Targeted Stealth Polymer Capsules Encapsulating Ln3+-Doped LaVO4 Nanoparticles for Bioimaging Applications.

Abstract

We report synthesis of targeted PEGylated polymer capsules encapsulating Stoke's shift and upconverting LaVO4 nanoparticles by following a unique approach for bioimaging applications. First, LaVO4:Ln3+@silica (Ln3+ = Tb3+, Eu3+, and Yb3+/Er3+) core-shell nanoparticles are prepared by sol-gel method followed by layer-by-layer assembly of polymers and PEGylation over core-shell particles. Second, removal of silica core facilitates the trapping of LaVO4:Ln3+ nanoparticles inside the PEGylated polymer capsules. Finally, capsules are surface modified with antibodies to target cancer cells. The nanoparticles-loaded polymer capsules are found to be internalized and biocompatible with various cells (e.g., HeLa, A498, H460, MCF-7, Schwann, L929, and IC-21) suggesting their applicability in different types of cells. In addition, the capsules modified with antibodies show more specific uptake suggesting their targeting ability by 3-fold for MCF-7 and 10-fold for H460 cancer cells. Moreover, the nanoparticle-loaded polymer capsules were internalized by HeLa cells via macropinocytosis mechanism. We observed localized bright Stoke's shift (Tb3+ ions, λex = 488 nm) and upconversion (Er3+ ions, λex = 980 nm) green fluorescence from cells suggesting their potential use as targeted bioimaging agents.