RESEARCH PAPER Quantum dot bio-conjugate: as a western blot probe for highly sensitive detection of cellular proteins Sonia Kale • Anup Kale • Haribhau Gholap • Abhimanyu Rana • Rama Desai • Arun Banpurkar • Satishchandra Ogale • Padma Shastry Received: 18 December 2010 / Accepted: 9 January 2012 / Published online: 10 February 2012 Ó Springer Science+Business Media B.V. 2012 Abstract In the present study, we report a quantum dot (QD)-tailored western blot analysis for a sensitive, rapid and flexible detection of the nuclear and cytoplasmic proteins. Highly luminescent CdTe and (CdTe)ZnS QDs are synthesized by aqueous method. High resolution transmission electron microscopy, Raman spectroscopy, fourier transform infrared spec- troscopy, fluorescence spectroscopy and X-ray dif- fraction are used to characterize the properties of the quantum dots. The QDs are functionalized with antibodies of prostate apoptosis response-4 (Par-4), poly(ADP-ribose) polymerases and b actin to specif- ically bind with the proteins localized in the nucleus and cytoplasm of the cells, respectively. The QD- conjugated antibodies are used to overcome the limitations of conventional western blot technique. The sensitivity and rapidity of protein detection in QD-based approach is very high, with detection limits up to 10 pg of protein. In addition, these labels provide the capability of enhanced identification and localiza- tion of marker proteins in intact cells by confocal laser scanning microscopy. Keywords Western blot Á Quantum dot Á Rapid Á Detection Á Imaging Á Sensors Á Nanomedicine Introduction The detection and analysis of biological agents has become an important frontier in basic life science research, pathology, biosensor technology, clinical diagnosis, drug discovery and environmental studies. Majority of the current techniques in biomolecular detection rely heavily on the phenomenon of fluores- cence. Indeed, fluorescence detection is a well estab- lished technology which is quite sensitive and is commonly used in life science research (Ache 1989; Haugland 2002; Prasad 2004a; Waggoner 2006; Goldys 2009). The various fluorescence based S. Kale and A. Kale have contributed equally to this work. S. Kale Á R. Desai Á P. Shastry (&) National Centre for Cell Science, Ganeshkhind, Pune 411007, India e-mail: padma@nccs.res.in Present Address: S. Kale Agharkar Research Institute, Pune, India A. Kale Á H. Gholap Á A. Rana Á S. Ogale (&) Physical & Materials Chemistry Division, National Chemical Laboratory, Dr. Homi Bhabha Road, Pashan, Pune 411008, India e-mail: sb.ogale@ncl.res.in Present Address: A. Kale Center for Materials for Information Technology, University of Alabama, Tuscaloosa 35487, AL, USA H. Gholap Á A. Banpurkar Department of Physics, University of Pune, Pune 411007, India 123 J Nanopart Res (2012) 14:732 DOI 10.1007/s11051-012-0732-9