Browsing by Author "Boltman, Taahirah"

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    Liposomal drug delivery to brain cancer cells
    (University of the Western Cape, 2015) Boltman, Taahirah; Ekpo, Okobi; Meyer, Mervin
    Neuroblastomas (NBs) are the most common solid extra-cranial tumours diagnosed in childhood and characterized by a high risk of tumour relapse. Like in other tumour types, there are major concerns about the specificity and safety of available drugs used for the treatment of NBs, especially because of potential damage to the developing brain. Many plant-derived bioactive compounds have proved effective for cancer treatment but are not delivered to tumour sites in sufficient amounts due to compromised tumour vasculature characterized by leaky capillary walls. Betulinic acid (BetA) is one such naturally-occurring anti-tumour compound with minimum to no cytotoxic effects in healthy cells and rodents. BetA is however insoluble in water and most aqueous solutions, thereby limiting its therapeutic potential as a pharmaceutical product. Liposomes are self-assembling closed colloidal structures composed of one or more concentric lipid bilayers surrounding a central aqueous core. The unique ability of liposomes to entrap hydrophilic molecules into the core and hydrophobic molecules into the bilayers renders them attractive for drug delivery systems. Cyclodextrins (CDs) are non-reducing cyclic oligosaccharides which proximate a truncated core, with features of a hydrophophilic outer surface and hydrophobic inner cavity for forming host-guest inclusion complexes with poorly water soluble molecules. CDs and liposomes have recently gained interest as novel drug delivery vehicles by allowing lipophilic/non-polar molecules into the aqueous core of liposomes, hence improving the therapeutic load, bioavailability and efficacy of many poorly water-soluble drugs. The aim of the study was to develop nano-drug delivery systems for BetA in order to treat human neuroblastoma (NB) cancer cell lines. This was achieved through the preparation of BetA liposomes (BetAL) and improving the percent entrapment efficiency (% EE) of BetA in liposomes through double entrapment of BetA and gamma cyclodextrin BetA inclusion complex (γ-CD-BetA) into liposomes (γ-CD-BetAL). We hypothesized that the γ-CD-BetAL would produce an increased % EE compared to BetAL, hence higher cytotoxic effects. Empty liposomes (EL), BetAL and γ-CD-BetAL were synthesized using the thin film hydration method followed by manual extrusion. Spectroscopic and electron microscopic characterization of these liposome formulations showed size distributions of 1-4 μm (before extrusion) and less than 200 nm (after extrusion). As the liposome size decreased, the zeta-potential (measurement of liposome stability) decreased contributing to a less stable liposomal formulation. Low starting BetA concentrations were found to be more effective in entrapping higher amounts of BetA in liposomes while the incorporation of γ-CD-BetA into liposomes enhanced the % EE when compared to BetAL, although this was not statistically significant. Cell viability studies using the WST-1 assay showed a time-and concentration-dependent decrease in SK-N-BE(2) and Kelly NB cell lines exposed to free BetA, BetAL and γ-CD-BetAL at concentrations of 5-20 ug/ml for 24, 48 and 72 hours treatment durations. The observed cytotoxicity of liposomes was dependant on the % EE of BetA. The γ-CD-BetAL was more effective in reducing cell viability in SK-N-BE(2) cells than BetAL whereas BetAL was more effective in KELLY cells at 48-72 hours. Exposure of all cells to EL showed no toxicity while free BetA was more effective overall than the respective liposomal formulations. The estimated IC₅₀ values following exposure to free BetA and BetAL were similar and both showed remarkable statistically significant decrease in NB cell viability, thus providing a basis for new hope in the effective treatment of NBs.
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    Synthesis of chlorotoxin functionalized metallic nanoparticles and their in vitro evaluation of cytotoxic effects in nervous system cancer cell lines
    (Institute of Physics Publishing, 2024) Boltman, Taahirah; Sibuyi, Nicole Remaliah Samantha; Ekpo, Okobi; Meyer, Mervin
    The treatment of glioblastoma (GB) and neuroblastoma (NB)remains a challenge, as current chemotherapies are plagued with systemic toxicity, drug resistance, and inadequate blood–brain barrier(BBB) penetration. Therefore, novel therapeutic strategies with high specificity and the capacity to bypass the BBB are required. Chlorotoxin (CTX)selectively targets gliomas and neuroectodermal tumors, hence the use of CTX-targeted nanoparticles(NPs)represents a promising therapeutic approach for nervous system (NS) cancers. Bimetallic NPs composed of two metals such as gold-platinum NPs(AuPtNPs) exhibit enhanced anticancer properties compared to single-metal NPs, however their application in studying NS tumors has been relatively limited. CTX-functionalized monometallic gold NPs(CTX-AuNPs) and bimetallic gold-platinum NPs(CTX-AuPtNPs)were synthesized in this study. The NPs were characterized by Ultraviolet-Visible Spectroscopy (UV–vis), Dynamic Light Scattering (DLS), Transmission Electron Microscopy (TEM) and Fourier Transform Infra-Red Spectroscopy (FTIR). Cytotoxicity of NPs was investigated in cancer(U87 and SH-SY5Y) and non-cancer(KMST-6) cells using the water-soluble tetrazolium (WST)-1 assay. The CTX-AuNPs and CTX-AuPtNPs had a core size of∼5 nm. The CTX-AuPtNPs showed significant anticancer activity in U87 cells possibly due to the synergistic effects of combined metals. Findings obtained from this study demonstrated that CTX can be used to target NS cancers and that bimetallic NPs could be effective in their treatment. More studies are required to investigate the mechanisms of NPs toxicity, and further explore the hyperthermia treatment of NS cancer using the CTX-AuPtNPs.