Huazhong University of Science Zhuming Jiang, Li Chong groups: visible AIE drive type switch fluorescent molecule and super-resolution imaging applications

Dithienyl ethylene (DTE) having a unique fluorescent molecule bistable switching characteristic and excellent in fatigue resistance and has broad applications in the field of optical storage and fluorescence imaging. However, two-thienyl ethylene typically require ultraviolet driven photoisomerization reaction loop, which limits their usefulness in certain extent. Particularly in super-resolution fluorescence imaging, microscopy systems because of cost, compatibility, security, and other factors not typically equipped with a UV light source, resulting in compatibility with an existing imaging system dithienyl ethylene probe poor. Meanwhile, compared to visible light, ultraviolet light with a shorter wavelength, higher energy, injury to the operator or the larger sample, and worse penetration. Accordingly, an urgent need to develop milder alternative to the use of visible ultraviolet driven dithienyl ethylene switch fluorescent molecule. In recent years, two-thienyl ethylene responsive to visible gradually attracted attention, but not more reports, and focused on the photochromic system, and fluorescence studies of the switching system less. Two fluorescent molecule thienyl ethylene switching system as compared to a photochromic systems are more complex in structure and molecular properties, in addition to considering the photochromic properties, but also into account the nature of the fluorescent switch, how to design a high performance visible light currently regulated dithienyl ethylene fluorescent molecule switch remains a challenge. Further, conventional fluorescent molecules and fluorescent dyes as switches, which in high concentration, aggregation, aggregation prone to induce fluorescence quenching in the solid state (ACQ) problems limit their performance in optical applications. Academician TANG Zhong AIE (the AIE) concept also provide an important way to solve the problem ACQ switch fluorescent molecule. Currently, two-thienyl ethylene driven research visible light-induced color change reaction and both were AIE have made some progress, but the two functions and how to obtain both a fluorescent molecule fluorescence switch for switching high contrast remains a challenge.

华中科技大学朱明强、李冲团队:可见光驱动的聚集诱导发光型荧光分子开关及其超分辨成像应用
FIG 1 is driven AIE visible dithienyl ethylene type fluorescent molecule switch, and TPE-2DTE OTPE-2DTE structure and photochromic process.

aggregation induced by light, visible light response, high fluorescence switch than the \”triple play\”

Recently, Huazhong University of Science and Technology, Wuhan National Research Center for Optoelectronics Lee Chong lecturers and professors Zhu Mingjiang team by double dithienylglycolic an ethylene group substituted with a single AIE (tetraphenyl ethylene derivative TPE / oxygen-containing heterocyclic ringTetraphenyl ethylene derivative OTPE) strategy visible constructed two switching drive having a high ratio of fluorescence of two ethylene-thienyl AIE fluorescent molecule switch, and TPE-2DTE OTPE-2DTE (FIG. 1), and successfully applied in the super-resolution imaging. Since the AIE molecules containing group, a ring-opening state and TPE-2DTE OTPE-2DTE showed significant feature AIE (FIG. 2). OTPE-2DTE due to oxygen-containing heterocyclic structure, or solid state of aggregation enhanced fluorescence emission peak at above 560 nm, containing only tetraphenyl ethylene TPE-2DTE is located near 500 nm. Meanwhile, four phenylvinyl group is a class of electron conjugated group, effectively reducing the energy gap, promote dithienyl ethylene structure and absorption of visible light in response. 405 nm visible light can be efficiently closed-loop drive and reaction TPE-2DTE OTPE-2DTE, since the emission spectrum of two-state closed-loop thiazol absorption spectrum of the fluorophore overlaps thienyl ethylene effective, capable of quenching the fluorescence energy transfer. Steady state light, TPE-2DTE OTPE-2DTE and closed states, respectively, to obtain 50% conversion and 40%. However, when the aggregation state, the 405 nm light, TPE-2DTE OTPE-2DTE and quickly quenching fluorescence, the maximum fluorescence ratios of the switch 1196: 1 and 1983: 1 (FIGS. 3a and 3B), which is mainly attributed to inter-molecular energy transfer quenching due to amplification. Then another beam using a long wavelength of visible light (e.g. 621 nm) irradiating the sample, the sample color and fluorescence will restore the initial state. Alternate long, short-wavelength visible illumination of the sample, it is possible to achieve reversible switching cycle fluorescence, and exhibits good fatigue resistance (FIGS. 3b and 3c).

华中科技大学朱明强、李冲团队:可见光驱动的聚集诱导发光型荧光分子开关及其超分辨成像应用
FIG 2, TPE-2DTE OTPE-2DTE performance and the AIE. (A) and (b) are (fluorescence intensity of the current I / THF fluorescence intensity I0) and TPE-2DTE FIG OTPE-2DTE relative fluorescence intensity at different ratios THF / H2O mixed solvent. I / I0 represents the effect of the strength of the AIE.

rewritable optical information recording

and the use of TPE-2DTE OTPE-2DTESwitch drive excellent visible fluorescence properties can be realized in optical applications is the operating wavelength of visible light. For example, the ring-opening state and TPE-2DTE OTPE-2DTE doped to a chloroform solution containing the PMMA in the solution using a brush dipped into written text on a glass plate, it is possible to make the text written temporarily \”invisible\” (FIGS. 3e and 3f ). In the dark, using the weak 405 nm fluorescence excitation light, the glass sheet exhibits strong fluorescent orange and green letters. Reuse induce a rapid ring closure reaction intensity 405 nm light, the written text into the dark blue fluorescent light, while the fluorescence in the dark \”invisible.\” When using the 621 nm long wavelength followed by irradiation of visible light, but also to restore the initial sample was colorless and strongly fluorescent state, the above process can be repeated multiple times cycles. TPE-2DTE OTPE-2DTE and has potential applications in security, optical storage and other art work using the full visible wavelength.

华中科技大学朱明强、李冲团队:可见光驱动的聚集诱导发光型荧光分子开关及其超分辨成像应用
FIG. 3 fluorescence TPE-2DTE switching performance and the OTPE-2DTE. (A) and (b) are TPE-2DTE OTPE-2DTE and fluorescence spectra in THF (1×10-5M) containing 99% of water. (C) and (d) are TPE-2DTE OTPE-2DTE emission intensity and the fluorescence intensity at 550 nm at 405 nm and 621nm by FIGS switching cycles alternately visible fluorescence emitted at 490 nm. Using (e) TPE-2DTE and (f) OTPE-2DTE chloroform solution (PMMA) as \”invisible ink\” write text, color and fluorescence to achieve reversible transition at 405 nm and 621 nm alternately irradiated.

The optical diffraction limit break

with its excellent visible regulatory properties, the use of 405 nm and 561 nm visible light, and to TPE-2DTE OTPE-2DTE as a super-resolution imaging probe, realized block copolymers PEO-b-PSt nanorods self-assembly of super-resolution imaging micelles, the micelles fine morphology was observed, resolution better than 50 nm (FIG. 4). In FIG conventional fluorescent imaging, the optical cross-section of the half-peak somewhere micelle full width (FWHM) is about 400 nm, far from the true diameter of the micelles; and the super-resolutionFIG reconstruction, with the FWHM at only 37 nm, very close to the data measured in electron microscopy, resolution of the image super-resolution fluorescence imaging as compared to a conventional increased more than 10-fold. TPE-2DTE and OTPE-2DTE show a broad application prospects in the super-resolution imaging.

华中科技大学朱明强、李冲团队:可见光驱动的聚集诱导发光型荧光分子开关及其超分辨成像应用
FIG 4 TPE-2DTE for super-resolution imaging. (A) a conventional fluorescent imaging view (upper portion) and a super-resolution imaging view (lower part). Analysis of the Yellow Line micelle half width direction sectional view (b) and FIG conventional super-resolution fluorescence imaging of the image in FIG. (C) Fourier-related ring (FRC) resolution.

The significance of this study is, TPE-2DTE and OTPE-2DTE aggregate having a good visible response induced emission type diarylethene fluorescent molecule switch, since the UV radiation can be avoided the adverse impacts and ACQ phenomenon, more suitable for super-resolution optical imaging applications, has important practical value. Meanwhile, the work on the future design of higher performance integrated visible driven diarylethanedione diene fluorescent molecule switches provide some guidance. Recent research published in the \”ACS Applied Materials & Interfaces\” journal, National Research Center for Optoelectronics Wuhan Li Chong (first, co-corresponding author), Kai Xiong, Chen Ying, Fan Cheng, Wang Yalong, Zhu Mingjiang (co-author) is authors. The study was \”973 Program\”, funded by the National Natural Science Foundation of China, the central fund basic scientific research universities and Natural Science Foundation of Hubei Province. Full access: https://pubs.acs.org/doi/abs/10.1021/acsami.9b05417

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