Guang-Wei Zhang

Cationic Conjugated Polymer/Fluoresceinamine-Hyaluronan Complex for Sensitive Fluorescence Detection of CD44 and Tumor-Targeted Cell Imaging

Simple, rapid, and sensitive detection of CD44 is of paramount importance since it plays pivotal roles in tumor initiation, growth and metastasis. Herein, we describe a novel method for sensitive, visual and facile fluorescence detection of CD44 and CD44-mediated cancer cell imaging, using a probe based on cationic conjugated polymer (CCP)-PFEP and fluoresceinamine-hyaluronan (FA-HA). HA is an anionic natural glycosaminoglycan that can specifically bind to the overexpressed CD44 on various kinds of cancer cells. PFEP and FA-HA formed a complex through electronic interactions, resulting in a highly efficient fluorescence resonance energy transfer (FRET) from PFEP to FA-HA; moreover, the efficiencies of FRET correlated with the concentrations of CD44 because the specific binding of HA-CD44 would separate FA-HA away from PFEP. This method did not require laborious and expensive dual-labeling or protein-labeling needed in previously reported detection methods of CD44. Just mix the sample and test solution containing the PFEP/FA-HA complex, and the results allowed naked-eye detection by observing fluorescent color of solutions with the assistance of a UV lamp. Most importantly, the use of a conjugated polymer with excellent amplification property as well as the specific binding of HA-CD44 endowed this method with high sensitivity and specificity, making it applicable for reliable quantitative detection of CD44. Furthermore, the PFEP/FA-HA complex formed nanoparticles in aqueous solution, and the nanoparticles can be selectively taken up by MCF-7 cells (cancer cell) through the HA-CD44 interaction, thereby giving rise to a dual-color tumor-targeted imaging probe with good photostability. The development of this fluorescent probe showed promising potential to make a reliable and routine method available for early diagnosis of cancer.

Friedel–Crafts Bottom-up Synthesis of Fluorene-Based Soluble Luminescent Organic Nanogrids

A series of fluorene-based grid molecules (so-called Grid fluorenes) have been synthesized by means of shape-supported cyclization, starting from H-shaped precursors via the alternative Friedel-Crafts reactions of fluorenols and Suzuki cross-coupling reactions with key cyclization yields up to 26%. Fluorenol approaches and nanogrids open a door to soluble one-, two-, or three-dimensional nanoporous polymers as next-generation polymer mechano-semiconductors facing a new era of consciousness.

Hindrance-functionalized π-stacked polymer based on polystyrene with pendent cardo groups for organic electronics

A hindrance-functionalized π-stacked polymer, poly(4-(9-phenyl-fluoren-9-yl)styrene) (PPFS), was designed and synthesized by the introduction of bulky 9-phenylfluorenyl moieties (PFMs) with 3D cardo structure into all the phenyl units of polystyrene (PS) through the sp3 carbon linkage. The PFMs obviously alter π-stacked conformation and interchain interactions with respect to the precursor PS. The suitable HOMO–LUMO energy gap, high triplet energy, and excellent thermal and morphological stabilities enable PPFS to serve as not only electrically bistable materials but also phosphorescent hosts. Memory devices using PPFS as an active layer exhibited nonvolatile flash memory performance with ON/OFF current ratio up to 104, high stability in retention time up to 104 s and a number of read cycles up to 105 under a read voltage of 1.5 V in both ON and OFF states, while PS based devices exhibited no memory performance. Polymer light-emitting devices (PLEDs) using PPFS as the host and FIrpic as the guest exhibited blue emission with CIE chromaticity coordinates (x, y) of (0.146, 0.349). These results indicate that hindrance-functionalization opens a way to transform commercially available general purpose polystyrenes into functional π-stacked macromolecules.

Bottom-up synthesis of nanoscale conjugation-interrupted frameworks and their electrical properties.

Soluble covalent organic nanoframeworks up to generation 2.5 (G2.5) are synthesized with self-similar H-shaped conformations by using a bottom-up approach including iterative C-H bond functionalization. The electrical characteristics of nanoscale thin-film semiconductors of the conjugation-interrupted frameworks can be tuned by post-modification with diazonium salt.

Supramolecular Luminescence from Oligofluorenol-Based Supramolecular Polymer Semiconductors

Supramolecular luminescence stems from non-covalent exciton behaviors of active π-segments in supramolecular entities or aggregates via intermolecular forces. Herein, a π-conjugated oligofluorenol, containing self-complementary double hydrogen bonds, was synthesized using Suzuki coupling as a supramolecular semiconductor. Terfluorenol-based random supramolecular polymers were confirmed via concentration-dependent nuclear magnetic resonance (NMR) and dynamic light scattering (DLS). The photoluminescent spectra of the TFOH-1 solution exhibit a green emission band (g-band) at approximately ~520 nm with reversible features, as confirmed through titration experiments. Supramolecular luminescence of TFOH-1 thin films serves as robust evidence for the aggregates of g-band. Our results suggest that the presence of polyfluorene ketone defects is a sufficient condition, rather than a sufficient-necessary condition for the g-band. Supramolecular electroluminescence will push organic devices into the fields of supramolecular optoelectronics, spintronics, and mechatronics.

A robust molecular unit nanogrid servicing as network nodes via molecular installing technology

Organic square nanogrid units have been designed in order to create molecular system nodes and their networks. A nanogrid that consists of four fluorenes and two carbazoles has been synthesized by molecular installing technology from an L-shaped synthon at a total yield of 21%. The fluorene-based nanogrids showed excellent thermal, electrochemical and spectral stability. Nanogrids will be one robust platform to polynodes for the exploration of molecular consciousness, intelligence and robotics.

Diarylfluorene-Based Shape-Persistent Organic Nanomolecular Frameworks via Iterative Friedel-Crafts Protocol toward Multicomponent Organic Semiconductors

We describe bottom-up fluorenol approach to create soluble covalent organic nanomolecular architectures (ONAs) as potential multicomponent organic semiconductors (MOSs). BPyFBFFA as a typical model of ONAs and MOSs exhibits a persistent chair-shaped geometric structure that consists of hole-transporting triphenylamine (TPA), high-efficiency terfluorene, and high-mobility pyrenes. BPyFBFFA was synthesized via the intermediates PyFA and BPyFA with iterative Friedel-Crafts reactions and Suzuki cross-coupling reactions. BPyFBFFA behaves as an efficient blue light-emitter without the low-energy green emission band. Complex diarylfluorenes (CDAFs) are promising candidates for nanoscale covalent organic frameworks and MOSs. Friedel-Crafts protocols offer versatile toolboxes for molecular architects to frame chemistry and materials, nanoscience, and molecular nanotechnology as well as molecular manufactures.

SYNTHESIS, CHARACTERIZATION AND QUENCHING BEHAVIOR OF A CATIONIC POLY(p-PHENYLENEVINYLENE) RELATED COPOLYMER

A cationic poly(p-phenylene vinylene) related copolymer without bulky phenylene substitutents attached to the conjugated backbone was prepared through Wittig reaction. The molecular structure and optical properties were highly investigated through 1H-NMR, UV and PL spectroscopy. The quenching behavior was also investigated, and the results demonstrate that incomplete quenching exists, which is consistent with the cationic poly(p-phenylene vinylene) related copolymer containing bulky phenylene substitutents, probably correlated with the conformation of conjugated backbone and intermolecular aggregation.

Dynamical process of exciton trapping in Fullerene

Abstract Due to the electron-lattice interaction, photoexcitation in C 60 induces bond distortion, which forms a self-trapping exciton and reduces the symmetry of C 60 from I h to D 5 d . The dynamical process of forming the self-trapping exciton is simulated by demonstrating the evolution of both bond distortion and electronic states. It is found that the relaxation time for the exciton trapping time is about 90 fs, which is four times faster than of charge transfer in C 60 .

Exciton Relaxation and Electron Pairing in Fullerene

The dynamical processes of photoexcitation and charge transfer in C60 are studied by calculating the time dependences of the bond structure and electronic spectrum. The evolutions of the bond distortion and gap states indicate that the relaxation time of the self- trapping exciton is 80 fs, but the relaxation time of the charge transfer is 300 fs. Meanwhile the calculation shows that the electron-lattice interaction in C60 can induce the electron pairing with the binding energy 0.05 eV.