Chemistry of Materials
Chemistry of Materials
5 years ago

Purple-, Blue-, and Green-Emitting Multishell Alloyed Quantum Dots: Synthesis, Characterization, and Application for Ratiometric Extracellular pH Sensing

Purple-, Blue-, and Green-Emitting Multishell Alloyed Quantum Dots: Synthesis, Characterization, and Application for Ratiometric Extracellular pH Sensing
Valle Palomo, Alan L. Huston, Kimihiro Susumu, Philip E. Dawson, James B. Delehanty, Eunkeu Oh, Lauren D. Field, Igor L. Medintz, Michael Hunt
We report the synthesis of a series of CdxZn1–xSe/CdyZn1–yS/ZnS and ZnSe/CdyZn1–yS/ZnS multishell alloyed luminescent semiconductor quantum dots (QDs) with fluorescence maxima ranging from 410 to 530 nm which cover the purple, blue, and green portion of the spectrum. Their subsequent surface modification to prepare water-soluble blue-emitting QDs, characterization, and application for ratiometric pH sensing in aqueous buffers and in an extracellular environment are further described. QDs were synthesized starting from ZnSe cores, and the fluorescence peak positions were tuned by (i) cation exchange with cadmium ions and/or (ii) overcoating with CdyZn1–yS layers. The as-prepared QDs had reasonably high fluorescence quantum yields (∼30–55%), narrow fluorescence bands (fwhm ∼25–35 nm), and monodispersed semispherical shapes. Ligand exchange with hydrophilic compact ligands was successfully carried out to prepare a series of water-soluble blue-emitting QDs. QDs coated with the hydrophilic compact ligands preserved the intrinsic photophysical properties well and showed excellent colloidal stability in aqueous buffers for over a year. The blue-emitting QDs were further conjugated with the pH-sensitive dye, fluorescein isothiocyanate (FITC), to construct a fluorescence resonance energy transfer-based ratiometric pH sensing platform, and pH monitoring with the QD-FITC conjugates was successfully demonstrated at pHs ranging between 3 and 7.5. Further assembly of the QD-FITC conjugates with membrane localization peptides allowed monitoring of the pH in extracellular environments. High quality, water-soluble blue-emitting QDs coated with compact ligands can help expand the practical fluorescence range of QDs for a variety of biological applications.

Publisher URL: http://dx.doi.org/10.1021/acs.chemmater.7b02174

DOI: 10.1021/acs.chemmater.7b02174

You might also like
Discover & Discuss Important Research

Keeping up-to-date with research can feel impossible, with papers being published faster than you'll ever be able to read them. That's where Researcher comes in: we're simplifying discovery and making important discussions happen. With over 19,000 sources, including peer-reviewed journals, preprints, blogs, universities, podcasts and Live events across 10 research areas, you'll never miss what's important to you. It's like social media, but better. Oh, and we should mention - it's free.

  • Download from Google Play
  • Download from App Store
  • Download from AppInChina

Researcher displays publicly available abstracts and doesn’t host any full article content. If the content is open access, we will direct clicks from the abstracts to the publisher website and display the PDF copy on our platform. Clicks to view the full text will be directed to the publisher website, where only users with subscriptions or access through their institution are able to view the full article.