Saudi Cultural Missions Theses & Dissertations
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Item Restricted Importance of light activation for plant Cryptochrome and antibacterial drug delivery strategies(Saudi Digital Library, 2022-12-18) Hammad, Merfat; Bashur, ChrisThe goal of this project is to investigate the benefits of applying light in different systems. In the first part, the magnetoreception process that occurs in the light- activated cryptochrome of Arabidopsis Thaliana was investigated. In the second part, photo-carbon monoxide releasing molecules (photo-CORMs) were investigated for their antibacterial effect to develop biomedical strategies. Overall, this has been achieved in three different studies. The first study investigated if the forward light-driven reaction is involved in the magnetoreception process or not in cryptochrome (CRY). To accomplish this, the plant seedlings were tested for 90 minutes as follows: 5 minutes in the light and 10 minutes in the dark. The in vivo phosphorylated cryptochrome was then measured directly and quantitatively by western blotting under the influence of a 500 μT static magnetic field (SMF). Second, the quantitative plant hypocotyl growth assay was tested. This has eliminated the possibility that that short-lived radical pairs produced in the light-driven reaction could be involved in the magnetic sensitivity of Arabidopsis Thaliana. In the second study, the magnetic sensitivity of CRY was investigated during interaction with different types of magnetic fields. Therefore, the Radiofrequency (RF) Magnetic Field and the Low-Level Field (LLF) were applied to confirm the effect of the weak static magnetic fields on the light-activated cryptochrome biological activity. This was detected via various quantitative assays to measure the cryptochrome response, including the phosphorylation assay, the hypocotyl growth assay, and the quantitative polymerase chain reaction (qPCR). This study demonstrated that RF and LLF significantly reduced cry activity, resulting in an increase in hypocotyl length. In the third study, the second part of the project aimed to use the light trigger strategy to investigate the antibacterial effect of CO. This was done through the activation of photo-CORMs to deliver controlled doses of CO upon activation. Scanning electron microscope (SEM) and zone of inhibition assay were used to study the effect of CO on E. coli. These results have shown that an organic diketone photo-CORM (DK4) compound has a dose-dependent antibacterial effect that affects bacterial cells' attachment to the substrate and biofilm maturation.17 0Item Restricted Evaluation of Ion Release, Antibacterial characteristics, and Optical Properties of Newly Formulated Dental Composites with Zinc-Containing Glass Fillers(Saudi Digital Library, 2023-10-31) Alreshidi, Sanad; Hill, Robert; Friel, TimIntroduction: To create bacteriocidal zinc-releasing glasses for dental restorative applications, the decomposition of zinc-containing bioactive glasses has been previously researched. At neutral and higher pHs, relatively little zinc is released in bioactive glasses; only under acidic conditions is the zinc significantly released. Marginal leakage and recurrent decay are the main issues with modern restorative resin composites. Therefore, the creation of bioactive dental composites that include apatite-forming bioactive glasses is currently of great interest. Such composites would benefit from having a bacteriocidal characteristic, especially if the glass could release zinc under acidic conditions but not under neutral ones. Aims: The purpose of this study was to explore the feasibility of developing a novel dental composite containing zinc-releasing glasses that has radiopacity comparable to that of currently used resins in dental composites but does not produce apatite in both acidic and neutral environments. Methods: A melt quench method was used to synthesise three glasses with varying ZnO contents (0, 5, and 10%), which were then ground and sieved to create fine glass powders measuring 38 microns. The experimental dental composite discs had a 10 mm diameter, a 2 mm thickness, and an average weight of 0.35 grams. They were made using zinc-containing glass. 30% zinc-containing glass and 70% resin made up the mixture. Their characteristics were determined using XRD, ATR-FTIR, and dissolution tests in both Tris buffer at pH 7.35 and 0.1M acetic acid at pH 4. With the use of an ICP-OES and a fluoride ion selective electrode, ion release was monitored as a function of immersion time. Results: The Zn-containing glasses that were created (0, 5 and 10%) were amorphous. However, the generated Zn-containing glasses (5 and 10%) demonstrated a shift from an amorphous glass structure to the formation of crystalline apatite upon immersion in acetic acid and Tris buffer, as shown by XRD examination. But when submerged in acetic acid, all the ZnO-containing glasses quickly disintegrated. In contrast, the glasses disintegrated slowly and released relatively little Zn in the Tris buffer. Moreover, the radiolucency of the prepared Zn-containing composites was decreased with the increase of Zn percentage. Conclusions: When the concentration of ZnO was raised, apatite could be produced by Zn-containing bioactive glasses in both acidic and neutral conditions. Zn-containing bioactive glasses are probably more likely to dissolve fast at acidic pH values while slowly evaporating at neutral pH values. Due to ZnO integration, the experimental Zn-containing composite loses radiolucency as ZnO content increases.11 0Item Restricted Minimally Invasive Dentistry via Dual-Function Novel Bioactive Low-Shrinkage-Stress Flowable Nanocomposite.(2023) Albeshir, Ebtehal; Xu, HuakunThe application of biomaterials science is unique in dentistry because of the complexity of the oral cavity. The oral environment is considered the most challenging for material in the body in which high mechanical loading, bacteria, changing pH, and a warm, fluid environment. Understanding the physical, chemical, biological, and biocompatibility of restorative material is very important when choosing materials for specific dental applications and designing the best solution to replace tissue lost to disease or trauma. Resin-based composite has been introduced into conservative dentistry to minimize acrylic resins' drawbacks and silicate cements and amalgam restorations. It is the material of choice in dailydental practice for several reasons, including their good mechanical properties, conservative cavity design, and superior esthetics. However, the longevity of current resin composite restorations ranges only 5-10 years. Gap formation, recurrent caries and tooth fracture are the most common types of failure of clinical service. These failures are often caused directly or indirectly by the polymerization shrinkage stress of the dental composite materials. Thus, there is an increased need to develop a new generation of bioactive dental composite with the ability to reduce polymerization shrinkage stress, long-term antibacterial, remineralization abilities, and excellent mechanical properties. Therefore, this dissertation aims to develop a new bioactive low-shrinkage- stress dental composite containing dimethylaminohexadecyl methacrylate (DMAHDM) and nanoparticles of amorphous calcium phosphate (NACP) and nanoparticles of calcium fluoride (nCaF2) which could be a promising approach to increase the chances of success of composite restorations and strengthen tooth structures. First, we formulated optimum percentage of bioactive low-shrinkage-stress resin composite with proper concentration of long lasting copolymerized antibacterial DMAHDM, and adequate percentage of remineralization nanoparticles. Second, we performed several investigations to test the novel formulations. The physical, mechanical, and biological experiments were studied. We found that the new bioactive low-shrinkage-stress resin composite significantly reduced the bacterial counts and metabolic activites, without compromising their mechanical properties in comparing to the commercial control and experimental control composites. The novel formulation of “45% UV+5% DMAHDM+20% NACP+30% glass” and “47% UV+3% DMAHDM+20% nCaF2+30% glass” potent triple benefits of antibacterial, remineralization, and lower shrinkage stress. They have a great potential to inhibit recurrent caries and increase restoration longevity.38 0Item Restricted Antioxidant and Antimicrobial Activity of Boswellia Serrata Extract for Cosmetic Ingredient(2023-05-30) Alraddadi, Bssmah Ghazi m; Hyun-Jae, ShinBoswellia serrata resin, which is an important source of gum oleoresin known as Indian frankincense and is well documented for its pharmaceutical properties due to its chemical structure, antibacterial and antioxidant properties, and the presence of several compounds such as polyphenols, phenols, and terpenoids. In the experimental study, it was observed that Boswellia Serrata resin extracts in- hibited antibacterial activity in all strains for the relevant concentrations. The diameter of the zone of inhibition for the B. serrata extract for S. epidermidis ranged from 13.3±0.58 to 10.3±0.58 mm, for M. furfur from10.6±0.58 to 9±0 mm, for M. pachy- dermatis from13.25±0.35 to 9.75±1.06 mm, and for C. acnes from 11.83±0.29 to 9.5±0 mm in the anaerobic jar. antioxidant activity was measured with DPPH It was confirmed that there was high- er activity in the Water Fr. compared to the Other fractions; respectively, Water Fr. IX showed the highest scavenging activity 902.19 ± 35.53 µg/mL, Ethyl acetate Fr. 20436 ± 652.19 µg/mL ,70% EtOH Fr. 8627.74± 369.22 µg/mL, and the Hexane Fr. Shows No scavenging activity. According to ABTS assay, the Water fraction demonstrated the maximum scavenging activity with a scavenging activity of 1845.08 ± 2265.74, followed by the ethyl acetate fraction with a scavenging activity of 12167.16 ± 8152.82 µg/mL. polyphenol and flavonoid content in the Water Fr. was the highest; it reached TPC 32.15 ± 0.75 ⅿg/mL and TFC 20.29 ± 1.47 ⅿg/mL. This study shows that the Boswellia serrata resin have some biological activities, and if they differ in terms of effectiveness and activity, they can be considered a good component of cosmetic products.38 0