Alotaibi, Hessah; (2024) Development of antimicrobial cyclodextrin metal organic frameworks polycaprolactone based mixed matrix membrane for biomedical applications. Doctoral thesis (Ph.D), UCL (University College London).

Text Development of antimicrobial cyclodextrin metal organic frameworks polycaprolactone based mixed matrix membrane for biomedical applications.pdf - Other Access restricted to UCL open access staff until 1 August 2028. Download (9MB)

Abstract

The escalating Antimicrobial resistance (AMR) developed in numerous microbes against different antimicrobial drugs, especially the antibiotics, has increasingly become a serious concern. The rise in the AMR cases has resulted in a significant rise in the mortality rate, length of hospitalisation, and healthcare costs. Silver nanoparticles (AgNPs) stand out as one of the promising antimicrobial agents due to their unique chemical, physical, optical, and electrical properties. The antimicrobial properties of AgNPs are determined by different factors including their shape and size. Therefore, a key objective of the project is synthesising ultra-small AgNPs by exploring the highly ordered nanoporous structure of metal-organic frameworks (MOFs) as a suitable template for the material preparation. Cyclodextrin metal-organic framework (CD-MOF) has shown great potential in biomedical applications, particularly as a drug delivery carrier, due to its excellent biocompatibility. Additionally, CD-MOF can serve as a template for the in situ synthesis of ultra-small AgNPs (2-5 nm) and effectively stabilise them upon their release in an aqueous solution. Further development of highly efficient mixed matrix membrane (MMM) for the sustained and controlled release of AgNPs is possible for various applications. The local sustained release of AgNPs at optimised concentration will minimise the need of frequent oral administration of antibiotics and help to overcome AMR. In this study, different modulators; cetyltrimethylammonium bromide (CTAB), poly(ethylene) glycol (PEG) and triethylamine (TEA) were evaluated for the synthesis of nano CD-MOF. The size of the nano CD-MOF synthesised by the three modulators was comparable, about ~200-300 nm. However, the use of bulky modulators (CTAB and PEG) was found to compromise the physicochemical properties of CD-MOFs as their complete removal from frameworks was nearly impossible. The BET surface area of the nano CD-MOF synthesised by TEA was measured to be 1075.5 m2/g, which is almost 50% higher than the other samples. The enhanced CD-MOF framework was utilised for the in-situ synthesis of AgNPs, resulting in improved antimicrobial efficacy tested against Staphylococcus aureus and Escherichia coli bacteria and Candida albicans fungus. The minimum inhibitory concentration (MIC) of AgNPs was recorded in the range of 12.5-0.75 μg/mL, significantly lower than other available AgNPs. Polycaprolactone (PCL) is a biocompatible and biodegradable polyester that has been widely used in biomedical applications. It was therefore used as a binder for the CD-MOF particles in the MMM. A series of PCL-Ag-CD-MOF MMMs, with the AgNPs concentrations varying from 0.3 to 4wt%, were developed using solvent casting. The thickness of the MMM ranged between 80 to 100 μm. Agar cut well tests showed that MMMs with 1.3 wt% of AgNPs were able to inhibit against Staphylococcus aureus and Escherichia coli bacteria and Candida albicans. By incorporating polyethylene oxide (PEO) into the MMM, the antimicrobial concentration was reduced to 0.6wt% AgNPs. The results indicate that the PCL-PEO-Ag-CD-MOF MMMs developed may have great potential for a range of biomedical applications, such as wound dressings, coatings for medical equipment, health-care products, and hygiene materials.

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