Effect of nature of nanoparticles on the photophysicochemical properties of asymmetrically substituted Zn phthalocyanines
- Authors: Magadla, Aviwe , Oluwole, David O , Britton, Jonathan , Nyokong, Tebello
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/234539 , vital:50206 , xlink:href="https://doi.org/10.1016/j.ica.2018.06.043"
- Description: In this work, low symmetry Zn mono caffeic acid tri-tert butyl (1) and Zn monocarboxyphenoxy tri-(tert-butylphenoxyl) (2) phthalocyanines (Pcs) were covalently linked to amino (using glutathione, GSH, or 3-aminopropyl)triethoxysilane, APTES) functionalised nanoparticles. The nanoparticles are represented as: AgNPs-GSH, SiNPs-APTES, Fe3O4-Ag-SiNPs-APTES and Fe3O4-AgNPs-GSH). The photophysical and photochemical behaviour of the complexes 1 and 2 and their conjugates with nanoparticles were investigated in dimethyl sulfoxide. The conjugates of the Pc complexes with the NPs afforded increase in triplet quantum yields with corresponding decrease in fluorescence quantum yield compared to the Pc complexes alone. The conjugates of 1-AgNPs-GSH, 2-SiNPs-APTES and 2-Fe3O4-Ag-SiNPs-APTES showed higher singlet oxygen quantum yield values as compared to the Pc complexes alone.
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- Date Issued: 2018
Evaluation of the photophysicochemical properties and photodynamic therapy activity of nanoconjugates of zinc phthalocyanine linked to glutathione capped Au and Au3Ag1 nanoparticles
- Authors: Oluwole, David O , Manoto, Sello L , Malabi, Rudzani , Maphanga, Charles , Ombinda-Lemboumba, Saturnin , Mthunzi-Kufa, Patience , Nyokong, Tebello
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/237886 , vital:50563 , xlink:href="https://doi.org/10.1016/j.dyepig.2017.11.019"
- Description: We report on the synthesis of glutathione capped gold (AuNPs–GSH) and gold–silver (Au3Ag1NPs–GSH) nanoparticles and their covalent attachment to Zn monocarboxyphenoxy phthalocyanine (1) via amide bond formation. The photophysicochemical properties and photodynamic therapy (PDT) activity of the complex and its nanoconjugates were assessed. The conjugates afforded improved triplet and singlet oxygen quantum yield as well as PDT activity (except for 1-Au3Ag1NPs which afforded decreased activity) in comparison to complex 1.
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- Date Issued: 2018
Glycosylated zinc phthalocyanine-gold nanoparticle conjugates for photodynamic therapy
- Authors: Dube, Edith , Oluwole, David O , Nwaji, Njemuwa , Nyokong, Tebello
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/234524 , vital:50205 , xlink:href="https://doi.org/10.1016/j.saa.2018.05.081"
- Description: In this work, we report on the synthesis of tris-[(2,2,7,7-tetramethyltetrahydro-3aH-bis([1,3]dioxolo)[4,5-b:4′,5′-d]pyran-5-yl)methoxy)-2-(4-benzo[d]thiazol-2-ylphenoxyphthalocyaninato] zinc(II) (complex 3) and its linkage to gold nanoparticles (AuNPs) of different shapes through S-Au/N-Au self-assembly. The conjugates of complex 3 (with both gold nanorods (AuNR) and nanospheres (AuNS)), displayed decreased fluorescence quantum yield with corresponding improved triplet and singlet quantum yields compared to complex 3 alone, however 3-AuNR showed improved properties than 3-AuNS. Complex 3 showed relatively low in vitro dark cytotoxicity against the epithelial breast cancer cells with cell survival ≥ 85% at concentration ≤ 160 μg/mL but afforded reduced photodynamic therapy activity which may be due to aggregation. 3-AuNR afforded superior PDT activity with more than 50% viable cells at concentration ≥ 40 μg/mL in comparison to 3-AuNS with more than 50% viable cells at concentration ≥ 80 μg/mL. The superior activity of 3-AuNR is attributed to the photothermal therapy effect since nanorods absorb more light at 680 nm than nanospheres.
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- Date Issued: 2018
Optical nonlinearity of pentadecylphenoxyl substituted sandwich–type metallophthalocyanines in the presence of Ag–CdSeTe/ZnTeSe nanocrystals: Effects of conjugation and central metals
- Authors: Oluwole, David O , Nyokong, Tebello
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187899 , vital:44708 , xlink:href="https://doi.org/10.1016/j.dyepig.2018.01.009"
- Description: Novel pentadecylphenoxyl substituted homoleptic sandwich–type metallophthalocyanines: bis (complexes 2 and 4 containing Eu and Dy, respectively) and tris (complexes 3 and 5 containing Eu and Dy, respectively) 2,9,16,23–tetrakis–(3–pentadecylphenoxyl) phthalocyanines and cadmium based (Ag–CdSeTe/ZnTeSe) nanocrystals (NCs) were synthesized. The nonlinear optical (NLO) behavior of the metallophthalocyanines and their composites with NCs were investigated using the open aperture Z–scan technique at excitation wavelength of 532 nm with 10 ns pulse. All of the samples exhibited interesting NLO attributes: among all the sandwich–type complexes, complex 5 afforded the most efficient NLO features accounting for large nonlinear absorption coefficient (βeff) value of 3500 cm/GW and limiting threshold (Ilim) value of 0.43 J cm−2. Overall, the composites of the triple decker sandwich–type complexes with Ag–CdSeTe/ZnTeSe yielded the best NLO characteristics with 3 and 5 accounting for the largest βeff value of 5500 cm/GW and Ilim value of 0.09 J cm−2. The synthesized complexes and their composites with NCs could be viable and efficient NLO absorber due to their interesting NLO activities.
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- Date Issued: 2018
Optimizing phthalocyanine based dye-sensitized solar cells: The role of reduced graphene oxide
- Authors: Chindeka, Francis , Mashazi, Philani N , Britton, Jonathan , Fomo, Gertrude , Oluwole, David O , Sindelo, Azole , Nyokong, Tebello
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187770 , vital:44695 , xlink:href="https://doi.org/10.1016/j.synthmet.2018.10.021"
- Description: Dye-sensitized solar cells (DSSC) were fabricated by incorporating graphene materials as catalysts at the counter electrode. Platinum was also used as a catalyst for comparison purposes. Different phthalocyanines: hydroxyl indium tetracarboxyphenoxy phthalocyanine (1), chloro indium octacarboxy phthalocyanine (2) and dibenzoic acid silicon phthalocyanine (3) were used as dyes. Complex 3 gave the highest power conversion efficiency (η) of 3.19% when using nitrogen doped reduced graphene oxide nanosheets (NrGONS) as a catalyst at the counter electrode, and TiO2 containing rGONS at the anode. The value is close to 3.8% obtained when using Pt catalyst instead of NrGONS at the cathode, thus confirming that NrGONS is a promising candidate to replace the more expensive Pt. The study also shows that placing rGONS on both the anode and cathode improves efficiency.
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- Date Issued: 2018
Photodynamic therapy activity of zinc phthalocyanine linked to folic acid and magnetic nanoparticles
- Authors: Matlou, Gauta G , Oluwole, David O , Prinsloo, Earl , Nyokong, Tebello
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/234429 , vital:50195 , xlink:href="https://doi.org/10.1016/j.jphotobiol.2018.07.025"
- Description: In this work, the photodynamic therapy (PDT) activities (using human carcinoma adherent MCF-7 cells) of zinc phthalocyanine derivatives: complexes 1 (Zn mono cinnamic acid phthalocyanine) and 2 (zinc mono carboxyphenoxy phthalocyanine) when covalently linked to folic acid (FA) and amine functionalized magnetic nanoparticles (AMNPs) are reported. The covalent linkage of asymmetric zinc cinnamic acid Pc (1) to FA (1-FA) through an amide bond is reported for the first time. Complex 1 is insoluble in water, but upon linkage to FA, (to form 1-FA) the molecule become water soluble, hence the UV–Vis spectrum and singlet oxygen quantum yield for 1-FA were also done in water since water solubility is essential for biological applications. The reported 2-FA is also water soluble. Linking complexes 1 and 2 to FA and AMNPs decreased the dark toxicity of 1 and 2 on MCF-7 cells. Pc-FA (1-FA and 2-FA) conjugates had better singlet oxygen quantum yields (Φ∆) in DMSO as compared to Pc-AMNPs (1-AMNPs and 2-AMNPs). The water- soluble 1-FA and 2-FA also achieved a better photodynamic therapy (PDT) activity as compared to 1-AMNPs and 2-AMNPs. Folic acid targeting on the tumor cells may have also facilitated better bioavailability of 1-FA and 2-FA and improved PDT activity on MCF-7 cells over AMNPs carriers.
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- Date Issued: 2018
Photophysicochemical properties and photodynamic therapy activity of highly water-soluble Zn (II) phthalocyanines
- Authors: Oluwole, David O , Sari, Fatma Aslihan , Prinsloo, Earl , Dube, Edith , Yuzer, Abdulcelil , Nyokong, Tebello , Ince, Mine
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/234507 , vital:50203 , xlink:href="https://doi.org/10.1016/j.saa.2018.05.090"
- Description: The syntheses of two zinc(II) phthalocyanines (ZnPcs) having either imidazole (ZnPc 1) or pyridiloxy (ZnPc 2) moieties as their macrocycle substituents are reported. Quaternization of the ZnPcs with methyl iodide afforded water soluble cationic phthalocyanines. The photophysical, photochemical properties and photodynamic therapy (PDT) activity of the ZnPcs were studied in solution. The fluorescence quantum yield and lifetime of ZnPc 1 were higher as compared to ZnPc 2. ZnPc 2 afforded higher triplet state (ΦT) and singlet oxygen quantum yields (ΦΔ) in comparison to ZnPc 1. The PDT activity of ZnPcs was investigated against human breast adenocarcinoma cells (MCF–7). The two compounds afforded a very minimal in vitro dark cytotoxicity with 85% viable cells at concentration ≤80 μM. On irradiation of the cells having the ZnPcs, ≥50% cell death was recorded for ZnPc 1 which was also evidenced by the cells photo–micrograph.
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- Date Issued: 2018