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This paper reports a novel design of an artificial pigment-protein complex, created by supramolecular binding of chlorophyll a (Chl a) in the hydrophobic cavity of single-ring mutant of bacterial GroEL (SR). The results show that Chl a molecules assembled in SR nano-ring retain their native structure, and an increase of loading amount (up to ~26 pigment molecules per protein nano-ring) with the equilibrium concentration of Chl a upon dialysis has been observed. It is further seen that the nanoscale organization of Chl a in SR leads to a significant quenching of Chl a fluorescence, especially at high loadings. Moreover, the photostability of Chl a encapsulated in SR is significantly enhanced in comparison with free Chl a, as evidenced by an up to 6-fold increase of its half-life time. Both the interaction of Chl a with SR and the interaction between Chl a molecules contribute to photostability. Finally, it is shown that the Chl a-SR complex has good photoreduction activity as well as photoelectrochemical activity under visible light illumination. The maximum photoelectric conversion efficiency of the Chl a-SR-sensitized solar cells is around 1.09%. The strategy presented herein is believed to be instrumental in the design of effective photoenergy conversion materials.

A novel annular spinneret was developed for the needleless mass production of nanofibers. Polymer solution was transported to the top of the annular where multiple jets were formed when the applied voltage exceeded a certain value. Electric field intensity values were simulated by finite element software. Morphology, diameter and productivity of nanofibers were investigated by changing the electrospinning process parameters which were solution concentration, applied voltage, collection distance and solution flow rate. The results showed the highest electric field strength value at the top of annular spinneret. The diameter of nanofibers gradually increased with the solution concentration. Increasing the applied voltage, collection distance and solution flow rate had some significant influence on the diameter of nanofibers. The highest productivity of nanofibers reached 4.5 g/h. Filtration properties and pore diameter distribution of the nanofibers membranes were investigated and these exhibited potential for air filtration. It was noteworthy that this method maximally utilized the solution to form multiple jets, since it significantly reduced the effect of solvent evaporation in the electrospinning process. Annular spinneret offered a potential for large scale production of nanofibers in the future. Keywords: Fiber technology, Electrospinning, Annular spinneret, Mass production