Synthesis and dark toxicity of 5-(4-carboxyphenyl)-10, 15, 20-tris (phenyl)-porphyrinato chlorido gallium (III) when conjugated to δ-aminolevulinic acid
- Authors: Managa, Muthumuni , Mkhize, Scebi , Britton, Jonathan , Prinsloo, Earl , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/240014 , vital:50789 , xlink:href="https://doi.org/10.1080/00958972.2016.1223292"
- Description: 5-(4-Carboxyphenyl)-10,15,20-tris(phenyl)-porphyrinato chlorido gallium(III) (2) was synthesized and then linked to ethyl ester δ-aminolevulinic acid to form 3. There was no shift in Soret band following conjugation. The fluorescence and singlet oxygen generating behavior of the porphyrins were also investigated. The highest singlet oxygen quantum yield (ΦΔ) obtained was that of 3. Complexes 2 and 3 as well as metal free 5-(4-carboxyphenyl)-10,15,20-tris(phenyl)-porphyrinato showed no dark toxicity on MCF-7 breast cancer cells.
- Full Text:
- Date Issued: 2016
Synthesis and nonlinear optical examination of 3 (4), 15 (16)-Bis-(4-tert-butyl-phenoxy)-10, 22-diaminohemiporphyrazinato chloroindium
- Authors: Britton, Jonathan , Antunes, Edith M , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241739 , vital:50965 , xlink:href="https://doi.org/10.1016/j.molstruc.2013.05.001"
- Description: 3(4),15(16)-Bis-(4-tert-butyl-phenoxy)-10,22-diaminohemiporphyrazinato chloroindium hemiporphyrazine was synthesized from 1,3,5-triaminobenzene and 4-tert-butyl-phenoxyisoindoline. The structure of the complex was confirmed using mass, nuclear magnetic resonance and infrared spectroscopies. The nonlinear parameters of the compound was also analyzed in dimethylformamide and found to be significantly greater than previously analyzed phthalocyanines.
- Full Text:
- Date Issued: 2013
Synthesis and photophysical properties of nanocomposites of aluminum tetrasulfonated phthalocyanine covalently linked to glutathione capped CdTe/CdS/ZnS quantum dots
- Authors: Oluwole, David O , Britton, Jonathan , Mashazi, Philani N , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241379 , vital:50934 , xlink:href="https://doi.org/10.1016/j.synthmet.2015.04.015"
- Description: Aluminum tetrasulfonated phthalocyanine (ClAlTSPc) was covalently linked with different sizes of glutathione capped CdTe/CdS/ZnS quantum dots (QDs). The photophysical and Förster resonance energy transfer (FRET) properties of the nanoconjugates were investigated. The CdTe/CdS/ZnS(6.3) nanocomposite showed the highest enhancement in its photophysical properties while (CdTe/CdS/ZnS(3.2) nanocomposite showed the least. Highest FRET efficiency was observed in the linked CdTe/CdS/ZnS(6.3) nanocomposites at 93%. Hence, the combination of CdTe/CdS/ZnS with ClAlTSPc exhibited excellent photophysical properties.
- Full Text:
- Date Issued: 2015
Synthesis of a near infrared-actuated phthalocyanine-lipid vesicle system for augmented photodynamic therapy
- Authors: Nwahara, Namdi , Managa, Muthumuni , Stoffels, Mihlali , Britton, Jonathan , Prinsloo, Earl , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185395 , vital:44383 , xlink:href="https://doi.org/10.1016/j.synthmet.2021.116811"
- Description: The efficacy of photodynamic therapy (PDT) is often limited by the poor bio-distributive properties of conventional photosensitizers and the local hypoxic microenvironment that characterises most solid tumours. Herein, a novel in situ oxygenic lipid formulation for photodynamic therapy (PDT) is reported. Such a hybrid was synthesized by adsorbing bimetallic nanozyme, MnO2@PtNPs (NPs = nanoparticles) onto graphene quantum dots (GQDs) – zinc (II) phthalocyanine conjugates, followed by liposomal encapsulation, affording it enhanced water solubility. The MnO2@PtNPs, which are is shown to possess excellent catalase-like properties surpassing that of MnO2 or PtNPs alone, serves to catalyze H2O2 to O2, while the zinc (II) phthalocyanine (1) serves to transform the formed oxygen to generate cytotoxic singlet oxygen immediately. We show that by combining each function of the respective building blocks, the as-synthesized 1-GQDs-MnO2@PtNPs-liposomes not only maintains the properties of oxygen supplementation through H2O2 catalysis but also displays cooperative properties for enhanced singlet oxygen production. Consequently, a remarkably improved PDT efficacy was observed for 1-GQDs-MnO2@PtNPs-liposomes in both normoxia and hypoxia. These results demonstrate the potential applicability of such nanozyme constituted 1-GQDs-MnO2@PtNPs-liposomes for achieving tumour treatment in hypoxic conditions by PDT.
- Full Text:
- Date Issued: 2021
Synthesis, photophysical and nonlinear optical properties of a series of ball-type phthalocyanines in solution and thin films
- Authors: Nwaji, Njemuwa , Mack, John , Britton, Jonathan , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188976 , vital:44803 , xlink:href="https://doi.org/10.1039/C6NJ03662G"
- Description: In this study, we report on the enhanced nonlinear optical properties of novel tetrakis-4-(hexadecane-1,2-dioxyl)-bis(phthalocyaninato zinc(II)) (4), tetrakis-4-(hexadecane-1,2-dioxyl)-bis(phthalocyaninato gallium chloride) (5) and tetrakis-4-(hexadecane-1,2-dioxyl)-bis(phthalocyaninato indium chloride) (6) both in solution and when embedded in polymer thin films. Complexes 5 and 6 bearing heavy atoms showed enhanced triplet quantum yield and nonlinear optical response. The nonlinear third-order susceptibility and second-order hyperpolarizability values are also reported. Time dependent density functional theory (TD-DFT) calculations were performed in order to explain the origin of the observed UV-vis and magnetic circular dichroism (MCD) spectra of the complexes.
- Full Text:
- Date Issued: 2017
The effect of point of substitution and silver based nanoparticles on the photophysical and optical nonlinearity of indium carboxyphenoxy phthalocyanine
- Authors: Oluwole, David O , Ngxeke, Sixolisile M , Britton, Jonathan , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188596 , vital:44768 , xlink:href="https://doi.org/10.1016/j.jphotochem.2017.07.032"
- Description: Indium(III) chloride 1,8(11),15(18),22(25)-tetra-(3-carboxyphenoxy) phthalocyanine (1) and indium(III) chloride 2,9(10),16(17),23(24)-tetra–(3-carboxyphenoxy) phthalocyanine (2) were covalently linked to glutathione capped silver nanoparticles (AgNPs–GSH) and silver selenide/zinc sulfide (Ag2Se/ZnS–GSH) quantum dots via amide bond formation. The photophysical and nonlinear optical behaviour of the metallophthalocyanines and their conjugates with nanoparticles were investigated using the open aperture Z–scan technique. Complex 2 showed enhanced photophysical properties compared to 1. The conjugates revealed improved triplet state quantum yields (except for 1-AgNPs-GSH which afforded lower triplet state quantum yields in comparison to 1) and nonlinear optical activities in comparison to the Pc complexes. The synthesized complexes, nanoparticles and their conjugates could be potential nonlinear optical materials due to their good nonlinear optical activities.
- Full Text:
- Date Issued: 2017
The effect of the cobalt and manganese central metal ions on the nonlinear optical properties of tetra (4-propargyloxyphenoxy) phthalocyanines
- Authors: Mwanza, Daniel , Louzada, Marcel , Britton, Jonathan , Sekhosana, Kutloano E , Khene, Samson M , Nyokong, Tebello , Mashazi, Philani N
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/233357 , vital:50083 , xlink:href="https://doi.org/10.1039/C8NJ00748A"
- Description: The metal-free (H2TPrOPhOPc), cobalt (CoTPrOPhOPc) and manganese (Mn(OAc)TPrOPhOPc) tetra propargyloxyphenoxy phthalocyanines were evaluated for their potential as optical limiting materials. The effect of the substituents and the central metal ions on the nonlinear optical properties was evaluated. The metal-free phthalocyanine exhibited better nonlinear optical properties when compared to the cobalt and manganese complexes owing to the metal ions quenching the excited state due to their half-filled d-orbitals. The nonlinear absorption coefficient (βeff, ×10−5 m MW−1) followed the trend of H2TPrOPhOPc > CoTPrOPhOPc > Mn(OAc)TPrOPhOPc. The values βeff (×10−5 m MW−1) using 532 nm Nd:YAG (560 nm monochromatic Ekspla) laser sources were 23.5 > 14.3 > 9.20 (14.4). The second-order nonlinear coefficient obtained using density functional theory calculations, the theoretical hyper-Rayleigh scattering (βHRS, ×10−28 esu), showed the decreasing trend for H2TPrOPhOPc (2.28) > CoTPrOPhOPc (2.10) > Mn(OAc)TPrOPhOPc (1.86). The 4-(propargyloxy)phenoxy substituents enhanced the optical limiting properties of the synthesized phthalocyanines.
- Full Text:
- Date Issued: 2018
The improved antibacterial efficiency of a zinc phthalocyanine when embedded on silver nanoparticle modified silica nanofibers
- Authors: Mapukata, Sivuyisiwe , Britton, Jonathan , Osifeko, Olawale L , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185784 , vital:44423 , xlink:href="https://doi.org/10.1016/j.pdpdt.2020.102100"
- Description: This work reports on the fabrication and modification of electrospun polymer free silica nanofibers (SiO2 NFs) with the aim of creating heterogeneous antibacterial catalysts. The optical and photophysical properties of the obtained NFs i.e. bare SiO2, Ag-SiO2, Pc-SiO2 and Pc@Ag-SiO2 NFs (Pc = phthalocyanine) were compared and reported. The singlet oxygen quantum yields of the Pc-SiO2 and Pc@Ag-SiO2 NFs were also quantified and found to be 0.08 and 0.12, respectively, in water. All the modified SiO2 NFs were found to possess photoactivity against S. aureus with the most effective being the Pc@Ag-SiO2 NFs due to the synergy between the Pc and Ag nanoparticles. The bare SiO2 NFs do not exhibit any antibacterial activity while the Ag-SiO2 and Pc@Ag-SiO2 NFs were found to also exhibit dark toxicity. The generated photocatalysts are attractive because they are active against bacteria and they are easily retrievable post-application. The nanocatalysts reported herein are therefore feasible candidates for real-life antibacterial applications.
- Full Text:
- Date Issued: 2021
The photocatalytic properties of zinc phthalocyanines supported on hematite nanofibers for use against methyl orange and Staphylococcus aureus
- Authors: Mapukata, Sivuyisiwe , Britton, Jonathan , Nwahara, Nnamdi , Nyokong, Tebello
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/230184 , vital:49751 , xlink:href="https://doi.org/10.1016/j.jphotochem.2021.113637"
- Description: Heterogeneous photocatalysis is a promising approach for environmental remediation from contaminants including microorganisms and organic pollutants. In this work, hematite nanofibers are fabricated and modified with a novel monosubstituted Pc (4) as well as an asymmetrical tetrasubstituted Pc (5) with the aim of creating hybrid photocatalysts. The photocatalytic activities of the unmodified and phthalocyanine modified hematite nanofibers were compared based on their efficiencies in the photoinactivation of S. aureus and photooxidation of methyl orange. For both applications, the hybrid nanofibers were found to be more efficient photocatalysts than the unmodified hematite nanofibers. Comparison of the modified nanofibers (4-Fe2O3 and 5-Fe2O3) showed that they have comparable antibacterial activity while the 5-Fe2O3 nanofibers are the best for the photooxidation of methyl orange. The singlet oxygen generation efficiency, high activity, versatility, regenerability and thus reusability of the fabricated hybrid nanofibers makes them ideal candidates for real life water treatment studies.
- Full Text:
- Date Issued: 2022
Third order nonlinear optical properties of phthalocyanines in the presence nanomaterials and in polymer thin films
- Authors: Britton, Jonathan , Durmus, Mahmut , Khene, Samson M , Chauke, Vongani , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241772 , vital:50968 , xlink:href="https://doi.org/10.1142/S108842461350003X"
- Description: Third order nonlinear optical properties were determined for phthalocyanine complexes 1–10 containing In, Ga and Zn central metals and tetra- or octa-substituted with benzyloxyphenoxy, phenoxy, tert-butylphenoxy and amino groups at peripheral or non-peripheral positions. The phthalocyanines were embedded in poly (methyl methacrylate) polymer in the presence of CdTe quantum dots. All complexes 1–10 were studied in the presence of CdTe quantum dots and embedded in poly (methyl methacrylate) to form thin films. Complex 3 tetrasubstituted with tert-butylphenoxy groups at non-peripheral positions was also studied in the presence of CdS, CdSe quantum dots, fullerenes, single walled carbon nanotubes. Third order nonlinear optical parameters generally increase for Pcs in the presence of CdTe quantum dots.
- Full Text:
- Date Issued: 2013