Thesis (Ph.D.) - Cairo University - Faculty of Veterinary Medicine - Department of Microbiology

Development of drug resistant strains such as multi drug resistant TB (MDR-TB) and extensive drug resistant TB (EXDR-TB) threatens the progress made in TB controls and prompt the need to alternative strategies. The aim of this work was to investigate the anti-mycobacterial activity of two noble metal nanoparticles either in non-conjugated form or conjugated with rifampicin. Gold (spheres and rods) and silver (spheres) nanoparticles were synthesized and characterized using TEM and UV{u2013}vis spectroscopy. The anti-mycobacterial activity of silver nanospheres (AgNSs) was studied using the malachite green decolorisation assay (MGDA) and cultivation on Lowenstein Jensen media, and the results indicate that AgNSs have a strong anti-mycobacterial effect with 80 æg/ml MIC. To test the cytotoxic effect of gold and silver nanospheres on RAW264.7 cell line as a macrophage cell model, which is the host of TB, we did a comparative study using XTT assay and microscopic examination. Results indicated that silver nanospheres were severely toxic while the gold nanospheres were safer to murine macrophage RAW264.7 cell. Therefore, silver nanospheres were excluded from this work as its toxicity to host cells. Gold nanoparticles (spheres and rods) were conjugated with rifampicin and the successful conjugation was confirmed with UV{u2013}vis spectroscopy. Then, the anti-mycobacterial activity of conjugated and non-conjugated AuNPs with rifampicin against extracellular TB were assayed using the malachite green decolorisation assay (MGDA) and cultivation on Lowenstein Jensen media and Middlebrook agar, the results revealed that the shapes of gold nanoparticles played an important role in the anti-mycobacterial activity, as the rods have a strong anti-mycobacterial activity while the spheres have no anti-mycobacterial effect. The impact of the cell types (RAW264.7 macrophage cell line, HSC-3 human oral squamous cell carcinoma and MCF7 human breast adenocarcinoma cells) on the gold nanoparticle uptake was studied using the dark field scattering microscopy

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