nanoscale sensors as medical diagnostics

8/14/2019 Nanoscale Sensors as Medical Diagnostics

1/18

Nanoscale sensors as medical diagnostics

Nanoscale sensors are under development in the Kelley laboratories that report on thepresence of disease-related biomolecules. The ultimate goal of this project is to provide newtechnologies that will enable the early diagnosis of cancer and other diseases where early

intervention is critical.

Nanoscale sensors for the detection of cancer biomarkers. Advances in genomic andproteomic methods now allow classification of disease based on molecular profiling. Thedetection of a molecular analytes and use of this type of information for disease diagnosis

requires methods with superior sensitivity and specificity, along with high-throughput.We are developing new analytical methods with these properties that will permit the

direct readout of nucleic acid sequences and protein biomarkers. Novel technologies forultrasensitive DNA and RNA sensing have been developed in our laboratories that use

electrochemical methods for readout. Nanomaterials play an important role in this effort,as detection sensitivity is greatly enhanced when measurements are performed at the

nanoscale. Our aim is to generate sensors applicable to the diagnosis of cancer and otherdisease states. Members of this project team fabricate devices, develop reporter assaysand work with biological and clinical samples to validate new technologies. Substantialcollaboration with engineers and clinical researchers is an important part of this project.

Nucleic acids biosensor based on gold nanowires

Representative publications

"Direct Electrocatalytic mRNA Detection Using PNA-Nanowire Sensors."Anal. Chem.,2008, in press.

"Ultrasensitive Detection of Enzymatic Activity with Nanowire Electrodes." M.A.Roberts, S.O. Kelley,J. Am. Chem. Soc. 2007, 129, 11356.


2/18

"An Intercalator Film as a DNA-Electrode Interface." B.J. Taft, M.A. Lapierre-Devlin,B.J. Taft, S.O. Kelley, Chem. Comm., 2006, 9, 962.

"Amplified Electrocatalysis at DNA-Modified Nanowires." M.A. Lapierre-Devlin, C.Asher, B.J. Taft, R. Gasparac, M.W. Roberts, S.O. Kelley,Nano Letters, 2005, 5, 1051.

"Ultrasensitive Electrocatalytic DNA Detection at 2D and 3D Nanoelectrodes." R.

Gasparac, B.J. Taft, M. Lapierre-Devlin, A.D. Lazareck, J.M. Xu, S.O. Kelley,J. Am.Chem. Soc.,2004, 126, 12270.

"Electrocatalytic Detection of Pathogenic DNA Sequences and Antibiotic ResistanceMarkers." M.A. Lapierre, M.M. O'Keefe, B.J. Taft, S.O. Kelley,Analytical Chemistry,

2003, 75, 6327.

Using Bacteria to Carry Nanoparticles Into Cells

Bacteria ferry nanoparticles into cells for early diagnosis, treatment

Researchers at Purdue University have shown that common bacteria can deliver avaluable cargo of smart nanoparticles into a cell to precisely position sensors, drugs orDNA for the early diagnosis and treatment of various diseases. The approach represents apotential way to overcome hurdles in delivering cargo to the interiors of cells, where theycould be used as an alterative technology for gene therapy, said Rashid Bashir, aresearcher at Purdues Birck Nanotechnology Center.
http://news.uns.purdue.edu/x/2007a/070613BashirSmartnano.htmlhttp://news.uns.purdue.edu/x/2007a/070613BashirSmartnano.html


3/18

The researchers attached nanoparticles to the outside of bacteria and linked DNA to thenanoparticles. Then the nanoparticle-laden bacteria transported the DNA to the nuclei ofcells, causing the cells to produce a fluorescent protein that glowed green. The samemethod could be used to deliver drugs, genes or other cargo into cells.

The released cargo is designed to be transported to different locations in the cells tocarry out disease detection and treatment simultaneously, said Bashir, a professor in the

Weldon School of Biomedical Engineering and the School of Electrical and ComputerEngineering. Because the bacteria and nanoparticle material can be selected from manychoices, this is a delivery system that can be tailored to the characteristics of the receivingcells. It can deliver diagnostic or therapeutic cargo effectively for a wide range of needs.

Harmless strains of bacteria could be used as vehicles, harnessing bacterias naturalability to penetrate cells and their nuclei, Bashir said. For gene therapy, a big obstaclehas been finding ways to transport the therapeutic DNA molecule through the nuclearmembrane and into the nucleus, he said. Only when it is in the nucleus can the DNAproduce proteins that perform specific functions and correct genetic disease conditions.

When the cargo-carrying bacteria attach to the recipient cell they are engulfed by its outermembrane, forming vesicles, or tiny spheres that are drawn into the cells interior.Once inside the cell, the bacteria dissolve the vesicle membrane and release the cargo.The method might be used to take images of diseased tissues by inserting a cargo offluorescent molecules into tumors that are ordinarily too small to be detected, said DemirAkin, a research assistant professor of biomedical engineering who specializes innanomedicine.

These bacteria can potentially deliver specific molecules into a variety of cells, saidAkin, the first author of a research paper appearing online this week in the journal NatureNanotechnology. Experiments were carried out in cultures of human cancer cells,

including intestinal, oral, liver, ovarian and breast cancer cells. The researchers alsotested their method on live mice and showed how the technique could be used to deliverspecific genes to various organs, including the liver and kidneys.

The cells in the organs receiving the bacteria with nanoparticles made the intendedtherapeutic proteins and emitted a light similar to a fireflys glow, Akin said. Certainbacteria are naturally programmed to dissolve vesicle membranes, a critical step todelivering the cargo. The nanoparticles are referred to as smart because they releasetheir cargo at precisely the right moment after entering the cell.

At the same time that the bacteria are breaking up this vesicle membrane, the cargo

dislodges from the bacteria, which are both crucial steps in delivering this cargo, Akinsaid. The nanoparticles, which range in size from 40 to 200 nanometers - or billionths ofa meter - are attached to the bacteria with linker molecules.

The use of commercially available polystyrene nanoparticles makes this delivery systemmuch simpler to implement than previous alternatives, Bashir said. This new deliverysystem also is more efficient than other experimental techniques using viruses andbacteria.


4/18

With other techniques, you can usually incorporate only one copy of your gene cargo toeach bacterium or virus particle, Akin said. In the new approach, bacteria can carryhundreds of nanoparticles, each of which can in turn carry hundreds of drug molecules,depending on the size of the nanoparticles.

The approach also could make it possible to insert relatively large structures, such assensors and hollow filaments called carbon nanotubes, into the interiors of cells.

The sensors could make it possible to monitor activities inside a single cell for the earlydetection of cancer and other diseases and to monitor the progress of disease andresponse to drug therapy. The carbon nanotubes could be delivered into diseased cellsand then exposed to light, causing them to heat up and kill only those diseased cells, Akinsaid.

The multidisciplinary research has been supported with funding from the Weldon Schoolof Biomedical Engineering. Research has been conducted by engineers and scientists atthe Birck Nanotechnology Center, the Bindley Bioscience Center and the OncologicalSciences Center, all at Purdues Discovery Park, and the School of Veterinary Medicine

and Department of Food Science.

The Nature Nanotechnology paper was authored by Akin; Jennifer Sturgis and KathyRagheb, both on the research staff at the Bindley Bioscience Center; Debby Sherman,director of the Life Science Microscopy Facility; Kristin Burkholder, a doctoral studentin the Department of Food Science; J. Paul Robinson, a professor in the Weldon Schoolof Biomedical Engineering and the School of Veterinary Medicine; Arun K. Bhunia, aprofessor of food microbiology in the Department of Food Science; Sulma Mohammed,an assistant professor of cancer biology in the School of Veterinary Medicine; andBashir. A print version will appear in July.

by curiouscat Tags: Engineering,Health Care,Life Science,Nanotechnology, Students,Universities

Permalink to: Using Bacteria to Carry Nanoparticles Into Cells Trackback:http://engineering.curiouscatblog.net/2007/06/20/using-bacteria-to-carry-nanoparticles-into-cells/trackba

Nanotechnology Breakthroughs for Computer Chips

Photo: Actual scanningtunneling microscopyimages of the

naphthalocyanine moleculein the on and the offstate. More images
http://engineering.curiouscatblog.net/category/engineering/http://engineering.curiouscatblog.net/category/health/http://engineering.curiouscatblog.net/category/health/http://engineering.curiouscatblog.net/category/health/http://engineering.curiouscatblog.net/category/life-science/http://engineering.curiouscatblog.net/category/nanotechnology/http://engineering.curiouscatblog.net/category/nanotechnology/http://engineering.curiouscatblog.net/category/education/students/http://engineering.curiouscatblog.net/category/education/students/http://engineering.curiouscatblog.net/category/education/universities/http://engineering.curiouscatblog.net/2007/06/20/using-bacteria-to-carry-nanoparticles-into-cells/http://www-03.ibm.com/press/us/en/presskit/22242.wsshttp://engineering.curiouscatblog.net/category/engineering/http://engineering.curiouscatblog.net/category/health/http://engineering.curiouscatblog.net/category/life-science/http://engineering.curiouscatblog.net/category/nanotechnology/http://engineering.curiouscatblog.net/category/education/students/http://engineering.curiouscatblog.net/category/education/universities/http://engineering.curiouscatblog.net/2007/06/20/using-bacteria-to-carry-nanoparticles-into-cells/http://www-03.ibm.com/press/us/en/presskit/22242.wss


5/18

IBM Unveils Two Major Nanotechnology Breakthroughs as Building Blocks for AtomicStructures and Devices

IBM scientists have made major progress in probing a property called magneticanisotropy in individual atoms. This fundamental measurement has importanttechnological consequences because it determines an atoms ability to store information.Previously, nobody had been able to measure the magnetic anisotropy of a single atom.

With further work it may be possible to build structures consisting of small clusters ofatoms, or even individual atoms, that could reliably store magnetic information. Such astorage capability would enable nearly 30,000 feature length movies or the entirecontents of YouTube millions of videos estimated to be more than 1,000 trillion bits ofdata to fit in a device the size of an iPod. Perhaps more importantly, the breakthroughcould lead to new kinds of structures and devices that are so small they could be appliedto entire new fields and disciplines beyond traditional computing.

In the second report, IBM researchers unveiled the first single-molecule switch that canoperate flawlessly without disrupting the molecules outer frame a significant step

toward building computing elements at the molecular scale that are vastly smaller, fasterand use less energy than todays computer chips and memory devices.

In addition to switching within a single molecule, the researchers also demonstrated thatatoms inside one molecule can be used to switch atoms in an adjacent molecule,representing a rudimentary logic element. This is made possible partly because themolecular framework is not disturbed.

Related: Self-assembling Nanotechnology in Chip Manufacturing -More MicrochipBreakthroughs -Nanotechnology posts

by curiouscat Tags: Engineering,Nanotechnology, Products, Research, StudentsPermalink to:Nanotechnology Breakthroughs for Computer Chips Trackback:

http://engineering.curiouscatblog.net/2007/09/02/nanotechnology-breakthroughs-for-computer-chips/trackbac

Nanoengineers Use Tiny Diamonds for Drug Delivery

Nanoengineers Mine Tiny Diamonds for Drug Delivery

Northwestern University researchers have shown that nanodiamonds much like thecarbon structure as that of a sparkling 14 karat diamond but on a much smaller scale

are very effective at delivering chemotherapy drugs to cells without the negative effectsassociated with current drug delivery agents.To make the material effective, Ho and his colleagues manipulated single nanodiamonds,each only two nanometers in diameter, to form aggregated clusters of nanodiamonds,ranging from 50 to 100 nanometers in diameter. The drug, loaded onto the surface of theindividual diamonds, is not active when the nanodiamonds are aggregated; it onlybecomes active when the cluster reaches its target, breaks apart and slowly releases the
http://www-03.ibm.com/press/us/en/pressrelease/22254.wsshttp://www-03.ibm.com/press/us/en/pressrelease/22254.wsshttp://engineering.curiouscatblog.net/2007/05/14/self-assembling-nanotechnology-in-chip-manufacturing/http://engineering.curiouscatblog.net/2007/01/27/more-microchip-breakthroughs/http://engineering.curiouscatblog.net/2007/01/27/more-microchip-breakthroughs/http://engineering.curiouscatblog.net/2007/01/27/more-microchip-breakthroughs/http://engineering.curiouscatblog.net/category/nanotechnology/http://engineering.curiouscatblog.net/category/engineering/http://engineering.curiouscatblog.net/category/nanotechnology/http://engineering.curiouscatblog.net/category/nanotechnology/http://engineering.curiouscatblog.net/category/products/http://engineering.curiouscatblog.net/category/research/http://engineering.curiouscatblog.net/category/education/students/http://engineering.curiouscatblog.net/category/education/students/http://engineering.curiouscatblog.net/2007/09/02/nanotechnology-breakthroughs-for-computer-chips/http://mccormick.northwestern.edu/news/articles/311http://www-03.ibm.com/press/us/en/pressrelease/22254.wsshttp://www-03.ibm.com/press/us/en/pressrelease/22254.wsshttp://engineering.curiouscatblog.net/2007/05/14/self-assembling-nanotechnology-in-chip-manufacturing/http://engineering.curiouscatblog.net/2007/01/27/more-microchip-breakthroughs/http://engineering.curiouscatblog.net/2007/01/27/more-microchip-breakthroughs/http://engineering.curiouscatblog.net/category/nanotechnology/http://engineering.curiouscatblog.net/category/engineering/http://engineering.curiouscatblog.net/category/nanotechnology/http://engineering.curiouscatblog.net/category/products/http://engineering.curiouscatblog.net/category/research/http://engineering.curiouscatblog.net/category/education/students/http://engineering.curiouscatblog.net/2007/09/02/nanotechnology-breakthroughs-for-computer-chips/http://mccormick.northwestern.edu/news/articles/311


6/18

drug. (With a diameter of two to eight nanometers, hundreds of thousands of diamondscould fit onto the head of a pin.)

The nanodiamond cluster provides a powerful release in a localized place aneffective but less toxic delivery method, said co-author Eric Pierstorff, a molecularbiologist and post-doctoral fellow in Hos research group. Because of the large amount ofavailable surface area, the clusters can carry a large amount of drug, nearly five times the

amount of drug carried by conventional materials.

Nanotube-producing Bacteria Show Manufacturing PromiseNanotubes may have high-tech applications, study involving UCR engineers reports(December 7, 2007)

Print Quality Image: Right click image and select "Save Target As."

Genus Shewanella. The nanotube filaments produced bybiological means could point toward semiconductor manufacturing processes with asmaller energy and environmental footprint. Image credit: Hor-Gil Hur, GISTRIVERSIDE, Calif. Two engineers at the University of California, Riverside are partof a binational team that has found semiconducting nanotubes produced by living bacteria a discovery that could help in the creation of a new generation of nanoelectronic

devices.

The research team believes this is the first time nanotubes have been shown to beproduced by biological rather than chemical means. It opens the door to the possibility ofcheaper and more environmentally friendly manufacture of electronic materials.

Study results appear in todays issue of the early edition of the Proceedings of theNational Academy of Sciences.

The team, includingNosang V. Myung, associate professor of chemical andenvironmental engineering in the Bourns College of Engineering, and his postdoctoral

researcher Bongyoung Yoo, found the bacterium Shewanella facilitates the formation ofarsenic-sulfide nanotubes that have unique physical and chemical properties not producedby chemical agents.

We have shown that a jar with a bug in it can create potentially useful nanostructures,Myung said. Nanotubes are of particular interest in materials science because the usefulproperties of a substance can be finely tuned according to the diameter and the thicknessof the tubes.
http://www.engr.ucr.edu/faculty/chemenv/myung.htmlhttp://www.engr.ucr.edu/faculty/chemenv/myung.htmlhttp://newsroom.ucr.edu/images/releases/1730_0hi.jpghttp://www.engr.ucr.edu/faculty/chemenv/myung.html


7/18

The whole realm of electronic devices which power our world, from computers to solarcells, today depend on chemical manufacturing processes which use tremendous energy,and leave behind toxic metals and chemicals. Myung said a growing movement inscience and engineering is looking for ways to produce semiconductors in moreecologically friendly ways.

Two members of the research team, Hor-Gil Hur and Ji-Hoon Lee from GwangjuInstitute of Science and Technology (GIST), Korea, first discovered somethingunexpected happening when they attempted to remediate arsenic contamination using themetal-reducing bacterium Shewanella. Myung, who specializes in electro-chemicalmaterial synthesis and device fabrication, was able to characterize the resulting nano-material.

The photoactive arsenic-sulfide nanotubes produced by the bacteria behave as metalswith electrical and photoconductive properties. The researchers report that theseproperties may also provide novel functionality for the next generation of semiconductorsin nano- and opto-electronic devices.

In a process that is not yet fully understood, the Shewanella bacterium secretespolysacarides that seem to produce the template for the arsenic sulfide nanotubes, Myungexplained. The practical significance of this technique would be much greater if abacterial species were identified that could produce nanotubes of cadmium sulfide orother superior semiconductor materials, he added.

This is just a first step that points the way to future investigation, he said. Each speciesofShewanella might have individual implications for manufacturing properties.

Myung, Yoo, Hur and Lee were joined in the research by Min-Gyu Kim, Pohang

Accelerator Laboratory, Pohang, Korea; Jongsun Maeng and Takhee Lee, GIST; Alice C.Dohnalkova and James K. Fredrickson, Pacific Northwest National Laboratory, Richland,Wash.; and Michael J. Sadowsky, University of Minnesota.

The Center for Nanoscale Innovation for Defense provided funding for Myungscontribution to the study.

Self-assembling Nanofibers Heal Spinal Cords in Mice

Self-assembling Nanofibers Heal Spinal Cords by Prachi Patel-Predd

An engineered material that can be injected into damaged spinal cords could help preventscars and encourage damaged nerve fibers to grow. The liquid material, developed byNorthwestern University materials science professor Samuel Stupp, contains moleculesthat self-assemble into nanofibers, which act as a scaffold on which nerve fibers grow.

Stupp and his colleagues described in a recent paper in the Journal of Neuroscience thattreatment with the material restores function to the hind legs of paralyzed mice.
http://www.technologyreview.com/Nanotech/20534/http://www.technologyreview.com/Nanotech/20534/


8/18

The new work is the first test for the material to heal spinal cord injuries in animals. AndKessler says that it worked better than the researchers expected. The researchersstimulated a spinal cord injury in mice and injected the material 24 hours later. Theyfound that the material reduced the size of scars and stimulated the growth of the nervefibers through the scars. It promoted the growth of both types of nerve fibers that makeup the spinal cord: motor fibers that carry signals from the brain to the limbs, and sensory

fibers that carry sense signals to the brain. What is more, the material encouraged thenerve stem cells to mature into cells that create myelinan insulating layer around nervefibers that helps them to conduct signals more effectively.

Micro-robots to swim Through Veins

Micro-robots take offPhoto: Transmission Electron Microscopyphotograph of an Escherichia coli bacterium with

flagella. The micro-robots are being developed tomimic the swimming behaviour of E.coli.

Micro-robots that can swim through thevascular and digestive systems of the human bodyto perform medical tasks via remote control and,

in many cases, avoid invasive major surgery, are being developed at Monash Universityfollowing todays announcement that the project has been funded through the AustralianResearch Councils Discovery Projects scheme.

Microbots Designed to Swim Like

Bacteria

By Bill Christensen

posted: 11 December 2006 11:00 am ET
http://www.monash.edu.au/news/newsline/story/1038http://www.technovelgy.com/http://www.livescience.com/php/multimedia/imagedisplay/img_display.php?s=technology&c=news&l=on&pic=061211_ecoli_hf.jpg&cap=Transmission+Electron+Microscopy+photograph+of+an+Escherichia+coli+bacterium+with+flagella.+Micro-robots+are+being+developed+to+mimic+the+swimming+behaviour+of+E.coli.+Credit%3A+Monash+University&title=http://www.monash.edu.au/news/newsline/story/1038http://www.technovelgy.com/


9/18

Transmission Electron Microscopy photograph of an Escherichia coli bacteriumwith flagella. Micro-robots are being developed to mimic the swimmingbehaviour of E.coli. Credit: Monash University

Tiny microrobots are under development at Monash University in Australia. Aremarkable micromotor will allow them to swim like anE. colibacterium, which uses itsflagella to move around.

A flagellum is a long, structure composed of microtubules; bacteria use them in a whip-like motion to move around.

James Friend's goal is to build a device no wider than 250 micronsthat's the width oftwo human hairsthat would be capable of swimming through thehuman body.

He and his team have already built a linear motor the size of a salt crystal. With a$300,000 grant from the Australian Research Council, Friend believes that his team willbe able to reduce the motor to the necessary size within three years.

According to Friend, the main difference between the microrobot motor and aconventional electromagnetic type is that the latter spins much faster but has much lesstwisting force. In an email interview with Technovelgy.com, he remarked:

"The swimming robot idea in and of itself has indeed been around a long timesince atleast the 1950's anyway, and our motor is of a scale and has the performancecharacteristics needed to actually make this sort of thing possible.

We're using ultrasonic motor technology here, which offer higher torques at lowerspeeds."

Friend said, "We've operating larger mm-sized prototypes of the motor, and have a fairlygood handle on the analysis, which turns out to be quite complicated for twisted-beamstructures." (See a design for theprototype microrobot.)

The micromotor that Friend and his team have designed for their propulsion systemshould be smaller overall than a similar microrobot propulsion system described inNovember by Moshe Shoham (see Propulsion System for 'Fantastic Voyage' Robot).Friend points out that his team has a "motor suitable for his [Shoham's] or our propulsionsystem that is far smaller than the technology he's [Shoham's] wanting to use."

Ultimately, tiny microrobots would give surgeons the ability to avoid traumatic and risky

procedures in some cases. A remotely-controlled microrobot would extend a physician'sability to diagnose and treat patients in a minimally invasive way.

Researchers at UCLA have gone in a different direction for a power source for amicrorobot; click on Musclebot: Microrobot with a Heart for an alternative tomicromotors. If you can't quite picture cell repair by medical nanorobots, clickhere for agraphic view.
http://www.livescience.com/technology/060512_ecoli_detector.htmlhttp://www.livescience.com/technology/060512_ecoli_detector.htmlhttp://www.livescience.com/php/trivia/index.php?quiz=bodyquiz3http://www.livescience.com/php/trivia/index.php?quiz=bodyquiz3http://www.livescience.com/php/trivia/index.php?quiz=bodyquiz3http://technovelgy.com/http://technovelgy.com/http://technovelgy.com/ct/Science-Fiction-News.asp?NewsNum=845http://www.technovelgy.com/ct/Science-Fiction-News.asp?NewsNum=811http://www.technovelgy.com/ct/Science-Fiction-News.asp?NewsNum=46http://www.technovelgy.com/ct/Science-Fiction-News.asp?NewsNum=161http://www.livescience.com/technology/060512_ecoli_detector.htmlhttp://www.livescience.com/php/trivia/index.php?quiz=bodyquiz3http://technovelgy.com/http://technovelgy.com/ct/Science-Fiction-News.asp?NewsNum=845http://www.technovelgy.com/ct/Science-Fiction-News.asp?NewsNum=811http://www.technovelgy.com/ct/Science-Fiction-News.asp?NewsNum=46http://www.technovelgy.com/ct/Science-Fiction-News.asp?NewsNum=161


10/18

Other sources for this story include this articleand this Monash University press release.

(This Science Fiction in the News story used with permission from Technovelgy.com where science meets fiction.)

Nanomachines:

Nanotechnology's Big Promise in a Small Package

By BRENT SILBY

Department of PhilosophyUniversity of Canterbury

www.def-logic.com/articles

Introduction

Nanomachines are devices built from individual atoms. Some researchers believe thatnanomachines will one day be able to enter living cells to fight disease. They also hope to

one day build nanomachines that will be able to rearrange atoms in order to constructnew objects. If they succeed, nanomachines could be used to literally turn dirt into foodand perhaps eliminate poverty.

In this article I will outline some of the possible uses of nanomachines. I will then assesssome of the problems involved in producing such machines. One of the problems I willlook at is that of producing self-replicating machines. Will these machines becontrollable? Or will their reproduction escalate exponentially, thus putting our wholeplanet in danger.

My conclusion will be that nanomachines offer humanity hope for the future, so the

research should be pursued. However, I will also suggest that the dangers involved inproducing self-replicating machines out weigh the potential gains and for this reason,self-replicating machines should not be built.

What are Nanomachines?
http://www.theage.com.au/news/education-news/big-plans-for-robot-microsurgery/2006/11/24/1164341402343.htmlhttp://www.theage.com.au/news/education-news/big-plans-for-robot-microsurgery/2006/11/24/1164341402343.htmlhttp://www.monash.edu.au/news/newsline/story/1038http://www.monash.edu.au/news/newsline/story/1038http://www.technovelgy.com/http://www.technovelgy.com/http://www.def-logic.com/articleshttp://www.theage.com.au/news/education-news/big-plans-for-robot-microsurgery/2006/11/24/1164341402343.htmlhttp://www.monash.edu.au/news/newsline/story/1038http://www.technovelgy.com/http://www.technovelgy.com/http://www.def-logic.com/articles


11/18

As the terminology implies, nanomachines are extremely small devices. Their size ismeasured in nanometers (a nanometer is about 1 billionth of a meter) and they are builtfrom individual atoms. During the 1980's and 1990's, futurist and visionary K. EricDrexler popularized the potential of nanomachines. For Drexler, the ultimate goal ofnanomachine technology is the production of the 'assembler'. The assembler is ananomachine designed to manipulate matter at the atomic level. It will be built withextremely small 'pincers' (as small as a chain of atoms) which will be used to move atoms

from existing molecules into new structures. The idea is that the assembler will be able torearrange atoms from raw material in order to produce useful items. In theory, one couldshovel dirt into a vat and wait patiently for a team of nanomachine assemblers to convertthe dirt into an apple, a chair, or even a computer. The machines in the vat would have amolecular schematic of the object to be built encoded in their 'memory'. They would thensystematically rearrange the atoms contained in the dirt to produce the desired item.

This is a representation of a nanomachine. The colored balls represent the individualatoms that comprise the machine. (Picture from Twibell (2000), see references.)

Another goal of nanotechnology is to design nanomachines that can make copies ofthemselves. The thought is that if a machine can rearrange atoms in order to build newmaterials, it should also be able to build copies of itself. If this goal is achieved, productsproduced by nanomachines will be extremely inexpensive. This is because the technology(once perfected) will be self-replicating and will not require specific materials, whichmight be rare and therefore cost money. Arthur C. Clarke has predicted thatnanotechnology will herald an end to conventional monetary systems.

If scientists manage to build nanomachines that can rearrange atoms, a world of excitingpossibilities will open up. Purpose designed nanomachines could be used to providebreakthrough treatments for many diseases. Medical nanomachines programmed torecognize and disassemble cancerous cells could be injected into the bloodstream ofcancer suffers, thus providing a quick and effective treatment for all types of cancer.Nanomachines could be used to repair damaged tissue and bones. They could even beused to strengthen bones and muscle tissue by building molecular support structures byreassembling nearby tissue. With the ability to manipulate human cells at the atomiclevel, medical science will rapidly devise treatments for most human illnesses. And sincenanomachines will be designed to make copies of themselves, these treatments will be

inexpensive and available to the entire population.

Food shortages and starvation will be a thing of the past if nanotechnology is perfected.Nanomachines will be able to turn any material into food, and this food could be used tofeed millions of people world wide. Again, since the technology is self replicating, foodproduced by nanomachines will be low cost and available to all.


12/18

As well as food, nanomachines will be able to build other items to satisfy the demands ofour growing population of consumers. Clothing, houses, cars, televisions, and computerswill be readily available at virtually no cost. Furthermore, there will be no concern aboutthe garbage produced by the new consumerist society because nanomachines will convertit all back into new consumable goods.

Environmental problems such as ozone depletion and global warming could be solved

with nanotechnology. Swarms of nanomachines could be released into the upperatmosphere. Once there, they could systematically destroy the ozone depletingchlorofluorocarbons (CFCs) and build new ozone molecules out of water (H2O) andcarbon dioxide (CO2). Ozone (O3) is built out of 3 oxygen atoms, and since water andcarbondioxide both contain oxygen, the atmosphere contains a plentiful supply of oxygenatoms. While the ozone construction teams are at work in the upper atmosphere, teams ofspecialized nanomachines could be employed to destroy the excess CO2 in the loweratmosphere. CO2 is a heat trapping gas, which has been identified as one of the majorcontributors to global warming. Removing excess CO2 could help halt global warmingand bring the planet's ecosystem back into balance. This will benefit all species on Earth.

The perfection of nanotechnology and the production of nanomachines could herald anew age for humanity. Starvation, illness, and environmental problems could quicklycome to an end. But how realistic are the goals of nanotechnology? Will it ever bepossible to produce machines the size of atoms? And if so, how feasible is it to buildnanomachines that can build objects from the atom up? Is it possible for nanomachines tobuild copies of themselves? Before we get carried away with the promises ofnanotechnology, we should take a look at some of the problems that are yet to be solved.

Challenges to overcome

An important challenge to overcome is one of engineering. How can we physically buildmachines out of atoms? Rearranging atoms into new shapes is essentially building newmolecules (nanomachines are sometimes called 'molecular machines') and this is no easytask. Using contemporary technology to rearrange atoms has been said to be analogous toassembling LEGO blocks while wearing boxing gloves. It is virtually impossible to snapindividual atoms together. All we can do is crudely push large piles of them together andhope for the best. Scientists hope that once this initial challenge is overcome,nanomachines will usher in a new age of molecular engineering and previous problemswill be a thing of the past. The new nanomachines will allow scientists to take off theboxing gloves and accurately snap together individual atoms to build virtually any

molecule (within the laws of physics, of course).

This is nice in principle, but the question of how to build thefirstnanomachines remains.Nanotechnologists think that it will be impossible to build the first nanomachines byusing large scale equipment (Chen C. 2000). Although progress is being made in theminiaturization of integrated circuits and in the ultra-fine finishing of high quality opticalcomponents, the large scale technology being used doesn't let us take off the boxinggloves. There is a limit to how far down these machines can go. Super smooth lens


13/18

polishing is one thing, but moving individual atoms is something else all together.Nanotechnologists need to get the boxing gloves off before they can build the firstnanomachines.

One way to work without boxing gloves is to patiently experiment with chemicalsynthesis. The idea is to build molecules of increasing complexity by allowing atoms toassemble or rearrange in natural ways. When molecules are mixed, they naturally form

new molecules. Through extensive experimentation, more control can be gained overhow molecules are formed. In time, it is conceivable that chemists will be able to positionindividual atoms by using a range of techniques developed in chemical synthesis.

One of these techniques might involve the removal and relocation of hydrogen atoms.This technique could be developed with knowledge of how hydrogen atoms interact withother atoms. For example, it is known that thepropynylradical C3H3 (its made out of 3carbon atoms and 3 hydrogen atoms) is 'attracted' to hydrogen. It is also known that thisradical has two ends. At one end there is a highly reactive radical, while at the other endthere is stable carbon. This feature means that chemists may be able to synthesize a largermolecule with thepropynylradical at one end (the rest of the molecule would be built

from the stable carbon end). If this larger molecule was held on a positioning device, itcould be used to extract hydrogen from a range of different molecules by passing them bythe reactive radical (Merkle R.C. 1993).

Chemical synthesis is promising. In computer simulations, molecularly stable gears andcogs have been formed through chemical synthesis.

A representation of nanogears made from graphitetubes billionths of a meter wide.

(Picture from the NanoGallery, see references)

If chemists and engineers succeed in building nanomachines the hope is that thesemachines will be able to build a whole range of new molecules from the atom up. If allgoes well, scientists will never have to move atoms round while wearing boxing glovesand the lengthy experimental process of chemical synthesis will no longer be required.But will it be that easy?


14/18

In order to make new molecules, a nanomachine has to somehow 'grab' individual atomswith its pincers and move them into new positions or attach them to other molecules. Thisseems to be quite simple, but as George M. Whitesides (2001) points out, there areserious problems that need to be overcome. Consider, for example, the fact that ananomachine's pincers will be made out of several atoms and will therefore be larger thanthe individual atoms that it needs to move around. This means that the intricacy andaccuracy of the nanomachine's movement will be severely limited. It will be clumsy.

Assembling atoms would be like trying to piece together a mechanical wristwatch withyour fingers rather than small tweezers.

Another problem arises from the fact that individual atoms are compelled to 'attach' toother atoms. Some atomic bonds can be extremely strong (especially with carbon atoms)so pulling them apart will require large amounts of energy. Furthermore, since carbonatoms attach to just about anything it seems likely that they will bond to thenanomachine's pincers after they've been pried away from their original molecules(Whitesides 2001). The only way to remove them could be to move them to moleculesthat they are more strongly attracted to. But then there is the possibility that the entirenanomachine will stick to the molecule. The situation is analogous to trying to build a

wristwatch with magnetized tweezers and screwdrivers. It can't be done because theindividual components stick to the tools.

Drexler et al (2001) brush aside these problems. They suggest that such concerns arisefrom a misunderstanding of how nanomachines work. For example, the idea thatnanomachines use 'pincers' to move objects around is nothing more than a poor metaphor.In reality, nanomachines might contain an active tip (like the hydrogen extractordescribed above), which is no larger than the atom it is designed to manipulate. SoWhitesides' concerns about the size of a nanomachine's pincers are easily answered.However, his concerns about the bonding of carbon atoms to nanomachines seem moredifficult to answer. Drexler attempts to bury the problem by citing theoretical work done

with the hydrogen extraction tool and by referring to experimental work done withhydrogen atoms. He doesn't directly address concerns about manipulating carbon atoms.This is important, because carbon is one of the most common atoms found on Earth andwill no doubt be involved if nanomachines are used to build new molecules. Progressmade with hydrogen might not translate easily to future work on carbon atoms.

Drexler does, however, mention some very promising work by Wilson Ho and HyojuneLee. In an experiment, Ho and Lee

"...used an STM tip first to locate two carbon monoxide (CO) molecules and one iron

(Fe) atom adsorbed on a silver surface in vacuum at 13 K. Next, they lowered the tip

over one CO molecule and increased the voltage and current flow of the instrument topick up the molecule; then they moved the tip-bound molecule over the surface-bound Fe

atom and reversed the current flow, causing the CO molecule to covalently bond to theFe atom, forming an iron carbonyl Fe(CO) molecule on the surface. Finally, the

researchers repeated the procedure, returning to the exact site of the first Fe(CO) and

adding a second CO molecule to the Fe(CO), forming a molecule of Fe(CO)2, which in

subsequent images of the surface appeared as a tiny "rabbit ears" structure, covalently


15/18

bound to the silver surface. Ho's group has also demonstrated single-atom hydrogenabstraction experimentally, using an STM" (Drexler et al. 2001).

This type of work will hopefully lead to more complex manipulation of atoms, and thiscould result in the development of tools that successfully 'pick and place' carbon atoms.

As our technological capacities develop, the promise of nanomachine technology

becomes more of a reality. We may one day see the successful creation of nanomachineassemblers. These machines could end hunger and bring in a new age of advancement forhumanity. Nanotechnology offers us big promises in a small package. However, theadvantages it promises do not come for free. They come with some very big risks.

Big risks come in small packages

Cutting edge technology can take a while to catch on in the commercial world. However,there is one place in which it catches on very quickly: The Military! During humanity's

history, technological research has moved fastest when there is a potential militaryapplication. The danger is that this trend will continue with nanotechnology. Imagine thepossible uses of nanomachines in warfare. Self replicating nanomachines designed totarget and destroy organic material could be released over enemy territory reducing thepopulation to dust within a matter of hours. If these machines were designed to destroyeach other after (say) 24 hours, the enemy's country would be left empty and safe to beinvaded by military forces. Biological warfare would be a thing of the past sincenanomachine warfare would be so much safer (well, for the 'good guys' anyway).

The only way to prevent this use of nanomachines would be through internationalagreements. Unfortunately, not all countries are willing to sign such agreements. And

those who do sign might be tempted to develop the technology in secret--just incase theenemy is doing the same thing. Perhaps the most we could hope for would be a stalematesituation like the one between the United States and the U.S.S.R during the cold war. Ifboth sides have the technology, they might be too nervous to use it, since they know thatthe other side will retaliate.

A more serious danger of nanomachine technology involves the ability to self replicate.Imagine that a nanomachine has the ability to make a copy of itself by rearranging theatoms contained in any nearby matter. Since it is producing an exact copy of itself, it islikely that the 'offspring' machine will be able to replicate. This is, after all, the way inwhich nanotechnologists intend to keep the cost of nanomachines down.

So now we have 2 nanomachines that can replicate. One more cycle will produce 2 more,which leaves a total of 4.

4 becomes 8.

8 becomes 16.


16/18

16 becomes 32, and so on.

After only 27 generations we would have over 134 million nanomachines on our hands.Since they are molecular, this doesn't seem like a big number. But the number could keepgrowing. After 39 generations there would be over 549 billion nanomachines on theplanet. The point is obvious. Without a way of controlling the reproduction ofnanomachines, the planet is in danger of being over run. Furthermore, since the

nanomachines are using the planet's resources as raw material with which to replicate, thedanger is that the planet could eventually be transformedinto a seething mass ofnanomachines.

George Whitesides (2001) responds to this problem by pointing out that Earth has alreadybeen ravaged by molecular machines--namely, biological cells. This is true. Earth was amuch different place 3.5 billion years ago before the emergence of life. Self replicatingcells have, over 3.5 billion years, completely transformed the planet. They have changedthe planet from a world of inorganic minerals with a CO2 rich atmosphere, to a worldthat is perfect for biological life.

But this fact doesn't negate the danger in creating replicating nanomachines. In fact,Whitesides has reminded us that it is possible for molecular machines to replicateexponentially and transform the planet. If self replicating nanomachines get out ofcontrol, then they could alter the planet to such an extent that it is no longer suitable forbiological life.

A possible solution to the problem is to limit the replicating abilities of nanomachines.For example, a mechanism could be developed by which new nanomachines are taggedwith a number. This number could represent their generation. So, a nanomachine labeled'gen 2' would produce offspring labeled 'gen 3', and their offspring would be labeled 'gen4'. The replicating algorithm could be designed to only function if the generation number

is less than 4. Also, nanomachines with a generation number higher than 1 could beencoded with a function that limits the number of reproductive cycles they can execute.By building in these safeguards, we may be able to control the population ofnanomachines while at the same time allowing the existence of a number necessary tofacilitate some of the advantages mentioned earlier.

However, these safeguards may not be enough. The biological world has shown us thatevolution occurs and cannot be stopped. The same may be true of the nano-world.Consider the idea that each time a nanomachine makes a copy of itself, there is apossibility that an error could be made during the copying process. Such errors could bevery small--perhaps no larger than a single 'bit' of information. Now imagine what would

happen if an error occurred while a nanomachine was building its offspring's copyingmechanism. To be more specific, imagine that a single 'bit' error occurred when encodingthe function that limits the machine's replicative abilities. So, instead of checking that themachine's generation number is less than 4, it checks to see that it is less than 40. Whenthis error is passed on to the machine's offspring, they will reproduce providing theirgeneration number is less than 40. Since the error will be passed on to each subsequentgeneration, there will be a substantial explosion in nanomachine population. A singleerror could have the potential to send the nanomachine population out of control. And the


17/18

more reproducing nanomachines there are, the greater the chance of another erroroccurring in at least one of them.

The only way to avoid the problem of uncontrollable replication is to avoid building self-replicating nanomachines. It may be true that self-replicating machines are the only wayto ensure a cheap supply of nanomachines, but the potential risks outweigh the benefits.If nanomachines are built individually in labs, they will still be useful to cure disease and

they will still be potentially useful for rearranging molecules to build new objects such asfood. The only drawback is that none of it will come for free. Someone will still have topay for the construction of the machines, and this means that their products will have tobe paid for by consumers. So, poverty will not be eradicated. However, it could be thatproducing food with nanomachines is faster and cheaper than conventional means, whichwill mean that poverty may be eased a bit. Furthermore, if governments are willing toinvest in the technology, nanomachines may be able to be used to fix some of ourenvironmental problems by repairing the damage we've done to the atmosphere. So theresearch is worth continuing.

Conclusion

Nanomachines offer humanity hope for the future. The idea that we could one day curediseases, fix the atmosphere, and reduce poverty in the world is an exciting one. Ifscientists can overcome the technical difficulties involved in producing nanomachinescapable of these goals, then the fruits of their efforts will benefit us all. However, wemust be cautious. The temptation to build self-replicating machines is strong, since it willgive us an endless supply of new nanomachines at virutally no cost but self-replicatingmachines have the potential to get out of control. The best efforts to limit their replicativeabilities may be insufficient, and our planet could be at risk of being over run by

machines that can consume anything to produce more machines at an astounding rate.

The benefits of building nanomachines that can manipulate matter are real and cannot beignored, so the technology should be pursued with vigor. However, the risks in producingself-replicating machines outweigh the benefits, so I conclude that self-replicatingnanomachine technology should not be pursued. We should focus our efforts onperfecting machines that can produce the benefits outlined in this article while neverbuilding machines that can make copies of themselves.

Copyright BRENT SILBY 2002=ALL RIGHTS RESERVED=

References and further reading

Caudle, Neil (2000). "Gearing up for Nanomachines",http://research.unc.edu/endeavors/spr2000/nano_side.htm
http://research.unc.edu/endeavors/spr2000/nano_side.htmhttp://research.unc.edu/endeavors/spr2000/nano_side.htm


18/18

Chen, Chau-Jeng (Jeremy) (2000). "Nanotechnology--Magic of Century 21",http://www.gwforecast.gwu.edu/documents/nanotech.doc

Drexler, K. Eric (1992).Nanosystems: Molecular Machinery, Manufacturing, andComputation (New York: Wiley, 1992).

Drexler, K. Eric (1991). Unbounding the Future : Nanotechnology Revolution (New

York: William Morrow, 1991)

Drexler, K. Eric; Forrest, David; Freitas, Robert A. Jr.; Hall, J. Storrs; Jacobstein, Neil;McKendree, Tom; Merkle, Ralph; Peterson, Christine (2001). "Many FutureNanomachines: A Rebuttal to Whiteside's Assertion That Mechanical MolecularAssemblers Are Not Workable and Not A Concern",http://www.imm.org/SciAmDebate2/whitesides.html

Johnson, Matt (2001). "On The Brink of Nano Technology",http://www.ce.org/vision_magazine/editions/2001/marapr/p19.asp

Merkle, Ralph C. (1993). "Molecular Manufacturing: Adding Positional Control toChemical Synthesis" in Chemical Design Automation News, Vol 8, Numbers 9 & 10,September/October 1993. Also available at:http://www.zyvex.com/nanotech/CDAarticle.html

The NanoGallery: http://nanozine.com/Dr.R.Smalley_Nobel.htm

Twibell, T.S. (2000). "Nano Law The Legal Implications of Self-ReplicatingNanotechnology", http://wwww.nanozine.com/nanolaw.htm

Whitesides, George M. (2001). "The Once and Future Nanomachine",

http://www.sciam.com/2001/0901issue/0901whitesides.html

"What is NanoTechnology?", http://www.nanozine.com/WHATNANO.HTM
http://www.gwforecast.gwu.edu/documents/nanotech.dochttp://www.imm.org/SciAmDebate2/whitesides.htmlhttp://www.ce.org/vision_magazine/editions/2001/marapr/p19.asphttp://www.zyvex.com/nanotech/CDAarticle.htmlhttp://nanozine.com/Dr.R.Smalley_Nobel.htmhttp://wwww.nanozine.com/nanolaw.htmhttp://www.sciam.com/2001/0901issue/0901whitesides.htmlhttp://www.nanozine.com/WHATNANO.HTMhttp://www.gwforecast.gwu.edu/documents/nanotech.dochttp://www.imm.org/SciAmDebate2/whitesides.htmlhttp://www.ce.org/vision_magazine/editions/2001/marapr/p19.asphttp://www.zyvex.com/nanotech/CDAarticle.htmlhttp://nanozine.com/Dr.R.Smalley_Nobel.htmhttp://wwww.nanozine.com/nanolaw.htmhttp://www.sciam.com/2001/0901issue/0901whitesides.htmlhttp://www.nanozine.com/WHATNANO.HTM

nanoscale sensors as medical diagnostics

Documents