Development of a biosensor for copper detection in aqueous solutions using an Anemonia sulcata recombinant GFP

Fluorescent proteins from marine organisms represent potential candidates for biosensor development. In this paper, we described the isolation of a native green fluorescent protein from Anemonia sulcata and the cloning and purification of its equivalent as a recombinant protein in Escherichia coli. Furthermore, the spectroscopic behaviours of the native and recombinant GFPs were investigated as a function of Cu(2+), Cd(2+), Pb(2+) and Ni(2+) concentration. Our results suggest the high selectivity of both proteins at copper than the other metals and, for the recombinant protein, a great sensitivity at a very low concentration (0.1-1 μM). Moreover, starting from these data, using the combination of molecular biology techniques and optical setup, we developed a device for the detection of Cu(2+) in water solutions. The quenching effect detected with the device showed that the relative attenuation of the signal (0.46 ± 0.02 AU) was slightly larger than the data measured by fluorescence spectra (0.65 ± 0.03 AU). The good sensitivity in the span of two orders of the magnitude of Cu(2+) concentration, the fact that the instrument is made up of low-cost and sturdy parts and the selective quenching of rAsGFP to copper ions make this setup suited as a low cost, on-the-field, copper ion-specific biosensor.