Browsing by Author "Yeh, Mei-Yu"

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A novel nanostructured supramolecular hydrogel self-assembled from tetraphenylethylene-capped dipeptides
(2016)
Yeh, Mei-Yu
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Huang, Chen-Wei
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Chang, Jui-Wen
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Huang, Yu-Tang
;
Lin, Jhong-Hua
Herein, we report a tetraphenylethylene-diglycine (TPE-GG) hydrogelator from a systematic study of TPE-capped dipeptides with various amphiphilic properties. From a chemical design, we found that the hydrogelation of TPE-GG molecules can be utilized to generate supramolecular nanostructures with a large TPE-based nanobelt width (similar to 300 nm) and lateral dimension ratio (>30 fold). In addition, TPE-GG has the lowest molecular weight and minimum number of atoms compared to any TPE-capped peptide hydrogelator reported to date. This minimal self-assembled hydrogelator can fundamentally achieve the gel features compared with other TPE-capped peptides. A combined experimental and computational study indicates the pi-pi interactions, electrostatic interactions and hydrogen-bonding interactions are the major driving forces behind the formation of self-assembled nanobelts. This study demonstrates the importance of structure-property relationships and provides new insights into the design of supramolecular nanomaterials.
Effect of Peptide Sequences on Supramolecular Interactions of Naphthaleneimide/Tripeptide Conjugates
(2016-08-02)
Yeh, Mei-Yu
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Huang, Ching-Ting
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Lai, Tsung-Sheng
;
Chen, Fang-Yi
;
Chu, Nien-Tzu
In this study, we reported a significant difference in the supramolecular hydrogelation of newly discovered NI-GFF (NI-Gly-L-Phe-L-Phe) and NI-FFG (NI-L-Phe-L-Phe-Gly) on the basis of their phase diagrams. With a small difference in the peptide chain between NI-GFF and NI-FFG, we observed a significant difference in their self-assembly properties; NI-GFF formed a stable gel at neutral pH, whereas NI-FFG did not, under the same conditions. From spectroscopic and computational studies, intermolecular pi-pi interactions and extended hydrogen bonding interactions might reinforce the intermolecular interactions of NI-GFF, which may facilitate the formation of the self-assembled nanostructures and the hydrogel. In addition, the aggregation-induced emission (AIE)-active NI-GFF reveals relatively good biocompatibility compared with that of NI-FFG for two commonly used cell lines, suggesting that it is a promising candidate for use as a supramolecular material in biomedical applications. Our results highlight the importance of tripeptide sequences in a self-assembling hydrogel system.
Electroactive Organic Dye Incorporating Dipeptides in the Formation of Self-Assembled Nanofibrous Hydrogels
(2014-10-01)
Liu, Yu-Hao
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Hsu, Shu-Min
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Wu, Fang-Yi
;
Cheng, Hsun
;
Yeh, Mei-Yu
In this study, we examined the self-assembly of four dipeptides conjugated with the electroactive dye naphthalenediimide (NDI). The presence of the NDI group at the N-terminus of Phe-Phe and Phe-Gly promoted the formation of one-dimensional (1-D) nanostructures and three-dimensional (3-D) colored hydrogels under both acidic and physiological conditions. The 1-D nanostructures of these gels were stabilized through intermolecular pi pi interactions of the conjugated systems and extended hydrogen bonding of the dipeptide units.
Functional Supramolecular Polymers: A Fluorescent Microfibrous Network in a Supramolecular Hydrogel for High-Contrast Live Cell-Material Imaging in 3D Environments
(2016-09-21)
Hsu, Shu-Min
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Wu, Fang-Yi
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Cheng, Hsun
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Huang, Yu-Tang
;
Hsieh, Yi-Ru
A new bottom-up strategy based on aromatic peptide amphiphile is developed for a high-contrast visualization of 3D live cell-material imaging-something that has been difficult to achieve previously because of the problems associated with the diffraction of light by the nanosized peptide materials and the aggregation-caused quenching of aggregated pi-conjugated fluorophores in the nanostructures. This study reports an example of a novel supramolecular hydrogelator, naphthaleneimide-phenylalanine (NI-Phe), which forms a self-supporting hydrogel displaying a unique microfibrous network and promising aggregation-induced emission characteristics at pH 7.4. The storage modulus of the NI-Phe gel supports the mass of a cell for 3D cell culturing. This work illustrates a new dopant-free supramolecular approach, complementary to well-established doping procedures that should facilitate the development of live cell imaging in 3D scaffolding materials.
Nanofibrous hydrogels self-assembled from naphthalene diimide (NDI)/amino acid conjugates
(2015-01-01)
Hsu, Ling-Huang
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Hsu, Shu-Min
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Wu, Fang-Yi
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Liu, Yu-Hao
;
Nelli, Srinivasa Rao
The combination of a naphthalene diimide (NDI) group and a single amino-acid of serine (Ser) or lysine (Lys) can be used to promote the formation of a supramolecular hydrogel, which indicates the aromatic amino acid is not necessary to be used in the structural design of NDI-capped small molecule hydrogelators. An equimolar ratio of NDI-Ser and NDI-Lys can form a stable hydrogel under neutral conditions and its gel-to-sol transition temperature is higher than 37 degrees C. This work, as the first example of NDI-containing hydrogelators without aromatic rings in the side chains of amino acids, illustrates a new approach to design NDI-capped supramolecular hydrogels.
Reverse thermo-responsive hydrogels prepared from Pluronic F127 and gelatin composite materials
(2017-01-01)
Yeh, Mei-Yu
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Zhao, Jiong-Yao
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Hsieh, Yi-Ru
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Lin, Jhong-Hua
;
Chen, Fang-Yi
Gelatin is an important hydrocolloid which has widespread applications in the pharmaceutical industry and biomedical science. However, despite its significance, clinical applications of gelatin are largely limited because of its gel-to-solution transition around human body temperature. In this work, we developed a series of F127-gelatin composite hydrogels with reverse thermo-responsive properties. The stiffness of F127-gelatin hydrogels can be adjusted by varying the types and contents of gelatin (type A, GA and type B, GB). The results of rheological data showed that F127-GA gels have higher gel strengths than those of F127-GB, which might be due to different isoelectric points between GA and GB. In addition, F127-gelatin gels showed significant cell viability and biocompatibility for human mesenchymal stem cells, indicating that these discovered hydrogels can serve as potential biomaterials and implantable scaffolds for applications in tissue engineering and regenerative medicine.
Self-Assembled Peptide-Based Hydrogels as Scaffolds for Proliferation and Multi-Differentiation of Mesenchymal Stem Cells
(2017-04-01)
Wang, Yung-Li
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Lin, Shih-Pei
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Nelli, Srinivasa Rao
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Zhan, Fu-Kai
;
Cheng, Hsun
Fluorenyl-9-methoxycarbonyl (Fmoc)-diphenylalanine (Fmoc-FF) and Fmoc-arginine-glycine-aspartate (Fmoc-RGD) peptides self-assemble to form a 3D network of supramolecular hydrogel (Fmoc-FF/Fmoc-RGD), which provides a nanofibrous network that uniquely presents bioactive ligands at the fiber surface for cell attachment. In the present study, mesenchymal stem cells (MSCs) in Fmoc-FF/Fmoc-RGD hydrogel increase in proliferation and survival compared to those in Fmoc-FF/Fmoc-RGE hydrogel. Moreover, MSCs encapsulated in Fmoc-FF/Fmoc-RGD hydrogel and induced in each defined induction medium undergo in vitro osteogenic, adipogenic, and chondrogenic differentiation. For in vivo differentiation, MSCs encapsulated in hydrogel are induced in each defined medium for one week, followed by injection into gelatin sponges and transplantation into immunodeficient mice for four weeks. MSCs in Fmoc-FF/Fmoc-RGD hydrogel increase in differentiation into osteogenic, adipogenic, and chondrogenic differentiation, compared to those in FmocFF/Fmoc-RGE hydrogel. This study concludes that nanofibers formed by the self-assembly of Fmoc-FF and Fmoc-RGD are suitable for the attachment, proliferation, and multi-differentiation of MSCs, and can be applied in musculoskeletal tissue engineering.
Theoretical analysis of the intermolecular interactions in naphthalene diimide and pyrene complexes
(2014-01-01)
Yeh, Mei-Yu
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Lin, Hsin-Chieh
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材料科學與工程學系
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Department of Materials Science and Engineering
Supramolecular assembly of donor-acceptor complexes as the key component in organic functional nanomaterials is a promising approach for future electronic devices. One representative example of the donor-acceptor complexes is the naphthalene diimide-pyrene (NDI-Py) system, which shows fascinating photoelectric properties. Herein, the analysis of the pi-pi interactions between NDI and Py has been investigated using the DFT/M06-2X and reduced density gradient methods. According to the calculations, the attractive forces for the stabilization of the NDI-Py dimer are dependent on the rotation angles, which provide physical insight into the experimental data reported by Wilson and co-workers (Langmuir, 2011, 27, 6554). Our results not only provide computational evidence for the origin of the rotation in the crystal structure of the NDI-Py but also address the role of the charge-transfer attractions in the complexes.
Theoretical Investigation of the Intermolecular Charge-Transfer Interactions of Poly-p-Phenylene Oligomers
(2018-01-01)
Yeh, Mei-Yu
;
Lin, Hsin-Chieh
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材料科學與工程學系
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Department of Materials Science and Engineering
A composite molecule (CM) model is used to investigate the nature of intermolecular interactions in the excited states of pi-conjugated oligomers of poly-(p-phenylene) (PPP). The dependence of the charge-transfer (CT) interactions in low-lying excited states as a function of intermolecular distance, conjugation length, and the translation shifts is examined. We demonstrate how the amplitude of CT mixing in two low-lying excited states of PPP dimer is sensitive to various aspects of molecular packing. The largest CT mixing in the two excited states is consistently obtained for cofacial packing. However, from a detailed examination of molecular orbital shapes and interactions, it is seen that specific arrangements promote the CT mixing in two low-lying transitions. With cofacial arrangements, it shows a larger percentage of CT in the first excited states than the corresponding second excited states for phenyl rings on the top of C-sp2-C-sp2 single bonds. This work illustrates the importance of molecular packing-CT mixing relationship of functional pi-conjugated materials.
Tumor targeting with DGEA peptide ligands: a new aromatic peptide amphiphile for imaging cancers
(2019-01-25)
Zhan, Fu-Kai
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Liu, Jyun-Cheng
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Cheng, Bill
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Liu, Yen-Chu
;
Lai, Tsung-Sheng
We report a novel fluorescent bioprobe, tetraphenylethylene-Phe-Asp-Gly-Glu-Ala (TPE-FDGEA), and its self-assembly behavior, photophysical properties, and biocompatibility. The hydrogelator TPE-FDGEA exhibited aggregation-induced emission characteristics, which facilitated imaging of PC-3 human prostate cancer cells, thereby demonstrating the utility of such fluorescent probes for specific labeling of target cells in vitro.