基于聚丙烯酰胺的凝胶光子晶体膜制备及其响应性研究

由单分散聚苯乙烯乳液制备了聚苯乙烯胶体晶体阵列,并采用光引发聚合法用聚丙烯酰胺凝胶成功固定了胶体晶体阵列,制备了在可见光下显示明亮Bragg衍射光的凝胶光子晶体膜(PCCA).该PCCA膜具有优异复水性能和循环使用性能.在浓度5%~30%范围内,乙醇浓度每改变5%,其Bragg衍射峰平均移动超过20 nm;水解后PCCA膜具有良好的p H响应性.随p H值增加,当p H值的范围为2.36~8.15时,其Bragg衍射峰红移;当p H值大于9.6时,其Bragg衍射峰蓝移.而且凝胶光子晶体膜Bragg衍射峰移动对应的颜色变化很容易实现裸眼识别.     

多重网络增强的层状光子晶体水凝胶及应力变色响应

基于PDGI/PAAm (PDGI/SN)层状光子晶体水凝胶,制备了多重网络PDGI/PAAm-PAMPS-PAAm(PDGI/TN)水凝胶,将水凝胶浸入6 : 4(V/V)乙醇水溶液中去溶胀,记为凝胶PDGI/TN-0.6。结果表明,引入多重网络之后,PDGI/TN凝胶的溶胀率从PDGI/SN的850% ± 45%提高到1070% ± 50%,颜色从蓝色(λ_max=450 nm)变为透明,去溶胀后Bragg衍射峰为670 nm,实现凝胶的Bragg衍射峰在450－670 nm间调控。拉伸和压缩实验说明,PDGI/TN-0.6力学性能优异,拉伸强度和压缩强度分别达到0.99和37.0 MPa。同时,PDGI/TN-0.6具有优异应力变色响应性,压缩应变(ε_c)从0增加到0.5,Bragg衍射峰发生蓝移,响应范围覆盖可见光;当撤去应力后,立即恢复初始状态,可重复多次。利用扫描电镜(SEM)进一步研究了层状光子晶体水凝胶层微观结构。     

镉离子响应性凝胶光子晶体传感膜的构建

将光子晶体与响应性水凝胶结合,采用“三明治”填充方法,以聚苯乙烯（PS）胶体晶体为模板,丙烯酰胺和烯丙基硫脲为单体制备得到一种对镉离子具有特异响应性的凝胶光子晶体传感膜,并对其进行了形貌表征和响应性研究。结果表明,该传感膜具有排列整齐的反蛋白石结构,可对不同浓度的Cd²⁺输出不同的光学信号。随着Cd²⁺浓度的增大,传感膜的Bragg衍射峰发生蓝移,并伴随有显著的颜色变化。在最优配比,适宜pH和离子强度条件下,衍射峰的最大位移值可达51.1 nm。在研究过程中发现其他干扰金属离子的存在不会影响传感膜对Cd²⁺的特异性响应,并且表现出了较快的响应速度。在多次循环实验中传感膜由于具备高度交联结构而表现出了良好的机械性和化学稳定性。该传感膜的构建为Cd²⁺的快速高效及裸眼可视检测提供了可能性。     

丙烯酰胺反蛋白石凝胶膜的制备及pH响应性能研究

以聚苯乙烯(PS)胶体晶体为模板,采用"三明治"法得到收缩率较低、表面无覆盖层、三维长程有序的聚丙稀铣胺(PAM)反蛋白石凝胶膜。实验发现,粒径较小的模板有利于得到结构规整的凝胶膜。反蛋白石凝胶膜有明显的pH响应性,随着pH增大,PAM反蛋白石凝胶膜的最大衍射波长红移,且在pH=8.49时,达到最大;pH继续增大时,最大衍射波长表现为蓝移趋势。并且可重复响应而不破坏其结构,表明该凝胶膜具有较大的实用价值。     

壳聚糖-聚丙烯酸复合水凝胶的药物控制释放行为

以壳聚糖(Cs)和丙烯酸(AA)为原料,利用自由基聚合法制备了具有孔洞结构的复合水凝胶Cs-PAA,并研究了AA的量、交联剂的量、聚合温度和AA的中和度对水凝胶溶胀度的影响以及复合水凝胶对烟酸的控制释放。 结果表明,Cs-PAA复合水凝胶具有良好的pH值、离子强度敏感性,且溶胀度最高达1228 g/g,其在pH=686的缓冲溶液中的烟酸累积释放率明显大于其在pH=1.80的缓冲溶液,因此Cs-PAA水凝胶可作为肠口服药物的载体。     

非紧密堆积型光子晶体凝胶的制备及其压敏性质研究

利用简单的离心-重悬浮方法去除二氧化硅胶体溶液中的杂质离子, 通过静电排斥作用自组装形成非紧密堆积型二氧化硅光子晶体; 丙烯酰胺单体原位聚合形成聚丙烯酰胺凝胶锁定二氧化硅光子晶体的有序结构得到非紧密堆积的二氧化硅光子晶体凝胶, 该凝胶的Bragg衍射峰可以覆盖整个可见光区域; 利用聚丙烯酰胺凝胶的环境响应特性, 研究了光子晶体凝胶的压力敏感性质. 实验结果表明: 作用于光子晶体凝胶的压力变化导致其体积发生改变, 直接体现在光子晶体凝胶的Bragg衍射峰位置发生改变. 光子晶体凝胶在可视化检测方面具有潜在的应用价值.     

蔗渣木聚糖磷酸酯-壳聚糖水凝胶的制备及其药物缓释作用

以蔗渣木聚糖磷酸酯和壳聚糖为主要原料,三聚磷酸钠为离子交联剂,制备了蔗渣木聚糖磷酸酯-壳聚糖水凝胶,并用SEM、IR表征了其结构。考察了影响制备及水凝胶粒子应用的因素,探讨了诸因素对水凝胶性能的影响。通过正交试验,分别得出两种方法制备水凝胶的优化条件:在pH=1.7的缓冲溶液中,蔗渣木聚糖磷酸酯浓度为0.10g/mL,壳聚糖浓度为0.04g/mL,三聚磷酸钠的浓度为0.20g/mL,成膜时间120min,用直接造粒法;在pH=6.8的缓冲溶液中,蔗渣木聚糖磷酸酯浓度为0.10g/mL,壳聚糖浓度为0.04g/mL,三聚磷酸钠浓度为0.20g/mL,成膜时间为90min,用间接造粒法。在优化制备条件下,通过模拟十二指肠缓冲溶液,得出在pH 4.8、三聚磷酸钠浓度为0.20mol/L时,水凝胶的载药量和药物释放行为较佳。     

稀土金属离子及pH诱导牛血清白蛋白构象变化的同步荧光光谱研究

用同步荧光法并辅以普通荧光法对不同浓度稀土离子及pH诱导的牛血清白蛋白(BSA)构象变化进行了详细研究, 发现稀土离子使色氨酸(Trp)残基的荧光蓝移, 荧光强度降低; 酪氨酸(Tyr)残基荧光峰位置不变, 稀土离子浓度较低时, 荧光峰强度降低, 而当浓度较高时, Tyr残基荧光峰强度反而增强. 据此推断了稀土离子与BSA结合反应中Trp残基微环境和Tyr残基微环境及构象的变化并与pH引起的变化进行了比较.     

毛细管区带电泳测定芦荟中的有效成分

 建立了毛细管区带电泳测定中药芦荟中的有效成分芦荟甙和芦荟大黄素的分析方法。采用24 mmol/L的磷酸盐(pH 10.85)作为缓冲溶液,在电压为15 kV和检测波长为254 nm的条件下进行分离实验,芦荟提取液中有效成分获得基线分离。定量分析表明,芦荟甙的质量浓度为0.029 g/L～1.00 g/L时,其峰面积与质量浓度呈线性关系(r=0.997);芦荟大黄素的质量浓度为5.4 mg/L～84 mg/L时,其峰面积与质量浓度呈线性关系(r=0.999)。此外,还讨论了缓冲溶液的pH值、有机改性剂对两种有效成分迁移行为的影响。     

苝酰亚胺功能化聚苯乙烯乳胶粒水凝胶膜

将带有硼酸基团的苝酰亚胺荧光分子引入聚苯乙烯共聚乳胶粒表面,再将其嵌入聚丙烯酰胺水凝胶膜内,合成了对葡萄糖敏感的水凝胶膜。通过扫描电子显微镜、激光粒径分析仪对微球的外观形貌、单分散性进行表征,并用原子吸收光谱法间接测定了微球表面苝酰亚胺的含量,研究了苝酰亚胺功能化聚苯乙烯乳胶粒的紫外-可见吸收光谱图及其水凝胶膜的荧光性能。结果表明:苝酰亚胺功能化聚苯乙烯乳胶粒水凝胶膜经浓度逐渐增大的葡萄糖溶液浸泡后,其荧光强度降低,但发射峰位置不变。当葡萄糖浓度达到200 mmol/L时,其荧光淬灭效率为0.34。     

甲基丙烯酸/丙烯酰胺双单体共聚反蛋白石光子晶体的制备

以烧结后的二氧化硅光子晶体为模板,采用溶胶凝胶法向模板间隙填充以甲基丙烯酸(MAA)和丙烯酰胺(AM)为双功能单体,N,N’-亚甲基双丙烯酰胺(BIS)为交联剂的聚合物前驱液,制备了甲基丙烯酸/丙烯酰胺共聚(PMAM)双单体反蛋白石凝胶光子晶体.通过紫外可见光谱分析表明,反蛋白石结构的凝胶膜对pH响应范围在4.0～7.0之间.由于其不受离子强度的影响,除了可以作为pH传感器外,还可以作为金属离子及生物小分子等分子印迹光子晶体传感器的基体膜.     

果菠萝蛋白酶在有机溶剂微扰时的分子折叠与活力变化的研究

本文用荧光、紫外差示及CD光谱研究果菠萝蛋白酶经甲醇、乙醇、乙二醇微扰后的构象与活力变化情况.酶的荧光强度随有机溶剂浓度增大而增强,表明Tyr、Trp微环境发生明显变化。232nm和285nm处出现紫外差吸收正峰。前峰与酶分于折叠的变化有关,而后峰与Tyr、Trp微环境的变化相关.甲醇、乙醇微扰后,天然酶的208nm和225nmCD双负峰逐渐加强,而乙二醇微扰后,225nm负峰加强。208nm负峰减弱并红移直至完全消失,说明酶分子完全伸展.     

Photocatalytic self-assembled solid porphyrin microcrystals from water-soluble porphyrins: Synthesis,characterization and application

In this article, we report on the formation of a photocatalytic porphyrin crystalline structure using two oppositely charged commercially available low cost porphyrins, [meso-tetra(N-methy-4-pyridyl)porphyrin tetratosylate (TMPyP) and zinc-tetrakis(4-sulfonatophenyl)porphyrin (Zn-TPPS)], by self-assembly at room temperature without acidification. Using optical microscopy, the crystals were determined to have a length of 30–55 μm and width of 2–50 μm, depending on the molar ratio of the porphyrins in the starting solution. The porphyrin crystals were characterized by means of powder X-ray diffraction and UV–Vis, fluorescence, and optical microscopic techniques. The UV–Vis absorbance spectrum of the crystalline structure is different than those of the monomer solutions, involving a broadened Soret band that is split into two blue-shifted and red-shifted peaks and broadened red-shifted Q-bands. The crystals exhibit a different emission spectrum from those of the porphyrin solutions in that they are red-shifted, split, and show a dramatic decrease in intensities. A hypothetical model for the crystal structure of the porphyrin crystals is developed. Illumination of the crystals in a 2,4,6-trinitrotoluene solution with a tungsten lamp results in TNT reduction to 1,3,5-trinitrobenzene and 4-amino-2,6-dinitrotoluene.     

Synthesis of Submicron-Sized Titania-Coated Silica Particles with a Sol-Gel Method and Their Application to Colloidal Photonic Crystals

A previously proposed method for preparing monodispersed titania particles was extended to preparation of titania-coated silica spherical particles. The core silica particles with an average size of 264 nm were prepared with Stöber method. The titania-coating was performed in ethanol/acetonitrile solvent in the presence of silica particles by a sol-gel method with the use of titanium tetraisopropoxide (TTIP) and methylamine (MA) catalyst. Average size of the silica-titania particles decreased from 457 to 292 nm with an increase in concentration of silica particles. Coefficient of variation for the particle size was less than 5%. Colloidal crystals could be fabricated with a dip-coating technique and a sedimentation process, respectively. Measurements of reflectance revealed peaks based on the Bragg diffraction. Those peaks red-shifted with an increase in titania shell thickness because of a high refractive index of titania. Annealing at high temperature transformed crystal structure of titania shell from amorphous to anatase (500°C) and rutile (1000°C), which led to red-shift of reflection peak because of an increase in refractive index of titania due to the crystallization.     

表面富含羧基的单分散交联聚合物微球的快速自组装制备胶体晶的研究

在20～70℃范围内,用垂直沉积的方法可使表面富含羧基的单分散交联聚合物微球在不同的基底上快速自组装成三维有序的胶体晶.不同粒径的微球形成的胶体晶其光禁带峰位不同,因此可调控不同波长的光在胶体晶中的传播.利用紫外-可见光谱研究了胶体晶的光禁带峰位与组成其微球粒径之间的关系.结果表明,随着构成胶体晶微球粒径的增大,胶体晶光禁带峰位发生了红移,而随着入射光角度的增大,胶体晶的光禁带峰位发生了蓝移.利用原子力显微镜和扫描电子显微镜研究了其它条件对聚合物微球有序排列的影响,发现聚合物微球在pH值为3.0～13.0范围内可以形成三维有序自组装胶体晶.这是由于在不同的pH值下,聚合物微球表面发生羧基化及去羧基化反应,导致在自组装过程中微球之间和微球与介质之间作用力的变化     

InSb纳米线阵列的可控制备与光谱表征

采用脉冲电沉积结合阳极氧化铝模板技术制备了不同生长方向的闪锌矿型InSb纳米线阵列. 结果表明, 控制电解液中十二烷基硫酸钠(SDS)的浓度, 可使纳米线的择优生长方向从[400]向[220]方向转变. 利用X射线衍射仪、 场发射扫描电子显微镜、 高分辨透射电子显微镜对所制备纳米线的相组成和微结构进行了表征. 激光拉曼光谱结果表明, 不同生长方向的InSb纳米线阵列的拉曼光谱有明显差异. 与体材料相比, InSb纳米线阵列的红外吸收声子散射峰发生强烈红移, 其吸收带边发生了明显蓝移.     

Effect of Ultrasonication on Optical Properties and Electronic States of Conjugated Polymer MEH-PPV

Poly[2-methoxy-5-（2＇-ethyl-hexyloxy）-1,4-phenylene vinylene]（MEH-PPV）solutions with different concen-trations were prepared in chloroform for different ultrasonication times.The ultraviolet absorption and photoluminescence（PL）spectra of the MEH-PPV solutions were measured,and the electronic states of the polymer chains under different experimental conditions were studied.The results showed that the effects of ultrasonication on the dilute and concentrated solutions were different.After ultrasonication,the intensity of the absorption peak at 280 nm significantly decreased,relative to the absorption peak at 500 nm for both dilute and concentrated solutions,indicating that the proportion of the two excited states in the polymer chains had changed.For dilute MEH-PPV solutions,the blue-shifted absorption（at about 500 nm）and PL spectra show that ultrasonication also led to polymer chain degradation and thus shortened the effective conjugation length.For concentrated solutions,however,the peak positions of the absorption spectra remained unchanged.In addition,the effects of the solution temperatures on the optical spectra for the MEH-PPV solutions were also discussed.     

The change of the proton magnetic shielding in red- and blue-shifted linear hydrogen-bonded complexes

The change in the proton magnetic shielding constant of FH and FArH on the formation of the vibrationally red-shifted FH... Rg and blue-shifted FArH... Rg (Rg = Ne, Ar). complexes was determined by GIAO ab initio computations at various levels of theory. The blue-shifted FArH... N₂ and red-shifted FArH... P₂ complexes were also studied. The characteristic downfield shift of the isotropic proton magnetic resonance in red-shifted hydrogen-bonded complexes is smaller in the blue-shifted complexes. In FArH... Ne and FArH... N₂ the proton NMR actually shifts to higher fields on complexation. These results are rationalized by considering the changes in the magnetic and electric contributions to the proton shielding in FH and FArH.     

Geometry relaxation-induced large Stokes shift in red-emitting borondipyrromethenes (BODIPY) and applications in fluorescent thiol probes

2-Thienyl and 2,6-bisthienyl BODIPY derivatives (BS-SS and BS-DS) were prepared that show intense absorption (ε = 65000 M(-1) cm(-1) at 507 nm) and a large Stokes shift (96 nm) vs the small Stokes shift of typical BODIPY (<15 nm). Control compounds with a thienyl unit at the 8-position or phenyl substituents at the 2,6-positions were prepared (BS-1 and 9). BS-1 shows absorption/emission in the blue-shifted range and a small Stokes shift (12 nm). Compound 9 shows absorption in the red-shifted range, but the Stokes shift (<30 nm) is much smaller than that for BS-SS and BS-DS. DFT calculations propose the large Stokes shifts of BS-SS and BS-DS are due to the remarkable geometry relaxation upon photoexcitation and its substantial effect on the energy levels of molecular orbitals. For the dyes with small Stokes shifts, much smaller geometry relaxations were found. The fluorophores were used for fluorescent thiol probes, with 2,4-dinitrobenzenesulfonyl (DNBS) as the fluorescence switch. Both fluorescence OFF-ON and unprecedented ON-OFF transduction were observed, which are attributed to the different photoinduced intramolecular electron-transfer (PET) profile. All the photophysics were rationalized by DFT calculations based on the concept of "electronic states" instead of the very often used approximation of "molecular orbitals".     

COOPERATIVITY OF THE DEHYDRATION BLUE-SHIFT OF BACTERIORHODOPSIN*

Abstract– Dehydration of purple membrane (PM) causes a hlue-shift of the absorbance maximum from 570 nm to about 530 nm [Lazarev and Terpugov (1980) Biochim. Biophys. Acta 590 .324–338; Hildebrandt and Stockburger (1984) Biochemistry 23 ,5539–5548]. The absorbance spectra of PM dried in films at pH 0, 7 and 11 were measured at controlled relative humidities (RH). At pH 7, a blue-shift was observed similar to that previously reported. At pH 0(1M H₂SO₄) a reversible transition was observed from the “acid blue membrane” (maximum near 600 nm at 100% RH) to a blue-shifted dehydrated pigment (maximum near 578 nm at 50% RH), with isosbestic points at 592 and 710 nm. At pH 11 (NaOH) the absorbance maximum shifted to 530 nm, similar to the dehydrated form at pH 7. The fraction of hydrated chromophore, X_h, was calculated (assuming only two chromophore states, hydrated and dehydrated) as a function of humidity and pH. The resulting curve at pH 7 showed a steep decline in X_h below 20% RH. Near this hydration level, water clusters on protein surfaces break up, causing side-chain pK reversals. The Hill coefficient for the transition was about 2, indicating the minimum number of water molecules involved in a cooperative transition. The results suggest that as few as two water molecules are coordinated to the protonated retinal Schiff base of bacteriorhodopsin. A mechanism for the pH 7 dehydration blue-shift is proposed, involving a pK reversal of the protonated Schiff base and a nearby carboxyl side chain. At pH 0, a sharp decline in X_h occurs between 100 and 70% RH. Near this hydration level, complete protein surface coverage by a water monolayer occurs. The Hill coefficient is about 20, suggesting involvement of a large region of the surface.