Electrochemical detection of biological reactions using a novel nano-bio-chip array

In this study we developed an innovative electrochemical 'lab on a chip' system that contains an array of nano-volume electrochemical cells on a silicon chip. Each of the electrochemical cells can be monitored simultaneously and independently, and each cell contains three embedded electrodes, which enable performance of all types of electrochemical measurements. The integration of living organisms on an electrochemical array chip that can emulates reactions of living organisms and senses essential biological functions have never been demonstrated before. In order to show the wide range of applications that can be benefited from this device, biological components including chemicals, enzymes, bacteria and bio-films were integrated within the nano-chambers for various applications. During the measurement period the bacteria remained active, enabling cellular gene expression and enzymatic activity to be monitored on line. The miniaturized device was designed in two parts to enable multiple measurements: a disposable silicon chip containing an array of nano-volume electrochemical cells that are housing the biological material, and a reusable unit that includes a multiplexer and a potentiostat connected to a pocket PC for sensing and data analysis. This electrochemical 'lab on a chip' was evaluated by measuring various biological reactions including the microbial current response to toxic chemicals. These bacteria were genetically engineered to respond to toxic chemicals by activating cascade of mechanisms, which leads to the generation of electrical current. A measurable current signal, well above the noise level, was produced within 5 min of exposure to phenol, a representative toxicant. Our work shows faster and more sensitive functional physiological detection due to the unique concept demonstrated here.