Design and Application of an Artificial Hybrid PromoterPluxI-lacOin Genetic Circuit to Achieve Lower Basal Expression Level.

Quorum quenching (QQ) enzymes, which degrade signaling molecules so as to disrupt the quorum sensing signaling process, have drawn much attention as alternative antimicrobial agents. However, the screening methods for evolution of such enzymes through constructing genetic circuits remain a challenge for its relatively high false positive rates caused by the higher basal expression level of the naturally acquired promoter. Thus, we presented an improved genetic circuit by introducing an artificial hybrid promoter PluxI-lacO combining PlacO originated from lactose promoter with QS regulatory promoter PluxI to control the expression of reporter gene rfp. Herein, we investigated the effect of various expression strengths of suppressive protein LacI and signaling molecule AHL on the expression of rfp. We found that the effect AHL exerted on the expression of rfp outweighed that from IPTG. The results also demonstrated that our genetic circuit could achieve the lower basal expression level of reporter gene and could respond to the expression of AiiA. The resulting circuits show the potential for screening the evolved AiiA more efficiently by virtue of inherent low basal expression level.

Polydopamine coating on individual cells for enhanced extracellular electron transfer.

A new strategy of redox mediator immobilization was developed by coating polydopamine (PDA) on individual live cells to enhance extracellular electron transfer. As a result of the synergistic effect of the redox properties of PDA and the ability to adsorb self-secreted flavin molecules, a double-mediator electron transport channel was achieved.

Embedding a Diketopyrrolopyrrole-Based Cross-linking Interfacial Layer Enhances the Performance of Organic Photovoltaics.

In this study, we prepared DPPBTDA, a diketopyrrolopyrrole-based small molecule presenting a terminal cross-linkable azido group, as a cathode modifying layer for organic photovoltaics (OPVs) having the inverted device structure glass/indium tin oxide/zinc oxide (ZnO) with or without the interfacial layer (IFL)/active layer/MoO3/Ag. The active layer comprising a blend of poly[4,8-bis(5-(2-ethylhexyl)thien-2-yl)benzo[1,2- b;4,5- b']dithiophene-2,6-diyl- alt-(4-(2-ethylhexyl)-3-fluorothieno[3,4- b]thiophene)-2-carboxylate-2,6-diyl] (PTB7-Th) as the electron donor and [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) as the electron acceptor. Atomic force microscopy, space-charge-limited current mobility, surface energy, electron spectroscopy for chemical analysis depth profile, ultraviolet photoelectron spectroscopy analysis, and OPV performance data revealed that the surface status of ZnO changed after inserting the DPPBTDA/PCBM hybrid IFL and induced an optimized blend morphology, having a preferred gradient distribution of the conjugated polymer and PC71BM, for efficient carrier transport. The power conversion efficiency (AM 1.5 G, 1000 W m-2) of the device incorporating the hybrid IFL increased to 9.4 ± 0.11% from 8.5 ± 0.15% for the preoptimized PTB7-Th/PCBM device (primarily because of an enhancement in the fill factor from 68.7 ± 1.1 to 72.1 ± 0.8%).