Novel POSS–PCU Nanocomposite Material as a Biocompatible Coating for Quantum Dots

Abstract

Quantum dots (QDs) are fluorescent nanoparticles with unique photophysical properties that enable them to potentially replace traditional organic dyes and fluorescent proteins in various bioimaging applications. However, the inherent toxicity of their cores based on cadmium salts limits their widespread biomedical use. We have developed a novel nanocomposite polymer emulsion based on polyhedral oligomeric silsesquioxane poly(carbonate-urea) urethane (POSS-PCU) that can be used to coat quantum dots to nullify their toxicity and enhance photostability. Here we report the synthesis and characterization of a novel POSS-PCU nanocomposite polymer emulsion and describe its application for coating QDs for biological application. The polymer was synthesized by a process of emulsion polymerization and formed stable micelles of ∼33 nm in diameter. CdTe/CdS/ZnS QDs were efficiently stabilized by the polymer emulsion through encapsulation within the polymer micelles. Characterization studies showed no significant change in the unique photophysical properties of QDs after coating. The polymer was biocompatible to HepG2, HUVECs, and mouse skeletal muscle cells at 2.5% after 24 h exposure on in vitro testing. Polymer encapsulated QDs showed enhanced photostability on exposure to high degrees of UV irradiation and air as well as significantly reduced cytotoxicity on exposure to HepG2 cells at 30 μg/mL for 24 h. We have therefore concluded that the POSS-PCU polymer emulsion has the potential to make a biocompatible and photostable coating for QDs enabling a host of biomedical applications to take this technology to the next level.

Heat- and water-proof quantum dot/siloxane composite film: Effect of quantum dot-siloxane linkage

“…First, QDs are dispersed in the mixture of silane precursors, which are MPTS/DPSD and ECTS/DPSD, separately, forgoing ligand‐exchange of QDs . During this step, hydrophobic interaction between oleic acid (OA, surface ligand on QDs) and functional groups of the silane precursors triggers encapsulation of the QDs . In the second step, the siloxane bonds of the siloxane network are formed by sol–gel condensation reaction between methoxy groups of MPTS and hydroxyl groups of DPSD, resulting QD/oligosiloxane (methacryl) resin (i of Fig.…”

“…c and d, respectively). This uniform QD dispersion of both QD/oligosiloxane resins can be ascribed to hydrophobic interaction between high content of functional groups of the two different siloxane matrices and ligand (OA) of QDs …”

Silsesquioxane‐Containing Hybrid Nanomaterials: Fascinating Platforms for Advanced Applications

“…Seifalian et al. coated QDs with a new developed POSS/poly‐(carbonate‐urea)urethane (POSS‐PCU) nanocomposite polymer for bioimaging applications . The resulting nanocomoposites are promising for long‐term bioimaging applications because they are biocompatible, highly photostable, and colloidally stable.…”

“…The resulting nanocomoposites are promising for long‐term bioimaging applications because they are biocompatible, highly photostable, and colloidally stable. The POSS‐based polymer not only protected the QDs but also assisted in QD solubility in aqueous solution …”

Nanocomposite Coatings: Preparation, Characterization, Properties, and Applications

“…The polymerization takes place by using electric power (electrodeposition) [19], oxidizing agents [17,18,105], or photon (photopolymerized) [40,106,107]. The similar methods are emulsion polymerization [108,109] or latex emulsions [110] for organic matrices (see Figure 4). …”