The dawn of the brave new world of computational biotechnology is upon us! In the 21st century we are poised for a new development--computers that do not have to be told what to do, but have the power to learn on their own. The development of a biological computer that is fast, small, and evolvable is no longer considered science fiction. Scientists are combining biological materials with the latest silicon-based technology in an effort to give us not only electronic devices that are smaller, but are also more flexible in terms of structure and function.
Ironically, our brain can serve as proof of concept. Many scientists now believe that individual neurons display wiring patterns and communication powers that resemble a human computer, and therefore may provide the framework for the design of a biological computer. The brain is composed of 10 billion neurons, each of which may be communicating with 1000 others. The neuron transmits electric signals along its arms, or axons. Inside each axon a parallel architecture of microtubules is interconnected with other proteins, not unlike the parallel computer's wiring. In fact, the structure of microtubules may have evolved toward optimal computational efficiency. The piezoelectric properties of these protein filaments allow them to bend as a result of electric fields or currents, which makes them ideal candidates as regulators of synaptic plasticity, a mechanism that could explain the popular principle of "use it or lose it." Thus the synaptic connections which are seldom used would be switched off in favor of more active ones.
Biologist Guenter Albrecht-Buehler demonstrated that cells perceive their environment through a tiny organelle called the centriole, composed of microtubules that were shown to interact with electromagnetic radiation. A German biotechnology group led by Eberhard Unger went on to demonstrate that microtubules themselves can be conductive, and they are now working on building nanoelectronic components using these and other proteins. At the same time, ideas of combining biological and silicon-based materials in hybrid arrangements are gaining more and more support for future bioelectronic applications. Nowhere is it more evident than at Starlab Inc., a private research laboratory in Brussels, which is the home and playground of 70 scientists from 28 countries involved in multidisciplinary research. Work is under way at Starlab to develop a biological chip. The objective is to design nanoelectronic components using hybrid protein-silicon structures with arrays of proteins as biological oscillators that can be stimulated by electrodes or acoustic couplers. This will provide an analog circuit with rich dynamics.
DNA computers are unlikely to become stand-alone competitors for electronic computers. But digital memory in the form of DNA and proteins is a real possibility with exquisitely efficient editing machines that navigate through the cell, cutting and pasting molecular data into the stuff of life. Beyond that, the innate intelligence built into DNA molecules could help fabricate tiny, complex structures--in essence using computer logic not to crunch numbers but to build things, an idea conceived by Eric Winfree and Paul Rothemund at the California Institute of Technology. A single test tube of DNA tiles could perform about 10 trillion additions per second--about a million times faster than an electronic computer. Lucent's Bernie Yurke intends to assemble ultrasmall DNA-based molecular motors as components for synthetic systems, "nanorobots," capable of carrying out individual tasks such that an arbitrarily complex pattern might be transferred to a silicon substrate to fabricate nanometer-scale circuits and transistors. Interfacing these structures with living cells will enable a host of medical and technological applications including noninvasive diagnostic and therapeutic medical applications and computational devices.
On an even grander scale, the $150 million gift from Netscape co-founder Jim Clark enabled Stanford University to assemble interdisciplinary research teams mixing biology with other fields in the so-called Bio-X initiative. Interdisciplinary research is one of the hottest trends in science, and scientists in the United States and elsewhere are crossing departmental glass walls. Multidisciplinary teams are being formed to model living structures and processes. For example, the goal of Project CyberCell, headed by University of Alberta's Michael Ellison, is to understand the dynamic and structural nature of cellular processes at sufficient detail such that a living cell can be recreated computationally. The prospect of examining and controlling cell physiology in silico would lay the foundation for the creation of other unicellular and, ultimately, multicellular cyberorganisms. Parallel efforts include The Virtual Cell Development Project based at North Dakota State University and supported by the National Science Foundation, whose long-term goal is to create an active learning environment focusing on the structure and function of the cell. In Europe, a similar but more research-oriented project tentatively called Sim-Cell is being prepared for funding by the European Union as collaboration between Starlab, BrainMedia of Marburg, Germany, and a host of academic partners.
Even applied mathematicians are jumping into the fray. In Canada, a federally funded network of centers of excellence called MITACS (Mathematics, Information Technology, and Complex Systems) includes a biomedical theme that deals with developing statistical tools for genetic research, mathematical and computer models of epidemics, biomedical models of cellular and physiological systems, and computer models in pharmaceutical development. In the U.S., a major new initiative to inject $2 billion into nanotechnology research with medical applications started with a National Institutes of Health symposium in June 2000 that focused, among other things, on the following topics: applications of nanotechnology to therapy, tissue engineering and diagnostics, development of biomimetic nanostructures, and electronic/biology interfaces. While former President Clinton once remarked that the 20th century belonged to physics and the 21st will belong to biology, we already see the power of breaking down interdisciplinary barriers in the case of nanoscale biotechnology. The pace of innovation and discoveries in this area is expected to be rapid.
Dr. Jack Tuszynski is a professor of biophysics at the University of Alberta, cross-appointed in the Faculties of Science and Medicine. He is the project leader of the MITACS Center of Excellence: "Mathematical Modelling in Pharmaceutical Development." For almost a year, Dr. Tuszynski has been research manager of the neurons group at the Brussels-based high-technology incubator Starlab. He is currently building an international and interdisciplinary team of scientists for a project called Sim-Cell to create a computer model of a living cell.