5car-bon fullerenes (buckyballs)6and nanoshells7totarget specific tissues and organs.

2 These nanopar-ticles may serve as diagnostic and therapeutic an-tiviral, antitumor or anticancer agents. But as thistechnology matures in the years ahead, complexnanodevices and even nanorobots will be fabri-cated, first of biological materials but later usingmore durable materials such as diamond toachieve the most powerful visionCan it be that someday nanorobots will be able totravel through the body searching out and clearingup diseases, such as an arterial atheromatousplaque?8 The first and most famous scientist tovoice this possibility was the late Nobel physicistRichard P.

3 Feynman. In his remarkably prescient1959 talk There s Plenty of Room at the Bottom, Feynman proposed employing machine tools tomake smaller machine tools, these are to beused in turn to make still smaller machine tools,and so on all the way down to the atomic level,noting that this is a development which I thinkcannot be avoided. 9 Feynman was clearly aware of the potentialmedical applications of this new technology. Heoffered the first known proposal for a nanoroboticsurgical procedure to cure heart disease: A friendof mine (Albert R.)

4 Hibbs) suggests a very interest-ing possibility for relatively small machines. Hesays that, although it is a very wild idea, it wouldbe interesting in surgery if you could swallow thesurgeon. You put the mechanical surgeon insidethe blood vessel and it goes into the heart andlooks around. (Of course the information has to befed out.) It finds out which valve is the faulty oneand takes a little knife and slices it [Imag-ine] that we can manufacture an object thatmaneuvers at that level!.Other small machinesmight be permanently incorporated in the body toassist some inadequately functioning organ.

5 9 Medical microroboticsThere are ongoing attempts to build microrobotsfor in vivo medical use. In 2002, Ishiyama et al. atTohoku University developed tiny magneticallydriven spinning screws intended to swim alongveins and carry drugs to infected tissues or even toburrow into tumors and kill them with , the MR-Sub project of Martel s group atthe NanoRobotics Laboratory of Ecole Polytechni-que in Montreal tested using variable MRI magneticfields to generate forces on an untethered micro-robot containing ferromagnetic particles.

6 Develop-ing sufficient propulsive power to direct the smalldevice through the human Nelson steam at the Swiss Federal Institute of Technologyin Zurich continued this approach. In 2005, theyreported the fabrication of a microscopic robotsmall enough (w200mm) to be injected into thebody through a syringe. They hope that this deviceor its descendants might someday be used to de-liver drugs or perform minimally invasive eyeARTICLE IN PRESS1743-9191/$ - see front matter 2005 Surgical Associates Ltd. Published by Elsevier Ltd.

7 All rights Journal of Surgery (2005)-, s simple microrobot has success-fully maneuvered through a watery maze using ex-ternal energy from magnetic fields, with differentfrequencies that are able to vibrate different me-chanical parts on the device to maintain selectivecontrol of different functions. Gordon s group atthe University of Manitoba has also proposed mag-netically controlled cytobots and karyobots for performing wireless intracellular and intranu-clear medical nanorobotsThe greatest power of Nanomedicine will emerge,perhaps in the 2020s, when we can design andconstruct complete artificial nanorobots using rigiddiamondoid nanometer-scale parts like moleculargears (Fig.)

8 1) and nanorobotswill possess a full panoply of autonomous subsys-tems including onboard sensors, motors, manipula-tors, power supplies, and molecular getting all these nanoscale components tospontaneously self-assemble in the right sequencewill prove increasingly difficult as machine struc-tures become more complex. Making complexnanorobotic systems requires manufacturingtechniques that can build a molecular structureby what is called positional assembly. This will in-volve picking and placing molecular parts one byone, moving them along controlled trajectoriesmuch like the robot arms that manufacture carson automobile assembly lines.

9 The procedure isthen repeated over and over with all the differentparts until the final product, such as a medicalnanorobot, is fully positional assembly of diamondoid struc-tures, some almost atom by atom, using molecularfeedstock has been examined theoretically14,15viacomputational models of diamond mechanosyn-thesis (DMS). DMS is the controlled addition of car-bon atoms to the growth surface of a diamondcrystal lattice in a vacuum-manufacturing environ-ment. Covalent chemical bonds are formed one byone as the result of positionally constrained me-chanical forces applied at the tip of a scanningprobe microscope apparatus, following a pro-grammed sequence.

10 Mechanosynthesis using sili-con atoms was first achieved experimentally atoms should not be far be practical, molecular manufacturing mustalso be able to assemble very large numbers ofmedical nanorobots very quickly. Approaches un-der consideration include using replicativemanufacturing systems or massively parallel fabri-cation, employing large arrays of scanning probetips all building similar diamondoid product struc-tures in example, simple mechanical ciliary arraysconsisting of 10,000 independent microactuators ona 1-cm2chip have been made at the Cornell Nation-al Nanofabrication Laboratory for microscale partstransport applications, and similarly at IBM for me-chanical data storage probearrays of 10.