Facile and Controllable Synthesis of the Renal-Clearable "Luminous Pearls" for <i>in Vivo</i> Afterglow/Magnetic Resonance Imaging.

To date, the strategic exploration of a synthetic approach to afford persistent luminescent nanoparticles (PLNPs) integrated with precisely controlled size/monodispersity and renal-clearable capability remains extremely challenging. Herein, we report a facile synthetic process with an elucidated mechanism to fine-tune the size for acquiring renal-clearable PLNPs, using mesoporous silica nanoparticles (MSNs) as a template. This strategy relies on the controlled crystallization of the precursor ions in the pore channels of MSNs at a high temperature, leading to the formation of monodispersed PLNPs with an average diameter as small as 2.5 nm after complete removal of MSN templates. The as-prepared ultrasmall PLNPs coated with polyethylene glycol exhibit uniform size, excellent water-dispersibility, good persistent luminescence, and high <i>T</i>₁ relaxivity (17.6 mM^-1·S^-1), ensuring their suitability for afterglow/magnetic resonance dual-modality imaging and subsequent <i>in vivo</i> renal clearance. Thus, our study provides a strategy to inspire the controlled synthesis of diverse PLNPs by using MSN templates, simultaneously addressing the critical issues of precise adjustment of size and body clearance for versatile biomedical applications.