| 1. |
- Kang, Yu, et al.
(author)
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Na+ and K+ ion selectivity by size-controlled biomimetic graphene nanopores
- 2014
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In: Nanoscale. - : Royal Society of Chemistry (RSC). - 2040-3364 .- 2040-3372. ; 6:18, s. 10666-10672
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Journal article (peer-reviewed)abstract
- Because biological ionic channels play a key role in cellular transport phenomena, they have attracted extensive research interest for the design of biomimetic nanopores with high permeability and selectivity in a variety of technical applications. Inspired by the structure of K+ channel proteins, we designed a series of oxygen doped graphene nanopores of different sizes by molecular dynamics simulations to discriminate between K+ and Na+ channel transport. The results from free energy calculations indicate that the ion selectivity of such biomimetic graphene nanopores can be simply controlled by the size of the nanopore; compared to K+, the smaller radius of Na+ leads to a significantly higher free energy barrier in the nanopore of a certain size. Our results suggest that graphene nanopores with a distance of about 3.9 A between two neighboring oxygen atoms could constitute a promising candidate to obtain excellent ion selectivity for Na+ and K+ ions.
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| 2. |
- Zhang, Zhisen, et al.
(author)
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Effects of Graphene Nanopore Geometry on DNA Sequencing
- 2014
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In: The Journal of Physical Chemistry Letters. - : American Chemical Society (ACS). - 1948-7185. ; 5:9, s. 1602-1607
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Journal article (peer-reviewed)abstract
- In this Letter we assess the effect of graphene nanopore geometries on DNA sequencing by considering DNA fragments including A, T, C, G, and 5-methylcytosine (MC) pulled out of graphene nanopores of different geometries with diameters down to similar to 1 nm. Using steered molecular dynamics simulations it is demonstrated that the bases (A, T, C, G, and MC) can be indentified at single-base resolution through the characteristic peaks on the force profile in a circular graphene nanopore but not in nanopores with other asymmetric geometries. Our study suggests that the graphene nanopore surface should be modified as symmetrically as possible in order to sequence DNA by atomic force microscopy or optical tweezers.
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| 3. |
- Li, Debing, et al.
(author)
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Separation of Hydrogen Gas from Coal Gas by Graphene Nanopores
- 2015
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In: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 119:45, s. 25559-25565
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Journal article (peer-reviewed)abstract
- We designed a series of porous graphene as the separation membrane for hydrogen gas in coal gas. The permeation process of different gas molecules (H-2, CO, CH4, and H2S) in porous graphene was evaluated under the atmospheric pressure and high pressure conditions. Our results indicate the hydrogen permeability and selectivity could be tuned by the size and the shape of the porous graphene. For graphene with bigger pores, the selectivity for hydrogen gas could decrease. In the porous graphene with same pore area, the hydrogen gas selectivity could be affected by the shape of the pore. The potential of mean force (PMF) of different gases to pass through a good separation candidate was calculated. The order of PMF for different gases to pass through the good separation candidate is H-2 < CO < CH4 approximate to H2S, which is also confirmed by the first-principle density function theory (DFT) calculation.
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| 4. |
- Liu, Lihui, 1985, et al.
(author)
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A binary solvent mixture-induced aggregation of a carbazole dendrimer host toward enhancing the performance of solution-processed blue electrophosphorescent devices
- 2015
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In: Journal of Materials Chemistry C. - : Royal Society of Chemistry (RSC). - 2050-7534 .- 2050-7526. ; 3:19, s. 5050-5055
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Journal article (peer-reviewed)abstract
- The emissive layer morphology strongly correlates with the charge transport and light-emitting performance of solution-processed phosphor-doped organic light-emitting diodes (PhOLEDs). Herein, morphology manipulation of the solution-processed emissive layer comprising of carbazole dendrimer (H2) host:blue phosphor (FIrpic) guest is realized via processing of the solvent and its influence on charge transport and light-emitting properties is investigated. The formation of H2 aggregates within its amorphous matrix processed with the toluene:p-xylene solvent mixture distinctively improves the hole and electron transport within the emissive layer, helping to lower the driving voltages and improve the light-emitting efficiency. However, excess aggregation of H2 would result in non-uniform dispersion of the FIrpic guest within the H2 host, leading to non-complete host-to-guest energy transfer and decreased electroluminescence performance. Through manipulation of the aggregates within the H2 host by varying the solvent mixture ratio, the trade off between charge transport and energy transfer is realized. Finally, the solution-processed blue PhOLED with optimized emissive layer morphology processed with toluene:p-xylene (9:1) solvent mixture achieves a high light-emitting efficiency of 27.8 cd A-1, corresponding to 25% enhancement compared to 22.2 cd A-1 of the control device processed with commonly used toluene solvent.
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| 5. |
- Zhang, Junqiao, et al.
(author)
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Interaction of P-glycoprotein with anti-tumor drugs : the site, gate and pathway
- 2015
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In: Soft Matter. - : Royal Society of Chemistry (RSC). - 1744-683X .- 1744-6848. ; 11:33, s. 6633-6641
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Journal article (peer-reviewed)abstract
- Understanding the mechanism and pathway of anti-cancer drugs to be pumped out by P-glycoprotein (P-gp) in cancer cell is very important for the successful chemotherapy. P-gp is a member of ATP-binding cassette (ABC) transporters. In this study, random accelerated molecular dynamics (RAMD) simulation was used to explore the potential egress pathway of ligands from the binding pocket. This could be considered as a reverse process of drug binding. The most possible portal of drugs to dissociate is TM4/TM6, which is almost the same for different drugs, such as paclitaxel and doxorubicin. The interactions in the binding site are found to be remarkably stronger than that outside of the binding site. The results were suggested by the free energy calculation between P-gp and different drugs from metadynamics simulation. All the results indicate that the flexibility of inner residues, especially the residue Phe339, is very important for the drugs to access the binding site.
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