title: Surface chemistry and photophysical properties of a diacetylene-peptide derivative capped quantum dots Langmuir monolayer.
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 (pi-A) isotherms, compression-decompression cycles, stability measurements, and in situ UV-vis and fluorescence spectroscopy. Two different pi-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 m Nm(-1) compared with 15 m Nm(-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 1h 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.
authors.affiliation: Department of Chemistry, University of Miami, Coral Gables, FL 33124, USA.
authors.forename: J
authors.initials: J
authors.lastname: Xu
authors.forename: C
authors.initials: C
authors.lastname: Wang
authors.forename: R M
authors.initials: RM
authors.lastname: Leblanc
mesh_terms: D000114:Acetylene / Q000737:chemistry; D002627:Chemistry, Physical / Q000379:methods*; D005231:Fatty Acids, Unsaturated / Q000737:chemistry; D008027:Light; D053768:Metal Nanoparticles / Q000737:chemistry; D049329:Nanostructures / Q000737:chemistry; D036103:Nanotechnology / Q000379:methods; D010455:Peptides / Q000737:chemistry; D010777:Photochemistry / Q000379:methods; D011312:Pressure; D045663:Quantum Dots; D013050:Spectrometry, Fluorescence / Q000379:methods; D013499:Surface Properties
chemical_list: C493048:10, 12-pentacosadiynoic acid; D005231:Fatty Acids, Unsaturated; D010455:Peptides; D000114:Acetylene