Synthesis and Characterization of Polymer-Coated Quantum Dots with Integrated Acceptor Dyes as FRET-Based Nanoprobes

Abstract

A fluorescence resonance energy transfer pair consisting of a colloidal quantum dot donor and multiple organic fluorophores as acceptors is reported and the photophysics of the system is characterized. Most nanoparticle-based biosensors reported so far use the detection of specific changes of the donor/acceptor distance under the influence of analyte binding. Our nanoparticle design on the other hand leads to sensors that detect spectral changes of the acceptor (under the influence of analyte binding) at fixed donor/acceptor distance by the introduction of the acceptor into the polymer coating. This approach allows for short acceptor-donor separation and thus for high-energy transfer efficiencies. Advantageously, the binding properties of the hydrophilic polymer coating further allows for addition of poly(ethylene glycol) shells for improved colloidal stability.

Nanoparticles Modified by Encapsulation of Ligands with a Long Alkyl Chain to Affect Multispecific and Multimodal Imaging

“…However, QDs obtained using this procedure are insoluble in water, and thus, surface modification with hydrophilic ligands is required to dissolve them in water and to make them biocompatible. This modification could be achieved by the cap-exchange chelate effect from the mono-or dithiol groups (1,12,13) or by the encapsulation onto the trioctylphosphine/trioctylphosphine oxide of the organic particles by hydrophobic absorption with silica shell (14), amphiphilic polymers (15)(16)(17), or lipids (18). The materials used to coat QDs facilitate their dissolution in water, protect QD surfaces from the aqueous environment, and offer accessible sites for chemical or biologic carriers.…”

Voltammetric determination of size and particle concentration of Cd-based quantum dots

“…In order to make the nanoparticles hydrophilic to render them compatible with aqueous media, the QDs were surface-modified with an amphiphilic polymer (based on poly-maleic anhydride functional groups), following a procedure described elsewhere [22].…”

Quantum dots and prion proteins

“…101 More importantly, anhydride groups are highly reactive toward amine-containing molecules, thus allowing covalent conjugation of various biomolecules to the polymer chains without the need for postencapsulation modification. 102,103 The choice of bioconjugation approach depends on the availability of ligands with suitable functional groups and on specific application requirements. However, common design criteria involve preserved QDs photo-physical properties and ligand biofunctionality, controlled ligand orientation and binding stoichiometry, compact probe size, and good stability in physiological environment.…”