Evaluation of quantum dot immunofluorescence and a digital CMOS imaging system as an alternative to conventional organic fluorescence dyes and laser scanning for quantifying protein microarrays

HHS Public Access Author manuscript Author Manuscript Proteomics. Author manuscript; available in PMC 2017 April 01. Published in final edited form as: Proteomics. 2016 April ; 16(8): 1271–1279. doi:10.1002/pmic.201500375. Evaluation of Quantum dot immunofluorescence and a digital CMOS imaging system as an alternative to conventional organic fluorescence dyes and laser scanning for quantifying protein microarrays Author Manuscript Aarti Jain 1,# , Omid Taghavian 1,# , Derek Vallejo 2 , Emmanuel Dotsey 1 , Dan Schwartz 3 , Florian G. Bell 3 , Chad Greef 3 , D. Huw Davies 1 , Jennipher Grudzien 3 , Abraham P. Lee 2 , Philip Felgner 1 , and Li Liang 1,* 1 Department of Medicine, division of infectious diseases, University of California Irvine, Irvine CA 2 Department 3 Grace of Biomedical Engineering, University of California Irvine, Irvine, USA 92697 Bio-Labs, Inc., 325 SW Cyber Drive, Bend, OR 97702 Abstract Author Manuscript Organic fluorescent dyes are widely used for the visualization of bound antibody in a variety of immunofluorescence assays. However, the detection equipment is often expensive, fragile and hard to deploy widely. Quantum dots (Qdot ® ) are nanocrystals made of semiconductor materials that emit light at different wavelengths according to the size of the crystal, with increased brightness and stability. Here we have evaluated a small benchtop ‘personal’ optical imager (ArrayCAM ™ ) developed for quantification of protein arrays probed by Qdot -based indirect immunofluorescence. The aim was to determine if the Qdot imager system provides equivalent data to the conventional organic dye-labelled antibody/laser scanner system. To do this, duplicate proteome microarrays of Vaccinia virus , Brucella melitensis and Plasmodium falciparum were probed with identical samples of immune sera, and IgG, IgA and IgM profiles visualized using biotinylated secondary antibodies followed by a tertiary reagent of streptavidin coupled to either P3 (an organic cyanine dye typically used for microarrays) or Q800 (Qdot). The data show excellent correlation for all samples tested (R>0.8) with no significant change of antibody reactivity profiles. We conclude that Qdot detection provides data equivalent to that obtained using conventional organic dye detection. The portable imager offers an economical, more robust and deployable alternative to conventional laser array scanners. Author Manuscript Correspondence should be sent to Dr. Li Liang lliang3@uci.edu, 376F MedSurge II, Dept. of Medicine, University of California Irvine, Irvine, CA 92697-1275. Phone: 949-824-7368. Fax: 949-824-0481. #These authors contributed equally to this work Conflict of Financial Interest FB, JG, DS and CG are employees of Grace Bio-Labs, Inc. DHD and PLF disclose a financial interest in Antigen Discovery Inc., which has licensed a protein microarray technology. DHD, PLF and the University of California, Irvine may financially benefit from this interest if the company is successful in marketing its products that are related to this research. The terms of this arrangement have been reviewed and approved by the University of California, Irvine, in accordance with its conflict of interest policies.