Fluorescent Composite Nano- and Microparticles Based on Xanthene Dyes and Iron Oxides

Abstract

Modern industry actively uses metal structural materials to create innovative devices and components. In order to prevent emergency situations in production, nondestructive testing methods are used to detect defects on the surface of the material being developed. Among the methods of nondestructive testing, one can highlight the method of luminescent magnetic flaw detection, which allows identifying defects on the surface and under the surface of the test sample with minimal effort. It is known that in some cases, the magnetic-powder method cannot achieve the required sensitivity due to the shape and location of defects themselves or due to certain conditions of object operation. To increase the visibility and sensitivity, magnetic nano- and microparticles can be conjugated with the dyes. Iron oxide nanoparticles (Fe₃O₄, γ-Fe₂O₃) can be used as such magnetic particles, since they are quite easy to obtain and have low toxicity, high chemical stability, and a wide variety of magnetic properties. To ensure fluorescence of magnetic particles, a wide variety of fluorescent dyes associated with such particles are used. The dyes can include morin, naphthalimide derivatives, as well as semiconductor quantum dots. This article provides a review of fluorescent composite micro- and nanoparticles based on xanthene dyes (rhodamine, fluorescein, and pyronine). Such dyes are economically available luminophores, have good binding to the surface of magnetic particles, and therefore can be suitable for luminescent magnetic flaw detection. This review article discusses methods for producing composite nano- and microparticles of iron oxides with xanthene dyes and provides prospects of using composite nano- and microparticles in nondestructive testing methods.