Disposable biosensor for detection of iron (III) in wines

This paper reports the tuning of a fast, disposable, and label-free biosensor for quantification of iron (III) in food liquid samples such as wine. The biosensor is based on a field effect transistor(FET) where a net work of single-walled carbonnanotubes (SWCNTs) acts as the conductor channel, constituting carbonnanotubes field effect transistors (CNTFETs). An antibody such as transferrin with two specific high-affinity iron (III) binding sites, directly adsorbed to SWCNTs, was used as immunoreaction. Several individual CNTFETs were tested showing a linear range between 0.05 and 2ngmL(-1) and a limit of quantification below 0.05ngmL(-1), much lower than previously reported analytical techniques. The mean coefficient of variation was 0.13% showing a low variability of the analytical response. On the other hand, it was not observed interference effect of zinc (II) ion at least until 1:4 iron-zinc ratio. Finally, recovery percentages of spiked wine samples were around 100%, showing the high accuracy of method. The main advantages of the devices developed are their speed, convenience (it is an economical method), and the avoidance excessive handling samples since they do not require further pre-treatment of samples.