Multifunctional carbon dots derived from dansyl chloride for ratiometric thermal sensor and reactive oxygen generation

Abstract

Carbon quantum dots (CDs) have emerged as a promising alternative of metal-free nanomaterials for a great variety of sensor applications. In this context, the present study is devoted to the characterization of morphological and spectroscopic properties of carbon dots derived from 5-(dimethylamino)naphthalene-1-sulfonyl chloride (dansyl chloride). By using the hydrothermal synthetic method, we obtain carbon dots (CD-DsCl) co-doped with nitrogen and sulfur, which exhibit a blue emission with a good quantum yield (16%) upon photoexcitation at 320 nm. The thermal and pH effects on CD-DsCl photoluminescence are also investigated, where a pronounced modification in the fluorescence spectrum takes place as the temperature and pH are varied. Our results indicate a relevant contribution of a thermally-activated mechanism to the CD-DsCl fluorescence. Furthermore, we analyze the possibility of using CD-DsCl in nanothermometry applications, determining the absolute and relative thermal sensitivities and thermal stability of nanoparticles in the temperature range of biological systems. In addition, it is also investigated the possibility of using CD-DsCl to generate reactive oxygen species (ROS) upon photoexcitation, envisaging their use as photosensitizers in photodynamic therapy applications. Within the above scenario, the present study shows that carbon dots derived from dansyl chloride possess interesting fluorescent properties, which can be exploited as a multifunctional material.