title: Photoinduced spectral changes of photoluminescent gold nanoclusters.
abstract: Ultrasmall photoluminescent gold nanoclusters (Au NCs), composed of several atoms with sizes up to a few nanometers, have recently stimulated extensive interest. Unique molecule-like behaviors, low toxicity, and facile synthesis make photoluminescent Au NCs a very promising alternative to organic fluorophores and semiconductor quantum dots (QDs) in broad ranges of biomedical applications. However, using gold nanoparticles (Au NPs) for bioimaging might cause their degradation under continuous excitation with UV light, which might result in toxicity. We report spectral changes of photoluminescent 2-(N-morpholino) ethanesulfonic acid (MES)-coated (Au-MES) NCs under irradiation with UV/blue light. Photoluminescent water soluble Au- MES NCs with a photoluminescence (PL) band maximum at 476 nm (λex = 420 nm) were synthesized. Under irradiation with 402 nm wavelength light the size of photoluminescent Au-MES NCs decreased (λem = 430 nm). Irradiating the sample solution with 330 nm wavelength light, nonluminescent Au NPs were disrupted, and photoluminescent Au NCs (λem = 476 nm) were formed. Irradiation with 330 nm wavelength light did not directly affect photoluminescent Au-MES NCs, however, increase in PL intensity indicated the formation of photoluminescent Au NCs from the disrupted nonluminescent Au NPs. This study gives a good insight into the photostability of MES-coated Au NPs under continuous excitation with UV/blue light.
authors.affiliation: National Cancer Institute, Biomedical Physics Laboratory, P. Baublio Street 3b, LT-08406 Vilnius, LithuaniabVilnius University, Biophotonics Group of Laser Research Centre, Sauletekio Avenue 9, LT-10222 Vilnius, Lithuania.
authors.forename: Marija
authors.initials: M
authors.lastname: Matulionytė
authors.affiliation: National Cancer Institute, Biomedical Physics Laboratory, P. Baublio Street 3b, LT-08406 Vilnius, Lithuania.
authors.forename: Raminta
authors.initials: R
authors.lastname: Marcinonytė
authors.affiliation: National Cancer Institute, Biomedical Physics Laboratory, P. Baublio Street 3b, LT-08406 Vilnius, LithuaniabVilnius University, Biophotonics Group of Laser Research Centre, Sauletekio Avenue 9, LT-10222 Vilnius, Lithuania.
authors.forename: Ričardas
authors.initials: R
authors.lastname: Rotomskis
mesh_terms: D017738:Alkanesulfonic Acids / Q000737:chemistry*; D002244:Carbon / Q000737:chemistry; D003102:Colloids / Q000737:chemistry; D006046:Gold / Q000737:chemistry*; D008027:Light; D049449:Luminescence; D053768:Metal Nanoparticles / Q000737:chemistry*; D009025:Morpholines / Q000737:chemistry*; D036103:Nanotechnology; D010316:Particle Size; D010777:Photochemistry; D017382:Reactive Oxygen Species; D013053:Spectrophotometry; D014466:Ultraviolet Rays; D014867:Water / Q000737:chemistry
chemical_list: D017738:Alkanesulfonic Acids; D003102:Colloids; D009025:Morpholines; D017382:Reactive Oxygen Species; D014867:Water; C004550:2-(N-morpholino)ethanesulfonic acid; D002244:Carbon; D006046:Gold