Preparative size-exclusion chromatography for purification and characterization of colloidal quantum dots bound by chromophore-labeled polymers and low-molecular-weight chromophores

Mingfeng Wang, Ghasem Rezanejade Bardajee, Sandeep Kumar, Mark Nitz, Gregory D. Scholes, Mitchell A. Winnik

Research output: Contribution to journalArticle

20 Scopus citations

Abstract

We explore the use of preparative size-exclusion chromatography (SEC) and high-performance liquid chromatography (HPLC) to purify quantum dots (QDs) after surface modification. In one example, in which Bio-Beads (S-X1) were used as the packing material for the preparative SEC column, CdSe QDs treated with a functional coumarin dye could be separated from the excess free dye by using tetrahydrofuran (THF) as the mobile phase. This column was unable to separate polymer-coated QDs from free polymer (M ∼ 8000) because of the relatively low cutoff mass of the column. Here a preparative HPLC column packed with TOYOPEARL gel allowed the effective separation of polymer-bound QDs from the excess free polymer by using N-methyl-2-pyrrolidinone (NMP) as the mobile phase. When other solvents such as absolute ethanol, acetonitrile, THF, and THF-triethylamine mixtures were used as the eluent, QDs stuck to the column. While NMP was an effective medium to remove excess free polymer from the QDs, it was difficult to transfer the purified QDs to more volatile solvents and maintain colloidal stability.

Original languageEnglish (US)
Pages (from-to)5011-5019
Number of pages9
JournalJournal of Chromatography A
Volume1216
Issue number25
DOIs
StatePublished - Jun 19 2009
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Analytical Chemistry
  • Biochemistry
  • Organic Chemistry

Keywords

  • Chromophores
  • High-performance liquid chromatography
  • Polymers
  • Quantum dots
  • Size-exclusion chromatography

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