Core-Shell Nanoparticles for Biological Po2 Sensing

Ruthenium and porphyrin are the commonly employed fluorescent/phosphorescent complexes for pO2 sensing. They are frequently formulated into thin films (e.g., xerogels), mesoporous nanoparticles, or directly injected/localized into the target site of measurement. Inclusion/embedding in polymers offers multiple advantages, including preventing the dyes into tissues, the toxic reaction from singletO2, targeted sensing from cells/organelles, and increased lifetime, enabling easy and sensitive measurement of pO2. Core-shell nanoparticles (CSNP) can be engineered to possess better dispersibility, bio-, and cytocompatibility and hence are potentially suitable for intracellular pO2 sensing and targeted pO2 sensing. Accordingly, various CSNPs have been formulated for encapsulating fluorescent dyes for sensing biomedical/biophysical parameters. In this paper, pO2 sensing based on fluorescence lifetime measurements in the time domain approach using a multi-channel scaler has been demonstrated. Further, we discuss CSNPs that incorporate ruthenium and porphyrin dyes for pO2 sensing from three perspectives: (a) methods of preparation, (b) spectroscopic characteristics, and (c) reported applications. This paper reveals a quick overview of the CSNPs and their application to biomedical pO2 sensing.