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

Abstract

Herein, we report on a dual-color, photoswitchable donoracceptor nanosystem based on quantum dots (QD) and an anthryl quinolyl ethylene photoactive functional ligand (AQE-FL), in which a carboxylic group is used to anchor AQE-FL to QD. Photophysical and photochemical properties of the resulting photoswitchable QD system (psQD) were studied by steady state and time-resolved spectroscopic methods. Efficient Förster resonance energy transfer (FRET) from QD to AQE-FL was shown. Applicability of the Stern-Volmer formalism (with a subdivision into static and dynamic quenching) to the psQD studied is discussed. The spectral overlap integrals of QD emission and trans-and cis-AQE-FL isomers absorption differ by 3 times that which is used for controlling the FRET efficiency. Consequently, the psQD emission is redistributed between the QD (417 nm) and AQE (520 nm) channels, i. e. dual-color fluorescent switching between two observable states without the "off" state is recorded.

Ligand-protected nanocluster-mediated photoswitchable fluorescent nanoprobes towards dual-color cellular imaging

“…We note that such a high multicolor switching ratio has been rarely achieved in the reported multi-color uorescence photoswitchable nanoprobes. 36,[53][54][55][56] Previous studies found that uorescent switches fabricated by noncovalently conjugating the uorescence donor with the photochromic acceptor are more favorable for achieving a high switching ratio than that constructed by covalent binding. [57][58][59][60] Thus, instead of covalent conjugation, we adopted a rather mild strategy by physically encapsulating both AuNCs and spiropyran inside lipid NPs.…”

“…So far, a variety of nanoparticles have been used to construct photocontrolled uorescence switches, such as semiconductor quantum dots, 31 upconverting NPs, 32 perovskite nanocrystals 33 and metal nanoclusters. 34 However, multi-color uorescence photoswitches based on ligand-protected NPs have rarely been achieved, [34][35][36] and the distinct capability of NPs for modulating the photophysical properties of photochromic dyes has not been adequately exploited. 6,37,38 Photoisomerization kinetics of photochromic compounds is regarded as an important issue in determining their performance in applications.…”

“…16,39 Thus, a deep understanding of photoisomerization kinetics is essential for precisely controlling their photochromic properties, which was largely missing in many previous studies. [34][35][36][37][38] In particular, the underlying rationale for regulating their photoswitching performance (e.g. on/off ratio and anti-fatigue property) still needs further clarication.…”