Highly sensitive and simple fluorescence staining of proteins in sodium dodecyl sulfate-polyacrylamide-based gels by using hydrophobic tail-mediated enhancement of fluorescein luminescence

Fluorescein has an extremely low luminescence intensity in acidic aqueous media. However, when it was bound to proteins, subsequent increase of luminescence intensity took place. Furthermore, when a hydrophobic tail, such as aliphatic hydrocarbons, was introduced to fluorescein, more dramatic increase of luminescence intensity was observed upon binding to proteins. In the present study, by utilizing this luminescence enhancement, three hydrophobic fluorescein dyes (5-dodecanoyl amino fluorescein, 5-hexadecanoyl amino fluorescein, and 5-octadecanoyl amino fluorescein) were examined as noncovalent fluorescent stains of protein bands in sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Effective incorporation of the dyes to proteins in gels was accomplished either simply by adding dyes at the protein fixation step, or by treating gels with a staining solution after the fixation. The sensitivity of this staining method using the fluorescein derivatives was approximately 1 ng/band for most proteins. For some cases, protein bands containing as low as 0.1 ng were successfully visualized. In addition, the detection sensitivity showed much less protein-to-protein variation than silver staining. This new staining method was also successfully applied to two-dimensional electrophoresis of rat brain proteins. Its overall sensitivity was comparable to that of silver staining.     

Multistage homotopy perturbation method for nonlinear reaction networks

In this paper, we present the multistage homotopy perturbation method for finding the solution of the chemical kinetics with nonlinear reactions. We develop a general scheme for finding the analytic solution of chemical reaction networks and apply it to motivating chemical examples such as the enzyme kinetics model and the Brusselator model. We illustrate the numerical result for the models and show the accuracy of the method.     

Magnetic properties of neutron irradiated RPV steel

The neutron irradiated reactor pressure vessel (RPV) steels at various dose of 0–10¹⁸ n/cm² have been studied with Mössbauer, x-ray diffraction, and VSM. The Mössbauer data shows that the value of magnetic hyperfine field of Fe atom that exist at martensite is 330 kOe at site 1 and 305 kOe at site 2. At room temperature, the total absorption area of Mössbauer spectra with respect to irradiation of neutron is constant for the dose of 0–10¹⁶ n/cm², while over the dose of 0–10¹⁷ n/cm² the absorption area decreases rapidly. But the doublet area for the dose of 0–10¹⁶ n/cm² is constant, while over the dose of 10¹⁷ n/cm² it increases with increasing the fluence level of neutron. The coercivity and remanence of the neutron irradiated samples do not change significantly. But the maximum induction decreases by 5% at 10¹⁸ n/cm², compared with that of the as-received sample.     

Photoelectrochemical properties of MoO2 thin films

Thin MoO₂ films were electrodeposited on a selenium pre-deposited SnO₂|glass plate. The photoelectrochemical properties of MoO₂ films were investigated in 0.1 M Na₂SO₄ solution by the ultraviolet–visible spectrophotometry, linear sweep voltammetry, and altering current impedance measurement techniques. It was found that under illumination with the incident light of λ?=?366 nm, the photo response of the MoO₂|SnO₂|glass electrode resulted from the MoO₂ layer, while the SnO₂ layer served as a sink for photogenerated charge carriers. The MoO₂ film exhibited n-type conductivity. A schematic band structure diagram of MoO₂ in 0.1 M Na₂SO₄ solution was constructed. The flat band potential (E _fb), the donor concentration (N _D), the photogeneration current efficiency depended on MoO₂ film thickness. The [Fe(CN)₆]^4?/3? redox PEC cell with MoO₂|SnO₂|glass plate as a photoanode was constructed. Power output characteristics such as the open circuit voltage (V _OC), short circuit current (I _SC), the fill factor (FF), and the light-to-electrical conversion efficiency (η) were determined. The maximum light-to-electrical conversion efficiency exhibited by the PEC cell was 0.94 %.     

Study of K^ - \to \pi ^0 e^ - \overline \nu _e \gamma decay with ISTRA+ setup

Results of study of the $K^ - \to \pi ^0 e^ - \overline \nu \gamma $ decay at the ISTRA+ setup are presented. We observed 4476 events of this decay. The branching ratio is found to be $R = \frac{{Br(K^ - \to \pi ^0 e^ - \overline \nu _e \gamma )}}{{Br(K^ - \to \pi ^0 e^ - \overline \nu _e )}}$ = (1.81±0.03(stat.)±0.07(syst.)) × 10^?2 for E*_γ > 10 MeV and θ*_eγ > 10°. For comparison with the previous experiment the branching ratio with cuts E*_γ > 10 MeV, 0.6 < cos θ*_eγ < 0.9 is calculated: R = $\frac{{Br(K^ - \to \pi ^0 e^ - \overline \nu _e \gamma )}}{{Br(K^ - \to \pi ^0 e^ - \overline \nu _e )}}$ = (0.47±0.02(stat.) ± 0.03(syst.)) × 10^?2. For the cuts E*_γ > 30 MeV and θ*_eγ > 20°, used in most theoretical papers, Br = (3.06 ± 0.09(stat.) ± 0.14(syst.)) × 10^?4. For the asymmetry we get A _ξ = ?0.015 ± 0.021. At present it is the best estimate of this asymmetry.     

Synthesis of self‐assembled sphingolipid conjugates and their morphology effect on anticancer therapeutic potency

The shape of self‐assembling polymer–drug conjugates, influencing the cellular uptake, is one of the important factors to be considered for effective drug delivery. In this study, we described synthesis of polymeric drug conjugates of different morphologies with phytosphingosine (PHS) as a hydrophobic model drug and poly(amino acid) as a hydrophilic host polymer. By varying the amount of PHS grafted to poly(amino acid), PHS–poly(amino acid) conjugates exhibited morphological transition from spherical to worm‐like micellar aggregates in the aqueous media. We investigated the physicochemical properties of self‐assembled structures in terms of hydrodynamic size, surface charge, and critical aggregation concentration. The anticancer therapeutic potency of these self‐assembled structures was also discussed in terms of cellular uptake and cytotoxicity of prodrug micelles as a function of dose and time by in vitro cell study. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Improved Performance of an Amperometric Biosensor with Polydiaminonaphthalene on Electrochemically Deposited Au Nanoparticles

The performance of an enzyme sensor fabricated through covalent bond formation on the HRP‐bonded poly(1,8‐diaminonaphthalene) (polyDAN) layer with gold nanoparticles (AuNPs) was applied to catalyze the electrochemical reduction of H₂O₂. The surface characteristics of the sensor probe were studied using cyclic voltammetry, SEM, XPS, QCM, and impedance spectroscopy. The AuNP‐deposited surface resulted in higher conductivity and sensitivity for H₂O₂ detection in phosphate buffer solution. A linear calibration plot was obtained in the H₂O₂ concentration range between 10.0 μM and 25.0 mM with detection limit 5.0±1.25 μM. The lifetime of HRP/polyDAN/AuNP/GC probe was over 70 days without response loss.