Water‐Soluble, Thermostable, Photomodulated Color‐Switching Quantum Dots

Abstract

Photoswitchable probes are of great utility in fluorescence microscopy, permitting numerous determinations, including molecular localization for super-resolution, based on their modifiable emission intensity and spectra. We have coated a blue-emitting (425 nm) quantum dot (QD) with a diheteroarylethene photochrome (PCf), the closed form isomer of which has absorption and emission maxima at 440 and 520-530 nm, respectively, and thus functions as a fluorescent acceptor for the QD donor in Förster resonance energy transfer (FRET). The transition from the non-absorbing, non-fluorescent open state to the fluorescent closed state is achieved by irradiation in the near-UV and reversed by visible light. The PCf is coupled to an amphiphilic polymer that stably coats the QD, thereby creating a water-soluble color-switching QD (csQD) emitting in the blue after visible light irradiation and in the green after UV irradiation. Thus, csQDs photomodulate between two observable states, without the "off" state of previous constructs. The resulting change in the emission ratios of the QD and PCf is up to 180 %, and the csQD can undergo multiple photocycles with minimal fatigue.

Transducing Protease Activity into DNA Output for Developing Smart Bionanosensors

“…Cap‐exchanged QDs were extensively characterized by TEM, DLS, and other physicochemical techniques as described in refs. . Trypsin (Catalog # T8003, 24 kDa, specific activity—10000 units mg −1 ) and α‐Chymotrypsin (Catalog # C4129, 25 kDa, specific activity—40 units mg −1 ) were purchased from Sigma‐Aldrich (St. Louis, MO) as lyophilized powders and dissolved in buffer immediately prior to use.…”

Temperature and pH Responsive Light‐Harvesting System Based on AIE‐Active Microgel for Cell Imaging

“…In recent years, the fabrication of stimuli responsive light harvesting systems has gradually been a research hot spot. ,[ 2,3 ] However, most of these scaffolds usually suffer from either time‐consuming synthesis, poor photostability, or cytotoxicity.…”

Photomodulation of a Dual‐Color Luminescent System Combining Quantum Dots with a FRET Acceptor Ligand**

“…One of them is ZnSe/ZnS quantum dot covered with amphiphilic, diheteroarylethene-containing polymers, which requires two excitation wavelengths for fluorescence readout. [32] Another reported system is a polymer nanoparticle consisting of a photochromic spiropyran-linked amphiphilic copolymer. [33] Recently, we have developed a dual-color psQD based on the CdS QDs and 1-(9-anthryl)-2-(2-quinolyl) ethylene (AQE) as a photochrome.…”