Zn(II) detection in biological samples with a smart sensory polymer

Abstract

We have developed a new sensory material for the rapid and inexpensive determination of Zn(II), and we have carried out a proof of concept for the determination of Zn(II) in biological samples. The interaction with Zn(II) generates an OFF-ON fluorescence process on the material, which can be recorded both with a fluorimeter and with a smartphone by analyzing the RGB components of the taken photographs. This sensory material is prepared with 99.75% of commercially available monomers and contains 0.25% of a sensory monomer based on a quinoline structure. The sensory motifs are chemically anchored to the polymeric structure, and, accordingly, no migration of organic substances from the material occurs during the sensing process. Our method has been tested with freshly prepared Zn(II) aqueous solutions, but also with biological samples from exudates of chronic wounds. The proposed methodology provides limits of detection (LOD) of 13 and 27 ppb when employing a water-soluble polymer (WsP) and a hydrophilic polymeric film (HP), respectively, using emission spectroscopy. The measurements have been contrasted with ICP-MS as the reference method, obtaining reliable data. This study is the starting point toward a larger investigation with patients, which will address the challenge of establishing a direct relationship between the concentration of zinc(II), other cations and also of amino acids, with the protease activity and, finally, with the state/evolution of chronic wounds. In this context, the proposed sensory material and others we are now working with will act as a simple and cheap method for this purpose.