Compact quantum dot surface modification to enable emergent behaviors in quantum dot-DNA composites

J Chem Phys. 2019 Oct 14;151(14):144706. doi: 10.1063/1.5124690.

Abstract

Quantum dot (QD) biological imaging and sensing applications often require surface modification with single-stranded deoxyribonucleic acid (ssDNA) oligonucleotides. Furthermore, ssDNA conjugation can be leveraged for precision QD templating via higher-order DNA nanostructures to exploit emergent behaviors in photonic applications. Use of ssDNA-QDs across these platforms requires compact, controlled conjugation that engenders QD stability over a wide pH range and in solutions of high ionic strength. However, current ssDNA-QD conjugation approaches suffer from limitations, such as the requirement for thick coatings, low control over ssDNA labeling density, requirement of large amounts of ssDNA, or low colloidal or photostability, restraining implementation in many applications. Here, we combine thin, multidentate, phytochelatin-3 (PC3) QD passivation techniques with strain-promoted copper-free alkyne-azide click chemistry to yield functional ssDNA-QDs with high stability. This process was broadly applicable across QD sizes (i.e., λem = 540, 560, 600 nm), ssDNA lengths (i.e., 10-16 base pairs, bps), and sequences (poly thymine, mixed bps). The resulting compact ssDNA-QDs displayed a fluorescence quenching efficiency of up to 89% by hybridization with complementary ssDNA-AuNPs. Furthermore, ssDNA-QDs were successfully incorporated with higher-order DNA origami nanostructure templates. Thus, this approach, combining PC3 passivation with click chemistry, generates ssDNA-PC3-QDs that enable emergent QD properties in DNA-based devices and applications.

MeSH terms

  • Alkynes / chemistry
  • Azides / chemistry
  • Cadmium Compounds / chemistry
  • Click Chemistry
  • DNA, Single-Stranded / chemistry*
  • Fluorescence
  • Gold / chemistry
  • Metal Nanoparticles / chemistry
  • Nanocomposites / chemistry*
  • Nucleic Acid Hybridization
  • Oligodeoxyribonucleotides / chemistry
  • Phytochelatins / chemistry
  • Poly T / chemistry
  • Quantum Dots / chemistry*
  • Selenium Compounds / chemistry
  • Sulfides / chemistry
  • Surface Properties
  • Zinc Compounds / chemistry

Substances

  • Alkynes
  • Azides
  • Cadmium Compounds
  • DNA, Single-Stranded
  • Oligodeoxyribonucleotides
  • Selenium Compounds
  • Sulfides
  • Zinc Compounds
  • Poly T
  • Gold
  • Phytochelatins
  • cadmium selenide
  • zinc sulfide