Background: Low molecular mass hyaluronan (LMHA) is proinflammatory, but the role of the N-acetyl moieties is unknown. Results: Chemical reacetylation of LMHA results in maximal proinflammatory cytokine production by human macrophages, compared with other N-acylations. Partial N-butyrylation blocks cytokine stimulation.
Conclusion:The N-acetyl moieties of glucosamine are critical for LMHA proinflammatory properties. Significance: N-Acetylation and butyrylation of LMHA modulate proinflammatory cytokine production.
The viscoelastic properties of four novel, low molecular weight hyaluronic acid derivatives were investigated and compared to the parent hyaluronic acid compound. Briefly, all derivatives were synthesized by first deacetylating the parent hyaluronic acid. One sample was left as such, while two others were reacytelated. The final compound, of particular interest for its anti-inflammatory properties, was butyrylated. The compounds were dissolved in phosphate buffer solution (PBS) and studied at a concentration of 5 mg/mL. Shear thinning behaviour was observed for all compounds, however, derivative samples had a lower viscosity than the parent compound at high shear rates. Viscoelastic properties were also observed to decrease as a result of the derivative preparation method. It is believed that these changes are primarily caused by a decrease in hyaluronic acid molecular weight. By increasing the concentration of the anti-inflammatory compound, it may be possible to modulate the viscoelastic properties to more closely resemble those of commercial viscosupplements. As a result, an anti-inflammatory derivative of hyaluronic acid may potentially improve upon existing viscosupplements used to treat patients who are susceptible to flare up.
Es st ti im ma at ti io on n o of f F Fr re ee e R Ra ad di ic ca al l P Po ol ly ym me er ri iz za at ti io on n R Ra at te e C Co oe ef ff fi ic ci ie en nt ts s u us si in ng g C Co om mp pu ut ta at ti io on na al l C Ch he em mi is st tr ry y by Siziwe Bebe A thesis submitted to the Department of Chemical Engineering In conformity with the requirements for the degree of Doctor of Philosophy
Corrosion monitoring and management has been at the center of structural health monitoring protocols due to its damaging effects on metallic structures. Current corrosion prevention and management programs often fail to include environmental factors such as Cl− ions and surface wetness. Early detection of these environmental factors can prevent the onset of corrosion and reduce repair and maintenance-related expenses. There is growing interest in creating solution-processed thin film environmental sensors with high sensitivity to corrosion precursors, low-cost fabrication, and small footprint, rendering them viable candidates for investigation as potential corrosion sensors that could be easily integrated into existing structures and screen printed or patterned directly into surface coatings. In this work, we have implemented C60-based n-type organic thin film transistors (OTFTs) with functionalized graphene oxide for humidity sensing and functionalized graphene nanoparticles for Cl− ion detection, using low-cost solution processing techniques. The reduced graphene oxide (rGO)-coated OTFT humidity sensor is designed for the qualitative estimation of surface moisture levels and high levels of humidity, and it exhibits a relative responsivity for dry to surface wetness transition of 122.6% to surface wetness, within a response time of 20 ms. We furthermore implemented an in-house synthesized hydrogenated graphene coating in conjunction with a second OTFT architecture for Cl− ions sensing which yielded a sensitivity of 4%/ppm to ultrafine ionic concentrations, over an order of magnitude lower than the range identified to cause corrosion in aircraft structures.
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