Encapsulation of ultrasmall nanophosphors into liposomes by thin-film hydration

Ultrasmall nanophosphors (<10 nm) have been widely used in drug delivery for simultaneous cancer imaging and therapy. However, due to limited retention, the anti-tumor effects are not always satisfactory. The development of liposome-phosphor colloid nanosystems provides a versatile size-tunable approach to fabricate multifunctional therapeutic platforms. Herein, we developed a general approach to encapsulate ultrasmall nanophosphors into liposomes by thin-film hydration in this study. We chose two typical ultrasmall nanophosphors, i.e., fluorescent mesoporous silica nanoparticles (∼\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\sim $$\end{document}7 nm) and graphene quantum dots (∼\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\sim $$\end{document}3 nm), as experimental models for encapsulation. We found that these ultrasmall nanophosphors were distributed in clusters rather than a single nanoparticle within a liposome. Our results demonstrated that the stability of the nanophosphor-loaded liposome capsules is quite good, and their size (∼\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\sim $$\end{document}100 nm) did not change in an aqueous solution for 30 days. The experimental investigation also showed that this method could promote drug loading. The advances on ultrasmall nanophosphors encapsulation may enable the rational design of a convenient platform for biolabeling and drug delivery, which have important implications for biomedical photonics.