title: Luminescence of polyethylene glycol coated CdSeTe/ZnS and InP/ZnS nanoparticles in the presence of copper cations.
abstract: The use of click chemistry for quantum dot (QD) functionalization could be very promising for the development of bioconjugates dedicated to in vivo applications. Alkyne-azide ligation usually requires copper(I) catalysis. The luminescence response of CdSeTe/ZnS nanoparticles coated with polyethylene glycol (PEG) is studied in the presence of copper cations, and compared to that of InP/ZnS QDs coated with mercaptoundecanoic acid (MUA). The quenching mechanisms appear different. Luminescence quenching occurs without any wavelength shift in the absorption and emission spectra for the CdSeTe/ZnS/PEG nanocrystals. In this case, the presence of copper in the ZnS shell is evidenced by energy-filtered transmission electron microscopy (EF-TEM). By contrast, in the case of InP/ZnS/MUA nanocrystals, a redshift of the excitation and emission spectra, accompanied by an increase in absorbance and a decrease in photoluminescence, is observed. For CdSeTe/ZnS/PEG nanocrystals, PL quenching is enhanced for QDs with 1) smaller inorganic-core diameter, 2) thinner PEG shell, and 3) hydroxyl terminal groups. Whereas copper-induced PL quenching can be interesting for the design of sensitive cation sensors, copper-free click reactions should be used for the efficient functionalization of nanocrystals dedicated to bioapplications, in order to achieve highly luminescent QD bioconjugates.
authors.affiliation: LETI-DTBS-LFCM, Commissariat à l'Énergie Atomique, Grenoble, France.
authors.forename: Grégory
authors.initials: G
authors.lastname: Beaune
authors.forename: Sudarsan
authors.initials: S
authors.lastname: Tamang
authors.forename: Aude
authors.initials: A
authors.lastname: Bernardin
authors.forename: Pascale
authors.initials: P
authors.lastname: Bayle-Guillemaud
authors.forename: Daphna
authors.initials: D
authors.lastname: Fenel
authors.forename: Guy
authors.initials: G
authors.lastname: Schoehn
authors.forename: Françoise
authors.initials: F
authors.lastname: Vinet
authors.forename: Peter
authors.initials: P
authors.lastname: Reiss
authors.forename: Isabelle
authors.initials: I
authors.lastname: Texier
mesh_terms: D002623:Chemistry Techniques, Analytical; D057930:Click Chemistry; D003300:Copper / Q000737:chemistry*; D049449:Luminescence; D046032:Microscopy, Energy-Filtering Transmission Electron; D011092:Polyethylene Glycols / Q000737:chemistry; D045663:Quantum Dots; D018036:Selenium Compounds / Q000737:chemistry; D013440:Sulfides / Q000737:chemistry; D014961:X-Ray Diffraction; D017967:Zinc Compounds / Q000737:chemistry*
chemical_list: D018036:Selenium Compounds; D013440:Sulfides; D017967:Zinc Compounds; D011092:Polyethylene Glycols; D003300:Copper