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Proteins, peptides, and quantum dots.

Researchers at the U.S. Naval Research Laboratory and The Scripps Research Institute report on an issue that has intrigued scientists for years: how many of a particular protein or peptide can be attached, on average, to a semiconductor quantum dot (QD) nanocrystal and how can this be predicted? Although the use of many different QD bioconjugates is now quite frequent, questions still remain about what the overall loading capacity is and how to factor this in when preparing such materials. To address this, the authors systematically examine how QDs can be loaded with a series of peptides and proteins of increasing size including a <20 residue peptide, myoglobin, mCherry, and maltose binding protein, which together cover a range of masses from (2.2 to [approximately equal to] 44 kDa. Conjugation directly to the surface of dihydrolipoic acid functionalized QDs is facilitated by polyhistidine metal-affinity coordination. Increasing ratios of dye-labeled peptides and proteins are self-assembled to the QDs and the resulting bioconjugates are separated and analyzed using gel electrophoresis. This unique approach allowing fluorescent visualization of both the separated QD conjugates and unbound species in the gels provides a determination of maximum loading numbers. These results will contribute towards an understanding of how to engineer improved designer bioconjugates for QDs and other nanoparticle materials.

I. L. Medintz et al., Small DOI: 10.1002/srnll.200901845
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Title Annotation:Materials Views
Author:Ladden, S.
Publication:Plastics Engineering
Article Type:Brief article
Geographic Code:1USA
Date:Apr 1, 2010
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