Nanomedicine and 21st Century Health Care

Robert A. Freitas Jr.

Senior Research Scientist

Institute for Molecular Manufacturing

© 2004 Robert A. Freitas Jr.



This paper, authored in June 2004, is scheduled for publication in 2005 as a Foreword to the book:  Simon Young, Designer Evolution: A Transhumanist Manifesto, Prometheus Press, 2005. Young's book is available for purchase online at and at Barnes&


Biotechnology and genetic engineering are comparatively well-known because of their many important successes over the last several decades. But advocates of these approaches often ignore a future post-biotechnology discipline, just now appearing on the 2-3 decade R&D horizon, that can almost guarantee whole-body elimination of biological senescence and the indefinite maintenance of healthy mind and body, while producing few if any unwanted medical side effects. This new technology involves the application of molecular nanotechnology and nanorobotics to human health care [1]. Over the next decade or two, it will become increasingly clear that all of biotechnology is but a small subset – albeit an important subset – of nanotechnology. Indeed, the 21st century will be dominated by nanotechnology – the engineering and manufacturing of objects with atomic-scale precision – not biotechnology.

Humanity is finally poised at the brink of completion of one of its greatest and most noble enterprises [2]. Early in this century, our growing abilities to swiftly repair most traumatic physical injuries, eliminate pathogens, and alleviate suffering using molecular tools will begin to coalesce in a new medical paradigm called nanomedicine [1]. Nanomedicine may be broadly defined as the comprehensive monitoring, control, construction, repair, defense, and improvement of all human biological systems, working from the molecular level, using the emerging techniques of molecular nanotechnology and molecular manufacturing to produce engineered nanodevices and nanostructures, molecular machine systems, and – ultimately – nanorobots too small for the eye to see [2].

Nanotechnology applied to medicine generally means controlling biologically relevant structures with molecular precision. Even now, nanomedicine [1] is already exploring how to use carbon buckyballs, dendrimers (spherical treelike molecules), and other cleverly engineered nanoparticles in novel drugs to combat viruses, bacteria, and cancer. But in 10-20 years we may learn how to build the first medical nanorobots. These will be devices the size of a microbe, though incapable of self-replication [3], containing onboard sensors, computers, manipulators, pumps, pressure tanks, and power supplies. Building such sophisticated molecular machine systems will require molecular manufacturing – both the ability to make atomically precise objects, probably using diamond [4] or other similarly rigid materials, and the ability to make precise objects in very large numbers, probably using massively parallel assembly lines in nanofactories.

Methods to build these still-theoretical medical nanorobots are already being researched today [5]. The technology is still in a relatively primitive state [5]. We are just now learning how to build structures atom by atom [6], particularly structures made of diamond [7] and other similar durable materials [8]. These structures, or nanoparts, must then be assembled into complex components, and then these components must in turn be assembled into complete machine systems such as medical nanorobots [9]. After that, we must devise massively parallel production lines so that these nanorobots can be manufactured in batches of millions or billions of identical units [10]. It’s a big research agenda, but it’s doable. By 2020 we should begin to enjoy the fruits of these efforts, in our daily lives.

Once doctors gain access to medical nanorobots [11], they’ll be able to quickly cure most known diseases that hobble and kill people today, rapidly repair most physical injuries that our bodies can suffer, and vastly extend the human healthspan – independent of the cruder treatments that might already be available via biotechnology. A few specifics:

One simple device I designed 9 years ago was the respirocyte [12], an artificial red blood cell. Natural red cells carry oxygen and carbon dioxide throughout the human body. We have about 30 trillion of these cells in all our blood, occupying half our blood volume, with each disk-shaped red cell measuring about 3 microns thick and 8 microns in diameter. Respirocytes will be much smaller than red cells – spheres only 1 micron in diameter, about the size of a bacterium. Respirocytes are self-contained nanorobots built of 18 billion precisely arranged structural atoms. Most of this structure serves to enclose microscopic pressure tanks with a hull made mostly of flawless diamondoid crystal. Each device has an onboard computer and an onboard powerplant, along with thousands of molecular pumps arranged on the surface to load and unload oxygen and carbon dioxide gases from the pressurized tanks. Only 5 cc’s of respirocytes, just 1/1000th of our total blood volume, could duplicate the oxygen-carrying capability of the entire human blood mass. Each respirocyte transports hundreds of times more physiologically available oxygen molecules than an equal volume of natural red blood cells. A half a liter of respirocytes, the most that could possibly be safely added to our blood, would allow a person to survive four hours without breathing, as during a drowning accident or a heart attack, or alternatively to sprint at top Olympic speed for up to 12 minutes without taking a breath [13].

Nanorobotic phagocytes (artificial white cells) called microbivores [14] could patrol the bloodstream, seeking out and digesting unwanted pathogens including bacteria, viruses, or fungi. During each cycle of nanorobot operation, a target bacterium becomes bound to the surface of the bloodborne microbivore like a fly on flypaper, via species-specific reversible binding sites. Telescoping robotic grapples emerge from silos in the device surface, establish secure anchorage to the microbe’s plasma membrane, then transport the pathogen to the ingestion port at the front of the device where the pathogen cell is internalized into a 2 micron3 morcellation chamber. After sufficient mechanical mincing, the chopped-up remains of the cell are pistoned into a separate 2 micron3 digestion chamber where a preprogrammed sequence of 40 engineered enzymes are successively injected and extracted six times, progressively reducing the mash to amino acids, mononucleotides, simple fatty acids and sugars. These basic molecules are then harmlessly discharged back into the bloodstream through an exhaust port at the rear of the device, completing the 30-second digestion cycle. No matter that a bacterium has acquired multiple drug resistance to antibiotics or to any other traditional treatment – the microbivore will eat it anyway, achieving complete clearance of even the most severe bloodborne infections in minutes to hours [15] rather than taking weeks to months using present-day antibiotics, using only a few cc’s of nanorobots. Hence microbivores, each 2-3 microns in size, would be up to ~1000 times faster-acting than either unaided natural or antibiotic-assisted biological phagocytic defenses. Related nanorobots could be programmed to recognize and dissolve cancer cells, or to clear circulatory obstructions in a time on the order of minutes, thus quickly rescuing the stroke patient from ischemic damage.

Theoretical designs for respirocytes [16] and microbivores [17] suggest typical performance improvements of 100- to 1000-fold over natural biological systems. Other medical nanorobots may offer equally astonishing performance improvements over nature. For instance, micron-size artificial mechanical platelets or clottocytes [18] could staunch bleeding in seconds, even for moderately large wounds. This response time is on the order of 100-1000 times faster than the natural system. The baseline clottocyte is conceived as a glucose-powered spheroidal nanorobot measuring 2 microns in diameter, containing a compactly-folded biodegradable fiber mesh. Upon command from its control computer, the device promptly unfurls its mesh packet in the immediate vicinity of an injured blood vessel – following, say, a cut through the skin. Soluble thin films coating certain parts of the mesh dissolve upon contact with plasma water, revealing sticky sections (e.g., complementary to blood group antigens unique to red cell surfaces) in desired patterns. Blood cells are immediately trapped in the overlapping artificial nettings released by multiple neighboring activated clottocytes, and all bleeding halts at once [19]. Clottocytes may perform a clotting function that is equivalent in its essentials to that performed by biological platelets, but at only 0.01% of the bloodstream concentration of those cells or about 20 nanorobots per cubic millimeter of serum. Hence clottocytes look to be about 10,000 times more effective as clotting agents than an equal volume of natural platelets.

Nanorobots can also be used directly to repair individual cells. For example, tissue-repair nanorobots could selectively rebuild wounded flesh in minutes or hours. But the most likely site of pathological function in the cell is the nucleus – more specifically, the chromosomes. In one simple cytosurgical procedure, cell-repair nanorobots called chromallocytes, controlled by a physician, would extract existing chromosomes from a diseased cell and insert new ones in their place, a process I call “chromosome replacement therapy” [20]. The replacement chromosomes are manufactured to order, outside of the patient’s body in a laboratory benchtop production device that includes a molecular assembly line, using the patient’s individual genome as the blueprint. If the patient chooses, inherited defective genes could be replaced with nondefective base-pair sequences, permanently curing all genetic diseases or permitting cancerous cells to be reprogrammed to a healthy state.

More importantly, whole-body chromosome replacement therapy will allow us to replace our old worn-out genes with new digitally-correct chromosome copies installed in every tissue cell of our bodies, forestalling aging. Future medical technologies, especially nanomedicine, will permit us first to arrest, and later to reverse, the biological effects of aging and most of the current causes of natural death, severing forever the link between calendar time and biological health. Respirocytes, microbivores, and chromallocytes are examples of the new therapeutic capabilities that medical nanorobotics can bring in the decades to come, with benefits to include extending the human healthspan at least tenfold beyond its current maximum length.

I’ve defined the concept of “dechronification” [21] – or, more colloquially, “rolling back the clock” – founded on the principle that if you’re physiologically old and don’t want to be, then for you, oldness and aging are a disease, and you deserve to be cured. Dechronification – the nanotech version of the classical medical concept of “rejuvenation” – will first arrest biological aging, then reduce your biological age by performing three kinds of procedures on each one of the tissue cells in your body:

First, a respirocyte- or microbivore-class device will be sent to enter every tissue cell, to remove accumulating metabolic toxins and undegradable material. Afterwards, these toxins will continue to slowly re-accumulate as they have all your life, so you’ll probably need a whole-body cleanout to prevent further aging, maybe once a year.

Second, chromosome replacement therapy using chromallocyte nanorobots can be used to correct accumulated genetic damage and mutations in every one of your cells. This might also be repeated annually, or less often.

Third, persistent cellular structural damage that the cell cannot repair by itself such as enlarged or disabled mitochondria can be reversed as required, on a cell by cell basis, using cellular repair devices.

The net effect of these interventions will be the continuing arrest of all biological aging, along with the reduction of current biological age to whatever new biological age is deemed desirable by the patient. These interventions may become commonplace several decades from today. Using annual checkups and cleanouts, and some occasional major repairs, your biological age could be restored once a year to the more or less constant physiological age that you select. I see little reason not to go for optimal youth – a rollback to the robust physiology of your early twenties would be easy to maintain and lots of fun. You might still eventually die of accidental causes but you’ll live ten times longer than you do now – a healthy life expectancy of at least 1000 years is anticipated, based on the actuarial rates of fatal accidents and suicides [21]. Even if for some reason nearer-term efforts fail to accomplish similar objectives using biotechnology alone, nanotechnology – via nanomedicine – is almost guaranteed to achieve the desired results.

Some conservative bioethicists [22] are aghast at the prospect of vastly expanded human healthspans but there are many important advantages of “ageless bodies.” For example, rather than leading to “a life of lesser engagements and weakened commitments” [22], ageless bodies would enhance our personal commitment to the more distant future because we would now expect to live in it ourselves. This realization would inevitably lead to an increased respect for our bodies, for our friends and families, for our natural environment, and, most significantly, for strangers we’ve never met. With time to meet more people during an enhanced healthspan, with more time to consider the consequences of our personal actions, and with more healthy lifespan to lose by risking early death, the human proclivity for war and violence should markedly diminish, an unquestionable and historic major social benefit.



1. Robert A. Freitas Jr., Nanomedicine, Volume I: Basic Capabilities, Landes Bioscience, Georgetown, TX, 1999;

2. Robert A. Freitas Jr., “1.1 A Noble Enterprise,” Nanomedicine, Volume I: Basic Capabilities, Landes Bioscience, Georgetown, TX, 1999;

3. Robert A. Freitas Jr., Ralph C. Merkle, Kinematic Self-Replicating Machines, Landes Bioscience, Georgetown, TX, 2004;

4. Ralph C. Merkle, Robert A. Freitas Jr., “Speeding the development of molecular nanotechnology,” Foresight Institute website, December 2003;

5. Robert A. Freitas Jr., “Chapter 2. Pathways to Molecular Manufacturing,” Nanomedicine, Volume I: Basic Capabilities, Landes Bioscience, Georgetown, TX, 1999;

6. Ralph C. Merkle, Robert A. Freitas Jr., “Theoretical analysis of a carbon-carbon dimer placement tool for diamond mechanosynthesis,” J. Nanosci. Nanotechnol. 3(August 2003):319-324;

7. Jingping Peng, Robert A. Freitas Jr., Ralph C. Merkle, “Theoretical Analysis of Diamond Mechanosynthesis. Part I. Stability of C2 Mediated Growth of Nanocrystalline Diamond C(110) Surface,” J. Comp. Theor. Nanosci. 1(March 2004):62-70;; and David J. Mann, Jingping Peng, Robert A. Freitas Jr., Ralph C. Merkle, “Theoretical Analysis of Diamond Mechanosynthesis. Part II. C2 Mediated Growth of Diamond C(110) Surface via Si/Ge-Triadamantane Dimer Placement Tools,” J. Comp. Theor. Nanosci. 1(March 2004):71-80;

8. Robert A. Freitas Jr., “Technical Bibliography for Research on Positional Mechanosynthesis,” Foresight Institute website, 16 December 2003;

9. Robert A. Freitas Jr., “2.4 Molecular Components and Molecular Assemblers,” Nanomedicine, Volume I: Basic Capabilities, Landes Bioscience, Georgetown, TX, 1999;

10. Robert A. Freitas Jr., Ralph C. Merkle, “5.7 Massively Parallel Molecular Manufacturing,” Kinematic Self-Replicating Machines, Landes Bioscience, Georgetown, TX, 2004;

11. Robert A. Freitas Jr., “Say Ah!” The Sciences 40(July/August 2000):26-31;

12. Robert A. Freitas Jr., “Exploratory Design in Medical Nanotechnology: A Mechanical Artificial Red Cell,” Artificial Cells, Blood Substitutes, and Immobil. Biotech. 26(1998):411-430;


14. Robert A. Freitas Jr., “Microbivores: Artificial Mechanical Phagocytes using Digest and Discharge Protocol,” J. Evol. Technol. 14(April 2005):1-52; or


16. Nanomedicine Art Gallery, “Respirocyte Images,”

17. Nanomedicine Art Gallery, “Microbivore Images,”

18. Robert A. Freitas Jr., “Clottocytes: Artificial Mechanical Platelets,” Foresight Update No. 41, 30 June 2000, pp. 9-11;

19. Nanomedicine Art Gallery, “Clottocyte Images,”

20. Robert A. Freitas Jr., “The future of nanofabrication and molecular scale devices in nanomedicine,” Studies in Health Technol. Inform. 80(2002):45-59;

21. Robert A. Freitas Jr., “Death is an Outrage!” lecture delivered at the Fifth Alcor Conference on Extreme Life Extension, 16 November 2002, Newport Beach, CA;

22. “Chapter Four: Ageless Bodies,” in Leon Kass et al, eds., Beyond Therapy: Biotechnology and the Pursuit of Happiness, The President’s Council on Bioethics, Washington, D.C., October 2003;



Last updated by the author on 12 August 2005