Determination of metallothioneins by fluorescence and resonance light scattering strategies based on ciprofloxacin–Cu(II) system

Based on ciprofloxacin (CIP)–Cu(II) system, the novel methods for the detection of metallothioneins (MTs) have been developed by fluorescence (FL) and resonance light scattering (RLS) strategies. The FL strategy avoids the label and derivatization steps in common methods, while the RLS strategy can be applied for determining bio-macromolecules and small molecules without native fluorescence. The response signals linearly correlated with the concentration of MTs over the ranges of 1.03×10−8–1.23×10−6 mol L−1 for FL, and of 2.56×10−7–1.54×10−6 mol L−1 for RLS. The limits of detection (LOD) are 3.1×10−9 mol L−1 for FL and 7.68×10−8 mol L−1 for RLS. This study represents the comparison of these two methods using the same CIP–Cu2+–MTs system. They not only allow practical application for MTs detection but also serve as a potential choice for the operators according to their concrete needs. In addition, the mechanisms for FL and RLS enhancement of the system were also discussed.