Research Article

Nano Research

, Volume 2, Issue 2, pp 121-129

Open Access This content is freely available online to anyone, anywhere at any time.

Improved peptidyl linkers for self-assembly of semiconductor quantum dot bioconjugates

  • Lorenzo BertiAffiliated withCNR-INFM, National Research Center on nanoStructures and bioSystems at Surfaces (S3)University of California Davis Medical Center
  • , Paola Serena D’AgostinoAffiliated withCNR-INFM, National Research Center on nanoStructures and bioSystems at Surfaces (S3)
  • , Kelly BoenemanAffiliated withCenter for Bio/Molecular Science and Engineering Code 6900, U.S. Naval Research Laboratory
  • , Igor L. MedintzAffiliated withCenter for Bio/Molecular Science and Engineering Code 6900, U.S. Naval Research Laboratory Email author 

Abstract

We demonstrate improved peptide linkers which allow both conjugation to biomolecules such as DNA and self-assembly with luminescent semiconductor quantum dots. A hexahistidine peptidyl sequence was generated by standard solid phase peptide synthesis and modified with the succinimidyl ester of iodoacetamide to yield a thiol-reactive iodoacetyl polyhistidine linker. The reactive peptide was conjugated to dye-labeled thiolated DNA which was utilized as a model target biomolecule. Agarose gel electrophoresis and fluorescence resonance energy transfer analysis confirmed that the linker allowed the DNA to self-assemble with quantum dots via metal-affinity driven coordination. In contrast to previous peptidyl linkers that were based on disulfide exchange and were thus labile to reduction, the reactive haloacetyl chemistry demonstrated here results in a more stable thioether bond linking the DNA to the peptide which can withstand strongly reducing environments such as the intracellular cytoplasm. As thiol groups occur naturally in proteins, can be engineered into cloned proteins, inserted into nascent peptides or added to DNA during synthesis, the chemistry demonstrated here can provide a simple method for self-assembling a variety of stable quantum dot bioconjugates.

http://static-content.springer.com/image/art%3A10.1007%2Fs12274-009-9008-9/MediaObjects/12274_2009_9008_Fig1_HTML.jpg

Keywords

Semiconductor quantum dot peptide DNA nanocrystal bioconjugation iodoacetyl sulfhydryl polyhistidine metal-affinity fluorescence fluorescence resonance energy transfer (FRET)