Saudi Cultural Missions Theses & Dissertations
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Item Restricted The effect of components of electrospun material on S. aureus, P. aeruginosa and E. coli bacterial growth and biofilm formation(Saudi Digital Library, 2023-11-28) Alomair, Munirah; Powell, LydiaThe prevalence of chronic wounds in immunocompromised patients has risen recently, leading to increased morbidity and mortality rates. The emergence of antibiotic resistance has necessitated novel technology for the treatment of these wounds. In order to provide a bespoke wound dressing for patients, Corryn Biotechnologies is developing an innovative device that electrospins a polymer solution directly onto a wound. The antibiotic activity of the electrospun components, namely dimethyl sulfoxide (DMSO), collagen 1, acetone and a non-disclosed polymer solution, were tested against gram-positive methicillin-resistant Staphylococcus aureus (MRSA 1004A) and gram-negative Pseudomonas aeruginosa PAO1 and Escherichia coli IR57 in both planktonic and biofilm assays to determine their effect on bacterial growth and biofilm formation. Minimum inhibitory concentration (MIC) assays were used to evaluate the effect of DMSO against MRSA 1004A, P. aeruginosa PAO1, and E. coli IR57, with resultant MICs of 25%, 6.25%, and 12.5%, respectively. The MICs of collagen 1 and acetone were >50% for both gram-positive and gram-negative bacteria. Confocal laser scanning microscopy (CLSM) revealed that DMSO significant inhibited the formation of MRSA 1004A biofilm biomass at both concentrations of 1/2 MIC DMSO (p<0.0001) and 1/4 MIC DMSO (p=0.0017), with increased cell death achieved with 1/2 MIC DMSO treatment (p=0.0003). The MRSA 1004A biofilm roughness significantly increased with 1/2 MIC DMSO (p=0.0008), but the average thickness area and average thickness biomass were significantly decreased (both p<0.0001) at 1/2 MIC DMSO treatment. The P. aeruginosa PAO1 biofilm biomass significantly increased with 1/2 MIC DMSO treatment (p=0.03), while cellular death decreased with 1/4 MIC DMSO treatment (p=0.038). The effects of the components of the electrospun solution against the most common strains of gram-positive and gram-negative bacteria in chronic wounds highlight the potential application of these components to form a bespoke wound dressing to reduce biofilm formation and aid in chronic wound healing.12 0Item Restricted MECHANICAL PROPERTIES OF SINGLE ELECTROSPUN NANOFIBERS FOR BIOMEDICAL APPLICATIONS(Saudi Digital Library, 2023) Alharbi, Nouf Ayed; Guthold, MartinElectrospun fibers have garnered considerable attention for biomedical applications due to their unique properties, including high surface area-to-volume ratio, tunable mechanical properties, biocompatibility, and controlled drug release. Electrospinning is a versatile technique for producing fibers at the nanoscale. It can produce fibers from a wide range of materials, including synthetic polymers, natural polymers, and blends of both materials. Measuring the mechanical properties of electrospun fibers is crucial for understanding their suitability for various biomedical applications. We used a combination of an atomic force microscope and an inverted optical microscope to investigate the mechanical properties of a single electrospun nanofiber made of polycaprolactone (PCL) with three different molecular weights, a blend of PCL and fibrinogen, as well as hydrated PCL fibers and human fibrinogen. In addition, we determined the mechanical properties of a fibrous mesh made of human fibrinogen. The findings showed that the molecular weight of PCL has no significant impact on the mechanical properties of the fiber, as fibers produced from different molecular weights showed similar mechanical properties. The mechanical properties of blended fibers were observed to be influenced by the ratio of fibrinogen to PCL, with extensibility, elastic limit, and relaxation times increasing as the PCL ratio increased from 25% to 75%. Hydrated PCL fibers were found to have mechanical properties similar to those of dry single fibers. Interestingly, the extensibility of both dry and hydrated single human fibrinogen fibers was greater than that of other electrospun fibers. However, the hydrated fibers were more extensible and softer than the dry fibers and the fibrous fibrinogen meshes. The study found that stiffness-related mechanical properties, including the Young's modulus, stress at rupture, and elastic and total moduli, of electrospun fibers made from different polymers were dependent on fiber diameter. Specifically, when the fiber diameter decreased below a threshold between 100-200 nm, the Young's modulus increased several-fold compared to that of larger diameter fibers. However, when the diameter was larger than 100-200 nm, the modulus remained almost constant.33 0