Langmuir Aggregation of Coomassie Brill Blue on Protein and Determination of Protein by MPASC

The microphase adsorption–spectral correction technique (MPASC) has been applied to investigate the aggregation of coormassie brill blue G250 (CBBG) on protein in which the microelectrostatic fields exist. The Langmuir adsorption of CBBG in protein was confirmed, and the interaction is sensitive at pH 3.78. Results show that the adsorption ratio of CBBG to five proteins, e.g., BSA, OVA, Hb, Mb and -G are 100, 65, 30, 98 and 210, respectively, their adsorption constants are 9.92 × 10⁴, 8.04 x 10⁴, 9.38 × 10⁴, 1.66 × 10⁵, and 2.75 × 10⁴, and their absorptivities are 2.33 × 10⁶, 1.56 × 10⁶, 1.98 × 10⁶, 5.61 × 10⁵, and 4.48 × 10⁶ Lmol^–1 at 670 nm. The study indicates that 1 mg of protein adsorbs about 1.54 mmol of CBBG. For the protein determination of samples, the recovery of protein is between 88.0 and 111% and the relative standard deviation is 2.6%.     

Langmuir aggregation of Nile blue and safranine T on sodium dodecylbenzenesulfonate surface and its application to quantitative determination of anionic detergent.

We studied the interaction of sodium dodecylbenzenesulfonate (SDBS) with Nile Blue (NB) and Safranine T (ST) by a spectral correction technique. The aggregations of NB and ST on an SDBS surface obeyed Langmuir isothermal adsorption. The adsorption ratios of NB and ST to SDBS were both 0.5, and the adsorption constants of the aggregates were 1.80 x 10(5) and 9.49 x 10(4). The aggregations were applied to the quantitative determination of anion detergent in samples; the recovery of SDBS was between 90.3 and 106% together with an RSD of 3.78%.     

探针体在蛋白质大分子上Langmuir吸附聚集及应用──蛋白质/荧光桃红B(PB)结合反应研究

蛋白质化学是生物化学家当今感兴趣的前沿研究领域. 研究小分子(离子)在生物大分子上的聚集形式以及机理, 帮助人们弄清其污染物及毒物在生物大分子上的结合, 在病理分析、临床检测以及基因变异有重要意义. 常用光谱分析方法包括分光光度法[1～6]、荧光法[7,8]和共振光散射光谱技术(RRS)等[9～12]. 但是, 大分子与探针分子间的结合机理仍存在一些尚未解决的问题[13,14]. 蛋白质分子由于复杂的立体构象形成弱微静电场[15,16], 在其作用下, 带电荷的小分子以单分子层形式被吸附到微相电场表面.     

Sensitive, label-free protein assay using 1-ethyl-3-methylimidazolium tetrafluoroborate-supported microchip electrophoresis with laser-induced fluorescence detection

Based on the dimer-monomer equilibrium movement of the fluorescent dye Pyronin Y (PY), a rapid, simple, highly sensitive, label-free method for protein detection was developed by microchip electrophoresis with LIF detection. PY formed a nonfluorescent dimer induced by the premicellar aggregation of an anionic surfactant, SDS, however, the fluorescence intensity of the system increased dramatically when proteins such as BSA, bovine hemoglobin, cytochrome c, and trypsin were added to the solution due to the transition of dimer to fluorescent monomer. Furthermore, 1-ethyl-3-methylimidazolium tetrafluoroborate (EMImBF4) instead of PBS was applied as running buffers in microchip electrophoresis. Due to the excellent properties of EMImBF4, not only nonspecific protein adsorption was more efficiently suppressed, but also approximately ten-fold higher fluorescence intensity enhancement was obtained than that using PBS. Under the optimal conditions, detection limits for BSA, bovine hemoglobin, cytochrome c, and trypsin were 1.00x10(-6), 2x10(-6), 7x10(-7), and 5x10(-7) mg/mL, respectively. Thus, without covalent modification of the protein, a protein assay method with high sensitivity was achieved on microchips.     

Fluorescence quenching method for the determination of sodium dodecyl sulphate with near-infrared hydrophobic dye in the presence of Triton X-100

A fluorophotometric method for the determination of anionic surfactant sodium dodecyl sulphate (SDS) was proposed. The method is based on the quenching effect of SDS on the fluorescence of near-infrared (NIR) hydrophobic dye, 2-[4'chloro-7'(3'hexadecyl-2'benzothiazolinylidene)-3',5'-(1',3'-propanediyl)-1',3',5'-heptatriene-1'-yl]-3-ethylbenzothiazolium iodide (dye I) in the presence of Triton X-100. The calibration graph is linear in the concentration range from 0 to 2 x 10(-6) mol L(-1) of SDS with a detection limit (LOD) of 8.3 x 10(-8) mol L(-1). The relative standard deviation for the determination of 7 x 10(-7) mol L(-1) SDS was 4.1%. Recoveries of 95.3-110.3% were found for the addition to 1.0 x 10(-6) mol L(-1) SDS in the analysis of environmental water samples. Preliminary research shows that the fluorescence quenching is due to the formation of dye aggregate facilitated by SDS.     

Unburned carbon as a low-cost adsorbent for treatment of methylene blue-containing wastewater

Fly ash, natural zeolite, and unburned carbon separated from fly ash have been employed as low-cost adsorbents for dye adsorption in methylene blue-containing wastewater. It is found that the unburned carbon exhibits a much higher adsorption capacity than raw fly ash and natural zeolite. The adsorption capacities of fly ash, natural zeolite, and unburned carbon for methylene blue are 2 x 10(-5), 5 x 10(-5), and 2.5 x 10(-4) mol/g, respectively. Investigation also indicates that adsorption is influenced by initial dye concentration, particle size, dye solution pH, and adsorption temperature. Adsorption on unburned carbon increases with the initial dye concentration, solution pH, and temperature, but reduces with the increasing particle size. Kinetic studies show that adsorption of methylene blue on fly ash, natural zeolite, and unburned carbon can be best described by the pseudo-second-order adsorption model and that adsorption is a two-step diffusion process. The apparent activation energies for methylene blue adsorption on unburned carbon in the first and second diffusion processes are 12.4 and 39.3 kJ/mol, respectively.     

Langmuir Aggregation of Chromophore in Biomacromolecule and its Application: Interaction of Picramine CA (PCA) with Proteins

The microphase adsorption-spectral correction (MPASC) technique has been described. The formation of microelectrostatic fields in macromolecule is proposed and it causes the aggregation of a chromophore in protein. We have studied the interaction of picramine CA (PCA) with five proteins: bovine serum albumin (BSA), human n -globulin ( n -G), bovine hemoglobin (Hb), horse myoglobin (Mb) and ovalbumin (OVA). Results show that at pH 2.21, the adsorption ratios of PCA to BSA, n -G, Hb, Mb and OVA are 46, 54, 35, 15 and 21, respectively, their adsorption constants 3.17 ‐ 10 5 , 6.58 ‐ 10 4 , 1.40 ‐ 10 5 , 8.99 ‐ 10 4 and 1.68 ‐ 10 5 and their absorptivities 3.56 ‐ 10 5 , 3.06 ‐ 10 5 , 2.91 ‐ 10 5 , 1.10 ‐ 10 5 and 1.97 ‐ 10 5 l mol m 1 cm m 1 at 630 nm. The analysis of samples has given the satisfactory result.     

langmuir aggregation of alkali blue 6b in proteins: Study and application

The formation of microelectrostatic fields in biopolymers causes the adsorption of stain molecules in protein. The interactions between the dye alkali blue 6B (AB6B) and four proteins, bovine serum albumin (BSA), human γ-globulin (γ-G), horse myoglobin (Mb) and ovalbumin (OVA), were studied by the microphase adsorption/spectral correction technique. It was observed that the interactions obey the Langmuir isothermal adsorption. The Langmuir equilibrium constants of all the aggregates were determined. Interestingly, the adsorption of AB6B has no relation to the array sequence of amino acid residues, and an electrostatic field consists of constant amino acid residues. The novel method has been applied satisfactorily to the determination of the total protein content in two different samples.

     

Langmuir Aggregation of Stain on Ionic Surfactant and its Application: Interaction of Bromo‐Pyrogallol Red with Cetyl Trimethylammonium Bromide (CTAB) and Determination of Molybdenum Traces

The microphase adsorption‐spectral correction (MPASC) technique was de scribed and applied to study the interaction of bromo‐pyrogallol red (BPR) with cetyl trimethylammonium bromide (CTAB). The synergism mechanism of micelles was analyzed and discussed. The large electrostatic micelle adsorbs the chromophore in only the monolayer, and the adsorption obeys the Langmuir adsorption. The formation of the (BPR₂·CTAB)₇₈ aggregate accelerates the Mo‐BPR complex reaction. Experimental results showed the adsorption constant of the adsorption aggregate 6.20 × 10⁵ and its molar absorptivity ?_r^610nm = 1.40 × 10⁶ lmol^?1cm^?1. For analysis of samples, the recovery of Mo was between 97.4 and 107% and the RSD was less than 4.39%.     

Nonlinear studies of Pararosanilin dye in liquid and solid media

Solid-state dye-doped polymers are attractive alternative to the conventional liquid dye solutions. In this paper, nonlinear properties of the dye Pararosanilin has been studied. The third-order nonlinear optical properties of Pararosanilin dye in 1-butanol and dye-doped polymer film were measured by the Z-scan technique using 532 nm diode pumped Nd:Yag laser. This material exhibits negative optical nonlinearity. The dye at 0.4 mM concentration exhibited nonlinear refractive coefficient (n(2) = -6.8 x 10(-8) and -7.11 x 10(-8) (cm(2)/W) in liquid and solid media, respectively), nonlinear absorption coefficient (beta = -7.7 x 10(-4) and -7.93 x 10(-4)cm/W in liquid and solid media, respectively) and susceptibility (chi((3))=3.38 x 10(-6) and 3.53 x 10(-5)esu in liquid and solid media, respectively). These results show that Pararosanilin dye has potential applications in nonlinear optics.     

Comparative adsorption studies of indigo carmine dye on chitin and chitosan

The adsorption of indigo carmine dye onto chitin and chitosan from aqueous solutions was followed in a batch system. The ability of these materials to adsorb indigo carmine dye from aqueous solution was followed through a series of adsorption isotherms adjusted to a modified Langmuir equation. The maximum number of moles adsorbed was 1.24 +/- 0.16 x 10(-5) and 1.54 +/- 0.03 x 10(-4) mol g(-1) for chitin and chitosan, respectively. The same interactions were calorimetrically followed and the thermodynamic data showed exothermic enthalpic values of -40.12 +/- 3.52 and -29.25 +/- 1.93 kJ mol(-1) for chitin and chitosan, respectively. Gibbs free energies for the two adsorption processes of indigo carmine dye presented a positive value for chitin and a negative one for chitosan, reflecting that dye/surface interactions are thermodynamic favorable for chitosan and nonspontaneous for chitin at 298.15 K. The interaction processes were accompanied by an increase of entropy value for chitosan (90 +/- 6 J mol(-1)K(-1)) and a decrease for chitin (-145 +/- 13 J mol(-1)K(-1)). Thus, dye/chitosan interaction showed favorable enthalpic and entropic processes, reflecting thermodynamic stability of the formed complex, while dye/chitin interaction showed an exothermic enthalpic value and a highly nonfavorable entropic effect, resulting in a nonspontaneous thermodynamic system.     

Nonlinear studies of acid fuchsin dye in liquid and solid media

Solid-state dye-doped polymers are attractive alternative to the conventional liquid dye solutions. In this paper, nonlinear properties of the dye Acid Fuchsin has been studied. The third-order nonlinear optical properties of Acid Fuchsin dye in 1-butanol and dye-doped polymer film were measured by the Z-scan technique using 532 nm diode pumped Nd:Yag laser. This material exhibits negative optical nonlinearity. The dye at 0.4 mM concentration exhibited nonlinear refractive coefficient (n(2)=-8.72 x 10(-8) and -10.308 x 10(-8) (cm(2)/W) in liquid and solid media, respectively), nonlinear absorption coefficient (beta=-7.69 x 10(-4) and -8.294 x 10(-4)cm/W in liquid and solid media, respectively) and susceptibility (chi(3)=4.33 x 10(-6) and 5.13 x 10(-5)esu in liquid and solid media, respectively). These results show that Acid Fuchsin dye has potential applications in nonlinear optics.     

Interaction of Trypan Blue with Protein and Application

The microphase adsorption ‐ spectral correction (MPASC) technique has been described and applied to the aggregation of trypan blue (TB) in proteins. The formation of the microelectrostatic field in protein causes the Langmuir monolayer aggregation of TB. The adsorption ratio of TB to bovine serum albumin (BSA), ovalbumin (OVA), hemoglobin (Hb) and human γ‐globulin (γ‐G) was determined to be 14.8, 8.4, 2.8 and 27.6, respectively, and the adsorption constant of the aggregates to be 7.17 × 10⁵, 4.88 × 10⁶, 4.85 × 10⁶ and 2.99 × 10⁶. The adsorption ratio of TB to proteins interestingly indicates almost no relation to the array sequence of amino acid residues. The interaction of TB with proteins is sensitive at pH 3.29, and the reaction was applied to the determination of protein trace with satisfactory results.     

多色蓝在核酸分子上的Langmuir聚集吸附

用微相吸附-光谱修正（MPASC）新技术研究核酸与多色蓝(PCB)探针分子间的相互作用，分析核酸分子内双静电膜的形成与Langmuir吸附的关联性.通过pH 7.24的介质核酸-PCB反应的光谱研究，测定了结合产物的物理化学参数：结合比1PCB:2DNA-PCB、1PCB:3RNA-PCB, 平衡常数KDNA-PCB=5.42×104， KRNA-PCB=2.82×104,摩尔吸收系数ε(DNA-PCB, 625 nm)=5.65×103（mo1－1•L ）•cm－1， ε(RNA-PCB, 625 nm)=3.85×103 （mol－1•L）•cm－1.结果表明， RNA分子仅形成约60％双螺旋结构链，核酸双螺旋每一周期的负静电沟最大聚集10个PCB分子.该吸附反应用于核酸样品测定，结果良好.     

Engineering of efficient panchromatic sensitizers for nanocrystalline TiO(2)-based solar cells.

A new series of panchromatic ruthenium(II) sensitizers derived from carboxylated terpyridyl complexes of tris-thiocyanato Ru(II) have been developed. Black dye containing different degrees of protonation [(C(2)H(5))(3)NH][Ru(H(3)tcterpy)(NCS)(3)] 1, [(C(4)H(9))(4)N](2)[Ru(H(2)tcterpy)(NCS)(3)] 2, [(C(4)H(9))(4)N](3)[Ru(Htcterpy)(NCS)(3)] 3, and [(C(4)H(9))(4)N](4)[Ru(tcterpy)(NCS)(3)] 4 (tcterpy = 4,4',4' '-tricarboxy-2,2':6',2' '-terpyridine) have been synthesized and fully characterized by UV-vis, emission, IR, Raman, NMR, cyclic voltammetry, and X-ray diffraction studies. The crystal structure of complex 2 confirms the presence of a Ru(II)N6 central core derived from the terpyridine ligand and three N-bonded thiocyanates. Intermolecular H-bonding between carboxylates on neighboring terpyridines gives rise to 2-D H-bonded arrays. The absorption and emission maxima of the black dye show a bathochromic shift with decreasing pH and exhibit pH-dependent excited-state lifetimes. The red-shift of the emission maxima is due to better pi-acceptor properties of the acid form that lowers the energy of the CT excited state. The low-energy metal-to-ligand charge-transfer absorption band showed marked solvatochromism due to the presence of thiocyanate ligands. The Ru(II)/(III) oxidation potential of the black dye and the ligand-based reduction potential shifted cathodically with decreasing number of protons and showed more reversible character. The adsorption of complex 3 from methoxyacetonitrile solution onto transparent TiO(2) films was interpreted by a Langmuir isotherm yielding an adsorption equilibrium constant, K(ads), of (1.0 +/- 0.3) x 10(5) M(-1). The amount of dye adsorbed at monolayer saturation was (n(alpha) = 6.9 +/- 0.3) x 10(-)(8) mol/mg of TiO(2), which is around 30% less than that of the cis-di(thiocyanato)bis(2,2'-bipyridyl-4,4'-dicarboxylate)ruthenium(II) complex. The black dye, when anchored to nanocrystalline TiO(2) films achieves very efficient sensitization over the whole visible range extending into the near-IR region up to 920 nm, yielding over 80% incident photon-to-current efficiencies (IPCE). Solar cells containing the black dye were subjected to analysis by a photovoltaic calibration laboratory (NREL, U.S.A.) to determine their solar-to-electric conversion efficiency under standard AM 1.5 sunlight. A short circuit photocurrent density obtained was 20.5 mA/cm(2), and the open circuit voltage was 0.72 V corresponding to an overall conversion efficiency of 10.4%.     

Langmuir Aggregation of Thionin on Sodium Dodecyl Sulfate and Its Application

The microphase adsorption–spectral correction (MPASC) technique was applied to the interaction of thioin (TN) with sodium dodecyl sulfate (SDS) at pH 4.56. The synergism mechanism of SDS in solution was analyzed and discussed. The great electrostatic aggregation of TN on SDS obeys Langmuir monolayer adsorption. The property constants of the aggregate were determined and the quantitative determination of the anionic surfactant (AS) in samples was made in the presence of EDTA. Results showed that the large micellar aggregate is (TN–SDS₂)₃₁, the adsorption constant of the monomer aggregate is 1.85 × 10⁵ (18°C), and its molar absorptivity is 4.45 × 10⁶ L mol^–1 cm^–1. For analysis of samples, the recovery is between 94.5 and 111% and the RSD is less than 7.62%.     

Modeling of the whole expanded-bed protein adsorption process with yeast cell suspensions as feedstock

Expanded bed adsorption of bovine serum albumin (BSA) directly from a feedstock containing whole yeast cells has been investigated with an anion-exchanger DEAE Spherodex M. In the presence of 6% (w/w) yeast cells, the axial liquid-phase dispersion coefficient was found in the order of 10(-6) m2/s, which felled into the common range of 1.0 x 10(-6)-1.0 x 10(-5) m2/s observed previously without the use of cell suspensions as mobile phase. We found that the static and dynamic binding capacity of BSA decreased with increasing the yeast cell concentration due to the competitive adsorption of cells onto the outer surface of the anion-exchanger. However, because of the small size of the adsorbent, the large pore diffusivity of protein and the favorable column efficiency (low axial dispersion coefficient), the dynamic binding capacity of BSA in the presence of 6% (w/w) cells in the expanded bed reached 86% that of the equilibrium adsorption density. Then, the whole expanded bed adsorption process of BSA in the presence of cells, including feedstock loading, washing and elution steps, was predicted using a mathematical model with parameters all determined independently. In the elution stage, the steric mass-action adsorption isotherm with salt concentration as one of the model parameters was used to predict the step-gradient elution process with salt concentration increases. Computer simulations showed that the model was in good agreement with the experimental results for the whole operation process.     

Poly(ethylene oxide) facilitates the characterization of an affinity between strongly basic proteins with DNA by affinity capillary electrophoresis

In order to study kin17 protein-DNA affinity, we have developed a fast and reproducible capillary electrophoresis (CE) analysis of a strongly basic protein: kin17 protein, using a nonpermanent coating based on poly(ethylene oxide) (PEO) to avoid adsorption of kin17. The coating procedure was optimized to provide a residual and stable electroosmotic flow (EOF = 5 x 10(-5) cm(2)/V x s), exhibiting RSD of 0.3% and excellent long-term stability. Good intraday and interday reproducibility of kin17 migration times (0.8 and 0.3% relative standard deviation (RSD), respectively) enabled us to consider that the recovery percentage obtained for kin17 protein was satisfactory (79%). The potential of this PEO-based coating procedure was evaluated for affinity CE method in order to study the affinity of kin17 protein for two single-stranded DNA (ssDNA) models: polydeoxyadenylic acid and polydeoxycytidilic acid (pdA and pdC). Binding constants (1.5 x 10(7) +/- 17% and 1.7 x 10(7) + 25%M(-1)) were evaluated assuming a 1:1 affinity between kin17 and pdA or pdC, respectively.     

Enhanced spectrophotometric determination of nicotinic acid in a sodium dodecyl sulphate micellar medium

The spectrophotometric determination of pyridine and pyridine derivatives by means of the K?nig reaction was studied in micellar media of sodium dodecyl sulphate (SDS), N-cetylpyridinium chloride and Triton X-100. The sensitivity was largely increased in SDS micellar medium. The attack of the pyridine ring with cyanogen bromide to produce a glutaconic aldehyde was not affected by the presence of SDS, but the yield of the coupling reaction with an arylamine to produce a polymethine dye was largely increased. In the SDS micellar medium, aniline was superior to other coupling reagents. The limits of detection (LODs) were 6 x 10(-7), 1 x 10(-6) and 5 x 10(-7)M for pyridine, pyrrol-ylmethylpyridine and nicotinic acid, respectively, and the reproducibility for 2 x 10(-5)M solutions was ca. 2%. In the absence of SDS, the LODs were 3 x 10(-6), 3 x 10(-6) and 9 x 10(-6)M, respectively, and the reproducibility was ca. 3.5%. Application was made to the determination of nicotinic acid in pharmaceuticals.     

Sorption of methylene blue on an organoclay bearing thiol groups and application to electrochemical sensing of the dye

In this work, a thiol functionalized-clay was prepared by the covalent grafting of 3-mercaptopropyltrimethoxysilane (MPTMS) onto the surface of a natural smectite clay mineral originating from Cameroon. Effectiveness of the grafting process and properties of the resulting hybrid material were studied by various physico-chemical techniques, such as Fourier transform infrared (FTIR) spectroscopy, N(2) adsorption-desorption experiments (surface area measurements by the BET method) and thermal gravimetric analysis (TGA) coupled with mass spectrometry (MS). Sorption of methylene blue (MB), an electroactive cationic dye, was investigated for both the raw clay and its modified counterpart, as a function of shaking time, adsorbate concentration and pH, through batch experiments. A significant enhancement of the adsorption capacity towards MB was observed with the clay bearing thiol groups in comparison with the pristine one. The obtained sorption data matched the Langmuir isotherm model, from which it appeared that the organoclay adsorbed MB at a maximal loading of 1.04mmolg(-1), while the natural clay displayed a significantly poorer performance (0.31mmolg(-1)). The uptake of MB by the modified clay was found to be highly affected by pH, the cationic dye being more effectively adsorbed in alkaline medium. The possible use of the thiol functionalized-clay as electrode modifier for MB sensing purposes was then evaluated by means of carbon paste electrodes, using cyclic voltammetry. A calibration curve was obtained in the concentration range from 1x10(-6) to 1.4x10(-5)molL(-1), with a detection limit of 4x10(-7)molL(-1)(signal/noise=3).