Measurement of the Hydrodynamic Radius of Quantum Dots by Fluorescence Correlation Spectroscopy Excluding Blinking

Autor(es)

de Thomaz, A. A. ^[1] ; Almeida, D. B. ^[1] ; Pelegati, V. B. ^[1] ; Carvalho, H. F. ^{[2, 3]} ; Cesar, C. L. ^{[1, 3]}

Afiliação do(s) autor(es)

^[1] State Univ Campinas UNICAMP, Inst Phys Gleb Wataghin, Dept Quantum Elect, BR-13083859 Sao Paulo - Brazil

^[2] State Univ Campinas UNICAMP, Inst Biol, Dept Struct & Funct Biol, BR-13083865 Sao Paulo - Brazil

^[3] Natl Inst Photon Appl Cell Biol INFABIC, BR-13083865 Sao Paulo - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Journal of Physical Chemistry B; v. 119, n. 11, p. 4294-4299, MAR 19 2015.
• Citações Web of Science: 6

Resumo

One of the most important properties of quantum dots (QDs) is their size. Their size will determine optical properties and in a colloidal medium their range of interaction. The most common techniques used to measure QD size are transmission electron microscopy (TEM) and X-ray diffraction. However, these techniques demand the sample to be dried and under a vacuum. This way any hydrodynamic information is excluded and the preparation process may alter even the size of the QDs. Fluorescence correlation spectroscopy (FCS) is an optical technique with single molecule sensitivity capable of extracting the hydrodynamic radius (HR) of the QDs. The main drawback of FCS is the blinking phenomenon that alters the correlation function implicating in a QD apparent size smaller than it really is. In this work, we developed a method to exclude blinking of the FCS and measured the HR of colloidal QDs. We compared our results with TEM images, and the HR obtained by FCS is higher than the radius measured by TEM. We attribute this difference to the cap layer of the QD that cannot be seen in the TEM images. (AU)

• Processo FAPESP: 09/54164-9 - EMU: Laboratório de Microscopia Fotônica Multimodal: projeto complementar para criação do laboratório sede do INCT-INFABiC
• Beneficiário: Hernandes Faustino de Carvalho
• Modalidade de apoio: Auxílio à Pesquisa - Programa Equipamentos Multiusuários
• Processo FAPESP: 08/57906-3 - Instituto Nacional de Fotônica Aplicada à Biologia Celular - INFABIC
• Beneficiário: Hernandes Faustino de Carvalho
• Modalidade de apoio: Auxílio à Pesquisa - Temático