Nanotechnology and the Quest for the Ultimate Drug-Delivery System

Feb 02, 2008
Volume 32, Issue 2

Melgardt M. de Villiers, PhD
The story is told of a flea and an elephant that crossed a bridge together. After reaching the other side, the flea proudly says to the elephant, "Man! We sure did shake that bridge, didn't we!" It is not often that something small can claim to shake a bridge, but recently things that are very small, nanosized materials and systems for example, have begun to cause quite a stir among pharmaceutical scientists.

A review of papers indexed in Chemical Abstract Services that refer to nanoparticles revealed that the first paper to use the term was Kopf et al.'s 1976 "Study on Micelle Polymerization in the Presence of Low-Molecular-Weight Drugs. 1. Production and isolation of nanoparticles, residual monomer determination, physical-chemical data," published in Pharmazeutische Industrie. This was the only reference to nanoparticles that year. The number of references increased to four in 1980, 15 in 1985, 39 in 1990, and 478 in 1995. At that point, industry seemed to move into the age of nanotechnology as it is known today and as demonstrated by the huge increase in references from 3185 in the year 2000, to 17,688 in 2005, and 21,553 in 2007. Although the nanotechnology "flea" took a while to start moving the bridge, it is now quite the bridge-shaker.

Pharmaceutical scientists commonly accept Richard Feynman's 1959 talk at the American Physical Society annual meeting as the birth of nanotechnology. "I would like to describe a field, in which little has been done, but in which an enormous amount can be done in principle," he said. "This field is not quite the same as the others in that it will not tell us much of fundamental physics (in the sense of, "What are the strange particles?") but it is more like solid-state physics in the sense that it might tell us much of great interest about the strange phenomena that occur in complex situations.... What I want to talk about is the problem of manipulating and controlling things on a small scale."

In this seminal talk, Feynman proposed the potential to manipulate matter at the atomic scale. Inspired by this notion, the term nanotechnology was coined by Tokyo Science University Professor Norio Taniguchi in 1974 to describe the precision manufacture of materials with nanometer tolerances and was unknowingly appropriated by Drexler in his 1986 book, Engines of Creation: The Coming Era of Nanotechnology.

In Engines of Creation, Drexler extrapolates a world from the bottom up where we can build atom by atom using a process called molecular nanotechnology. Drexler looked at the proteins and enzymes operating inside humans and saw tiny biological machines that could turn genes on and off, thereby creating just about anything inside the human body—including more of themselves. Drexler's vision was extraordinary. If we can replicate biological machines to produce manmade molecular assemblers, we may be able to cure any disease or disability.

Initially, his vision was well supported, including by President William J. Clinton who proposed a nearly $500 million per year National Nanotechnology Initiative (NNI) to fund nanotech work in 2000. In announcing this initiative, Clinton said that one day such systems could lead to a "100% cure and prevention rate for every kind of cancer."

Feynman and Drexler's vision, however, also brought raised fear of these assemblers, which had the potential to become nanosize robots, or nanobots, that could turn into grey goo. Grey goo is also known as ecophagy, a hypothetical end-of-the-world scenario involving molecular nanotechnology in which out-of-control self-replicating nanobots consume all living matter while building more of themselves.

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