SrAl ₁₂ O ₁₉ : Fe ³⁺ @3‐aminopropyl triethoxysilane: Ambient aqueous stable near‐infrared persistent luminescent nanocomposites

Abstract

Abstract Near‐infrared (NIR) persistent luminescent nanoparticles (N‐PLNPs) endow a long‐term in vivo imaging with deep tissue penetration and high signal to noise ratio. However, synthesis route and applicable afterglow center for N‐PLNPs are still limited. Here, we report on a new synthesis by employing chemical precipitation as the central pivot, which is simpler and has controllable and reproducible routes than the existing technique. We also introduce Fe 3+ ion as a new member to join the group of afterglow emitters. Although its NIR luminescence is ubiquitous, its NIR afterglow is still almost never reported. In this paper, SrAl 12 O 19 : Fe 3+ N‐PLNPs display a NIR persistent luminescence from 750 to 1000 nm, which is assigned to 4 T 1 ( 4 G)→ 6 A 1 ( 6 S) transition of Fe 3+ . Furthermore, a surface‐amination technique is proposed to improve the stability of SrAl 12 O 19 : Fe 3+ N‐PLNPs in aqueous solution. After encapsulating the N‐PLNPs with 3‐aminopropyl triethoxysilane (APTES), SrAl 12 O 19 : Fe 3+ @APTES nanocomposites exhibit a hydrophilic stability beyond 20 days in aqueous solution. The results make them valuable in studying the biological functions of biomolecules and monitoring cellular networks in their native contexts.