A reversible fluorescent probe for monitoring Ag(I) ions.

Zelong Lim,Jonathan C Knowles,David G Smith,Rebecca L Mattison,Jacek L Kolanowski,Song-Yi Baek,Wojciech Chrzanowski,Elizabeth J New

doi:10.1098/rsif.2018.0346

Abstract

Silver-containing nanomaterials are of interest for their antibiotic properties, for a wide range of applications from medicine to consumer products. However, much remains to be learnt about the degradation of such materials and their effects on human health. While most analyses involve measurement of total silver levels, it is important also to be able to measure concentrations of active free Ag(I) ions. We report here the preparation of a coumarin-based probe, thiocoumarin silver sensor 1 (TcAg1), that responds reversibly to the addition of silver ions through the appearance of a new fluorescence emission peak at 565 nm. Importantly, this peak is not observed in the presence of Hg(II), a common interferent in Ag(I) sensing. To establish the utility of this sensor, we prepared silver-doped phosphate glasses with demonstrated bactericidal properties, and observed the Ag(I) release from these glasses in solutions of different ionic strength. TcAg1 is therefore a useful tool for the study of the environmental and medical effects of silver-containing materials.

Highlights

Silver is widely used in industrial applications due to its conductivity and malleability properties [1], as well as in medicine as an antibiotic coating and in wound treatment [2,3,4,5]
The shorter wavelength peak corresponds to the coumarin, which is a product of desulfurization, and 4 the longer wavelength peak was envisaged to be due to non-covalent association of Ag(I)
We investigated the effect of silver addition to coumarin 6, in which the thiocarbonyl sulfur is replaced with oxygen

Summary

Introduction

Silver is widely used in industrial applications due to its conductivity and malleability properties [1], as well as in medicine as an antibiotic coating and in wound treatment [2,3,4,5]. Because of its antibacterial properties, the use of silver coatings and nanoparticles is widespread in both the clinic and in everyday household items such as clothes, the lining of washing machines and refrigerators. In addition to their well-reported bactericidal properties [6,7], silver nanoparticles have found application as imaging agents [8,9] and drug delivery vehicles [10,11]. The high toxicity of silver is crucial for the unique antibacterial properties of this metal, but there is concern about the effect of aquatic silver pollution on freshwater invertebrates [12] and fish [13]. In terms of silver nanoparticles and their use in medicine, Ag(I) release is the primary reason for bacterial toxicity; nanoparticle size

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