Dong-En Wang

Simple preparation of aminothiourea-modified chitosan as corrosion inhibitor and heavy metal ion adsorbent

By a simple and convenient method of using formaldehyde as linkages, two new chitosan (CS) derivatives modified respectively with thiosemicarbazide (TSFCS) and thiocarbohydrazide (TCFCS) were synthesized. The new compounds were characterized and studied by Fourier transform infrared spectroscopy, elemental analysis, thermal gravity analysis and differential scanning calorimetry, and their surface morphologies were determined via scanning electron microscopy. These CS derivatives could form pH dependent gels. The behavior of 304 steel in 2% acetic acid containing different inhibitors or different concentrations of inhibitor had been studied by potentiodynamic polarization test. The preliminary results show that the new compound TCFCS can act as a mixed-type metal anticorrosion inhibitor in some extent; its inhibition efficiency is 92% when the concentration was 60 mg/L. The adsorption studies on a metal ion mixture aqueous solution show that two samples TSFCS and TCFCS can absorb As (V), Ni (II), Cu (II), Cd (II) and Pb (II) efficiently at pH 9 and 4.

Polydiacetylene liposome-encapsulated alginate hydrogel beads for Pb2+ detection with enhanced sensitivity

The development of a novel and simple method to trace lead ions (Pb2+) has received great attention due to its high toxicity to human health and the environment. In this paper, we describe a new polydiacetylene (PDA)-based liposome sensor for the colorimetric and fluorometric detection of Pb2+ in aqueous solution and in alginate hydrogel microbeads. In the sensor system, a dopamine group was rationally introduced into a diacetylene monomer to work as a strong binding site for Pb2+. The dopamine-functionalized monomer and 10,12-pentacosadiynoic acid (PCDA) were then incorporated into PDA liposomes in aqueous solution. After UV light-induced polymerization, deep blue colored liposome solutions were obtained. Upon the addition of various metal ions into the liposome solution, only Pb2+ could cause a distinct color change from blue to red and a dramatic fluorescence enhancement. To further improve its sensitivity and address its intrinsic aggregation, we then developed a liposome-immobilized detection system by encapsulating PDA–DA liposomes into alginate hydrogel beads through a microfluidic droplet-based method. The results showed that the PDA–DA liposome-containing hybrid hydrogel beads possessed excellent stability and high sensitivity. These interesting findings demonstrated that the PDA liposome system developed in the current study may offer a new method for Pb2+ recognition in a more efficient manner.

Reversible luminescence color switching in the crystal polymorphs of 2,7-bis(2′-methyl-[1,1′-biphenyl]-4-yl)-fluorenone by thermal and mechanical stimuli

Smart organic luminescence materials that exhibit a reversible stimuli-responsive change of luminescence color in the solid state without changing the chemical structure of their component molecules have attracted increasing interest. We employed the design strategy of introducing different weak interactions into the same molecular system to synthesize 2,7-bis(2′-methyl-[1,1′-biphenyl]-4-yl)-fluorenone (MPF). Two crystal polymorphs of MPF, green-yellow crystal G-MPF and orange crystal O-MPF, were obtained through culturing the single crystal under the different crystallization conditions of diffusing diethyl ether into its respective tetrahydrofuran or CH2Cl2 solution. Both of the two crystal polymorphs exhibit high luminous efficiency and reversible stimuli-responsive solid-state luminescence color switching. Upon heating the green crystal G-MPF or grinding the orange crystal O-MPF, their emission reversibly changes between green at 530 nm and orange at 570 nm. The X-ray single-crystal structures, characterization of the photophysical properties, powder X-ray diffraction and differential scanning calorimetry provide insight into the phase transformation and the luminescence behavior. The results indicate that the green emission of G-MPF originates from molecular J-aggregation and the orange emission of O-MPF originates from static excimers. This work discusses the relationship between the molecular stacking mode and the photophysical properties, and demonstrates a molecular design strategy to obtain stimuli-responsive organic solid-state luminescence switching materials.

A new rhodamine-based chemosensor for turn-on fluorescent detection of Fe3+

A new fluorescent probe RH-Fe based on rhodamine B lactam was developed as a colorimetric and fluorescent chemosensor for Fe3+. The optical feature of RH-Fe for Fe3+ was investigated using UV-vis absorption and fluorescence emission spectroscopy. Upon the addition of Fe3+, the RH-Fe displayed a distinct color change from colorless to pink and a significant fluorescence enhancement, which can be directly detected by the naked eye. The stoichiometry of RH-Fe to Fe3+ complex was found to be 1 : 1 and the detection limit was determined to be as low as 0.27 μM. The results suggest that the RH-Fe probe may provide a convenient method for the visual detection of Fe3+ with high sensitivity.

Self-immolative trigger-initiated polydiacetylene probe for β-glucuronidase activity

We report a novel probe for β-glucuronidase activity based on the colorimetric and fluorescent responses of polydiacetylene liposomes.

Click synthesis of neutral, cationic, and zwitterionic poly(propargyl glycolide)-co-poly(ɛ-caprolactone)-based aliphatic polyesters as antifouling biomaterials.

With the development of polymer-based biomaterials, aliphatic polyesters have attracted considerable interest because of their non-toxicity, non-allergenic property, and good biocompatibility. However, the hydrophobic nature and the lack of side chain functionalities of aliphatic polyesters limit their biomedical applications. In this study, we prepared four new polyesters: poly(sulfobetaine methacrylate)-, poly(2-methacryloyloxyethyl phosphotidylcholine)-, poly(ethylene glycol)-, and quaternized poly[(2-dimethylamino)ethyl methacrylate]-grafted poly(propargyl glycolide)-co-poly(ɛ-caprolactone). Their synthesis was conducted through ring-opening polymerization of acetylene-functionalized lactones and subsequent graft of bioactive units using click chemistry. The chemical structures of the polyesters were characterized through nuclear magnetic resonance and Fourier-transform infrared spectroscopy, and their physical properties (including molecular weight, glass transition temperature, and melting point) were determined using gel permeation chromatography and differential scanning calorimetry. For studies on their hydrophilicity, stability, and anti-bioadhesive property, a series of polymeric surfaces of these polyesters was prepared by coating them onto glass substrates. The hydrophilicity and stability of these polyester surfaces were examined by contact angle measurements and attenuated total reflection Fourier-transform infrared spectroscopy. Their anti-bioadhesive property was investigated through protein adsorption, as well as cellular and bacterial adhesion assays. The prepared polyesters showed good hydrophilicity and long-lasting stability, as well as significant anti-fouling property. The newly prepared polyesters could be developed as promising anti-fouling materials with extensive biomedical applications.

A dual functional probe: sensitive fluorescence response to H2S and colorimetric detection for SO32−

Hydrogen sulfide (H2S) and sulfite (SO32−) are two important sulfur-containing species that play different and important roles in industrial and biological processes. Accordingly, the development of efficient methods for simple, rapid, sensitive and selective monitoring of H2S and SO32− is of the utmost importance in both environmental and biological sciences. In this study, we developed a new dual functional probe NIR-DNP for discriminative detection of H2S and SO32−. This probe can sense H2S and SO32− via two different approaches, a significant near-infrared fluorescence enhancement and color change from purple to cyan induced by H2S as well as a visible color change from purple to colorless caused by SO32−. The detection limits of the probe NIR-DNP for H2S and SO32− in aqueous solutions were 36.53 nM and 33.33 nM, respectively. Competitive experiments demonstrated that the probe NIR-DNP had a high fluorescence selectivity for H2S and excellent colorimetric selectivity for SO32− over other analytes. The sensing mechanism of the probe toward H2S and SO32− was based on the H2S-induced thiolysis of dinitrophenyl ether and SO32−-induced nucleophilic addition, respectively. Further investigation showed that the probe NIR-DNP could be used to develop an easy-to-prepare and easy-to-detect paper-based test strip for cheap and effective detection of SO32−. Also, the probe NIR-DNP has the potential to image exogenous and endogenous H2S in living cells.

Fabrication of Polydiacetylene Liposome Chemosensor with Enhanced Fluorescent Self-Amplification and Its Application for Selective Detection of Cationic Surfactants

Polydiacetylene (PDA) materials have been adopted as one of the powerful conjugated polymers for sensing applications due to their unique optical properties. In this paper, we present a new PDA liposome-based sensor system with enhanced fluorescent self-amplification by tuning a fluorophore fluorescence emission. In this system, a 1,8-naphthalimide derivative employed as a highly fluorescent fluorophore was incorporated into a PDA supermolecule. During the formation of blue PDA liposomes, the fluorescence emission of the fluorophore can be directly quenched, while thermal-induced phase transition of PDA liposomes from blue to red can readily restore this fluorescence emission. These phenomena could be ascribed to the tunable Förster energy transfer between the excited fluorophore and PDA conjugated framework. To demonstrate the sensing performance of this newly prepared PDA liposome-based sensor, the sensor with fluorescent self-amplification was successfully applied for the detection of cationic surfactants (CS). The results show that the PDA liposomes displayed a distinct color change and fluorescence restoration in the presence of cationic surfactant species, and allowed detection of cationic surfactants with high sensitivity and selectivity. The limit of detection for target CS, such as cetyltrimethylammonium bromide (CTAB), can reach as low as 184 nM. Compared to the traditional methods based on colorimetric PDA liposomes, this newly fabricated PDA sensor system was superior for sensitivity. Thus, our findings offer an avenue for the design and development of new types of PDA sensors with enhanced sensitivity.

Synthesis, Characterization and Activity Evaluation of Matrinic Acid Derivatives as Potential Antiproliferative Agents

A series of new matrinic acid derivatives 5a–e was synthesized. The chemical structures of the synthesized compounds were confirmed by 1H-NMR, 13C-NMR, and electrospray ionization mass spectroscopy. The anti-tumor activities were also investigated in vitro by evaluating the effect of synthesized compounds on the proliferation of A375, A549, HeLa, and HepG2 cells. Compound 5e was found to be the most potent against A375 and HeLa cells, with IC50 values of 37 and 75.5 μg/mL, respectively. Compounds 5b, 5c, 5g, and 5h also exhibited antiproliferative activities against A549 cells, with IC50 values within the 36.2–47 μg/mL range. For HepG2 cells, 5e and 5i, with IC50 values of 78.9 and 61 μg/mL, respectively, showed higher antiproliferative activity than taxol.

Highly sensitive and selective coumarin probe for hydrogen sulfide imaging in living cells

Hydrogen sulfide (H2S) is the third endogenous gasotransmitter, following nitric oxide (NO) and carbon monoxide (CO). Efficient methods for selective monitoring H2S in biological systems are significant. In this study, we designed and synthesized a new coumarin-based probe DNPOCA for H2S with colorimetric and fluorescent dual signaling. In this probe, 7-hydroxycoumarin-4-acetic acid methyl ester was employed as a fluorophore and a dinitrophenyl (DNP) ether moiety was used as the recognition unit. The H2S probe exhibited excellent selectivity and high sensitivity with a detection limit as low as 49.7 nM. The cytotoxicity assay showed that DNPOCA possessed a low effect on cell viability. Furthermore, DNPOCA could be successfully applied for H2S imaging in living cells.