Conference Programme

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Overview
Session
T2-04: Symp T
Time:
Tuesday, 20/Jun/2017:
1:30pm - 3:30pm

Session Chair: Zhenguo Chi, Sun Yat-sen University
Location: Nicoll 3

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Presentations
1:30pm - 1:45pm
Oral

Permeabilization and Ultrafast Delivery of AIEgens using Saponin Nanoparticles: Applications in Plant and Animal Cells

Alexander NICOL, Ryan T. K. KWOK, Ben Zhong TANG

The Hong Kong University of Science and Technology, Hong Kong S.A.R. (China)

Saponins are a class of naturally occurring bioactive and biocompatible glycosides produced by plants. Saponins are amphiphilic composed of one or more hydrophilic sugar moieties and a lipophilic steroid group. Some saponins such as α-hederin exhibit unique cell membrane interactions. At concentrations above their critical micelle concentration, α-hederin will interact and aggregate with membrane cholesterol to form transient pores in the cell membrane. In this project, we utilized the unique cell membrane permeabilization properties of α-hederin to deliver AIEgens into both mammalian and plant cells. For mammalian cells, we used α-hederin as a micelle to encapsulate and stabilize large red emitting AIE nanoparticles of varying sizes. We were able to successfully deliver these nanoparticles into cells in under 5 min. This is around 20x faster than previously reported nanoparticle delivery systems since this delivery method is diffusion rather than endocytosis dependent. We found this method to be biocompatible, inexpensive, ultrafast and applicable to deliver a wide variety of AIEgens into mammalian cells. For plant cells, bioimaging has been a persistent challenge because the cell wall is extremely difficult for most fluorescent probes to traverse. This is a particular issue for AIEgens which has limited their application in plant cell biology. In this study, we developed several techniques to permeabilize the cell wall using saponin allowing AIEgens to enter and stain plant cells. We confirmed the entry of our AIEgen probes by performing a series of plasmolysis experiments. Arabidopsis thaliana was used to demonstrate that our AIEgens could be used to stain a variety of plant tissues including xylem, phloem and meristematic tissues. We found that this method was compatible with both wild type and mutant GFP transgenic Arabidopsis thaliana plants. The photostability and resolution of our AIEgens was higher than that of commercially used dyes like propidium iodide.


1:45pm - 2:15pm
Invited

Recent Advances in Stimuli-Responsive Aggregation-Induced Emission Materials

Zhenguo CHI, Zhiyong YANG, Juan ZHAO, Tao YU, Shizhao ZHENG, Yi ZHANG, Siwei LIU, Jiarui XU

Sun Yat-sen University, China

Stimuli-responsive luminescent materials are a class of “smart” materials with luminescent properties that change in response to external stimuli. These materials are widely used in sensors, memory chips, and security inks. As an important class of anti-aggregation-caused quenching (anti-ACQ) materials, aggregation-induced emission (AIE) materials have exhibited a number of interesting stimuli-responsive luminescent features.

Here we present several stimuli-responsive phenomena of AIE molecules, such as mechanofluorochromism, mechanoluminescence, and photochromism.

Acknowledgements:

The authors gratefully acknowledge the financial support from the NSF of China (51473185, 21672267) and Guangdong Science and Technology Plan (2015B090913003).

References:

[1] Xu, S.; Liu, T.; Mu, Y.; Wang, Y.; Chi, Z.; Lo, C.; Liu, S.; Zhang, Y.; Lien, A.; Xu, J. Angew. Chem. Int. Ed. 2015, 54, 874-878.

[2] Mao, Z.; Yang, Z.; Mu, Y.; Zhang, Y.; Wang, Y.; Chi, Z.; Lo, C.; Liu, S.; Lien, A.; Xu, J. Angew. Chem. Int. Ed. 2015, 54, 6270-6273.

[3] Yang, Z.; Mao, Z.; Zhang, X.; Ou, D.; Mu, Y.; Zhang, Y.; Zhao, C.; Liu, S.; Chi, Z.; Xu, J.; Bryce, M. Angew. Chem. Int. Ed. 2016, 55, 2181-2185.

[4] Xie, Z.; Chen, C.; Xu, S.; Li, J.; Zhang, Y.; Liu, S.; Xu, J.; Chi, Z. Angew. Chem. Int. Ed. 2015, 54, 7181-7184.

[5] Xu, B.; Mu, Y.; Mao, Z.; Xie, Z.; Wu, H.; Zhang, Y.; Jin, C.; Chi, Z.; Liu, S.; Xu, J., Wu, Y.; Lu, P.; Lien, A.; Bryce, M. Chem. Sci. 2016, 7, 2201-2206.

[6] Ou, D., Yu, T., Yang, Z., Luan, T., Mao, Z., Zhang, Y., Liu, S., Xu, J., Chi, Z., Bryce, M. Chem. Sci., 2016, 7, 5302 - 5306.

[7] Yu, T., Ou, D., Yang, Z., Huang, Q., Mao, Z., Chen, J., Zhang, Y., Liu, S., Xu, J., Bryce, M., Chi, Z. Chem. Sci., 2017, DOI: 10.1039/C6SC03177C.


2:15pm - 2:30pm
Oral

Near-Infrared Aggregation-Induced Emission Materials for Highly Bright Imaging of Tumor in Living Mice

Ji QI, Ryan Tsz Kin KWOK, Jacky Wing Yip LAM, Ben Zhong TANG

The Hong Kong University of Science and Technology, Hong Kong S.A.R. (China)

Much effort has been devoted to developing organic near-infrared (NIR) luminescent materials for in-vivo applications, as they possess a lot of advantages over imaging in the visible region, such as, deep-tissue penetration, less photo-damage, and high signal-to-noise ratio. Conventional organic NIR dyes based on core units of cyanine, BODIPY, and rhodamine have been extensively investigated. For example, indocyanine green (ICG), whose excitation and emission are both located in the NIR biological window (700-900 nm), was the first organic NIR fluorophore to be approved by FDA for use in human, which highlights the great potential of organic luminogens for clinical application. All conventional organic dyes show bright emission in solution, however, their emission is partially or completely quenched when aggregated in aqueous medium or inside living cells. Thus, it is desirable to develop organic NIR dyes with high fluorescence efficiency in the aggregate state for in-vivo applications.

Unlike conventional organic dyes, aggregation-induced emission luminogens (AIEgens) are newly developed luminescence materials, which show much brighter light emission in the aggregate state. However, few NIR AIEgens have been prepared because of the synthetic difficulty. To endow the luminogen with AIE property, one may introduce twisting units into the molecular structure to hamper the π-π stacking. However, this will disrupt the π-conjugation, and leading to blue-shift, instead of red-shift in the emission. By systemic structure modification, we have developed several new donor-acceptor type NIR AIE materials, which show typical AIE characteristics, and very high luminescence quantum yields in the solid state. These new NIR AIEgens have been used for biological imaging in living mice, and they exhibit great advance compared to conventional dyes, for the higher brightness, better photostability, and good biocompatibility. These fascinating results are expected to trigger the development of new NIR AIEgens and exploration of their further high-technological applications.


2:30pm - 2:45pm
Oral

Tetraphenylethene-labled Nylon-6 with Unique Emission

Longcheng GAO

Beihang University, China

In this work, tetraphenylethene-labled nylon-6 was synthesized. The resultant nylon-6 shows strong emission in its solid state. When dissolved in formic acid, the dilute solution shows weak luminescence. With gradual increase in the fraction of THF, the emission of becomes enhanced, and blue-shift can be seen when the fraction of THF is up to 50%. Temperature effect on the light emissions of the sample was investigated. The emission is firstly diminished upon heating to 120 oC, and blue shifted. Interestingly, the intensity is kept constant up to 200 oC, which is closed to its melting point. The wide angle X ray scattering results show that the crystal structure undergoes transiton gradually from α form to γ form, which is more stable, as a result, enhancing emission, with compensation of the temperature induced emission decrement.


2:45pm - 3:00pm
Oral

Ultrasound-induced Transformation of Fluorescent Organic Nanoparticles from a Molecular Rotor into Rhomboidal Nanocrystals with Enhanced Emission

Dirk M. GULDI

University of Erlangen, Germany

Fluorescent organic nanoparticles (FONs) based on aggregation-induced emission (AIE) are receiving increasing attention owing to their simple preparation, enhanced optical properties, and wide range of applications. Therefore, finding simple methods to tune the FON’s structural and emissive properties is highly desirable. In this context, we discuss the preparation of highly emissive, amorphous AIE spherical nanoparticles based on a structurally-simple molecular rotor and their sonochemical transformation into rhomboidal nanocrystals. Interestingly, the ultrasound-induced modification of the morphology is accompanied by a remarkable enhancement in the stability and emission of the resulting nanocrystals. A detailed characterization of both spherical and rhomboidal nanoparticles was carried out by means of several microscopic, crystallographic, and spectroscopic techniques as well as quantum mechanical calculations. In a nutshell, this work provides a unique example of the ultrasound-induced switching of morphology, stability, and emission in FONs.


3:00pm - 3:15pm
Oral

Interrogating the Photobehavior of HOFs Crystals, Defects and their Monomers: Relevance to Nanophotonics

Eduardo GOMEZ1, Mario GUTIERREZ1, Boyko COHEN1, Ichiro HISAKI2, Abderrazzak DOUHAL1

1Department of Physical Chemistry, Facultad de Ciencias Ambientales y Bioquimica y INAMOL, University of Castilla la Mancha (UCLM), Spain; 2Department of Material and Life Science, Graduate School of Engineering, Osaka University, Japan

MOFs, COFs and HOFs are emerging as smart new materials for promising applications in several fields of science and technology. Recently, we have observed a rich dynamics of a Zr-based MOF containing different dayes and involving MLCT, energy transfer, and exciplex formation.[1-4] New HOFs have been synthesized and their structures have been reported. [5,6] In this talk, I will focus on the fluorescence behavior of a series of these HOFs using ultrafast spectroscopy and time-resolved single crystal (molecule) emission microscopy. I will show how H-bonding induced aggregation and disaggregation of a family of COFs, which is affected by the solvent nature (H-bonding) exhibit a rich emission spectroscopy (fluorescence from blue to the red side of the electromagnetic spectrum) and relaxation processes from ps to ms regime. We identify different emitters, relaxation pathways and mechanisms which depend on the degree of aggregation and solvation when the HOFs are dispersed in solution. I will discuss the importance of defects at a single crystal level on the observed emission lifetime, spectra, polarization and its relevance to the photonics of these new materials. Finally, I will show a case of a HOFs-based LED emitting a white light.

Acknowledgments:

This work was supported by the (Spain) JCCM and MINECO through projects: PEII-2014-003-P, and MAT2014-57646-P; I.H. thanks for KAKENHI (J15H00998) from MEXT Japan

References:

[1] Gutiérrez, M. et al., J. Mater. Chem. C, 2015, 3, 11300.

[2] Gutiérrez, M. et al., Phys. Chem. Chem. Phys. 2016, 18, 5112.

[3] Gutiérrez, M. et al., Chem. Eur. J., 2016, 22, 13072.

[4] Gutiérrez, M. et al., Phys. Chem. Chem. Phys. 2016, 18, 27761.

[5] Hisaki, I. et al., Angew. Chem. Int. Ed. 2015, 54, 3008.

[6] Hisaki, I. et al., J. Am. Chem. Soc. 2016, 138, 6617.



 
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