58º Congresso Brasileiro de Genética
Resumos do 58o Congresso Brasileiro de Genética • 11 a 14 de setembro de 2012
Rafain Palace Hotel e Convention Center • Foz do Iguaçu • PR • Brasil
www.sbg.org.br - ISBN 978-85-89109-06-2
32
A novel magic-sized quantum dot coupled
to an Fab antibody for imunohistochemistry
analysis of breast cancer cells
Maia, LP1; Silva, ACA2; Freschi, APP1,2; Araújo, TG1; Rodrigues, CM1; Matias, BF1; Goulart, LR1; Dantas, NO2
1
Instituto de Genética e Bioquímica, UFU, Uberlândia, MG; 2Instituto de Física, UFU, Uberlândia, MG.
[email protected]
Keywords: magic-sized quantum dot, bioconjugation, fluorescence, antibody, breast cancer.
Semiconductor quantum dots (QDs) are nanocrystals that exhibit quantum confinement effects and their optical
properties are strongly controlled by the size, shape and structure allowing the same material could absorb and emit
in a predetermined range of the electromagnetic spectrum. Recently, CdSe QDs with sizes in the range of 1-2 nm
and well-defined structures, called as magic-sized QDs (msQDs) has attracted much attention due to its unique
characteristics as such, extremely stable sizes which can be observed during and after growth, close-shell structure
with few unit cells in their composition and possibly with different thermodynamically stable structure. But mostly
emerging as a new class of fluorescent labels for biology and medicine, stood out for having numerous advantages over
other fluorescent molecules. However, to use QDs in biological applications, the particles must be hydrophilic with
surface chemistry adaptable to varied biological studies, mainly to make it less toxic and to prevent aggregation and
nonspecific binding. The aim of this study was test the efficiency of a novel ms-QD couple to a specifc breast cancer
Fab antibody (QD-Ab) in an immunohistochemistry assays. We have synthesized in an aqueous environment a 2-nm
ms-CdSe QDs functionalized with a carboxyl group (CdSe-COOH), which conferred high stability, non-toxicity and
high fluorescence signals. The ms-QDs were modified with nitrilotriacetic acid and niqkel foi the Fab coupling. Human
breast cancer cell culture (MDA-MB) was fixed and permeabilized for QD-Ab detection by confocal microscopy. The
imaging analysis showed high fluorescence intensity demonstrating that the CdSe ms-QDs were efficiently conjugated
to antibodies antibodies with high specificity to breast cancer cells when compared with the controls with non-labeled
QDs. The novel ms-QD properties (stability, non-toxic, broad-band width, high brightness, photostability and
multiplex capability) make it highly suitable for many imaging strategies. The ability to synthesize water monodisperse
CdSe ms-QDs also enables them to be used in other sensing, therapeutic and in vivo imaging applications.
Financial support: CAPES, CNPq, FAPEMIG, UFU.