Water-Dispersed Perovskite Nanocube@SiO2-C18-PC Core–Shell Nanoparticles for Cell Imaging

Recently emerging perovskite quantum dots (PQDs) with extremely high (near 100%) fluorescence quantum yield (FQY) may have attractive applications in sensing and bioimaging. However, practical applications of PQDs as signal probes in aqueous media, especially in long-time bioimaging, have been greatly limited by the well-known poor stability of PQDs in water. In this work, a single intact CsPbBr3 PQD nanocrystal was well encapsulated with a SiO2 shell using a simple and highly successful coating strategy. In the synthesis, polyvinyl pyrrolidone (PVP) instead of classic oleic acid (OA) and oleylamine (OAm) was used as the ligand and surfactant to increase the affinity between PQDs and SiO2, significantly increasing the coating efficiency of PQD single nanocrystals. Meanwhile, easily hydrolyzed trimethoxysilane (TMOS) was adopted as the silicon source to shorten the hydrolysis time of silane, which obviously decreased the degradation of PQDs during SiO2 coating. The obtained PVP-PQD@SiO2 core–shell nanoparticles were uniform in size, maintained a high FQY of PQDs, and exhibited excellent air and ultraviolet (UV) stability. Moreover, PVP-PQD@SiO2 core–shell nanoparticles could be easily modified with trimethoxyoctadecylsilane (C18) and lecithin, in turn, to assemble a lipid layer on their surfaces, yielding very well water-dispersed, long-term water-stable, highly fluorescent, and low-cytotoxic PVP-PQD@SiO2@C18-PC nanoprobes. It was demonstrated that these good properties of the obtained PVP-PQD@SiO2@C18-PC nanoprobes enabled their successful application in cell imaging.