Book Reviews

NANOMEDICINE, VOLUME 1: BASIC CAPABILITIES, by Robert A. Freitas Jr., Landes Bioscience, Austin, Texas, 1999, xxi + 509 pp., ISBN 1-57059-645-X Index (Hardback, $89.00).

The possibilities of using microrobots in medicine have been well explored in the literature, but this book goes further in that it considers manipulation at the molecular level. The prefix nano-, indicating ten to the minus nine, has also been adopted to indicate operation at the molecular level and is appropriate since a nanometre is about the width of six carbon atoms.

Nanomedicine is not with us yet, but the author of the book is confident that it can be expected on the basis of current trends, and in his first chapter, on: “The Prospect of Nanomedicine” he estimates that molecular technology will be the main paradigm of scientific medicine from the year 2010. The present period, from 1940 to 2010, he terms: “Molecular scientific” in which living processes are understood in terms of molecular structures, but without the means of directly manipulating them by placing individual atoms or atomic groups at will.

The first chapter puts the discussion in context by reviewing the history of medicine from very early times, with some gruesome details of operations before the introduction of anaesthesia, and other intriguing details. Although nanomedicine is still “in the pipeline” it is held to be at a stage where its implications should be seriously considered, including ethical considerations. Some of the ethical aspects are already under discussion in connection with genetically modified crops and cloned animals, and nanotechnology would allow such developments with enormously greater ease and speed. Applied to the nervous system it could allow personality modification, with obvious ethical complications.

The author is in no doubt that these developments are imminent and his affiliation is to an Institute of Molecular Manufacturing in Palo Alto, California. The present volume is the first of three, with the others already in preparation. The aim of this first volume is “to describe basic capabilities common to all medicinal nanodevices, and the physical, chemical, thermodynamic, mechanical and biological limits of such devices.” Its intended audience is a variety of specialists engaged in basic research. The second volume is to deal with: “aspects of device control and configuration, biocompatibility and safety issues, and basic nanomedical components and simple systems.” Its primary audience is a variety of specialists engaged in applied research. The third volume is to come still closer to medical practice, with discussion of treatments for specific conditions and injuries and is aimed at clinical specialists and research physicians.

The reasons for believing that molecular manufacturing is not only feasible but just around the corner are given in the second chapter, on: “Pathways to Molecular Manufacturing”. Approaches are classed as top-down and bottom-up. The former term is used to refer to successive scaling-down from normal engineering practice, where micromanipulators would be used to build still smaller micromanipulators, and so on. This has resulted in a technique of MEMS (Micro Electro-Mechanical Systems) with some very impressive results but not allowing operation at the truly molecular level.

The bottom-up approaches come under the three headings of biotechnology, supramolecular chemistry and scanning probes. Biotechnology provides almost ready-made solutions. The cell component termed the ribosome can be seen as a programmed protein molecule assembler and it has been found possible to use bacterial ribosomes to produce such molecules to order. Approaches under the heading of supramolecular chemistry are extensions of existing methods for organic synthesis, and a bewildering collection of impressive results is quoted, emphasizing the widespread attention being given to these matters. There is overlap between the supramolecular chemistry approach and the biotechnology one, especially since nanodevices for most medical applications will need to be available in large numbers and should be amenable to mass production, or, better still, self-replication.

Particularly impressive under this heading are possible structures formed of the “fullerene” or “buckyball” allotrope of carbon, which actually allow meshing gear wheels and rack-and-pinion mechanisms. The pictures shown are from computer simulations of the structures, but presumably using simulation packages that embody appropriate constraints to confirm that the structures are feasible.

The third class of approach is through the use of scanning probes. Scanning probe microscopes, in which the surface to be examined is traversed by a physical probe, are well known and commercially available, and are capable of imaging individual molecules. The technique has been extended to allow the deposition or transport of single atoms or molecules, and nanoassembly robots are visualised.

Later chapters deal with specific aspects, starting with “Molecular transport and sortation”, in which there are proposals for devices to allow the passage of selected molecules, for example by having them adhere to the ends of spokes of molecular wheels that rotate and so convey the molecules through a barrier. The other chapter headings are: “Shapes and Metamorphic Surface”, “Power”, “Communication”, “Navigation”, “Manipulation and Locomotion”, and “Other Basic Capabilities”.

“Transportation and sortation” are important since important medical applications will come under the heading of scavenging, after the fashion of leucocytes in the blood. Metamorphic surfaces are ones that are able to deform in a useful way by local activation, for example as part of a swimming action. Under “Communication” there is consideration of input and output devices allowing interaction with a human host of nanorobots, or his physician, through display panels made to appear on an appropriate area of skin such as the back of the left hand. In the final chapter, possibilities of onboard computation in nanorobots are considered, with a remarkably detailed discussion of theoretical power requirements for computation. Also in this chapter it is acknowledged that nanorobots may have to fight and destroy malignant organisms by mechanical rather than chemical means, using something in the nature of nano-jaws and teeth.

All of the topics are developed in considerable detail, involving a degree of extrapolation that is certainly courageous and perhaps foolhardy. The treatment is supplemented by quite a lot of tabular data, much of it rather unnecessary since it can be found in standard reference works, though including some items that are important in the special context but would be difficult to find elsewhere. References to other published work are indicated by the superscripted numbers, most of them four-digit numbers since the total of such citations is 3728. The actual number of references is substantially greater than this, since many of the numbered items give a primary reference and others in support. Many useful websites are quoted. A curious feature is that the numerical ordering of the references follows no obvious pattern, so that the only systematic way of finding a vaguely-remembered reference is to search for its number in the relevant section of the main text. An index linking authors’ names to reference numbers would be a useful addition, which the author may planning to provide when all three volumes have been completed.

Whether or not the “peek into the future” (as it is described in an Afterword to the book) will turn out to be accurate is impossible to say. The author gives compelling arguments in support of the picture he paints but of course it would be naive to dismiss the possibility of hidden pitfalls. At the very least, though, this is a thorough and fascinating exploration of a field that could bring enormous benefits.

Alex M. Andrew
95 Finch Road,
Earley,
Reading, RG6 7JX
(UK)

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Last updated on 7 January 2004