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Bionanotechnology

[from Mill Hill Essays 2003, ISBN 0-9546302-1-1]

Nanotechnology concerns structures, devices and phenomena that are on a scale between atomic distances and the wavelength of visible light. Bionanotechnology uses biological starting materials, biological design principles or has biological or medical applications. The prefix nano means a one-billionth part, so for instance a nanometre (nm) is one billionth of a metre. Chemists, physicists and biologists each view nanotechnology as a branch of their own subject, and collaborations in which they each contribute equally are common.

Using light microscopy we can see single living cells but not the individual proteins, DNA and other components from which they are made. This limits our ability to understand the processes involved in human health and disease. One aim of bionanotechnology is to provide tools to study the molecules of living cells and to build devices to help diagnose and cure diseases.

In the last fifteen years new technologies have enabled us to look inside cells, see individual molecules at work and also to image and manipulate individual molecules. In Scanned Probe Microscopy a mechanical probe, with a tip just a few nanometres wide, scans the specimen to be imaged. The deflections of the tip caused by the specimen are measured by bouncing a beam of light off the tip and onto a detector. The resolution depends on the diameter of the tip and the electronics that control it. As these improve it will become possible to see the structure of an individual protein in living conditions.

We are beginning to understand life processes at a molecular level and need new techniques to study living cells and molecules. Nanotechnology will make a significant contribution to the new post-genomic era of medical science.

proteins inside a living cell shown using total internal reflection fluorescence microscopyIndividual proteins inside a living cell are shown using a technique called total internal reflection fluorescence microscopy. Spots of light correspond to individual molecules (left). Atomic Force Microscopy (AFM) enables individual protein molecules to be visualised in aqueous conditions at room temperature. A Molecular Imaging © AFM enables muscle protein molecules to be seen.