Research

QDs versus Alexa: reality of promising tools for immunocytochemistry

Helena Montón¹ , Carme Nogués² , Emma Rossinyol¹ , Onofre Castell¹ and Mònica Roldán¹

¹  Servei de Microscòpia, Universitat Autònoma de Barcelona, Bellaterra Campus, 08193 Bellaterra, Barcelona, Spain

²  Departament de Biologia Cellular, Fisiologia i Immunologia, Universitat Autònoma de Barcelona, Bellaterra Campus, 08193 Bellaterra, Barcelona, Spain

author email corresponding author email

Journal of Nanobiotechnology 2009, 7:4doi:10.1186/1477-3155-7-4

Published:	27 May 2009

Abstract

Background

The unique photonic properties of the recently developed fluorescent semiconductor nanocrystals (QDs) have made them a potential tool in biological research. However, QDs are not yet a part of routine laboratory techniques. Double and triple immunocytochemistries were performed in HeLa cell cultures with commercial CdSe QDs conjugated to antibodies. The optical characteristics, due to which QDs can be used as immunolabels, were evaluated in terms of emission spectra, photostability and specificity.

Results

QDs were used as secondary and tertiary antibodies to detect β-tubulin (microtubule network), GM130 (Golgi complex) and EEA1 (endosomal system). The data obtained were compared to homologous Alexa Fluor 594 organic dyes. It was found that QDs are excellent fluorochromes with higher intensity, narrower bandwidth values and higher photostability than Alexa dyes in an immunocytochemical process. In terms of specificity, QDs showed high specificity against GM130 and EEA1 primary antibodies, but poor specificity against β-tubulin. Alexa dyes showed good specificity for all the targets tested.

Conclusion

This study demonstrates the great potential of QDs, as they are shown to have superior properties to Alexa dyes. Although their specificity still needs to be improved in some cases, QDs conjugated to antibodies can be used instead of organic molecules in routine immunocytochemistry.