酶直接电化学与第三代生物传感器

本文详细地评述并展望了酶直接电化学与第三代生物传感器这个领域已取得的成果，主要内容涉及生物电催化的三个发展阶段，实现酶与电极之间的直接电子转移方法和相应机理、以及第三代酶传感器的研制。     

Synthesis and chiroptical properties of optically active polymer liquid crystals containing azobenzene chromophores

A series of optically active methacrylic homopolymers, poly[(4‐{4′‐[(S)‐2‐methyl‐1‐butyloxycarbonyl]phenylazo}phenoxyl)x‐methylene methacrylate] (x = 0, 2, 6, or 11), were synthesized. The structures of the polymers were characterized by IR, ¹H NMR, UV, differential scanning calorimetry, and gel permeation chromatography. The chiroptical properties of the polymers in films were investigated with circular dichroism (CD) measurements. The CD and UV spectra of the films suggested that CD absorptions occurred in the films of the polymers with long spacers (x = 6 or 11) but not in the films of the polymers with short spacers (x = 0 or 2). After irradiation with linearly polarized light at 442 nm, the CD values were amplified in all the polymeric films. The amplificatory values of the CD bands in the absorption region (260–360 nm) of azobenzene chromophores suggested that the spacer length had an effect on both the transfer of chirality and photoinduced chirality in the polymeric films. The largest level of photoinduced chirality was induced in the polymer containing six methylene units. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3210–3219, 2006     

Electrochemical behavior of thiamine on a self-assembled gold electrode and its square-wave voltammetric determination in pharmaceutical preparations.

The electrochemical behavior of thiamine on a self-assembled electrode of L-cysteine (Cys/SAM/Au) has been investigated and Cys/SAM/Au can be used to detect thiamine using square-wave voltammetry (SWV). At pH 11.40 Britton-Robinson buffer, thiamine exhibits a well-defined anodic peak on Cys/SAM/Au. Under the optimized conditions, the anodic peak current of SWV was linear with the content of thiamine in the range of 1.1 x 10(-8) - 2.2 x 10(-6) mol/L; the detection limit was 5.5 x 10(-9) mol/L. The method was successfully applied to the determination of thiamine in pharmaceutical preparations.     

Combinatorial method for the study of new co-fluorescence enhancement system

The new co-fluorescence enhancement system was found in polymer matrix and studied with a combinatorial approach based on Re(DBM)3phen (Re3+: Tb3+, La3+, Gd3+, Y3+; dbm: dibenzoylmethane; phen: phenanthroline) and Sm3+ complex co-doped poly(methyl methacrylate)(PMMA). We have presents a new methodology for the rapid optimization of the luminescence conditions of thin-film sample in arrays of microwells. Two libraries were generated in order to study the effect of the species and content of enhancing ions on the luminescence enhancing efficiency, respectively. At the optimal content of 20 wt.% Sm(DBM)3phen, the maximum sensitization efficiency of Tb(DBM)3phen is about nine times. The intramolecular and intermolecular energy transfer processes in rare-earth complex-doped PMMA are discussed. The energy transfer processes make the co-fluorescence effect come true. Although, the methodology described here was implemented for optimization of co-fluorescence conditions, it is can be further implemented for a variety of applications in which optimization of parameters can be studied in situ using spectroscopic tool.     

Sm(DBM)3Phen-doped poly(methyl methacrylate) for three-dimensional multilayered optical memory

We report on the formation of submicrometer voids within Sm(DBM)3Phen-doped poly(methyl methacrylate) (PMMA) under multiphoton absorption excited by an infrared laser beam. An ultrashort-pulsed laser beam with a pulse width of 200 fs at a wavelength of 800 nm is focused into doped PMMA. The large changes in refractive index and the fluorescence associated with a void allow conventional optical microscopy and reflection-type confocal microscopy to be used as detection methods. Voids can be arranged in a three-dimensional multilayered structure for high-density optical data storage.     

梯度折射率聚合物细棒的制备和数学模拟

在聚甲基丙烯酸甲酯 (Poly(methylmethacrylate) ,PMMA)管中 ,加入单体甲基丙烯酸甲酯 (Methylmethacrylate ,MMA)和另一种高折射率的掺杂剂溴苯 (Bromobenzene ,BB) ,用界面凝胶均聚合方法制备了梯度折射率聚合物光纤预制棒 .这种光纤预制棒的梯度折射率是通过具有不同折射率的分子扩散而形成的 .通过对界面凝胶聚合过程的描述 ,该工作讨论了预制棒中聚合物的浓度分布及边界条件的假设 .并根据自由体积理论对其折射率分布进行理论模拟 .将得到的折射率抛物线分布与实验结果进行对比 ,结果表明聚合浓度的分布为ω =a(r/R) 2 +b时 ,理论预计的光纤预制棒的折射率分布与实验结果有着较好的符合 .同时 ,对聚合体系中BB对聚合物浓度分布的影响进行了讨论     

Nonlinear optical switching of PDA/Ag hybrid materials based on temperature- and pH-responsive threading and dethreading of cyclodextrin polypseudorotaxane

We developed a novel temperature and pH dual-responsive supramolecular system in which the aggregation and disaggregation of polydiacetylene/silver (PDA/Ag) hybrid nanocrystals can be mediated by environmentally responsive threading and dethreading processes of polypseudorotaxane. The PDA/Ag hybrid nanocrystals provide a nonlinear optical (NLO) property. The host?Cguest interaction between poly(ethylene glycol) (PEG) and cyclodextrin (CD) cavities on the surface of the hybrid nanocrystals causes the PDA/Ag hybrid nanocrystals to be sufficiently close to each other for providing an enhanced surface plasmon resonance and a corresponding NLO effect. NLO switching of the colloidal materials can be easily realized by varying temperature and pH. The facile preparation procedures and their response to the surrounding media render these novel hybrid colloidal materials potential candidates for applications in sensors, catalysis and optical/electronic devices.     

Dynamic orientation of azopyridine units within the shell of vesicles PNIPAM‐b‐PAzPyn copolymers

Vesicles with hydrophobic shells have been self‐assembled through three kinds of amphiphilic block copolymers containing pendent azopyridine groups with different spacers, namely PNIPAM‐b‐PAzPyn (n = 0, 2, 6), respectively. By polarization laser‐trapping Raman spectroscopy, the photoinduced orientation behaviors of azopyridine groups within the vesicle shells have been investigated and it is found that spacer lengths affect the orientation of the azopyridine groups and the morphologic structure of the vesicle shells. The exact experimental results show that the orientation is dynamic for the pendent azopyridine groups with connecting spacers of 2 or 6 methylene units rather than those without spacers, so the vesicles of PNIPAM‐b‐PAzPy6 can be changed to show a typical “soft” character compared with its solid films when irradiated with a relatively weak polarized UV light of 190 µW/cm². However, the vesicles of PNIPAM‐b‐PAzPy0 without spacers do not change even though the azopyridine units can be oriented. By quantitative Raman spectral analysis, it is found that the isomerization degree of azopyridine units is 70% for PNIPAM‐b‐PAzPy6 yet it is 10% for PNIPAM‐b‐PAzPy0, which shows a close relationship between aggregation and isomerization of azopyridine units under a weak UV light. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 415–421     

Investigation into the crystal structure of bis(pyridine)-bis(trichloroacetato) copper(II) and its electrophotochemical properties

A novel chained Cu(II) complex was synthesized from trichloroacetato copper(II) and pyridine in ethanol solvent, and characterized by elemental analysis and infrared (IR) spectroscopy. The special crystal structure of the Cu(II) complex was determined by X-ray single-crystal diffraction. The results indicate that a chained structure of the Cu(II) complex formed through intermolecular hydrogen bonds. Cu(CCl₃COO)₂(C₅H₅N)₂(H₂O) was monoclinic, with unit cell P21/c and cell parameters as follows: a = 14.389(3) Å, b = 7.1911(14) Å, c = 23.107(8) Å, V = 2,257.5(10) Å³, Z = 4, M _r = 564.51, D _c = 1.661 mg/m³, T = 293(2) K, F(000) = 1,124, μ(Mo K_α) = 1.704 mm^?1, R = 0.0984, and ωR = 0.2791. The electrochemical behavior of the Cu(II) complex on a glassy carbon working electrode determined by cyclic voltammetry showed the electrochemical activity of the title compound at 0.2 to ?0.3 V (versus SCE) in NH₃–NH₄Cl buffer solution (pH 9.2), and the redox peak current of the complex had a good linear relationship with the square root of the scan rate in the range 0.02–0.2 V/s.     

Multifunctional Uniform Core–Shell Fe3O4@mSiO2 Mesoporous Nanoparticles for Bimodal Imaging and Photothermal Therapy

Multimodal imaging and simultaneous therapy is highly desirable because it can provide complementary information from each imaging modality for accurate diagnosis and, at the same time, afford an imaging‐guided focused tumor therapy. In this study, indocyanine green (ICG), a near‐infrared (NIR) imaging agent and perfect NIR light absorber for laser‐mediated photothermal therapy, was successfully incorporated into superparamagnetic Fe₃O₄@mSiO₂ core–shell nanoparticles to combine the merit of NIR/magnetic resonance (MR) bimodal imaging properties with NIR photothermal therapy. The resultant nanoparticles were homogenously coated with poly(allylamine hydrochloride) (PAH) to make the surface of the composite nanoparticles positively charged, which would enhance cellular uptake driven by electrostatic interactions between the positive surface of the nanoparticles and the negative surface of the cancer cell. A high biocompatibility of the achieved nanoparticles was demonstrated by using a cell cytotoxicity assay. Moreover, confocal laser scanning microscopy (CLSM) observations indicated excellent NIR fluorescent imaging properties of the ICG‐loaded nanoparticles. The relatively high r₂ value (171.6 mM ^?1 s^?1) of the nanoparticles implies its excellent capability as a contrast agent for MRI. More importantly, the ICG‐loaded nanoparticles showed perfect NIR photothermal therapy properties, thus indicating their potential for simultaneous cancer diagnosis as highly effective NIR/MR bimodal imaging probes and for NIR photothermal therapy of cancerous cells.