Cantilever arrays were functionalised to detect Cu2+ ions in low concentrations. At the time points indicated, Cu2+ ions were injected in 100 nanomolar and 1 nanomolar concentrations, respectively.
The sensitivity at a 1nM concentration equals 0.00006 ppm of Cu2+.
The curves show the differential deflection between the functionalised cantilever and a reference cantilever as a function of time.
Cantilevers were functionalized with glutathione, a tri-peptide, with two carboxy-groups able to bind divalent cations.
CaCl2 was injected at the timepoints indicated and subsequently removed by the injection of Tris-buffer and Tris-buffer with EDTA, respectively. The time-resolved data show that Ca2+ is removed faster in the presence of EDTA. These kind of measurements provide valuable information about affinities and reaction kinetics.