Surface chemistry and photophysical properties of a diacetylene-peptide derivative capped quantum dots Langmuir monolayer

J. Xu, C. Wang, Roger Leblanc

Research output: Contribution to journalArticle

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Abstract

A diacetylene derivative, 10,12-pentacosadiynoic acid (PDA), was conjugated to a small peptide chain Cysteine-Cysteine-Glycine (CCG) through the solid-phase peptide synthesis. The (CdSe)ZnS core-shell quantum dots (QDs) capped with trioctylphosphine ligands were modified through a surface ligand reaction to prepare the PDA-CCG QDs conjugate. Both systems, PDA-CCG and PDA-CCG QDs, were investigated as Langmuir monolayer at the air-water interface through the surface pressure-area (π-A) isotherms, compression-decompression cycles, stability measurements, and in situ UV-vis and fluorescence spectroscopy. Two different π-A isotherms were observed for the systems investigated showing the importance of the peptide moiety in PDA-CCG to form a Langmuir monolayer up to a surface pressure of 50 mN m-1 compared with 15 mN m-1 for the PDA component alone. The compression-decompression cycles and stability measurements for both systems suggest the formation of a stable Langmuir monolayer over 1 h time period. Although the in situ UV-vis spectroscopy of PDAA-CCG and PDA-CCG QDs does not show an absorption spectrum, we observed by in situ fluorescence spectroscopy the photoluminescence (PL) of the PDA-CCG QDs at 560 nm, with an intensity of the PL increasing linearly with the increase of the surface pressure. Irradiating the PDA-CCG QDs Langmuir monolayer at 254 nm, we observe the photopolymerization with two distinct bands at 575 (blue band) and 630 nm (red band) of the polymer.

Original languageEnglish
Pages (from-to)163-168
Number of pages6
JournalColloids and Surfaces B: Biointerfaces
Volume70
Issue number2
DOIs
StatePublished - May 1 2009

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Keywords

  • 10,12-Pentacosadiynoic acid
  • Langmuir monolayer
  • Photopolymerization
  • Quantum dots

ASJC Scopus subject areas

  • Biotechnology
  • Colloid and Surface Chemistry
  • Physical and Theoretical Chemistry
  • Surfaces and Interfaces

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