Ceria/polymer nanocontainers for high-performance encapsulation of fluorophores.

Kartheek Katta,Stanislav Baluschev,Dmitry Busko,Rafael Muñoz-Espí,Katharina Landfester,Yuri Avlasevich

doi:10.3762/bjnano.10.53

Abstract

We report the synthesis of high-performance organic–inorganic hybrid fluorescent nanocapsules comprising a polymer shell armored with an inorganic layer and a liquid core containing a fluorophore. The polymeric capsules are synthesized by free radical miniemulsion polymerization and contain covalently bound carboxylate surface functionalities that allow for the binding of metal ions through electrostatic interaction. A cerium(IV) oxide nanoparticle layer, formed in situ at the surface of the hybrid nanocapsules, acts as oxygen scavenger and keeps external reactive molecular oxygen from entering into the capsules, eventually resulting in a reduction of the photooxidation of encapsulated fluorescent molecules. This approach shows an increase in the fluorescence of the model organic fluorophore terrylene diimide by avoiding the ground-state molecular oxygen to react with electronically excited states of the fluorescent hydrocarbon molecule.

Highlights

Hybrid polymeric core–shell nanoparticles with encapsulated fluorescent dye molecules are frequently employed for lifescience applications, such as cell labeling and drug delivery [1,2,3,4,5]
Acrylic acid plays a crucial role in binding the cerium ions to the surface of nanocapsules and is helpful to increase the hydrophilic nature of the system
We demonstrate that the armoring with CeO2 of polystyrene nanocapsules containing a model fluorophore molecule results in a significant enhancement of the fluorescence

Summary

Introduction

Hybrid polymeric core–shell nanoparticles with encapsulated fluorescent dye molecules are frequently employed for lifescience applications, such as cell labeling and drug delivery [1,2,3,4,5]. Polymeric hybrid nanoparticles and nanocapsules with tailored inorganic components on the surface have attracted great interest because of the possibility to tune size, composition, porosity, stability, surface functionality, and colloidal stability [6,7,8,9,10,11,12]. Fluorescent dye molecules are sensitive to the external environment, which leads to unwanted chemical reactions [13]. Molecular oxygen is a well-known quencher of fluorescence. The shell properties of the nanocontainers are often.

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