A label free programmable biosensor for electrochemical detection of metal ions using on-chip synthesized probe was developed. This system was expected to be detecting multiple metal ions by synthesizing the specific peptide probes on the chip. The electrochemical chipwas integrated with three Au electrodes and a PDMS microfluidic chip. For the detection of copper ion, a new peptide probe, Gly-Gly-Gly (GGG) was synthesized directly over chemically modified gold electrode using solid phase peptide synthesis (SPPS) on microchip. On-chip synthesized probe was found to be able to detect the copper ion in concentration range of 1×10-7 M.
Environmental contamination by trace metals is a serious problem not only for ecosystems, but also for human health. Current electrochemical methods for heavy metals detection have particular advantages of high sensitivity, inherent simplicity, miniaturization and low cost. The conventional biosensors, however, are manufactured for fixed target ions, and do not have a flexibility to change the target on-site and on-demand. We already proposed the concept of programmable biosensor which can flexibly change the target by synthesizing different probes on-site and on-demand [1]. Recently, a metal ion specific oligopeptide probes were reported [2]. By using these peptide probes, the programmable biosensor for metallic ion can also be developed.
In this paper, we developed anprogrammable biosensor to detect the metal ions by flexibly changing the probe sequence, directly synthesized on the chip. A new design of microfluidic electrochemical chip was proposed to synthesize the metal ion specific probe sequence on the chip. The electrochemical setup for electrochemical analysis of metal ions was integrated with the microfluidic peptide synthesizer. A new oligopeptide probe GGG was synthesized over chemically modified gold working electrode.After probe synthesis, copper ion solution was added to chip to be preconcentrate the electrode, and copper ion form a complex with GGG peptide. The captured metal ion was detected using Differential pulse voltammetry (DPV) techniques,and step by step modification of Au surface was analyzed using electrochemical impedance spectroscopy (EIS)and cyclic voltammetry (CV).

Author:1. R.Bhardwaj, 2. Y.Ukita , 3. M.Biyani and 4. Y.Takamura