Native agarose gel electrophoresis and electroelution: A fast and cost‐effective method to separate the small and large hepatitis B capsids

Hepatitis B core antigen (HBcAg) expressed in Escherichia coli is able to self‐assemble into large and small capsids comprising 240 (triangulation number T = 4) and 180 (triangulation number T = 3) subunits, respectively. Conventionally, sucrose density gradient ultracentrifugation and SEC have been used to separate these capsids. However, good separation of the large and small particles with these methods is never achieved. In the present study, we employed a simple, fast, and cost‐effective method to separate the T = 3 and T = 4 HBcAg capsids by using native agarose gel electrophoresis followed by an electroelution method (NAGE‐EE). This is a direct, fast, and economic method for isolating the large and small HBcAg particles homogenously based on the hydrodynamic radius of the spherical particles. Dynamic light scattering analysis demonstrated that the T = 3 and T = 4 HBcAg capsids prepared using the NAGE‐EE method are monodisperse with polydispersity values of ～15% and ～13%, respectively. ELISA proved that the antigenicity of the capsids was not affected in the purification process. Overall, NAGE‐EE produced T = 3 and T = 4 capsids with a purity above 90%, and the recovery was 34% and 50%, respectively (total recovery of HBcAg is ～84%), and the operation time is 15 and 4 times lesser than that of the sucrose density gradient ultracentrifugation and SEC, respectively.     

Oscillatory interaction between two like‐charged nanoparticles induced by polyelectrolyte brush–solvent interface

We use two‐dimensional (2D) self‐consistent field theory to study the effective interactions between two like‐charged cylindrical nanoparticles mediated by an oppositely weakly charged polyelectrolyte brush in a solvent solution. In a poor solvent, where a sharp brush–solvent interface forms, an oscillatory interaction is observed when two nanoparticles are both located at the brush–solvent interface. This oscillatory interaction depends on the penetration depths of the particles and their geometric orientations with respect to the substrate. When the particles are both immersed in the brush and/or the particles are oriented vertically or diagonally with large angles to the substrate, the oscillatory behavior disappears. We interpret our findings by analyzing in detail the contributions to the free energy from electrostatic interaction, nonelectrostatic interaction, and entropies, separately. Briefly, the deformations of the interface and the ion layers formed in the vicinity of the interface are responsible for this oscillatory behavior. In a good solvent, where the narrow brush–solvent interface vanishes, the effective particle–particle interactions behave like that for both particles immersed into the brush with poor solvent. They are found to be repulsive. The influences of the particle size, grafting density, and amount of charges and ions are also briefly discussed. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 1458–1468     

A Resettable Keypad Lock with Visible Readout Based on Closed Bipolar Electrochemistry and Electrochromic Poly(3‐methylthiophene) Films

A closed bipolar electrode (BPE) system was developed with electrochromic poly(3‐methylthiophene) (PMT) films electropolymerized on the ITO/rGO electrode as one pole of BPE in the reporting reservoir and the bare ITO electrode as another pole of BPE in the analyte reservoir, in which rGO represents reduced graphene oxide. Under a suitable driving voltage (V_tot), the electrochemical reduction/oxidation of electroactive probes, such as H₂O₂/glutathione (Glu), in the analyte reservoir could induce the reversible color change of PMT films in the reporting reservoir between blue and red. Based on this, a keypad lock with H₂O₂, Glu, and V_tot=?3.0 V as the three inputs and the color change of PMT films as the visible output was established. This system was easily operated and did not need to synthesize the complex compounds or DNA molecules. The security system was easy to reset and could be used repeatedly.     

Telaprevir fragments as organocatalysts in asymmetric direct aldol reactions of aldehydes

We have demonstrated that the fragments of Telaprevir can act as organocatalysts for asymmetric aldol reactions between aromatic aldehydes and acetone under mild conditions. The reaction conditions have been optimized in terms of the catalyst nature, choice of temperature, solvent, additive, and the catalyst loading. Under proper conditions, fairly good yield and enantioselectivity have been achieved.     

Chemoselective hydrogenation of α,β-unsaturated aldehydes with modified Pd/C catalyst

Selective hydrogenation of α, β-unsaturated aldehydes with modified Pd/C catalyst was developed.The reduction of C=O bond could be efficiently inhibited by the addition of carbonates,and high selectivity to the corresponding saturated aldehydes was achieved under mild conditions.This protocol provides an alternative for efficient preparation of saturated aldehydes.