Semiconductor Nanocrystals with Multifunctional Polymer Ligands

Abstract

In this letter, we describe the preparation of a versatile polymer ligand, which can be attached to CdSe/ZnS semiconductor nanocrystals via a phase transfer reaction. The ligand is based on a chain of reactive esters, which can, in principle, be substituted by any compound containing amino-functionalities. The polymer/nanocrystal complexes are characterized in terms of structure and photostability.

Bioconjugation of quantum dots: Review & impact on future application

“…A number of amphiphilic copolymers (e.g. poly(maleic anhydride) copolymers [20]) and polyelectrolytes (poly-acrylamide [21], biopolymers like DNA [22]) were already synthesized to modify QDs surface [23]. Surfactant can also be used as encapsulant but is considered to be unstable in biological environment because of the relatively weak anchoring and does not protect the QDs from non-specific interactions.…”

Amphipol-encapsulated CuInS2/ZnS quantum dots with excellent colloidal stability

“…Free polymer was removed by four cycles of dilution followed by ultra-filtration using Centrisart I (20 kDa supplied by Generon) centrifuge tubes (see supporting information, Figures 1 & 2). Dynamic Light Scattering and Zeta potential For dynamic light 40 scattering (DLS) experiments a Malvern Zeta Sizer-Nano SeriesZen 3600 was used. A minimum of six measurements was acquired for each sample.…”

“…A recent study observing primates treated with CdSe QDs did not show any acute toxic effects; however, their spleen, kidneys, and lungs contained raised levels of toxic elements (Cd and Se) 6 , which potentially cause chronic toxicity. Many questions still remain regarding nanotoxicity and 40 the possibility for safe use of Cd-based QDs in healthcare applications is doubtful. The task therefore is to develop QDs with similar optical properties (extinction coefficient and photoluminescent quantum yield, PLQY) to Cd-based QDs from elements that are inherently less toxic.…”

“…The successful transfer of several hydrophobic NP types into the aqueous phase has been demonstrated by 35 employing various PMAL derivatives, 32-35 amphiphilic PEG polymers 5,36 and alkyl modified poly-acrylic acid. [37][38][39] Electrostatic interactions have also been utilized in order to encapsulate QDs in polymer, for example between the positively charged side chains of poly(acrylamide) (PAM) and the 40 negatively charged mercapto-acetic acid ligands on the surface of CdSe/ZnS QDs. 40 The photostability of QDs passivated with amphipols has been shown to be significantly improved in comparison to those encapsulated in micelles.…”

“…[37][38][39] Electrostatic interactions have also been utilized in order to encapsulate QDs in polymer, for example between the positively charged side chains of poly(acrylamide) (PAM) and the 40 negatively charged mercapto-acetic acid ligands on the surface of CdSe/ZnS QDs. 40 The photostability of QDs passivated with amphipols has been shown to be significantly improved in comparison to those encapsulated in micelles. 41 In general, stability in the aqueous environment is achieved 45 through either the presence of polyethylene glycol (PEG) chains or chargeable polar groups.…”