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Protein adhesion regulated by the nanoscale surface conformation
Cho, Eun Chul,Kong, Hyunjoon,Oh, Tae Byeong,Cho, Kilwon The Royal Society of Chemistry 2012 Soft matter Vol.8 No.47
<P>Protein adhesion and adsorption behaviors vary in response to variations in surface wettability; however, few reports have examined the dependence of such behaviors on variations in the surface molecular conformations. This study examines the degree to which molecular disorder at the surface of a surface-modified hydrocarbon chain monolayer regulates protein adhesion. Octadecyltrichlorosilane (OTS) molecules were deposited onto silicon wafers at two temperatures, 5 °C or 55 °C, to prepare two OTS surfaces with different degrees of molecular disorder. Atomic force microscopy (AFM) was used to evaluate the nanoscale adhesion force between proteins and the two types of OTS monolayers during a short contact time (<1 s). Bovine serum albumin (BSA) and human fibrinogen (HF) adhered more strongly to the disordered than to the ordered OTS monolayer. The adhesion strength at longer contact times (30 s–90 min) was evaluated by investigating the resistance of proteins on the OTS monolayer to detachment by washing. The magnitude of the resistance could be predicted from the topologies of the monolayers, as determined by AFM, after the adsorption of proteins and the subsequent washing experiments. After a 90 min adsorption period, BSA displayed a higher resistance to detachment from the disordered OTS monolayer than from the ordered OTS monolayer. HF displayed a higher resistance to detachment from the disordered OTS monolayer for only very short adsorption times of less than 1 min. The results suggest that the proteins altered their adhesion onto monolayers with different OTS conformations and that different adsorption times were required for each protein to present the different degrees of adhesion.</P> <P>Graphic Abstract</P><P>The molecular order of an underlying organic monolayer determines the adhesion behaviors of proteins onto these surfaces. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c2sm27204k'> </P>
Cho, Illhun,Park, Sang Kyu,Kang, Boseok,Chung, Jong Won,Kim, Jin Hong,Yoon, Won Sik,Cho, Kilwon,Park, Soo Young The Royal Society of Chemistry 2016 Journal of Materials Chemistry C Vol.4 No.40
<▼1><▼1><P><I>Via</I> the cooperative effects of intramolecular charge transfer interactions and extension of conjugation, low-band gap organic semiconductors have successfully been prepared.</P></▼1><▼2><P>A series of low-band-gap π-conjugated molecules comprising <I>N</I>,<I>N</I>′-dihexylindolo[3,2-<I>b</I>]indole as an electron donor (D) and dicyanovinyl as an electron acceptor (A) with A–π–D–π–A architecture have been designed and synthesized to fabricate a single-component ambipolar organic field-effect transistor (OFET). Molecules with different π-bridging units (none, thiophene, and bithiophene) were synthesized and characterized to investigate their structure–property correlation. <I>Via</I> the cooperative effects of intramolecular charge transfer (ICT) interactions and extension of conjugation, the band gap of the newly synthesized molecules was reduced to 1.41 eV in the solution state. Among other compounds, 2H2TIDID-DCV (with a thiophene π-spacer) exhibited highly balanced ambipolar charge transport with hole and electron mobilities of 0.08 cm<SUP>2</SUP> V<SUP>−1</SUP> s<SUP>−1</SUP> and 0.09 cm<SUP>2</SUP> V<SUP>−1</SUP> s<SUP>−1</SUP>, respectively, from a vacuum-deposited OFET device. Spin-coated OFET devices using OD2TIDID-DCV, in which the hexyl side chains of 2H2TIDID-DCV are replaced by 2-octyldodecyl groups, also exhibited an ambipolar charge-transporting nature (mobilities of 9.67 × 10<SUP>−2</SUP> cm<SUP>2</SUP> V<SUP>−1</SUP> s<SUP>−1</SUP> for holes and 3.43 × 10<SUP>−3</SUP> cm<SUP>2</SUP> V<SUP>−1</SUP> s<SUP>−1</SUP> for electrons). Both 2H2TIDID-DCV and OD2TIDID-DCV exhibited favorable thin-film morphology for the formation of charge-transporting channels, and structural analyses of these films revealed the same molecular packing characteristics of a three-dimensional lamellar π-stacking structure.</P></▼2></▼1>
Cho, Kilwon,Yang, Jaeho,Yoon, Soong,Hwang, Minku,Nair, Sobha V. Wiley Subscription Services, Inc., A Wiley Company 2005 Journal of applied polymer science Vol.95 No.3
<P>The toughening behavior of polycarbonate modified with core-shell type particles was investigated. The alloys were found to exhibit maximum impact strength upon addition of a modifier with a poly(butyl acrylate) rubbery core of 0.25 μm diameter. The incorporation of particles with diameter greater than 0.25 μm resulted in decreased impact strength. The influence of rubber phase contents on toughness was also studied. It was observed that the alloys exhibited maximum impact strength upon addition of 4 wt % rubber phase. Further increase in the rubber phase content resulted in reduced impact strength. Fractography of the samples showed that, below 4 wt % rubber phase content, the fracture occurs mainly by internal crazing and, from 4 wt % onward, only by shear deformation. When the effect of dual particle size distribution was analyzed, it was found that there was only a moderate increase in toughness compared with alloys containing monosized particles. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 748–755, 2005</P>