Synthesis of phthalocyanine conjugates with gold nanoparticles and liposomes for photodynamic therapy
- Authors: Nombona, Nolwazi , Maduray, Kaminee , Antunes, Edith M , Karsten, Aletta , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/245798 , vital:51406 , xlink:href="https://doi.org/10.1016/j.jphotobiol.2011.11.007"
- Description: The efficiency of [2,9,17,23-tetrakis-(1,6-hexanedithiol)phthalocyaninato]zinc(II) as a photodynamic therapy (PDT) agent was investigated. This compound belongs to the second generation of photosensitizers currently tested for the cellular photo-damage of cancer cells. The production of reactive oxygen species (ROS) and phototoxicity of the photosensitizer were assessed. Healthy fibroblast cells and breast cancer (MCF-7) cells were treated with either free phthalocyanine or phthalocyanine bound to either gold nanoparticles or encapsulated in liposomes. Cell viability studies showed the optimum phototoxic effect on non-malignant cells to be 4.5 J cm−2. The PDT effect of the liposome bound phthalocyanine showed extensive damage of the breast cancer cells. Gold nanoparticles only showed a modest improvement in PDT activity.
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- Date Issued: 2012
Synthesis, photophysics and photochemistry of phthalocyanine-ɛ-polylysine conjugates in the presence of metal nanoparticles against Staphylococcus aureus
- Authors: Nombona, Nolwazi , Antunes, Edith M , Chidawanyika, Wadzanai J U , Kleyi, Phumelele , Tshentu, Zenixole , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/244439 , vital:51257 , xlink:href="https://doi.org/10.1016/j.molstruc.2015.02.040"
- Description: This work reports on the photodynamic activity of Zn phthalocyanine-ɛ-polylysine conjugates in the presence of gold and silver nanoparticles (NPs) towards the inactivation of Staphylococcus aureus (S. aureus). The conjugates showed high photoinactivation with ∼6% growth at a drug dose of 3 μM and fluence of 39.6 mW/cm2 for 10 min irradiation time in the presence of silver nanoparticles. The presence of silver nanoparticels from the minimal inhibition concentration (MIC50) studies showed remarkable growth inhibition for the tested conjugates even at low concentrations. The MIC50 was lowest for the conjugate of 3 with ɛ-polylysine at concentrations of less than 0.0058 μM in the presence of AgNPs. The lethal photosensitization of microorganisms has emerged as a promising treatment since bacteria have reduced possibilities of developing resistance to photodynamic therapy.
- Full Text:
- Date Issued: 2015
The determination of the photosensitizing properties of mercapto substituted phthalocyanine derivatives in the presence of quantum dots capped with mercaptopropionic acid
- Authors: Moeno, Sharon , Antunes, Edith M , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247870 , vital:51625 , xlink:href="https://doi.org/10.1016/j.jphotochem.2010.12.009"
- Description: This work reports on the synthesis of several novel water soluble metallophthalocyanines containing Zn2+, In3+, Ga3+ or Si4+ as central metal ions and tetra substituted with mercaptoacetic acid and mercaptopropionic acid. The complexes were characterized using infra red, nuclear magnetic resonance and mass spectroscopies as well as elemental analysis. All the complexes are water soluble but the majority are highly aggregated in water and organic solvents. The complex containing Zn as a central metal and mercaptopropionic acid as a substituent was not aggregated allowing for the determination of photophysical parameters. This complex had triplet state quantum yield of 0.61 in DMF and 0.88 in DMSO while the fluorescence quantum yield was 0.13 in DMSO. The determination of photophysical properties of the complex containing Zn as a central metal and mercaptopropionic acid were carried out in the presence of mercaptopropionic acid capped CdTe quantum dots. There is an increase in triplet state quantum yield from 0.88 (for the phthalocyanine alone) to 0.94 (in the presence of CdTe quantum dots) in DMSO.
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- Date Issued: 2011
The development of catalytic oxovanadium (IV)-containing microspheres for the oxidation of various organosulfur compounds
- Authors: Ogunlaja, Adeniyi S , Khene, Samson M , Antunes, Edith M , Nyokong, Tebello , Torto, Nelson , Tshentu, Zenixole R
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241783 , vital:50969 , xlink:href="https://doi.org/10.1016/j.apcata.2013.05.004"
- Description: The development of poly[allylSB-co-EGDMA] beads containing a tetradentate ligand was achieved via suspension polymerization. The catalyst poly[allylSB-co-EGDMA]-VO was synthesized by reacting VIVOSO4 with poly[allylSB-co-EGDMA]. XPS and EPR were used to confirm the presence of vanadium (V4+) on the beads. The synthesized catalyst (poly[allylSB-co-EGDMA]-VO) was found to have a BET surface area of 22 m2 g−1 and porosity of 135 Å, with the atomic force microscopy (AFM) showing more insight on the porous nature of the beads. Oxidation of thiophene (TH), benzothiophene (BT), dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT) was carried out using tert-butyl hydroperoxide (t-BuOOH) as oxidant. An overall conversion of 60%, 82%, 98% and 87% was achieved for thiophene (TH), benzothiophene (BT), dibenzothiophene (DBT) and 4,6 dimethyldibenzothiophene (4,6-DMDBT) respectively at higher (t-BuOOH) to substrate ratio and at a temperature of 40 °C. The efficient oxidation of the various organosulfur compounds presents potential for the possible application of this catalyst in oxidative desulfurization (ODS) of crude oil.
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- Date Issued: 2013
The development of novel nickel selective amine extractants
- Authors: Okewole, Adeleye I , Antunes, Edith M , Nyokong, Tebello , Tshentu, Zenixole R
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241641 , vital:50957 , xlink:href="https://doi.org/10.1016/j.mineng.2013.04.019"
- Description: A chelating ion exchanger, prepared by functionalising Merrifield resin with 2,2′-pyridylimidazole, was utilized to selectively adsorb and separate nickel from other base metal ions in synthetic sulfate solutions. The sorbent material was characterized by scanning electron microscopy (SEM), microanalysis, infrared (IR), X-ray photoelectron spectroscopy (XPS) and BET surface area. The distribution ratio (D) and the sorption capacity of the microspheres toward Ni(II), Cu(II), Co(II) and Fe(II) ions was studied by using the batch and column methods, respectively. Ni(II) followed by Cu(II) showed the highest distribution ratio (D) and the highest sorption efficiency of nickel(II) ions around pH 2. The binary separation of nickel(II) from copper(II), cobalt(II) and iron(II) respectively, undertaken in a column study, through loading the metal ions at pH ≈ 2 followed by selective decomplexation, demonstrated the selectivity of the sorbent material for nickel(II). Thus, 2,2′-pyridylimidazole can be regarded as a nickel-specific extractant.
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- Date Issued: 2013
The synthesis and characterisation of magnetic nanoparticles and their interaction with a zinc phthalocyanine
- Authors: Antunes, Edith M , Rapulenyane, Nomasonto , Ledwaba, Mpho , Litwinski, Christian , Chidawanyika, Wadzanai J U , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/242111 , vital:51002 , xlink:href="https://doi.org/10.1016/j.inoche.2012.12.010"
- Description: A variety of nanoparticles (NPs), including FePt nanoparticles with Fe as the shell (2) or Pt as the shell (3), Pt NPs (4), and FePd (5) were synthesised, characterised and their effect on a zinc phthalocyanine (1) tetra-substituted with a pyridyl-oxy substituent studied using UV/Vis and fluorescence spectroscopy (including time correlated single photon counting, TCSPC). The nanoparticles were characterised using a number of techniques including UV/Vis and inductively coupled plasma-optical emission (ICP-OES) spectroscopies, transmission electron microscopy (TEM), differential scanning calorimetry (DSC), X-ray powder diffraction (XRD) and electron paramagnetic resonance (EPR) spectroscopy. Nanocomposites (NCs, 6,7) where the ZnPc (1) was used as the stabiliser, instead of oleic acid and or oleylamine, were also synthesised and characterised.
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- Date Issued: 2013
The synthesis and fluorescence behaviour of phthalocyanines unsymmetrically substituted with naphthol and carboxy groups
- Authors: Nombona, Nolwazi , Antunes, Edith M , Nyokong, Tebello
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/261534 , vital:53418 , xlink:href="https://doi.org/10.1016/j.dyepig.2009.11.010"
- Description: Unsymmetrically substituted phthalocyanines 8,15,22-tris-(naphtho)-2-(carboxy)phthalocyanine, [8,15,22-tris-(naphtho)-2-(carboxy)phthalocyanato]zinc(II), 8,15,22-tris-(naphtho)-4,5-(3-carboxy-1,2-dioxyphenyl)phthalocyanine and [8,15,22-tris-(naphtho)-4,5-(3-carboxy-1,2-dioxyphenoxy)phthalocyanato]zinc(II) were prepared using the mixed phthalonitrile cyclotetramerization of 3-(1-naphthoxy) phthalonitrile with a carboxylic acid phthalonitrile. The phthalocyanines were separated using column chromatography employing a mixture of THF, ammonia and water. The novel compounds were characterized using UV–Vis, IR, 1H NMR and mass spectrometry as well as elemental analysis. Fluorescence quantum yields were found to range from 0.05 to 0.16.
- Full Text:
- Date Issued: 2010
Unquenched fluorescence lifetime for β-phenylthio substituted zinc phthalocyanine upon conjugation to gold nanoparticles
- Authors: Forteath, Shaun , Antunes, Edith M , Chidawanyika, Wadzanai J U , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/245774 , vital:51404 , xlink:href="https://doi.org/10.1016/j.poly.2011.12.015"
- Description: Photoinduced processes in phthalocyanine-functionalized gold nanoparticles have been investigated by spectroscopic measurements. The zinc phthalocyanine used contained four phenylthio peripheral substituents (ZnPc(SPh)4). The conjugates formed are represented as ZnPc(SPh)4–AuNP. The absorption spectrum of the ZnPc(SPh)4–AuNP shows a broadening of the phthalocyanine Q-band absorption, probably due to a tight packing of the phthalocyanines on the gold nanoparticle surface. For the attached phthalocyanines, the two fluorescence lifetimes obtained by time-correlated single photon counting (TCSPC) were determined to be both longer and shorter than that of the free Pc. The fluorescence lifetimes were resolved using time resolved fluorescence spectroscopy (TRES).
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- Date Issued: 2012