Genetically Engineered Microdevices

Nanostructured microdevices may soon be produced in bulk at lower costs, and with a wider variety of compositions and shapes than was once possible, resulting in dramatic improvements in device functionality by utilizing very small biologically generated structures.

These completely new biologically enabled techniques are described in the July 2005 of the International Journal of Applied Ceramic Technology. This study's newly devised methods for the low-cost mass production of micro-devices could yield unprecedented advancements in genetically engineered microdevices (GEMs) for biomedical, computing, environmental cleanup, defense, and many other applications.

Traditional microfabrication processes, similar to techniques used to create computer microchips, are costly and not well-suited for producing large numbers of complicated, three-dimensional (3D) nanostructured devices with a wide variety of chemistries and characteristics. Nevertheless, nature provides impressive examples of microorganisms that synthesize microscopic nanostructured shells with highly controlled and very reproducible 3D shapes and characteristics currently unachievable by manmade processes. However, the naturally occurring diatom microshells do not have the specific properties required for device applications, such as biocompatibility, electrical conductivity, thermal stability, and chemical compatibility.

According to the published study, the marketability of such devices will require precise 3D fabrication of chemically customized structures on a fine scale and mass production of such structures on a large scale. These often-contradictory challenges can be tackled with a ground-breaking new paradigm that combine biologic self-assembly with synthetic chemistry: bioclastic and shape-preserving inorganic conversion (BaSIC). Among the most extraordinary of nature's microorganisms are diatoms (unicellular algae). Each of the tens of thousands of diatom species assembles silica nanoparticles into a microshell with a distinctive 3D contour and pattern of fine (nanoscale) characteristics. The repeated doubling associated with biologic reproduction enables huge amounts of such 3D microshells to be generated. Such genetic accuracy is highly appealing for device manufacturing. However, the natural chemistries assembled by diatoms (and other microorganisms) are relatively limited. With BaSIC processes, biogenic assemblies can be converted into a wide variety of new functional chemistries, while maintaining the 3D morphologies. Ongoing developments in genetic engineering have the potential to generate microorganisms geared at creating nanoparticle structures with device-specific shapes. Large-scale culturing of such genetically modified microorganisms, combined with shape-preserving chemical conversion (via BaSIC processes), would then provide low-cost 3D GEMS.

According to the study's lead author, Kenneth Sandhage, Ph.D., from the Institute for Bioengineering and Biosciences, Georgia Institute of Technology (Atlanta, GA, USA), By demonstrating that biologically derived structures can be chemically modified without changing the starting shapes or fine features, we have opened the door for new research and development in the processing and application of many devices that would otherwise be very difficult or expensive to produce.



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