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A Fluorescence Fluctuation Spectroscopy Assay of Protein-Protein Interactions at Cell-Cell Contacts
摘要： A variety of biological processes involves cell-cell interactions, typically mediated by proteins that interact at the interface between neighboring cells. Of interest, only few assays are capable of specifically probing such interactions directly in living cells. Here, we present an assay to measure the binding of proteins expressed at the surfaces of neighboring cells, at cell-cell contacts. This assay consists of two steps: mixing of cells expressing the proteins of interest fused to different fluorescent proteins, followed by fluorescence fluctuation spectroscopy measurements at cell-cell contacts using a confocal laser scanning microscope. We demonstrate the feasibility of this assay in a biologically relevant context by measuring the interactions of the amyloid precursor-like protein 1 (APLP1) across cell-cell junctions. We provide detailed protocols on the data acquisition using fluorescence-based techniques (scanning fluorescence cross-correlation spectroscopy, cross-correlation number and brightness analysis) and the required instrument calibrations. Further, we discuss critical steps in the data analysis and how to identify and correct external, spurious signal variations, such as those due to photobleaching or cell movement.
关键词： Issue 142,cell-cell adhesion,fluorescence correlation spectroscopy,cell-cell interactions,Protein-protein interactions,number and brightness,fluorescence fluctuation spectroscopy,Biochemistry,N&B
更新于2025-09-09 09:28:46
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[IEEE 2018 19th International Conference on Electronic Packaging Technology (ICEPT) - Shanghai (2018.8.8-2018.8.11)] 2018 19th International Conference on Electronic Packaging Technology (ICEPT) - Plasma Impact on PI Roughness
摘要： The standard pillar bump structure [1-3] is shown in Figure 2. Polyimide Re-passivation (PI) layer is widely used for pillar bump structure due to the increasingly stringent reliability requirements [4-5]. PI layer serves as stress buffer layer which can enhance the structure reliability performance. And PI will be the direct surface contact material to FCBGA molding compound, so the PI surface roughness is a key factor to the adhesion between PI and molding compound. Lower surface roughness will cause delamination between PI and molding compound while higher surface roughness may cause flip chip process issue like back-grinding tape residue due to higher adhesion between PI and back-grinding tape [6-7]. During the pillar bump process, the PI surface roughness is influenced by many plasma steps like gas and so on. In the present paper, plasma process parameters such as gas, process power and process time are studied in order to get the correlation between these process parameters and PI surface roughness result. This correlation can be used to further study the surface roughness with the assembly site required at the assembly process. As depicted in Figure 3, there are distinctions in the diffraction values of Selected Area Diffraction Pattern (SADP) in different process steps (PI Curing, O2 Descum, RF, Etch, Ar Descum). The influence of different gases plasma on PI surface roughness is quite significant, among which O2 plasma has more significant impact than others, which provides guidance for further research of PI surface roughness in FCBGA
关键词： PI surface roughness,Plasma,PI layer,Adhesion
更新于2025-09-09 09:28:46
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Determination of interfacial fracture energy for 'pop-in' delaminations in a glass-epoxy system using the indentation method
摘要： The adhesion of coatings often controls the performance of the substrate-coating system. Certain engineering applications require an epoxy coating on a brittle substrate to protect and improve the performance of the substrate. Interfacial adhesion measurements of such systems provide a quantitative metric of that performance. Indentation experiments were performed to induce interfacial delaminations in a glass substrate-epoxy coating system. Delamination loads and radii were measured and applied to an analytical solution originally developed by Rosenfeld et al. (1990) to estimate the interfacial fracture energy of the substrate-coating adhesive bond. Results suggest an interfacial bond strength far exceeding that of similar previously studied glass-epoxy systems.
关键词： bonding,indentation,glass,coatings,epoxy,interfaces,fracture energy,adhesion
更新于2025-09-09 09:28:46
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Surface Modification of Fluoropolymer Using Open-Air Plasma Treatment at Atmospheric Pressure with Ar, Ar＋O<sub>2</sub>, and Ar＋H<sub>2</sub> for Application in HighAdhesion Metal Wiring Patterns
摘要： We performed open-air plasma treatment of polytetrafluoroethylene (PTFE) at atmospheric pressure to increase the adhesion strength between PTFE and an Ag metal film formed from Ag ink. Coloration of the PTFE surface occurred during 600 s treatment with Ar plasma. The Ag/PTFE adhesion strength was 0.06 N/mm. To resolve the problem of coloration and to improve the adhesion strength, O2 or H2 gas was added. During treatment with Ar + O2 plasma with O2 content of 0.33% for 600 s, no coloration occurred but the adhesion strength decreased to zero. During treatment with Ar + H2 plasma for 600 s, coloration did not occur. Moreover, the adhesion strength increased to 0.25-0.55 N/mm. These results showed that H2 addition was effective for preventing coloration and improving adhesion strength during long-period plasma treatment. Furthermore, the uniformity of surface treatment with Ar + H2 plasma was higher than that for Ar plasma.
关键词： Adhesion,Ag Ink,Printed Circuit Board for High-Frequency,Polytetrafluoroethylene (PTFE),Atmospheric Plasma Treatment
更新于2025-09-09 09:28:46
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Deposition of pure Cu films on glass substrates by decomposition of Cu complex pastes at 250 °C and additional Cu plating
摘要： Pure Cu film strongly adherent to glass substrates was deposited by printing Cu(COOH)2-containing paste and decomposing it at 250 °C in nitrogen atmosphere. The complete transformation of Cu(COOH)2 into Cu required 30 min and generated a low sheet resistance of 0.167 Ω/sq (volume resistivity: 15.0 μΩ·cm). Maximum adhesion between the Cu film and substrate was attained at the Cu complexes:α-terpineol mixing ratio of 6:4 by weight. The spike-shaped microstructure at the Cu/glass interface was determined to be the main cause for the outstanding adhesion properties. The resistance further decreased to 0.084 Ω/sq by increasing the thickness and modifying the surface of the Cu film via electroless Cu plating.
关键词： Cu complex paste,Cu film,Glass substrate,Decomposition,Adhesion
更新于2025-09-04 15:30:14
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Heparin-grafted PVA hydrogels: a material for the optical part of artificial cornea
摘要： Heparin (Hep) was grafted to a poly(vinyl alcohol) (PVA) hydrogel surface by using the covalent grafting method. The structure of the modified hydrogel was determined from Fourier transform infrared attenuated total reflection and X-ray photoelectron spectroscopy. The effects of the concentration of (3-aminopropyl)triethoxysilane (kh550) and Hep on visible light transmittance, moisture content, equilibrium swelling, hydrophilicity and percentage of Hep sodium release of the composite hydrogel were studied. The visible light transmittance of the modified PVA hydrogel was above 94%. The time of swelling equilibrium was about 60 min and the equilibrium swelling ratio ranged from 3·0 to 3·5. The hydrophilicity was enhanced, and the static water contact angle decreased from 41 to 28°. The bioeffects of the PVA–kh550–Hep hydrogel were evaluated by studying cell adhesion and proliferation. During the adhesion assay in vitro, cell adhesion significantly decreased after the interfaces had been modified with Hep. The Cell Counting Kit-8 assay showed that the biocompatibility of the PVA–kh550–Hep hydrogel improved obviously compared to that of pure PVA. The experimental results demonstrated that the PVA–kh550–Hep hydrogel had good stability, bioactivity and biocompatibility, suggesting its potential applications in artificial corneas.
关键词： biocompatibility,surface modification,adhesion
更新于2025-09-04 15:30:14
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Neuronal Expression of Junctional Adhesion Molecule-C is Essential for Retinal Thickness and Photoreceptor Survival
摘要： Background: Photoreceptor cell death is a key pathology of retinal degeneration diseases. To date, the molecular mechanisms for this pathological process remain largely unclear. Junctional adhesion molecule-c (Jam-c) has been shown to play important roles in different biological events. However, its effect on retinal neuronal cells is unknown. Objective: To determine the effect of Jam-c on adult mouse eyes, particularly, on retinal structure, vasculature and photoreceptor cells, in order to explore potential important target molecules for ocular diseases. Methods: Jam-c global knockout mice, endothelial-specific and neuronal-specific Jam-c conditional knockout mice using Tie2-Cre and Nestin-Cre mice respectively were used in this study. Mouse eyes were harvested from the different groups and eye size examined. Cryosections of the eyes were made and stained with Hematoxylin and Eosin (H&E) and the thicknesses of retinal layers measured. Retinal blood vessels and cone and rod photoreceptors were analyzed using isolectin B4, peanut agglutinin and rhodopsin as markers respectively. In vivo Jam-c knockdown in mouse eyes was performed by intravitreal injection of Jam-c shRNA. Jam-c expression in the retinae was quantified by real-time PCR. Results: Global Jam-c gene deletion in mice resulted in smaller eyes and decreased the diameters of lens and iris. Jam-c-/- mice display marked thinning of the outer nuclear layer (ONL), less numbers of photoreceptor cells, and abnormal retinal vasculature. Importantly, neuronal-specific Jam-c deletion led to similar phenotype, whereas no obvious defect was observed in endothelial-specific Jam-c knockout mice. Moreover, Jam-c knockdown by shRNA also decreased ONL thickness and photoreceptor numbers. Conclusion: We found that Jam-c is critically required for the normal size and retinal structure. Particularly, Jam-c plays important roles in maintaining the normal retinal thickness, vasculature and photoreceptor numbers. Jam-c thus may therefore have important roles in various ocular diseases.
关键词： retina,photoreceptor degeneration,neuroprotection.,vasculature,Junctional adhesion molecule-c
更新于2025-09-04 15:30:14
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Effect of interfacial voltage on tribological characteristics of polysilicon micro-contacts tested in ambient air under dynamic impact conditions
摘要： A polycrystalline silicon microtribometer was used to examine the evolution of tribological properties under dynamic mechanical impact and hot switching conditions. Changes in surface properties were tracked via periodic static adhesion tests. Surfaces experienced two distinct periods in the course of the dynamic lifetime – a run-in phase with little measurable surface modification and a degradation phase with significant surface modification and corresponding increases in the measured adhesion force. No statistically significant differences were found in either the run-in period length or the degradation rate between hot switching conditions and purely mechanical switching, microelectromechanical systems.
关键词： asperity contacts,surface hydrocarbons,hot switching,tribology,Adhesion,ambient air testing
更新于2025-09-04 15:30:14
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Photodetachable Adhesion
摘要： Peeling from strong adhesion is hard, and sometimes painful. Herein, an approach is described to achieve both strong adhesion and easy detachment. The latter is triggered, on-demand, through an exposure to light of a certain frequency range. The principle of photodetachable adhesion is first demonstrated using two hydrogels as adherends. Each hydrogel has a covalent polymer network, but does not have functional groups for bonding, so that the two hydrogels by themselves adhere poorly. The two hydrogels, however, adhere strongly when an aqueous solution of polymer chains is spread on the surfaces of the hydrogels and is triggered to form a stitching polymer network in situ, in topological entanglement with the pre-existing polymer networks of the two hydrogels. The two hydrogels detach easily when the stitching polymer network is so functionalized that it undergoes a gel–sol transition in response to a UV light. For example, two pieces of alginate–polyacrylamide hydrogels achieve adhesion energies about 1400 and 10 J m?2, respectively, before and after the UV radiation. Experiments are conducted to study the physics and chemistry of this strong and photodetachable adhesion, and to adhere and detach various materials, including hydrogels, elastomers, and inorganic solids.
关键词： hydrogels,light-triggered,photodetachable adhesion,topological
更新于2025-09-04 15:30:14