Huifang Su

Spontaneous Amino-yne Click Polymerization: A Powerful Tool toward Regio- and Stereospecific Poly(β-aminoacrylate)s

Efficient synthesis of poly(enamine)s has been a great challenge because of their poor stability, poor solubility, and low molecular weights. In this work, a spontaneous amino-yne click polymerization for the efficient preparation of poly(enamine)s was established, which could proceed with 100% atom efficiency under very mild conditions without any external catalyst. Through systematic optimization of the reaction conditions, several soluble and thermally stable poly(β-aminoacrylate)s with high molecular weights (Mw up to 64400) and well-defined structures were obtained in excellent yields (up to 99%). Moreover, the polymerization can perform in a regio- and stereospecific fashion. Nuclear magnetic resonance spectra analysis revealed that solely anti-Markovnikov additive products with 100% E-isomer were obtained. The reaction mechanism was well demonstrated with the assistance of density functional theory calculations. In addition, by introducing the tetraphenylethene moiety, the resulting polymers exhibit unique aggregation-induced emission characteristics and could be applied in explosives detection and bioimaging. This polyhydroamination is a new type of click polymerization and opens up enormous opportunities for preparing functional polymeric materials.

Non-conventional fluorescent biogenic and synthetic polymers without aromatic rings

Non-conventional fluorescent materials without aromatic structures have attracted much research attention in recent years. However, the working mechanism responsible for their fluorescence remains mysterious. Here we decipher the origin of fluorescence by studying the photophysical properties of a series of non-aromatic biogenic and synthetic peptides. An experimental study suggests that the turn-on fluorescence in the aggregation state/condensed phase is associated with the communication of amide groups, where hydrogen bonds are playing a critical role in bringing these functionalities into close proximity. This explanation is further justified by the study of the hierarchical influence on fluorescence and applied to biomimetic polymers in a more general content. This discovery provides a more comprehensive insight into the bioluminescence system. It may stimulate future development of new fluorescent materials, and inspire research on disease diagnostics, biomechanics measurements, etc. that are associated with protein morphology.

New AIEgens with delayed fluorescence for fluorescence imaging and fluorescence lifetime imaging of living cells

A series of luminogens with both aggregation-induced emission and delayed fluorescence features are synthesized and characterized. Biocompatible fluorescent nanoparticles are fabricated by encapsulating them within a bovine serum albumin matrix, and perform well in fluorescence imaging and fluorescence lifetime imaging of living cells.

Polyyne bridged AIE luminogens with red emission: design, synthesis, properties and applications

Construction of a donor-acceptor (D-A) structure and extension of π-conjugation are the commonly used strategies to shift the emission of luminophores to the red region. However, molecules with high conjugation and a strong D-A effect tend to show weak emission due to the severe π-π interactions and twisted intramolecular charge transfer (TICT) effects. The turn-on characteristic of AIE luminogens (AIEgens) will also be lost due to the conjugation-enhanced emission in the solution state. Herein, a polyyne-bridged AIE luminogen (2TPE-4E) with long wavelength absorption and red emission has been afforded. Despite its large π-conjugation, 2TPE-4E suffers from no emission quenching resulted from strong π-π interactions and twisted intramolecular charge transfer effects. The strong red emission and the high photostability of 2TPE-4E inspired us to use it for targeted-imaging of cancer cells and monitoring the receptor mediated endocytosis process.

Near-infrared emissive lanthanide hybridized carbon quantum dots for bioimaging applications

Lanthanide hybridized carbon quantum dots (Ln-CQDs) were synthesized by a facile one-pot hydrothermal method using citric acid as a carbon precursor and Yb3+ or Nd3+ as a doping ion. The morphology and chemical structures of Ln-CQDs were investigated by TEM, XRD, XPS, and FTIR spectroscopy. The obtained Ln-CQDs are spherical and well dispersed in water, and their aqueous solutions emit strong blue emission under UV excitation. The Ln-CQDs exhibit excitation-dependent PL behavior with the emission maximum ranging from 443 to 552 nm under 300-520 nm excitation. Moreover, the carbon quantum dots can not only act as visible imaging agents, but also as antennae for photoluminescence (PL) of lanthanide ions. Hence, CQDs hybridized with Yb3+ or Nd3+ ions exhibit the characteristic emission in the near-infrared region with the emission maximum centered at about 998 and 1068 nm, respectively. The MTT assay against HeLa cells verified the low cytotoxicity of Ln-CQDs. They have been used as excellent optical probes for multicolor cell-imaging, demonstrating their great potential for both visible/NIR bioimaging and biomedical applications in vivo.

NORAD Expression Is Associated with Adverse Prognosis in Esophageal Squamous Cell Carcinoma

Background: NORAD (non-coding RNA-activated by DNA damage) is a conserved, abundant, and broadly expressed long non-coding RNA, which functions to preserve genome stability. However, its prognostic significance in esophageal squamous cell carcinoma (ESCC) remains unclear. Material and Methods: The expression of NORAD was detected by quantitative real-time polymerase chain reaction in pairs of tumorous and adjacent normal tissues derived from 106 ESCC patients. We analyzed the potential relationship between NORAD expression levels in tumor tissues and clinicopathological features of ESCC patients and clinical outcome. Results: The relative expression levels of NORAD were significantly upregulated in tumor tissues (p < 0.001) compared to adjacent normal tissues. In addition, high expression of NORAD was correlated with larger tumor size (p = 0.021) and T stage (p = 0.045). Kaplan-Meier analysis indicated that patients with high NORAD expression had poor overall and disease-free survival (p < 0.001). Moreover, multivariate analysis showed that increased expression of NORAD was an independent predictor of overall survival (p = 0.001). Conclusion: Our data indicate that increased NORAD expression might serve as a novel molecular predictor of poor prognosis in ESCC patients and maybe a potential target for diagnosis and gene therapy.

Facile synthesis of N-rich carbon quantum dots from porphyrins as efficient probes for bioimaging and biosensing in living cells

N-rich metal-free and metal-doped carbon quantum dots (CQDs) have been prepared through one-step hydrothermal method using tetraphenylporphyrin or its transition metal (Pd or Pt) complex as precursor. The structures and morphology of the as-prepared nanoparticles were analyzed by X-ray diffraction, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared spectra. Three kinds of nanocomposites show similar structures except for the presence of metal ions in Pd-CQDs and Pt-CQDs indicated by X-ray photoelectron spectroscopy. All of them display bright blue emission upon exposure to ultraviolet irradiation. The CQDs exhibit typical excitation-dependent emission behavior, with the emission quantum yield of 10.1%, 17.8%, and 15.2% for CQDs, Pd-CQDs, and Pt-CQDs, respectively. Moreover, the CQDs, Pd-CQDs, and Pt-CQDs could serve as fluorescent probes for the specific and sensitive detection of Fe3+ ions in aqueous solution. The low cytotoxicity of CQDs is demonstrated by MTT assay against HeLa cells. Therefore, the CQDs can be used as efficient probes for cellular multicolor imaging and fluorescence sensors for the detection of Fe3+ ions due to their low toxicity, excellent biocompatibility, and low detection limits. This work provides a new route to synthesize highly luminescent N-rich metal-free or metal-doped CQDs for multifunctional applications.

Dynamics of random laser and coherent backscattering of light from ZnO amplifying random medium

We investigated the dynamics of coherent backscattering cone and random laser in a disordered gain medium of ZnO powder. Theoretical fit to the coherent backscattering cone yields a transport mean free path l approximately equal to the probe wavelength λ, indicating that the scattering process is in the strong scattering regime. Supernarrow emissions from the laser are accompanied by enhancement and sharpening of the coherent backscattering cone. This enhanced and sharpened backscattering cone returns to a normal profile within 10–20ps, indicating an ultrafast gain lifetime in the medium, which is in good agreement with the time-resolved measurement of the random laser emissions.

Fluorogenic Ag+–Tetrazolate Aggregation Enables Efficient Fluorescent Biological Silver Staining

Abstract Silver staining, which exploits the special bioaffinity and the chromogenic reduction of silver ions, is an indispensable visualization method in biology. It is a most popular method for in‐gel protein detection. However, it is limited by run‐to‐run variability, background staining, inability for protein quantification, and limited compatibility with mass spectroscopic (MS) analysis; limitations that are largely attributed to the tricky chromogenic visualization. Herein, we reported a novel water‐soluble fluorogenic Ag+ probe, the sensing mechanism of which is based on an aggregation‐induced emission (AIE) process driven by tetrazolate‐Ag+ interactions. The fluorogenic sensing can substitute the chromogenic reaction, leading to a new fluorescence silver staining method. This new staining method offers sensitive detection of total proteins in polyacrylamide gels with a broad linear dynamic range and robust operations that rival the silver nitrate stain and the best fluorescent stains.

Aptamer-Decorated Self-Assembled Aggregation-Induced Emission Organic Dots for Cancer Cell Targeting and Imaging

A facile and simple one-step method was developed to fabricate aptamer-decorated self-assembled organic dots with aggregation-induced emission (AIE) characteristics. With integration of the advantages of AIE aggregates with strong emission and the cell-targeting capability of aptamers, the as-prepared Apt-AIE organic nanodots can specifically target to cancer cells with good biocompatibility, high image constrast, and photostability. On the basis of this universal method, a variety of versatile organic fluorescent nanoprobes with high brightness, specific recognition, and clinical-transitional potential could be facilely constructed for biological sensing and imaging applications.