Characterization of phthalocyanine functionalized quantum dots by dynamic light scattering, laser Doppler, and capillary electrophoresis
- Ramírez-García, Gonzalo, Oluwole, David O, Nxele, Siphesihle Robin, d’Orlyé, Fanny, Nyokong, Tebello, Bedioui, Fethi, Varenne, Anne
- Authors: Ramírez-García, Gonzalo , Oluwole, David O , Nxele, Siphesihle Robin , d’Orlyé, Fanny , Nyokong, Tebello , Bedioui, Fethi , Varenne, Anne
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/238184 , vital:50595 , xlink:href="https://doi.org/10.1007/s00216-016-0120-x"
- Description: In this work, we characterized different phtalocyanine-capped core/shell/shell quantum dots (QDs) in terms of stability, ζ-potential, and size at various pH and ionic strengths, by means of capillary electrophoresis (CE), and compared these results to the ones obtained by laser Doppler electrophoresis (LDE) and dynamic light scattering (DLS). The effect of the phthalocyanine metallic center (Zn, Al, or In), the number (one or four), and nature of substituents (carboxyphenoxy- or sulfonated-) of functionalization on the phthalocyanine physicochemical properties were evaluated. Whereas QDs capped with zinc mono-carboxyphenoxy-phtalocyanine (ZnMCPPc-QDs) remained aggregated in the whole analyzed pH range, even at low ionic strength, QDs capped with zinc tetracarboxyphenoxy phtalocyanine (ZnTPPc-QDs) were easily dispersed in buffers at pH equal to or higher than 7.4. QDs capped with aluminum tetrasulfonated phthalocyanine (AlTSPPc-QDs) and indium tetracarboxyphenoxy phthalocyanines (InTCPPc-QDs) were stable in aqueous suspension only at pH higher than 9.0 due to the presence of functional groups bound to the metallic center of the phthalocyanine. The ζ-potential values determined by CE for all the samples decreased when ionic strength increased, being well correlated with the aggregation of the nanoconjugates at elevated salt concentrations. The use of electrokinetic methodologies has provided insights into the colloidal stability of the photosensitizer-functionalized QDs in physiological relevant solutions and thereby, its usefulness for improving their design and applications for photodynamic therapy.
- Full Text:
- Date Issued: 2017
- Authors: Ramírez-García, Gonzalo , Oluwole, David O , Nxele, Siphesihle Robin , d’Orlyé, Fanny , Nyokong, Tebello , Bedioui, Fethi , Varenne, Anne
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/238184 , vital:50595 , xlink:href="https://doi.org/10.1007/s00216-016-0120-x"
- Description: In this work, we characterized different phtalocyanine-capped core/shell/shell quantum dots (QDs) in terms of stability, ζ-potential, and size at various pH and ionic strengths, by means of capillary electrophoresis (CE), and compared these results to the ones obtained by laser Doppler electrophoresis (LDE) and dynamic light scattering (DLS). The effect of the phthalocyanine metallic center (Zn, Al, or In), the number (one or four), and nature of substituents (carboxyphenoxy- or sulfonated-) of functionalization on the phthalocyanine physicochemical properties were evaluated. Whereas QDs capped with zinc mono-carboxyphenoxy-phtalocyanine (ZnMCPPc-QDs) remained aggregated in the whole analyzed pH range, even at low ionic strength, QDs capped with zinc tetracarboxyphenoxy phtalocyanine (ZnTPPc-QDs) were easily dispersed in buffers at pH equal to or higher than 7.4. QDs capped with aluminum tetrasulfonated phthalocyanine (AlTSPPc-QDs) and indium tetracarboxyphenoxy phthalocyanines (InTCPPc-QDs) were stable in aqueous suspension only at pH higher than 9.0 due to the presence of functional groups bound to the metallic center of the phthalocyanine. The ζ-potential values determined by CE for all the samples decreased when ionic strength increased, being well correlated with the aggregation of the nanoconjugates at elevated salt concentrations. The use of electrokinetic methodologies has provided insights into the colloidal stability of the photosensitizer-functionalized QDs in physiological relevant solutions and thereby, its usefulness for improving their design and applications for photodynamic therapy.
- Full Text:
- Date Issued: 2017
First example of nonlinear optical materials based on nanoconjugates of sandwich phthalocyanines with quantum dots
- Oluwole, David O, Yagodin, Alexey V, Mkhize, Nhlakanipho C, Sekhosana, Kutloana E, Martynov, Alexander G, Gorbunova, Yulia G, Tsivadze, Aslan Yu, Nyokong, Tebello
- Authors: Oluwole, David O , Yagodin, Alexey V , Mkhize, Nhlakanipho C , Sekhosana, Kutloana E , Martynov, Alexander G , Gorbunova, Yulia G , Tsivadze, Aslan Yu , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/238014 , vital:50577 , xlink:href="https://doi.org/10.1002/chem.201604401"
- Description: We report original, selective, and efficient approaches to novel nonlinear optical (NLO) materials, namely homoleptic double- and triple-decker europium(III) complexes 2 and 3 with the A3B-type phthalocyanine ligand (2,3-bis[2′-(2′′-hydroxyethoxy)ethoxy]-9,10,16,17,23,24-hexa-n-butoxyphthalocyanine 1) bearing two anchoring diethyleneglycol chains terminated with OH groups. Their covalently linked nanoconjugates with mercaptosuccinic acid-capped ternary CdSeTe/CdTeS/ZnSeS quantum dots are prepared in the presence of an ethyl(dimethylaminopropyl)carbodiimide activating agent. Optical limiting (OL) properties of the obtained low-symmetry complexes and their conjugates with quantum dots (QDs) are measured for the first time by the open-aperture Z-scan technique (532 nm laser and pulse rate of 10 ns). For comparison, symmetrical double- and triple-decker EuIII octa-n-butoxyphthalocyaninates 5 and 6 and their mixtures with trioctylphosphine oxide-capped QDs are also synthesized and studied. It is revealed that both lowering of molecular symmetry and expansion of the π-electron system upon moving from double- to triple-decker complexes significantly improves the OL characteristics, making the low-symmetry triple-decker complex 3 the most efficient optical limiter in the studied family of sandwich complexes, affording 50 % lowering of light transmittance below 0.5 J cm−2 input fluence. Conjugation (both covalent and noncovalent) with QDs affords further enhancement of the OL properties of both double- and triple-decker complexes. Altogether, the obtained results contribute to the development of novel nonlinear optical materials for future nanoelectronic and optical device applications.
- Full Text:
- Date Issued: 2017
- Authors: Oluwole, David O , Yagodin, Alexey V , Mkhize, Nhlakanipho C , Sekhosana, Kutloana E , Martynov, Alexander G , Gorbunova, Yulia G , Tsivadze, Aslan Yu , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/238014 , vital:50577 , xlink:href="https://doi.org/10.1002/chem.201604401"
- Description: We report original, selective, and efficient approaches to novel nonlinear optical (NLO) materials, namely homoleptic double- and triple-decker europium(III) complexes 2 and 3 with the A3B-type phthalocyanine ligand (2,3-bis[2′-(2′′-hydroxyethoxy)ethoxy]-9,10,16,17,23,24-hexa-n-butoxyphthalocyanine 1) bearing two anchoring diethyleneglycol chains terminated with OH groups. Their covalently linked nanoconjugates with mercaptosuccinic acid-capped ternary CdSeTe/CdTeS/ZnSeS quantum dots are prepared in the presence of an ethyl(dimethylaminopropyl)carbodiimide activating agent. Optical limiting (OL) properties of the obtained low-symmetry complexes and their conjugates with quantum dots (QDs) are measured for the first time by the open-aperture Z-scan technique (532 nm laser and pulse rate of 10 ns). For comparison, symmetrical double- and triple-decker EuIII octa-n-butoxyphthalocyaninates 5 and 6 and their mixtures with trioctylphosphine oxide-capped QDs are also synthesized and studied. It is revealed that both lowering of molecular symmetry and expansion of the π-electron system upon moving from double- to triple-decker complexes significantly improves the OL characteristics, making the low-symmetry triple-decker complex 3 the most efficient optical limiter in the studied family of sandwich complexes, affording 50 % lowering of light transmittance below 0.5 J cm−2 input fluence. Conjugation (both covalent and noncovalent) with QDs affords further enhancement of the OL properties of both double- and triple-decker complexes. Altogether, the obtained results contribute to the development of novel nonlinear optical materials for future nanoelectronic and optical device applications.
- Full Text:
- Date Issued: 2017
Improved nonlinear optical behaviour of ball type indium (III) phthalocyanine linked to glutathione capped nanoparticles
- Nwaji, Njemuwa, Oluwole, David O, Mack, John, Louzada, Marcel, Khene, Samson M, Britton, Jonathan, Nyokong, Tebello
- Authors: Nwaji, Njemuwa , Oluwole, David O , Mack, John , Louzada, Marcel , Khene, Samson M , Britton, Jonathan , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/239654 , vital:50752 , xlink:href="https://doi.org/10.1016/j.dyepig.2017.01.066"
- Description: The synthesis of ball–type indium phthalocyanine (complex 4) and its covalent attachment to glutathione (GSH–) capped (Ag, Au, CdTeSe, CdTeSe/ZnO) nanoparticles are reported in this work. Furthermore, their photophysical and nonlinear optical behaviour were investigated. We observed a decrease in the fluorescence quantum yield with corresponding increase in the triplet quantum yield of the nanoconjugates in comparison to complex 4 alone. The reverse saturable absorption was found to be dependent on excited state absorption. The optical limiting threshold ranges from 0.40–0.78 (J/cm2). The nanoconjugate of the complex 4 with GSH–CdTeSe/ZnO (QD1) accounted for the most improved triplet state parameters and nonlinear optical behaviour in comparison to complex 4 and the other nanoconjugates studied in this work.
- Full Text:
- Date Issued: 2017
- Authors: Nwaji, Njemuwa , Oluwole, David O , Mack, John , Louzada, Marcel , Khene, Samson M , Britton, Jonathan , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/239654 , vital:50752 , xlink:href="https://doi.org/10.1016/j.dyepig.2017.01.066"
- Description: The synthesis of ball–type indium phthalocyanine (complex 4) and its covalent attachment to glutathione (GSH–) capped (Ag, Au, CdTeSe, CdTeSe/ZnO) nanoparticles are reported in this work. Furthermore, their photophysical and nonlinear optical behaviour were investigated. We observed a decrease in the fluorescence quantum yield with corresponding increase in the triplet quantum yield of the nanoconjugates in comparison to complex 4 alone. The reverse saturable absorption was found to be dependent on excited state absorption. The optical limiting threshold ranges from 0.40–0.78 (J/cm2). The nanoconjugate of the complex 4 with GSH–CdTeSe/ZnO (QD1) accounted for the most improved triplet state parameters and nonlinear optical behaviour in comparison to complex 4 and the other nanoconjugates studied in this work.
- Full Text:
- Date Issued: 2017
Investigation of photophysicochemical properties of zinc phthalocyanines conjugated to metallic nanoparticles
- Dube, Edith, Nwaji, Njemuwa, Oluwole, David O, Mack, John, Nyokong, Tebello
- Authors: Dube, Edith , Nwaji, Njemuwa , Oluwole, David O , Mack, John , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/233425 , vital:50089 , xlink:href="https://doi.org/10.1016/j.jphotochem.2017.09.020"
- Description: The syntheses of zinc(II) tetra–[3–(4–phenoxy) (propanoic acid) phthalocyanine] (2) and zinc(II) mono–[3–(4–phenoxy) (propanoic acid) phthalocyanine (3) are reported in this work. Compounds 2 and 3 were covalently linked to glutathione capped silver (AgNPs–GSH), gold (AuNPs–GSH) and silver-gold alloy (Ag3Au1NPs–GSH) nanoparticles (NPs) via an amide bond formation to afford the conjugates: 2–AgNPs–GSH, 3–AgNPs–GSH, 2–AuNPs–GSH, 3–AuNPs–GSH, 2-Ag3Au1NPs–GSH and 3-Ag3Au1NPs–GSH. The photophysicochemical behaviours of the compounds and their conjugates with NPs were assessed in solution. The conjugates afforded a decrease in fluorescence quantum yields and lifetimes with improved triplet quantum yields in comparison to the compounds. Accordingly, the AgNPs and AuNPs conjugates with the compounds afforded high singlet quantum yields. On the contrary, the conjugates of the alloy afforded decreased singlet quantum yields probably due to the screening effect. The compounds and their conjugates with NPs could serve as a viable and efficacious photosensitizer for photodynamic therapy.
- Full Text:
- Date Issued: 2017
- Authors: Dube, Edith , Nwaji, Njemuwa , Oluwole, David O , Mack, John , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/233425 , vital:50089 , xlink:href="https://doi.org/10.1016/j.jphotochem.2017.09.020"
- Description: The syntheses of zinc(II) tetra–[3–(4–phenoxy) (propanoic acid) phthalocyanine] (2) and zinc(II) mono–[3–(4–phenoxy) (propanoic acid) phthalocyanine (3) are reported in this work. Compounds 2 and 3 were covalently linked to glutathione capped silver (AgNPs–GSH), gold (AuNPs–GSH) and silver-gold alloy (Ag3Au1NPs–GSH) nanoparticles (NPs) via an amide bond formation to afford the conjugates: 2–AgNPs–GSH, 3–AgNPs–GSH, 2–AuNPs–GSH, 3–AuNPs–GSH, 2-Ag3Au1NPs–GSH and 3-Ag3Au1NPs–GSH. The photophysicochemical behaviours of the compounds and their conjugates with NPs were assessed in solution. The conjugates afforded a decrease in fluorescence quantum yields and lifetimes with improved triplet quantum yields in comparison to the compounds. Accordingly, the AgNPs and AuNPs conjugates with the compounds afforded high singlet quantum yields. On the contrary, the conjugates of the alloy afforded decreased singlet quantum yields probably due to the screening effect. The compounds and their conjugates with NPs could serve as a viable and efficacious photosensitizer for photodynamic therapy.
- Full Text:
- Date Issued: 2017
Nonlinear optical dynamics of benzothiazole derivatized phthalocyanines in solution, thin films and when conjugated to nanoparticles
- Nwaji, Njemuwa, Jones, Benjamin M, Mack, John, Oluwole, David O, Nyokong, Tebello
- Authors: Nwaji, Njemuwa , Jones, Benjamin M , Mack, John , Oluwole, David O , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/190426 , vital:44993 , xlink:href="https://doi.org/10.1016/j.jphotochem.2017.05.042"
- Description: Benzothiazole phthalocynines complexes: tetrakis[(benzo[d]thiazol-2-ylphenoxy)phthalocyaninato] indium(III) chloride (1) and tetrakis[(benzo[d]thiazol-2-ylthio)phthalocyaninato] indium(III) chloride (2) were synthesisized and their nanosecond nonlinear optical behaviours in solution, solid state and when conjugated to metallic nanoparticles were examined and compared to those of the corresponding ZnPc and GaPc which are designated as: tetrakis[(4-benzo[d]thiazol-2-ylphenoxy)phthalocyaninato] zinc(II) (3), tetrakis[(4-benzo[d]thiazol-2-ylphenoxy)phthalocyaninato] gallium(III) chloride (4), tetrakis[(4-benzo[d]thiazol-2-ylthio)phthalocyaninato] zinc(II) (5) and tetrakis[(4-benzo[d]thiazol-2-ylthio)phthalocyaninato] gallium(III) chloride (6). Trends in the electronic structures were identified through a comparison of the UV–vis absorption and magnetic circular dichroism (MCD) spectroscopy of the complexes and calculated spectra predicted by time dependent density functional theory (TD-DFT). Of all the complexes and nanoconjugates, complex 2 (containing sulphur linkages and In as a central metal) gave the best optical limiting behaviour.
- Full Text:
- Date Issued: 2017
- Authors: Nwaji, Njemuwa , Jones, Benjamin M , Mack, John , Oluwole, David O , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/190426 , vital:44993 , xlink:href="https://doi.org/10.1016/j.jphotochem.2017.05.042"
- Description: Benzothiazole phthalocynines complexes: tetrakis[(benzo[d]thiazol-2-ylphenoxy)phthalocyaninato] indium(III) chloride (1) and tetrakis[(benzo[d]thiazol-2-ylthio)phthalocyaninato] indium(III) chloride (2) were synthesisized and their nanosecond nonlinear optical behaviours in solution, solid state and when conjugated to metallic nanoparticles were examined and compared to those of the corresponding ZnPc and GaPc which are designated as: tetrakis[(4-benzo[d]thiazol-2-ylphenoxy)phthalocyaninato] zinc(II) (3), tetrakis[(4-benzo[d]thiazol-2-ylphenoxy)phthalocyaninato] gallium(III) chloride (4), tetrakis[(4-benzo[d]thiazol-2-ylthio)phthalocyaninato] zinc(II) (5) and tetrakis[(4-benzo[d]thiazol-2-ylthio)phthalocyaninato] gallium(III) chloride (6). Trends in the electronic structures were identified through a comparison of the UV–vis absorption and magnetic circular dichroism (MCD) spectroscopy of the complexes and calculated spectra predicted by time dependent density functional theory (TD-DFT). Of all the complexes and nanoconjugates, complex 2 (containing sulphur linkages and In as a central metal) gave the best optical limiting behaviour.
- Full Text:
- Date Issued: 2017
Optical limiters with improved performance based on nanoconjugates of thiol substituted phthalocyanine with CdSe quantum dots and Ag nanoparticles
- Oluwole, David O, Yagodin, Alexey V, Britton, Jonathan, Martynov, Alexander G, Gorbunova, Yulia G, Tsivadze, Aslan Yu, Nyokong, Tebello
- Authors: Oluwole, David O , Yagodin, Alexey V , Britton, Jonathan , Martynov, Alexander G , Gorbunova, Yulia G , Tsivadze, Aslan Yu , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/238286 , vital:50605 , xlink:href="https://doi.org/10.1039/C7DT03867D"
- Description: Two alternative synthetic approaches affording a low-symmetry A3B-type phthalocyanine 1 bearing two [2′-(2′′-mercaptoethoxy)ethoxy] anchoring substituents were developed. Due to the presence of thiol groups, this phthalocyanine could be conjugated with TOPO-capped (TOPO - trioctylphosphine)-capped CdSe quantum dots (CdSe-QDs) or oleylamine capped silver nanoparticles (Ag-NPs). The nonlinear optical behaviour of starting phthalocyanine, quantum dots, nanoparticles and their conjugates was studied by using an open aperture Z-scan technique, revealing that the grafting of 1 onto the nanomaterials resulted in a significant enhancement of the optical limiting of 1-Ag and 1-CdSe in comparison with the individual components. The conjugate 1-CdSe, being the first example of Pc-based thiol conjugated with quantum dots, revealed superior limiting characteristics with a limiting threshold below 0.18 J cm−2.
- Full Text:
- Date Issued: 2017
- Authors: Oluwole, David O , Yagodin, Alexey V , Britton, Jonathan , Martynov, Alexander G , Gorbunova, Yulia G , Tsivadze, Aslan Yu , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/238286 , vital:50605 , xlink:href="https://doi.org/10.1039/C7DT03867D"
- Description: Two alternative synthetic approaches affording a low-symmetry A3B-type phthalocyanine 1 bearing two [2′-(2′′-mercaptoethoxy)ethoxy] anchoring substituents were developed. Due to the presence of thiol groups, this phthalocyanine could be conjugated with TOPO-capped (TOPO - trioctylphosphine)-capped CdSe quantum dots (CdSe-QDs) or oleylamine capped silver nanoparticles (Ag-NPs). The nonlinear optical behaviour of starting phthalocyanine, quantum dots, nanoparticles and their conjugates was studied by using an open aperture Z-scan technique, revealing that the grafting of 1 onto the nanomaterials resulted in a significant enhancement of the optical limiting of 1-Ag and 1-CdSe in comparison with the individual components. The conjugate 1-CdSe, being the first example of Pc-based thiol conjugated with quantum dots, revealed superior limiting characteristics with a limiting threshold below 0.18 J cm−2.
- Full Text:
- Date Issued: 2017
Photophysical behavior and photodynamic therapy activity of conjugates of zinc monocarboxyphenoxy phthalocyanine with human serum albumin and chitosan
- Oluwole, David O, Prinsloo, Earl, Nyokong, Tebello
- Authors: Oluwole, David O , Prinsloo, Earl , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188497 , vital:44759 , xlink:href="https://doi.org/10.1016/j.saa.2016.09.032"
- Description: Zincmonocarboxyphenoxy phthalocyanine (ZnMCPPc) was linked to human serum albumin (HSA) and chitosan via amide bond formation. The photophysical behavior and photodynamic therapy (PDT) activity (against human breast adenocarcinoma cell line (MCF-7 cells) of ZnMCPPc alone and its conjugates were investigated. The conjugates showed improved fluorescence, triplet and singlet oxygen quantum yields when compared to ZnMCPPc alone. The in vitro dark cytotoxicity and PDT studies were carried out at a dose of 3.6 μg/mL to 57.1 μg/mL. The in vitro dark cytotoxicity studies of ZnMCPPc showed cell viability more than 50% at 28.6 μg/mL and 57.1 μg/mL, while the conjugates showed > 50% in all their tested concentrations (3.6 to 57.1) μg/mL. Thus, conjugation of ZnMCPPc to HSA and chitosan improves its dark cytotoxicity, an important criteria for molecules meant for photodynamic therapy. Complex 1 showed the most efficacious PDT activity with cell viability more than 50% at concentration range of (14.3 to 57.1) μg/mL in comparison to the conjugates which only showed more than 50% cell viability at 28.6 μg/mL and 57.1 μg/mL for 1-HSA and 57.1 μg/mL for 1-Chitosan.
- Full Text:
- Date Issued: 2017
- Authors: Oluwole, David O , Prinsloo, Earl , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188497 , vital:44759 , xlink:href="https://doi.org/10.1016/j.saa.2016.09.032"
- Description: Zincmonocarboxyphenoxy phthalocyanine (ZnMCPPc) was linked to human serum albumin (HSA) and chitosan via amide bond formation. The photophysical behavior and photodynamic therapy (PDT) activity (against human breast adenocarcinoma cell line (MCF-7 cells) of ZnMCPPc alone and its conjugates were investigated. The conjugates showed improved fluorescence, triplet and singlet oxygen quantum yields when compared to ZnMCPPc alone. The in vitro dark cytotoxicity and PDT studies were carried out at a dose of 3.6 μg/mL to 57.1 μg/mL. The in vitro dark cytotoxicity studies of ZnMCPPc showed cell viability more than 50% at 28.6 μg/mL and 57.1 μg/mL, while the conjugates showed > 50% in all their tested concentrations (3.6 to 57.1) μg/mL. Thus, conjugation of ZnMCPPc to HSA and chitosan improves its dark cytotoxicity, an important criteria for molecules meant for photodynamic therapy. Complex 1 showed the most efficacious PDT activity with cell viability more than 50% at concentration range of (14.3 to 57.1) μg/mL in comparison to the conjugates which only showed more than 50% cell viability at 28.6 μg/mL and 57.1 μg/mL for 1-HSA and 57.1 μg/mL for 1-Chitosan.
- Full Text:
- Date Issued: 2017
Photophysicochemical behaviour of anionic indium phthalocyanine when grafted onto AgxAuy and porous silica nanoparticles
- Dube, Edith, Oluwole, David O, Nyokong, Tebello
- Authors: Dube, Edith , Oluwole, David O , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188899 , vital:44796 , xlink:href="https://doi.org/10.1016/j.jlumin.2017.05.071"
- Description: This work reports on the synthesis of glutathione functionalised Ag3Au1 (Ag rich alloy, denoted as AgAu) and Ag1Au3 (Au rich alloy – denoted as AuAg) nano alloys as well as aminopropyl triethoxylsilane capped Ag1Au3 doped silica nanoparticles (NPs). The NPs were covalently linked to indium(III) chloride 2,9(10),16(17),23(24)–tetra–(3–carboxyphenoxy)phthalocyanine (1) via amide bond to form 1–AgAuNPs–GSH and 1–AuAgNPs–GSH. The AgAuNPs were also doped into aminopropyl triethoxylsilane (APTES) silica NPs (SiNPs-APTES) followed by linkage to complex 1 to form 1–AgAu-SiNPs–APTES. The photophysicochemical behaviour of complex 1 and its nanoconjugates were investigated. Decrease in the fluorescence quantum yields and lifetimes was observed in the conjugates in comparison to 1 alone. The singlet oxygen quantum yield for 1–AgAuNPs–GSH and 1–AuAgNPs–GSH decreased probably due to the screening effect caused by the NPs, while that of 1–AgAu-SiNPs–APTES increased in dimethylsulfoxide probably due to the permeability of the porous silica matrix to molecular oxygen.
- Full Text:
- Date Issued: 2017
- Authors: Dube, Edith , Oluwole, David O , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188899 , vital:44796 , xlink:href="https://doi.org/10.1016/j.jlumin.2017.05.071"
- Description: This work reports on the synthesis of glutathione functionalised Ag3Au1 (Ag rich alloy, denoted as AgAu) and Ag1Au3 (Au rich alloy – denoted as AuAg) nano alloys as well as aminopropyl triethoxylsilane capped Ag1Au3 doped silica nanoparticles (NPs). The NPs were covalently linked to indium(III) chloride 2,9(10),16(17),23(24)–tetra–(3–carboxyphenoxy)phthalocyanine (1) via amide bond to form 1–AgAuNPs–GSH and 1–AuAgNPs–GSH. The AgAuNPs were also doped into aminopropyl triethoxylsilane (APTES) silica NPs (SiNPs-APTES) followed by linkage to complex 1 to form 1–AgAu-SiNPs–APTES. The photophysicochemical behaviour of complex 1 and its nanoconjugates were investigated. Decrease in the fluorescence quantum yields and lifetimes was observed in the conjugates in comparison to 1 alone. The singlet oxygen quantum yield for 1–AgAuNPs–GSH and 1–AuAgNPs–GSH decreased probably due to the screening effect caused by the NPs, while that of 1–AgAu-SiNPs–APTES increased in dimethylsulfoxide probably due to the permeability of the porous silica matrix to molecular oxygen.
- Full Text:
- Date Issued: 2017
Photophysicochemical behaviour of metallophthalocyanines when doped onto silica nanoparticles
- Oluwole, David O, Nyokong, Tebello
- Authors: Oluwole, David O , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188518 , vital:44761 , xlink:href="https://doi.org/10.1016/j.dyepig.2016.08.053"
- Description: Aluminum(III) chloride 2,9(10),16(17),23(24)–tetra–(4–tert–butylphenoxy)phthalocyanine (1), zinc(II) 2,9(10),16(17),23(24)–tetra–(4–tert–butylphenoxy)phthalocyanine (2), zinc(II) 1,8(11),15(18),22(25)–tetra–(4–tert–butylphenoxy) phthalocyanine (3) and zinc(II) 2,9(10),16(17),23(24)–tetra–(4–carboxylphenoxy) phthalocyanine (4) were doped onto silica nanoparticles (SiNPs). There were no significant changes in fluorescence quantum yields and lifetimes of the metallophthalocyanines ( MPcs) when doped onto SiNPs. The triplet quantum yields of the MPcs alone range from 0.22 to 0.85 and in the presence of SiNPs the values range from 0.17 to 0.89. We observed a general decrease of triplet quantum yields of phthalocyanines in the conjugates except for 2 where there was an increase. The values were highly affected by aggregation. Complexes 1 and 3 were highly aggregated when doped onto SiNPs, while 2 and 4 did not show much aggregation.
- Full Text:
- Date Issued: 2017
- Authors: Oluwole, David O , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188518 , vital:44761 , xlink:href="https://doi.org/10.1016/j.dyepig.2016.08.053"
- Description: Aluminum(III) chloride 2,9(10),16(17),23(24)–tetra–(4–tert–butylphenoxy)phthalocyanine (1), zinc(II) 2,9(10),16(17),23(24)–tetra–(4–tert–butylphenoxy)phthalocyanine (2), zinc(II) 1,8(11),15(18),22(25)–tetra–(4–tert–butylphenoxy) phthalocyanine (3) and zinc(II) 2,9(10),16(17),23(24)–tetra–(4–carboxylphenoxy) phthalocyanine (4) were doped onto silica nanoparticles (SiNPs). There were no significant changes in fluorescence quantum yields and lifetimes of the metallophthalocyanines ( MPcs) when doped onto SiNPs. The triplet quantum yields of the MPcs alone range from 0.22 to 0.85 and in the presence of SiNPs the values range from 0.17 to 0.89. We observed a general decrease of triplet quantum yields of phthalocyanines in the conjugates except for 2 where there was an increase. The values were highly affected by aggregation. Complexes 1 and 3 were highly aggregated when doped onto SiNPs, while 2 and 4 did not show much aggregation.
- 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
- Oluwole, David O, Ngxeke, Sixolisile M, Britton, Jonathan, Nyokong, Tebello
- 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
- 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
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