Rational design of polymeric core shell ratiometric oxygen-sensing nanostructures

A new approach for the fabrication of luminescent ratiometric sensing nanosensors is described using core-shell nanoparticles in which the probe and reference are spatially separated into the shell and core of the nanostructure respectively. The isolation of the reference in the core of the particle ensures a stable emission reference signal unaffected by the external environment. The core shell structure was prepared by engineering structurally well-defined Ru-conjugated block copolymers which acted as emulsifiers in the miniemulsion polymerisation of BODIPY loaded styrene nanoparticles. The resulting particles are highly stable and show excellent size monodispersity. The nanosensors exhibit dual emission under a single excitation wavelength with a reversible and quantitative ratiometric response to the O₂ content in aqueous media. In the presence of a low concentration of CTAB, the particles cross the cell membrane and the particles show negligible cytotoxicity. Such an approach to sensor nanoparticles should be of value across a range of applications where a stable ratiometric signal in diverse environments is required.