Browsing by Subject "Coatings"

Now showing 1 - 5 of 5
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    16S RNA data for biofilm in contact with antimicrobial peptide coatings
    (2020-04-23) Aparicio, Conrado; Moussa, Dina G.; apari003@umn.edu; Aparicio, Conrado; Minnesota Dental Research Center for Biomaterials and Biomechanics
    Dual-indexed 16S rRNA gene amplicon sequencing using the V3-V4 region on the Illumina MiSeq platform 300PE for triplicate samples of biofilm from stocks of oral plaque sample grown on hydroxyapaptite discs without (CTRL) and with antimicrobial peptide (1018, DJK2, D-GL13K) coatings, treated and non-treated with PMA. This data was collected as part of the NIDCR funded project R01-DE to determine the effects of antimicrobial peptides in the microbiome of biofilms from oral plaque stocks to prevent degradation of dental restorations. The data was generated at the University of Minnesota Genomics Center and analyzed at the University of Minnesota Informatics Institute. The data is released to be of public access following submission of a manuscript presenting and analyzing this data.
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    Coating and printing on chemically patterned surfaces.
    (2012-03) Kalpathy, Sreeram Krishnamoorthy
    A number of emerging applications like flexible electronic devices and displays and patterned microfluidic devices require selective deposition of material on micro- and nanoscale patterns. At these length scales, mathematical models with appropriate simplifying assumptions would prove handy to understand liquid dewetting mechanisms in coating and printing processes. For example, the liquid films in many coating and printing processes may be assumed to be thin enough so that intermolecular forces are important and the lubrication approximation can be invoked. Using a combination of nonlinear simulations and linear stability analysis, three important problems pertaining to coating and printing on chemically patterned surfaces are examined. The first problem is concerned with the liquid displacement phenomenon that occurs in lithographic printing processes. The model allows us to obtain physical insights into and numerical estimates of the smallest and largest feature sizes that can be printed, as well as the minimum spacing between feature sizes that can be tolerated. In addition, the model provides insights into experimental observations on a closely related process, wire-wound rod coating on chemically patterned surfaces. Next, the model is used to examine the effect of shear on the liquid displacement process. Linear theory reveals that the growth rate of interfacial perturbations has an imaginary component, indicating the existence of traveling waves. Nonlinear simulations show that shear delays interfacial rupture, and suppression of rupture occurs beyond a critical shear rate. Propagation of traveling waves along the interface, and subsequent weakening of van-der-Waals-driven dewetting, is found to be the cause of the rupture delay. Finally, the dewetting of a solitary liquid film resting on a chemically patterned surface, under the combined action of thermally induced Marangoni effects and the intermolecular forces is explored. The model results suggest that combined localized heating and cooling may be used to modify the film rupture dynamics induced by the disjoining forces and cause rupture at desired locations. This physical phenomenon provides a handle to deposit liquids on surfaces whose wettability is difficult to control. The work presented here has special practical relevance for manipulating liquid flow in industrial applications like templating, coating and printing processes, and microfluidics.
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    Flow and Drying Dynamics in Gravity- and Capillary-Driven Coating Processes
    (2017-06) Lade, Robert
    Liquid-applied coatings are ubiquitous. Buildings, bridges, soda cans, compact discs, and newspapers make up a small fraction of everyday objects whose surfaces are enhanced by coatings. Typical processing steps for a liquid-applied coating include coating formulation, application, post-deposition flow, and solidification. This thesis focuses on the balance between the last two steps of this process and how this balance influences coating behavior and the ultimate quality of the final film. Specifically, post-deposition coating flows driven by gravity or capillarity are investigated in liquid systems that undergo evaporation-induced drying. In Chapter 2, coating defects caused by excessive gravity-driven flow (‘sag’) are studied. A novel particle tracking method is first developed to monitor sag in a model aqueous polymer system. A computational model is developed concurrently to validate the measurements made using particle tracking. This model is then used to generate a novel framework for predicting sag in liquid-applied coatings. Chapters 3–5 focus on capillary-driven flows in open microchannels. First, in Chapter 3, capillary flow dynamics of non-evaporating liquids are studied and compared against existing theoretical models. In Chapter 4, this work is extended to open microchannels fabricated using several three-dimensional (3D) printing technologies. 3D printed microchannels are found to confer unique flow dynamics to the capillary flow, including a distinct start–stop motion caused by surface roughness introduced by the 3D printing process. Finally, in Chapter 5, the influence of drying on capillary flow dynamics is investigated, again using a model aqueous polymer coating system. Drying is found to permanently pin the advancing contact line partway down the channel; three mechanisms of pinning are identified and characterized. Post-pinning flows induced by the coffee ring effect are found to lead to highly non-uniform dry film morphologies. The influence of surfactant, drying rate, and channel width are investigated. Throughout all of this work, the goal is to better understand the balance between flow and drying to facilitate prediction and control of coating behavior during relevant coating processes. As part of this goal, case studies are conducted throughout this thesis, investigating flow and drying behavior in real systems used in commercial coating processes, including latex paints and functional inks used in the manufacture of printed electronic devices.
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    Immunomodulation of oral keratinocytes through titanium surface peptide coatings of cell adhesion oligopeptide motifs and IL-23 Receptor antagonist
    (2021-11) Pizarek, John
    Objectives: Peri-implantitis is the leading cause of implant failure with a prevalence of 8-34%. The dysbiotic bacterial invasion of the peri-implant surface leads to an inflammatory reaction of oral keratinocytes (OK) that attach to the implant surface via the junctional epithelium. During stages of inflammation, the attachment of keratinocytes to bound surfaces decreases. We evaluated OKs’ cytokine response to cell adhesion motif peptides, shown to increase hemidesmosomes (LamLG3 and Net1), bound to plasma activated glass (pGlass), compared to controls pGlass and activated pGlass (DIBO). Next, the innate inflammatory response of OKs through cytokine production, specifically the IL-17/IL-23 inflammatory axis, can induce activation of neutrophils and Th17 cells that are present in higher levels in peri-implantitis. We evaluated an IL-23 receptor antagonist (IL-23Ra) bound to etched titanium for cell proliferation of OKs, production of IL-17 and 23, and cytokine secretome regulation. By inducing cell adhesion or regulating the IL-17/23 pathway may reduce the induction and recruitment of aforementioned inflammatory cells, promoting integrity of the soft tissue interface of implants at sites of bacterial infection.Methods: Plasma disks were covalently functionalized with Net1 and LamLG3 and titanium disks were covalently functionalized with IL-23Ra using silanization. Disks in the cell adhesion studied had activated pGlass (DIBO), uncoated surface, and an antimicrobial peptide serving as controls, and the IL-23Ra study had disks with a randomized sequence peptide and non-coated disks serving as controls. IL-23Ra-coatings were physicochemically analyzed with water contact angle and X-ray photoelectron spectroscopy. Proliferation of OKs was measured. ELISAs were used to analyze levels of IL-23 and IL-17 in presence and absence of pro-inflammatory Porphyromonas gingivalis lipopolysaccharide (LPS). For both studies, supernatant and cell lysates were collected at 5 days and analyzed using a 20 and 36-target cytokine array. The IL-23Ra study assessed the cytokine array with a functional protein association network analysis (STRING). ANOVA and Tukey post-hoc tests assessed statistical significance (p<0.05) Results: Physicochemical analysis demonstrated the successful immobilization of the peptide coatings. The cell adhesion peptides showed a decrease in the production of pro-inflammatory cytokines compared to the three controls. On the other hand, the IL-23Ra-coated titanium significantly increased proliferation of OKs. Further, the IL-23Ra significantly decreased secretion of IL-17 and IL-23, both with and without LPS stimulation, compared to controls. Conclusions: Our results support the use of IL-23Ra-coatings for reduction of the keratinocyte IL17/23 pro-inflammatory pathway and the use of cell adhesion peptides for the reduction of pro-inflammatory cytokine secretion, and may inform immunomodulatory dental implant designs for soft tissue attachment to thereby reduce peri-implantitis rates.
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    Stress and microstructure development in particle-based coatings
    (2014-09) Price, Kyle Kirk-Arthur
    Particle-based coatings have a wide range of uses and applications in everyday life. Stress development during the drying process has the potential to impact the performance of the coating. Stress development can be monitored in-situ using a cantilever deflection technique with a laser-photodiode combination. Stress development in the film is directly related to the development of the coating microstructure during drying. Cryogenic scanning electron microscopy (cryoSEM) is a powerful characterization method capable of visualizing the microstructure of the coating during the intermediate stages of drying. Using this method, the coating is frozen to arrest microstructure development and solidify the sample so that it can survive the high-vacuum environment of the SEM. This thesis explores the connections between stress and microstructure development in particle-based coatings during drying. Characterization is often complicated by lateral drying, a common phenomenon in particle-based coatings. To avoid these complications, walled substrates were developed which are used to suppress lateral drying and promote drying uniformity. CryoSEM revealed that latex coatings dried on substrates (with photoresist walls) exhibit a greater degree of drying uniformity. Silicon cantilevers with poly(dimethyl siloxane) (PDMS) walls along the perimeter were used to suppress the effects of lateral drying during stress measurement. The walled cantilevers were used to characterize stress development in ceramic particle coatings and latex films. For the ceramic particle coatings, stress measurements were combined with cryoSEM revealing the origins of stress development in hard particle coatings. Stress development was correlated with the extent of drying and the degree of saturation in the coating. Stress development in latex particle coatings was influenced by the composition and morphology of the latex particles. Additionally, the influence of coalescing aids on stress development was also investigated. The film formation behavior was studied using a variety of techniques including AFM, cryoSEM, and minimum film formation temperature (MFFT) measurements.