Silica nanoparticles with dual visible–NIR luminescence affected by silica confinement of Tb(III) and Yb(III) complexes for cellular imaging application

The work introduces silica confinement of Tb(III) and Yb(III) complexes with p-sulfonatothiacalix[4]arene (TCAS) arisen from their doping into silica nanoparticles (51–60 nm) as the reason for efficient dual green–NIR luminescence. pH-regulated water solubility of the lanthanide complexes is highlighted as prerequisite for the balance between efficient doping of the complexes into silica nanoparticles and their size/shape university. The impact of Tb(III) → Yb(III) energy transfer on the NIR and visible luminescence of the nanoparticles was revealed from photophysical studies of the nanoparticles doped with different couples of lanthanide complexes (Tb–Gd, Tb–Yb, Yb–Gd) at various molar ratios. The optimal balance between green and NIR luminescence is achieved for the silica nanoparticles doped with Tb–Yb complexes at 2:1 (Tb:Yb) ratio due to both Tb(III) → Yb(III) energy transfer and specific distribution of Tb(III) and Yb(III) complexes within silica nanoparticles. The dual luminescent nanoparticles exhibit efficient cellular uptake behavior after amino-decoration of their surface, which is confirmed by confocal microscopy images of the cells incubated by the heterometallic nanoparticles.