Voltage-biased solid-state nanopores are well established in their ability to detect and characterize single polymers, such as DNA, in electrolytes. The addition of a pressure gradient across the nanopore yields a second molecular driving force that provides new freedom for studying molecules in nanopores. In this work, we show that opposing pressure and voltage bias enables nanopores to detect and resolve very short DNA molecules, as well as to detect near-neutral polymers.
α-Synuclein (α-Syn) is an abundant cytosolic protein involved in the release of neurotransmitters in presynaptic terminal and its aberrant aggregation is found to be associated with Parkinson’s disease. Recent study suggests that the oligomers formed at the initial oligomerization stage may be the root cause of cytotoxicity. While characterizing this stage is challenging due to the inherent difficulties in studying heterogeneous and transient systems by conventional biochemical technology. Here we use solid-state nanopores to study the time-dependent kinetics of α-Syn oligomerization through a label-free and single molecule approach. A tween 20 coating method is developed to inhibit non-specific adsorption between α-Syn and nanopore surface to ensure successful and continuous detection of α-Syn translocation. We identify four types of oligomers formed in oligomerization stage and find an underlying consumption mechanism that the formation of large oligomers consumes small oligomers. Furthermore, the effect of lipid membrane on oligomerization of α-Syn is also investigated and the results show that 1,2-dioleoyl-sn-glycero-3-[phospho-L-serine] (DOPS) small unilamellar vesicles (SUVs) dramatically enhances the aggregation rate of α-Syn while do not alter the aggregation pathway.
Singlet fission (SF) is a spin-allowed process, which is expected to be a feasible strategy to realize photon downward conversion. To achieve a significant increase in the photoelectric conversion efficiency of solar cells, SF molecules should have not only a high SF efficiency, but also suitable energies of the first singlet excited state [E(S1)] and the first triplet excited state [E(T1)] to act as SF sensitizers in solar cells. Aryl-substituted diketopyrrolopyrrole (DPP) is one of the few organic molecules, which can undergo SF efficiently after photoexcitation. In order to find suitable DPP-based SF sensitizers for solar cells, we designed a series of DPP derivatives by varying aromatic substituents, including changing the conjugation and constitution of aromatic substituents, as well as introducing side-substituents on the aromatic substituents. Detailed analysis focused on the molecular structures, the frontier molecular orbitals, multiple diradical characters, and SF relevant excited-state energy levels. The results indicate that introduction of no more than two aromatic rings and modification of the aromatic rings with side-substituents are both practical ways to get suitable SF sensitizers for solar cells. This work would give a deep understanding of DPP-based SF molecules, and pave the way towards the development of new DPP-based SF sensitizers for solar cells.
A series of mononuclear ruthenium arene complexes with thiosemicarbazone (TSC) ligands (A-type, 1-8) and their corresponding di-nuclear analogues (B-type, 9-16) were synthesized and characterized by NMR, elemental analysis and HR-ESI-mass spectrometry. The molecular structures of 1, 2, 6, 9-11 and 13-16 were determined using single-crystal X-ray diffraction analysis. The Gibbs free energy of the two examples of the two types of complexes (1 and 9) and the bonding order in their single-crystals were studied using density functional theory (DFT) calculations. The compounds were further evaluated for their in vitro antiproliferative activities against CNE-2 human nasopharyngeal carcinoma, KB human oral epithelial carcinoma, SGC-7901 human gastric carcinoma, HepG2 human liver carcinoma, HeLa human cervical carcinoma and HEK-293T noncancerous cell lines. Furthermore, the interactions between the compounds and DNA were studied by electrophoretic mobility spectrometry studies.
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