Yuezhi Cui

A highly selective and sensitive fluorescent sensor for the rapid detection of Hg2 + based on phenylamine-oligothiophene derivative

A fast-responsive fluorescent phenylamine-oligothiophene sensor 3TDDA was reported. This sensor exhibited highly selective and sensitive detection of Hg(2+) ion in aqueous solution (THF/CH3CN/H2O, 45/50/5, v/v) through fluorescence quenching. The detection was not affected by the coexistence of other competitive metal ions such as Na(+), K(+), Ag(+), Ca(2+), Fe(3+), Al(3+), Co(2+), Ni(2+), Zn(2+), Pb(2+), Cd(2+), Fe(2+) and Cr(3+). A stoichiometric ratio (1:1) of the sensor and Hg(2+) was determined by a Jobs plot and mole-ratio curves. The binding of sensor 3TDDA and Hg(2+) was also chemically reversible with EDTA. The detection limit was calculated as low as 4.392×10(-7) M.

Anti-degradation gelatin films crosslinked by active ester based on cellulose

Functionalization of microcrystalline cellulose (MCC) with EDTA dianhydride (EDTAD) was first achieved using an esterification reaction. N-Hydroxysuccinimide-activated MCC-EDTAD ester (MEN), a novel macromolecule crosslinker based on MCC, was synthesized for the modification of gelatin films. The reaction between gelatin and MEN was verified by the residual free amino test, FTIR and XRD spectra. The introduction of MEN into gelatin decreased the film degradation ratio and increased its thermal stability, flexibility, hydrophobicity, light barrier performance and water uptake ability. Additionally, SEM images proved the successful surface grafting reaction and degradation phenomenon. This unique gelatin film material with advanced properties broke the limitation of the blending method for modification of gelatin with macromolecules and broadened its application as a novel sustained-release material.

Highly selective, sensitive and fast-responsive fluorescent sensor for Hg2 +

A phenylamine-oligothiophene-based fluorescent sensor 2TBEA was reported. This sensor exhibited highly selective, sensitive and rapid detection of Hg(2+) ion in THF/H2O (7/3, v/v) solution through fluorescence quenching. The detection was unaffected by the coexistence of other competitive metal cations including Na(+), K(+), Ag(+), Ca(2+), Fe(3+), Al(3+), Co(2+), Cu(2+), Ni(2+), Zn(2+), Pb(2+), Cd(2+), Fe(2+) and Cr(3+). A1:1 binding ratio for 2TBEA - Hg(2+) was demonstrated by Jobs plot and mole-ratio curves. The coordination process was chemically reversible with EDTA. The detection limit was evaluated to be as low as 6.164×10(-8)M.

New views on the reaction of primary amine and aldehyde from DFT study.

A general theoretical investigation on the reaction of primary amine with aldehyde was carried out by density functional theory. The calculation systems involve three kinds of primary amines (methylamine, vinylamine, and phenylamine) and three kinds of aldehydes (formaldehyde, acetaldehyde, and acrylaldehyde). The steric and electronic inductive effects on the reaction mechanism were studied. Results reveal that the nucleophilic attack of primary amine on aldehyde under neutral conditions leads to carbinolamines, rather than Schiff bases. The nucleophilic attack on the protonated aldehyde produces the protonated Schiff base. The steric hindrance of the aldehyde slows down the nucleophilic attack but allows enough time to abstract a H; consequently, the formation of the protonated Schiff base is preferred. During the carbinolamine protonation, the H(+) preferably locates on the amine nitrogen and then is abstracted by the hydroxyl oxygen over an energy barrier, leaving protonated Schiff base after timely water liberation. The formation of a prereaction potential energy well obviously softens the steric and electronic inductive effects on the active barrier for different reactants.

Facile fabrication of AIE/AIEE-active fluorescent nanoparticles based on barbituric for cell imaging applications

Four barbituric derivatives (1–4), were synthesized with obvious aggregation induced emission (AIE) or aggregation induced emission enhancement (AIEE) behaviors. The optical properties in different states and the mechanisms of the enhanced emission of 1–4 were investigated. We found that there were a large number of globular or blocky nanoparticles with average diameters from 229 to 394 nm in tetrahydrofuran (THF)/water solutions when the water fraction (fw) was 90%. The single crystal data of 2 and 4 reveal that multiple intermolecular interactions restrict the intramolecular motions, and promote the formation of a herringbone arrangement (4), thus permitting intense emission in the aggregate state. In addition, the frontier molecular orbital energy and band gap calculated by density functional theory (DFT) are consistent with the experimental results. Compound 4 is cell-permeable: upon entering the live cells, the dye molecules can accumulate in the lysosomes and turn on the fluorescence.

Preparation and characterization of gelatin film modified by cellulose active ester

Functionalization of microcrystalline cellulose (MCC) with 1,2,3,4-butanetetracarboxylic acid dianhydride (BTCAD) was obtained by esterification reaction. A novel macromolecule cross-linker, MCC-BTCAD-NHS (MBN), was successful prepared through amidation between N-hydroxysuccinimide (NHS) and MCC-BTCAD to modify gelatin films. The reaction between gelatin and MBN was confirmed by the residual free amino test, FTIR, elemental analysis, and XRD spectra. The results indicated that the addition of MBN into gelatin decreased the film degradation ratio and increased its thermal stability, flexibility, hydrophobicity, light barrier performance, and water adsorption ability. In addition, SEM images further proved the successful cross-linking reaction. The particular gelatin film material with excellent performance ended up the limitation of blending modification method for gelatin with natural macromolecule and extended its application in many fields.

Detection of nitroaromatic explosives by a 3D hyperbranched σ–π conjugated polymer based on a POSS scaffold

A three-dimensional hyperbranched polymer (3D-HP) with σ–π conjugated PDMPS (poly(dichloromethylphenylsilane)s) units covalently bonded to a polyhedral oligosilsesquioxane (POSS) scaffold was prepared by a one-step “thiol–ene click chemistry” reaction. Compared with POSS-based organic polymers, the 3D-HP with a flexible Si–Si chain showed enhanced solubility. This 3D hyperbranched polymer exhibited outstanding thermal stability and optimal photophysical properties. For probing nitroaromatics (NACs), the 3D-HP showed excellent sensitivity (Ksv = 2.83 × 104 M−1) against the presence of a tetrahydrofuran (THF) solution of 2,4,6-trinitrotoluene (TNT). In addition, the 3D-HP coated on glass films exposed to saturated DNT vapor exhibited a high quenching efficiency (ηEP) of the fluorescence of 3D-HP film, which was drastically suppressed (82%) for 300 s. The excellent fluorescent quenching performance of the 3D-HP can be attributed to the following points: (i) hyperbranched conjugated polymers afford multi-dimensional transport pathways for excitons migration; (ii) there exists in the polymer high electron affinity and rapid electron delocalization of σ–π conjugated polysilanes; (iii) noncovalent interactions between the electropositive δ+ Si atoms of σ–π conjugated polysilanes and N and/or O atoms of electron-deficient nitroaromatics (NACs) facilitate the adsorption of NACs. Furthermore, the bulky octathiol-POSS units in the 3D-HP can improve the permeability of the film sensor. This 3D hyperbranched σ–π conjugated polymer 3D-HP has the potential to be used to prepare sensitive, selective, and stable sensors for the detection of NACs explosives.

Carbazole-grafted silicone hydrogel with a high refractive index for intraocular lens

The refractive index (RI) is an important parameter for intraocular lens biomaterials. In this paper, a novel carbazole-grafted methacrylic polysiloxane macromonomer (MA-CZ-PDMS) with a high RI value was synthesized and its structure was confirmed by proton nuclear magnetic resonance (1H NMR). The polysiloxane macromonomer can copolymerize with monomers of 3-methacryloxypropyl tris(trimethylsiloxy) silane (TRIS) and N,N-dimethylacrylamide (DMA) to prepare transparent high RI silicone hydrogel. Increasing MA-CZ-PDMS macromonomer content in the silicone hydrogels improved its water content, RI value, and mechanical properties, however decreased slightly glass transition temperature (Tg) and transmittance of blue light. The carbazole-grafted silicone hydrogel possessed good cytocompatibility and in vivo biocompatibility in rabbit eyes. The results demonstrate that the carbazole-grafted silicone hydrogel has a potential application as high RI ocular refractive correction biomaterial.

Structure evolution of gelatin particles induced by pH and ionic strength.

Microstructure of gelatin particles played a key role in determining the physicochemical properties of gelatin. Ionic strength and pH as systematic manners were considered to affect gelatin particles structure on the micrometer scale. Scanning electron microscopy was used for depicting the morphologies of gelatin particles. Increasing pH to 10.0 or decreasing pH to 4.0, spherical, spindle, and irregular aggregates of gelatin particles at 2, 6, 10, and 14% solution (w/w) were all transformed to spindle aggregates. When NaCl was added to the system, the molecular chains of gelatin possibly rearranged themselves in a stretched state, and the ribbon aggregates was observed. The structural transitions of gelatin aggregates were strongly depended on the electrostatic repulsion. In the gelatin–sodium dodecyl sulfate (SDS) case, the micrometer scale of aggregates was larger and the different degrees of cross‐links were induced through hydrophobic interaction and electrostatic repulsion. Microsc. Res. Tech. 76:272–281, 2013.

Evaluation of nitriloacetic acid modified cellulose film on adsorption of methylene blue

A novel composite film (MCαN) based on microcrystalline cellulose (MCC) and nitrilotriacetic acid anhydride (NTAA) was prepared via casting method for the adsorption of methylene blue (MB) from aqueous solution. FT-IR, XRD, elemental analysis and TGA analysis demonstrated the success of modification. The swelling behavior, mechanical properties and MB adsorption performance of the modified MCαN films were improved obviously. The recycling study illustrated that MC2N film could be recycled and exhibited constant adsorption performance for five successful runs. In addition, mechanism study found that adsorption behavior of the composite films was better consistent with the pseudo-second order kinetic model and the Langmuir model. All the results suggested that the MCαN films could be considered as a promising candidate for dye wastewater treatment.