title: Optical characterization of core-shell quantum dots embedded in synthetic saliva: Temporal dynamics.
abstract: The present work reports the spectroscopic and thermo-optical properties of CdSe/ZnS and CdSe/CdS core-shell quantum dots (QDs) embedded in synthetic saliva. Spectroscopy studies were performed applying nonfunctionalized CdSe/ZnS QDs (3.4, 3.9 and 5.1 nm cores) and hydroxyl group-functionalized ultrasmall CdSe/CdS core-shell quantum dots (1.6 nm core) suspended in artificial saliva at different potential of hydrogen (pH) values. Saliva was chosen because it is important in a variety of functions such as protecting teeth through the buffering capacity of the formed biofilm, hydration, and dental remineralization. Thermo-optical characterizations using the thermal lens (TL) technique were performed in QD-biofluids for different QD sizes and pH values (3.9-8.3) of the synthetic oral fluids. Transient TL measurements were applied to determine the fluorescence quantum efficiency (η) in QD-biomaterial systems. High η value was obtained for ultrasmall CdSe/CdS QDs. Fluorescence spectral measurements of the biomaterials support the TL results. In addition, for nonfunctionalized (3.4 and 5.1 nm) and hydroxyl group-functionalized QDs, the temporal behavior of the fluorescence spectra was accomplished about approximately 1200 h at two different biofluid pH values (3.9 and 8.3). The temporal fluorescence intensity result is dependent on the pH of the saliva in which the QDs were embedded, QD functionalization and QD sizes. The time for an approximately 50% decrease in the peak intensity fluorescence of CdSe/ZnS QDs (3.4 nm core) and ultrasmall CdSe/CdS QDs is respectively 25 h and 312 h at pH 3.9 and 48 h and 360 h at pH 8.3.
authors: Grupo de Propriedades Ópticas e Térmicas de Materiais (GPOTM), Instituto de Física, Universidade Federal de Uberlândia - UFU, Av. João Naves de Ávila 2121, Uberlândia, MG 38400-902, Brazil.
authors: Juliana F
authors: JF
authors: de Santana
authors: Grupo de Propriedades Ópticas e Térmicas de Materiais (GPOTM), Instituto de Física, Universidade Federal de Uberlândia - UFU, Av. João Naves de Ávila 2121, Uberlândia, MG 38400-902, Brazil. Electronic address: vivianepilla@infis.ufu.br.
authors: Viviane
authors: V
authors: Pilla
authors: Laboratório de Novos Materiais Isolantes e Semicondutores (LNMIS), Instituto de Física, Universidade Federal de Uberlândia - UFU, Av. João Naves de Ávila 2121, Uberlândia, MG 38400-902, Brazil.
authors: Anielle C A
authors: AC
authors: Silva
authors: Laboratório de Novos Materiais Isolantes e Semicondutores (LNMIS), Instituto de Física, Universidade Federal de Uberlândia - UFU, Av. João Naves de Ávila 2121, Uberlândia, MG 38400-902, Brazil.
authors: Noelio O
authors: NO
authors: Dantas
authors: Grupo de Propriedades Ópticas e Térmicas de Materiais (GPOTM), Instituto de Física, Universidade Federal de Uberlândia - UFU, Av. João Naves de Ávila 2121, Uberlândia, MG 38400-902, Brazil.
authors: Djalmir N
authors: DN
authors: Messias
authors: Grupo de Propriedades Ópticas e Térmicas de Materiais (GPOTM), Instituto de Física, Universidade Federal de Uberlândia - UFU, Av. João Naves de Ávila 2121, Uberlândia, MG 38400-902, Brazil.
authors: Acácio A
authors: AA
authors: Andrade
mesh_terms: D019187:Cadmium Compounds / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D049329:Nanostructures / Q000737:chemistry; D045663:Quantum Dots / Q000737:chemistry*; D012463:Saliva / Q000737:chemistry*; D018036:Selenium Compounds / Q000737:chemistry; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet; D017967:Zinc Compounds / Q000737:chemistry
chemical_list: D019187:Cadmium Compounds; D018036:Selenium Compounds; D017967:Zinc Compounds; C058667:cadmium selenide; C044696:zinc selenide
keywords: Fluorescence; Quantum dots; Radiative quantum efficiency; Saliva; Thermal lens