Abstract:Polyethylenimine (PEI) is a cationic polymer able to interact with nucleic acids. Taking advantage of this property, PEI-modified functional surfaces for the capture of DNA were developed and characterized with X-ray photoelectron spectroscopy (XPS) during every step of the preparation. The XPS demonstrated the presence of PEI on the functional surfaces, while the density of PEI primary amino groups was quantified with a colorimetric test, resulting in 6 10 14 amino groups/cm 2 . Different amounts of DNA were … Show more
“…The slight negative shift of the Au 4 f peaks indicated that the gold surface was reduced by the non-protonated amino groups of PEI 13 . The positive shift of the C = O peak after PEI adsorption indicates the interactions between C = O and the positively charged amino groups of PEI 14,15 . These results show that the PEI layer interacts with both the carbonyl groups present on the treated surface and the Au metal surface.Figure 2XPS spectra of ( a ) N 1 s, ( b ) C 1 s of a PEI-O 2 Au electrode, and ( c ) C 1 s of an O 2 Au electrode.…”
Section: Resultsmentioning
confidence: 99%
“…After plasma treatment on Au surface, gold oxide is formed, carbon contamination is removed, and polar groups (e.g. CO) appear 14,15 . It has been reported that gold oxide and the sites of polar groups are non-uniform and discontinuous on the surface 17 .…”
High-performance devices based on conducting polymers (CPs) require the fabrication of a thick CP-coated electrode with high stability. Herein, we propose a method for enhancing the interfacial adhesion strength between a gold electrode and an electropolymerized polypyrrole (pPy) layer by introducing a polyethyleneimine (PEI) layer. Although this insulating layer hinders the initial growth of the pPy layer on the Au surface, it improves the adhesion by up to 250%. Therefore, a thick layer of pPy can be fabricated without delamination during drying. X-ray photoelectron spectroscopy shows that the PEI layer interacts with the Au surface via polar/ionic groups and van der Waals interactions. Scanning electron microscopy reveals that the cohesion of the pPy layer is stronger than the interfacial adhesion between the PEI layer and the pPy layer. Importantly, the electroactivities of pPy and its dopant are unaffected by the PEI layer, and the electrochemical storage capacity of the pPy layers on the PEI-coated Au electrodes increases with thickness, reaching ~530 mC/cm2. Negative potential sweep is detrimental to pPy layer adhesion: pPy layers on a bare Au electrode peel off instantly as the potential is swept from 0.2 to −0.7 V, and most of the charge stored in the layer becomes inaccessible. In contrast, pPy layers deposited on PEI coated Au electrode are mechanically stable and majority of the charge can be accessed, demonstrating that this method is also effective for enhancing electrochemical stability. Our simple approach can find utility in various applications involving CP-coated electrodes, where thickness-dependent performance must be improved without loss of stability.
“…The slight negative shift of the Au 4 f peaks indicated that the gold surface was reduced by the non-protonated amino groups of PEI 13 . The positive shift of the C = O peak after PEI adsorption indicates the interactions between C = O and the positively charged amino groups of PEI 14,15 . These results show that the PEI layer interacts with both the carbonyl groups present on the treated surface and the Au metal surface.Figure 2XPS spectra of ( a ) N 1 s, ( b ) C 1 s of a PEI-O 2 Au electrode, and ( c ) C 1 s of an O 2 Au electrode.…”
Section: Resultsmentioning
confidence: 99%
“…After plasma treatment on Au surface, gold oxide is formed, carbon contamination is removed, and polar groups (e.g. CO) appear 14,15 . It has been reported that gold oxide and the sites of polar groups are non-uniform and discontinuous on the surface 17 .…”
High-performance devices based on conducting polymers (CPs) require the fabrication of a thick CP-coated electrode with high stability. Herein, we propose a method for enhancing the interfacial adhesion strength between a gold electrode and an electropolymerized polypyrrole (pPy) layer by introducing a polyethyleneimine (PEI) layer. Although this insulating layer hinders the initial growth of the pPy layer on the Au surface, it improves the adhesion by up to 250%. Therefore, a thick layer of pPy can be fabricated without delamination during drying. X-ray photoelectron spectroscopy shows that the PEI layer interacts with the Au surface via polar/ionic groups and van der Waals interactions. Scanning electron microscopy reveals that the cohesion of the pPy layer is stronger than the interfacial adhesion between the PEI layer and the pPy layer. Importantly, the electroactivities of pPy and its dopant are unaffected by the PEI layer, and the electrochemical storage capacity of the pPy layers on the PEI-coated Au electrodes increases with thickness, reaching ~530 mC/cm2. Negative potential sweep is detrimental to pPy layer adhesion: pPy layers on a bare Au electrode peel off instantly as the potential is swept from 0.2 to −0.7 V, and most of the charge stored in the layer becomes inaccessible. In contrast, pPy layers deposited on PEI coated Au electrode are mechanically stable and majority of the charge can be accessed, demonstrating that this method is also effective for enhancing electrochemical stability. Our simple approach can find utility in various applications involving CP-coated electrodes, where thickness-dependent performance must be improved without loss of stability.
“…Similarly, it is possible to rule out that the increase in this band is related to the presence of hydroxyls (OH) in the hydrolyzed silane, because in the analysis of elemental composition, there was no significant change in the O/C ratio (0.33) on the surface of the sample Ox-Si, with respect to the Ox fiber. The high-resolution C 1s spectra of the Ox-PRE fiber besides the peak assigned to C-Si (confirming the presence of silane on the sample surface) an increase of the CO peak of 68.10 and 21.46% with the C-Si peak, respectively, which is attributed to the presence of epoxide groups present in the chemical structure of the resin coating [9,32]. A significant decrease in the peak assigned to COOH was observed, which allows saying that the surface chemistry of the Ox-PRE fiber is dominated by the epoxy coating, hiding the functional groups promoted with the oxidation treatment.…”
Section: Evaluation Of the Mwcnts Deposition Onmentioning
confidence: 68%
“…Furthermore, from the XPS high-resolution C 1s , the spectrum of the Ox-Si fiber, evidenced the appearance of a new peak at around 283.3 eV, which has been assigned to the C-Si bond [3,29,31], corroborating the presence of the silane on the sample. In addition, growth of the 286.6 eV peak is observed, which could be due to the presence of the Si-O-C bond and/or to the epoxide groups of the silane structure [3,9,32]. The formation of the Si-O-C covalent bond appears to be generated from the reaction and subsequent condensation between the silane and the carboxylic acid groups (Figure 3), due to a decrease in the COOH peak and an increase in the C=O, with respect to the Ox fiber.…”
Section: Evaluation Of the Mwcnts Deposition Onmentioning
Abstract. Multiwall carbon nanotubes (MWCNTs) previously treated with a cationic polymer were incorporated on the surface of carbon fibers modified by three different chemical treatments, namely, oxidation, oxidation-silanization and oxidation-pre-impregnation. Prior to the incorporation of the MWCNTs, the physical surface properties of the fibers were studied by contact angle and the chemical surface properties by X-ray photoelectron spectroscopy (XPS). The interfacial shear strength (IFSS) of the different systems carbon fiber-MWCNTs-matrix was evaluated using the single-fiber fragmentation test (SFFT) and it was observed that the IFSS of the oxidized-pre-impregnated fibers, was considerably higher than that observed for the other fiber-matrix systems. This was attributed to enhanced interfacial interactions because the fiber surface treatments improved the wettability of the carbon fiber and the MWCNTs, which resulted in a better fiber-matrix mechanical interlocking and to the formation of covalent bonds between the different phases of the composite.
“…After coating of CP, the peak A (401.9 eV) decreased, whereas peak B and peak C (400.2 eV, 398.4 eV) that were attributed to the CP clearly increased (Supplementary Fig. 5c) 44,45 . When APC was complexed with plasmid DNA, the elimination of peak A was due to the shielding effect after DNA complexation with APC (Supplementary Fig.…”
53We herein report the first optogenetically activatable CRISPR/Cas9 nanosystem for 54 programmable genome editing in the second near-infrared (NIR-II) optical window. The 55 nanosystem is composed of a cationic polymer-coated gold nanorod (APC) and Cas9 56 plasmid driven by a heat-inducible promoter. APC not only serves as a carrier for 57 intracellular plasmid delivery, but also can harvest external NIR-II photonic energy and 58 convert into local heat to induce the gene expression of Cas9 endonuclease. Due to high 59 transfection activity, APC shows strong ability to induce significant level of disruption in 60 different genome loci upon optogenetic activation. Moreover, the precise control of 61 genome editing activity can be simply programmed by finely tuning exposure time and 62 irradiation times in vitro and in vivo, and also enables editing at multiple time points, thus 63 proving the sensitivity and reversibility of such an editing modality. The NIR-II optical 64 feature of APC enables therapeutic genome editing at the deep tissue of the tumor-65 bearing mice, by which tumor growth could be effectively inhibited as a proof-of-concept 66 therapeutic example. Importantly, this modality of optogenetic genome editing can 67 significantly minimize the off-target effect of CRISPR/Cas9 in the most potential off-target 68 sites. The optogenetically activatable CRISPR/Cas9 nanosystem we have developed 69 offers a useful tool to expand the current applications of CRISPR/Cas9, and also defines 70 a programmable genome editing strategy towards unprecedented precision and 71 spatiotemporal specificity.
72
Introduction
73The RNA-guided clustered, regularly interspaced, short palindromic repeats (CRISPR)-74 associated nuclease protein 9 (Cas9) is originally an adaptive immune defense system, 75 by which many bacteria exploit to protect themselves from invading genetic elements 1 . It 76 has been recently harnessed as an efficient tool for genome editing in both single cells 77 and the whole organism for a wide range of biomedical applications in biology, genetics, 78 and medicine, etc 2,3 . In principle, the CRISPR/Cas9 is composed a single-guide RNA 79 (sgRNA) for the identification of DNA targets and a Cas9 endonuclease that can bind 80 and process the recognized DNA targets 4 . CRISPR/Cas9-based genome editing 81 technology offers a powerful and reliable strategy for the targeted modifications of the 82 genome, enabling the precise perturbation of virtually any genomic sequence in living 83 cells 2-6 . Due to its genome-wide specificity and multiplexing capability, Cas9 and its 84 variants have shown great potentials in the generation of loss-of-function animals 7,8 , the 85 correction of genetic disorders 9,10 , functional genome screening [11][12][13][14][15] , and the treatment of 86 infectious diseases 16,17 . Despite of these excitements, the lack of temporal and spatial 87 precision during editing process has severely constrained the current CRISPR/Cas9 88 systems from complicated and diverse genome-editing s...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
