Search

Temperature of tissues and organs is one of the first parameters affected by physiological and pathological processes, such as metabolic activity, acute trauma, or infection-induced inflammation. Therefore, the onset and development of these processes could be detected by monitoring deviations from basal temperature. To accomplish this, minimally invasive, reliable, and accurate measurement of the absolute temperature of internal organs is required. Luminescence nanothermometry is the ideal technology for meeting these requirements. Although this technique has lately undergone remarkable developments, its reliability is being questioned due to spectral distortions caused by biological tissues. In this work, we demonstrate how the use of bright Ag2S nanoparticles featuring temperature-dependent fluorescence lifetime enables reliable and accurate measurement of the absolute temperature of the liver in mice subjected to lipopolysaccharide induced inflammation. Beyond the remarkable thermal sensitivity (≈ 3% °C–1around 37 °C) and thermal resolution obtained (smaller than 0.3°C), the results included in this work set a blueprint for the development of new diagnostic procedures based on the use of intra-corporeal temperature as a physiological indicator.

Research on near-infrared (NIR) bioimaging has progressed very quickly in the past few years, as fluorescence imaging is reaching a credible implementation as a preclinical technique. The applications of NIR bioimaging in theranostics have contributed to its increasing impact. This has brought about the development of novel technologies and, simultaneously, of new contrast agents capable of acting as efficient NIR optical probes. Among these probes, Ag2S nanoparticles (NPs) have attracted increasing attention due to their temperature-sensitive NIR-II emission, which can be exploited for deep-tissue imaging and thermometry,and their heat delivery capabilities. This multifunctionality makes Ag2S NPs ideal candidates for theranostics. This review presents a critical analysis of the synthesis routes, properties and optical features of Ag2S NPs. We also discuss the latest and most remarkable achievements enabled by these NPs in preclinicalimaging and theranostics, together with a critical assessment of their potential to face forthcoming challenges in biomedicine.