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Highlights in Chemical Technology

Chemical technology news from across RSC Publishing.

Enzymes power molecular logic

12 March 2010

A self-powered biomolecular security system has been developed by US scientists. This could be used to encrypt financial, military, or other confidential information. 

Recent developments in the field of biocomputing have led to biomolecular systems that use chemical information to mimic digital electronics. Now, Evgeny Katz and his team at Clarkson University, Potsdam, have taken the research a step further to make a keypad lock that powers itself using a biofuel cell. 

The biocatalyst system is composed of three enzyme-catalysed reaction steps, explains Katz. The enzymes are used as input signals to trigger the biochemical reactions. Only when the enzymes are added in the correct order does the cascade reaction from starch to gluconic acid occur. Formation of gluconic acid produces a change in pH, which turns on a polymer-brush modified electrode inside a biofuel cell integrated in the keypad system. At pH greater than 5.5, the poymer-brush is in a non-protonated hydrophobic state that inhibits electrochemical reactions, but as the pH falls pyridine groups in the polymer-brush are protonated until it forms a positively charged hydrophilic thin-film allowing the electrode to conduct electricity. 

Biomolecular keypad

Only the correct enzyme password operates the biofuel cell

When the correct order of enzymes are used, the resulting acidic solution activates the cathode, switching on the biofuel cell, which produces an increase in current and power output. If the enzymes are added in the wrong order, the biofuel cell is not activated. This allows the security system to be operated without the need for an external power source as electrical power is produced when the correct enzyme 'password' is used. 

'This is a fine example of how molecular logic and computation is growing,' comments A P de Silva, an expert in molecular-based logic and molecular switches at Queen's University Belfast, UK. 

Katz says that while this work demonstrates the proof of concept, more work is needed to engineer a lab-on-a-chip microfluidic device that could find real applications. Also, up to 10 enzymes could be used and immune recognition components could be added to increase the system complexity. 

Nicola Wise 


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Link to journal article

Self-powered biomolecular keypad lock security system based on a biofuel cell
Jan Halámek, Tsz Kin Tam, Guinevere Strack, Vera Bocharova, Marcos Pita and Evgeny Katz, Chem. Commun., 2010, 46, 2405
DOI: 10.1039/b925484f

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