Bio-engineers are working on the development of biological computers with the aim of designing small circuits made from biological material that can be integrated into cells to change their functions. In the future, such developments could enable cancer cells to be reprogrammed, thereby preventing them from dividing at an uncontrollable rate. Stem cells could likewise be reprogrammed into differentiated organ cells.
The researchers have not progressed that far yet. Although they have spent the past 20 years developing individual components and prototypes of biological computers, bio-computers today still differ significantly from their counterparts made of silicon, and bio-engineers still face several major obstacles.
A silicon chip, for example, computes with ones and zeros -- current is either flowing or not -- and it can switch between these states in the blink of an eye. In contrast, biological signals are less clear: in addition to 'signal' and 'no signal', there is a plethora of intermediate states with 'a little bit of signal'. This is a particular disadvantage for bio-computer components that serve as sensors for specific biomolecules and transmit the relevant signal. Sometimes, they also send an output signal if no input signal is present, and the problem becomes worse when several such components are connected consecutively in a circuit.
ETH doctoral candidate Nicolas Lapique from the group led by Yaakov Benenson, Professor of Synthetic Biology in the Department of Biosystems Science and Engineering at ETH Zurich in Basel, has now developed a biological circuit that controls the activity of individual sensor components using internal "timer." This circuit prevents a sensor from being active when not required by the system; when required, it can be activated via a control signal. The researchers recently published their work in the scientific journal Nature Chemical Biology.
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