The construction of phthalocyanine- carbon nanoparticle conjugates for applications in photodynamic therapy and non-linear optics
- Matshitse, Refilwe Manyama Stephina
- Authors: Matshitse, Refilwe Manyama Stephina
- Date: 2021-10-29
- Subjects: Phthalocyanines , Nanodiamonds , Photochemotherapy , Nonlinear optics , Quantum dots
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/188397 , vital:44750 , 10.21504/10962/188397
- Description: The syntheses and characterization of symmetric and asymmetric Pcs functionalized at the peripheral position and sometimes positively charged are reported. The Pcs had either H2, zinc or silicon as central metals and have pyridyloxy, benzothiozole phenoxy, and respective cationic analogues as ring substituents. The Pcs were linked to carbon based nanoparticles such as graphene quantum dots, carbon dots, and detonation nanodiamonds (DNDs) via an ester, amide bond and/or π - π stacking. The physicochemical characteristics of the Pcs were assessed when alone and when in a conjugated system. Both symmetrically and asymmetrically substituted benzothiozole Pcs when quaternised displayed higher triplet and singlet oxygen quantum yields than their unquaternised counterparts. Linkage to carbon nanoparticles (especially to detonation nanodiamonds) had an increasing effect on triplet and singlet oxygen quantum yield. However, a general decrease in singlet oxygen quantum yield on linkage to doped detonation nanodiamonds was associated with the screening effect of DNDs. Heteroatom doped DNDs-Pc nanohybrids have less singlet oxygen than Pcs alone due to molecular structural stability associated with strain that is relatively reduced upon linking Pcs. The In vitro dark cytotoxicity and photodynamic therapy of selected Pc complexes and conjugates against MCF-7 cells was tested. All studied Pc complexes and conjugates showed minimum dark toxicity making them applicable for PDT. When Pc complexes are alone, there is less phototoxicity with >22% cell viability at concentrations ≤ 50 μg/mL relative to conjugates with <22% cell viability at concentrations ≤ 50 μg/mL. There was no direct relationship between PDT and singlet oxygen quantum yields. Nonlinear optical characteristics of complexes was improved upon conjugation of DNDs. Absorbance, input energy, percentage loading, central metal, substituent of Pc and nature of interaction (covalent, noncovalent) are amongst some of the factors that influence nonlinear absorption properties of materials used in this study. All materials followed reverse saturable absorption through two photon absorption mechanism at the excitation wavelength of 532 nm. Aggregates reduce excited state lifetime and Beff under high concentrations/absorbance. A direct relationship between absorbance and Beff of DNDs nanoconjugated systems at low concentrations result in increased optical limiting characteristics of materials. The findings from this work show the importance of linking (nonlinear optics and photodynamic therapy) and doping (photodynamic therapy) photosensitisers such as phthalocyanines and sometimes boron dipyrromethenes onto carbon based nanoparticles for the enhanced characteristics in variable applications. , Thesis (PhD) -- Faculty of Science, Chemistry, 2021
- Full Text:
- Date Issued: 2021-10-29
- Authors: Matshitse, Refilwe Manyama Stephina
- Date: 2021-10-29
- Subjects: Phthalocyanines , Nanodiamonds , Photochemotherapy , Nonlinear optics , Quantum dots
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/188397 , vital:44750 , 10.21504/10962/188397
- Description: The syntheses and characterization of symmetric and asymmetric Pcs functionalized at the peripheral position and sometimes positively charged are reported. The Pcs had either H2, zinc or silicon as central metals and have pyridyloxy, benzothiozole phenoxy, and respective cationic analogues as ring substituents. The Pcs were linked to carbon based nanoparticles such as graphene quantum dots, carbon dots, and detonation nanodiamonds (DNDs) via an ester, amide bond and/or π - π stacking. The physicochemical characteristics of the Pcs were assessed when alone and when in a conjugated system. Both symmetrically and asymmetrically substituted benzothiozole Pcs when quaternised displayed higher triplet and singlet oxygen quantum yields than their unquaternised counterparts. Linkage to carbon nanoparticles (especially to detonation nanodiamonds) had an increasing effect on triplet and singlet oxygen quantum yield. However, a general decrease in singlet oxygen quantum yield on linkage to doped detonation nanodiamonds was associated with the screening effect of DNDs. Heteroatom doped DNDs-Pc nanohybrids have less singlet oxygen than Pcs alone due to molecular structural stability associated with strain that is relatively reduced upon linking Pcs. The In vitro dark cytotoxicity and photodynamic therapy of selected Pc complexes and conjugates against MCF-7 cells was tested. All studied Pc complexes and conjugates showed minimum dark toxicity making them applicable for PDT. When Pc complexes are alone, there is less phototoxicity with >22% cell viability at concentrations ≤ 50 μg/mL relative to conjugates with <22% cell viability at concentrations ≤ 50 μg/mL. There was no direct relationship between PDT and singlet oxygen quantum yields. Nonlinear optical characteristics of complexes was improved upon conjugation of DNDs. Absorbance, input energy, percentage loading, central metal, substituent of Pc and nature of interaction (covalent, noncovalent) are amongst some of the factors that influence nonlinear absorption properties of materials used in this study. All materials followed reverse saturable absorption through two photon absorption mechanism at the excitation wavelength of 532 nm. Aggregates reduce excited state lifetime and Beff under high concentrations/absorbance. A direct relationship between absorbance and Beff of DNDs nanoconjugated systems at low concentrations result in increased optical limiting characteristics of materials. The findings from this work show the importance of linking (nonlinear optics and photodynamic therapy) and doping (photodynamic therapy) photosensitisers such as phthalocyanines and sometimes boron dipyrromethenes onto carbon based nanoparticles for the enhanced characteristics in variable applications. , Thesis (PhD) -- Faculty of Science, Chemistry, 2021
- Full Text:
- Date Issued: 2021-10-29
Photo-physicochemical studies and photodynamic therapy activity of indium and gallium phthalocyanines
- Tshangana, Charmaine Sesethu
- Authors: Tshangana, Charmaine Sesethu
- Date: 2015
- Subjects: Quantum dots , Nanoparticles , Photochemotherapy , Phthalocyanines
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4548 , http://hdl.handle.net/10962/d1017928
- Description: The potential toxicity of seven different types of quantum dots without shell (L-cysteine-CdTe, TGA-CdTe, MPA-CdTe, TGA-CdSe) and with the shell (GSH-CdSe@ZnS, GSH-CdTe@ZnS,) with different capping agents were evaluated. The growth inhibitory effects of the various quantum dots on human pancreatic BON cancerous cells were determined. The least cytotoxic of the various quantum dots synthesized and the one displaying the lowest growth inhibitory potential and no embryotoxicity was determined to be the GSH-CdSe@ZnS quantum dots. The GSH-CdSe@ZnS quantum dots were then conjugated to gallium, aluminium and indium octacarboxy phthalocyanine and the photophysical behaviour of the conjugates studied for potential use in photodynamic therapy and imaging applications. The sizes, morphology, thermal stability and confirmation of successful conjugation was determined using X-ray diffraction (XRD), transmission electron microscopy (TEM), thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR), respectively. The study was extended by conjugating amino functionalized magnetic nanoparticles (Fe₃O₄) to indium octacarboxy phthalocyanine to study the photophysical behaviour of the conjugate as a potential bi-functional anti-cancer agent (hyperthermia and photodynamic therapy applications). A three-in-one multifunctional nanocomposite comprising of the quantum dots, magnetic nanoparticles and indium octacarboxy phthalocyanine was developed with the aim of developing a multifunctional composite that is able detect, monitor and treat cancer. All conjugates showed improved and enhanced photophysical behaviour. Finally, GSH-CdSe@ZnS conjugated to aluminium octacarboxy phthalocyanine was applied in human pancreatic carcinoid BON cells. The conjugates induced cell death dose-dependently.
- Full Text:
- Date Issued: 2015
- Authors: Tshangana, Charmaine Sesethu
- Date: 2015
- Subjects: Quantum dots , Nanoparticles , Photochemotherapy , Phthalocyanines
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4548 , http://hdl.handle.net/10962/d1017928
- Description: The potential toxicity of seven different types of quantum dots without shell (L-cysteine-CdTe, TGA-CdTe, MPA-CdTe, TGA-CdSe) and with the shell (GSH-CdSe@ZnS, GSH-CdTe@ZnS,) with different capping agents were evaluated. The growth inhibitory effects of the various quantum dots on human pancreatic BON cancerous cells were determined. The least cytotoxic of the various quantum dots synthesized and the one displaying the lowest growth inhibitory potential and no embryotoxicity was determined to be the GSH-CdSe@ZnS quantum dots. The GSH-CdSe@ZnS quantum dots were then conjugated to gallium, aluminium and indium octacarboxy phthalocyanine and the photophysical behaviour of the conjugates studied for potential use in photodynamic therapy and imaging applications. The sizes, morphology, thermal stability and confirmation of successful conjugation was determined using X-ray diffraction (XRD), transmission electron microscopy (TEM), thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR), respectively. The study was extended by conjugating amino functionalized magnetic nanoparticles (Fe₃O₄) to indium octacarboxy phthalocyanine to study the photophysical behaviour of the conjugate as a potential bi-functional anti-cancer agent (hyperthermia and photodynamic therapy applications). A three-in-one multifunctional nanocomposite comprising of the quantum dots, magnetic nanoparticles and indium octacarboxy phthalocyanine was developed with the aim of developing a multifunctional composite that is able detect, monitor and treat cancer. All conjugates showed improved and enhanced photophysical behaviour. Finally, GSH-CdSe@ZnS conjugated to aluminium octacarboxy phthalocyanine was applied in human pancreatic carcinoid BON cells. The conjugates induced cell death dose-dependently.
- Full Text:
- Date Issued: 2015
Photophysical studies of zinc and indium tetraaminophthalocyanines in the presence of CdTe quantum dots
- Authors: Britton, Jonathan
- Date: 2010
- Subjects: Indium , Zinc , Quantum dots , Phthalocyanines , Photochemotherapy , Nonlinear optics , Nanocrystals
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4332 , http://hdl.handle.net/10962/d1004993 , Indium , Zinc , Quantum dots , Phthalocyanines , Photochemotherapy , Nonlinear optics , Nanocrystals
- Description: CdTe QDs capped with mercaptopropionic acid (MPA) and thioglycolic acid (TGA) were covalently linked to zinc and indium tetraaminophthalocyanines (TAPcs) using N-ethyl-N(3-dimethylaminopropyl) carbodiimide (EDC) and N-hydroxy succinimide (NHS) as the coupling agents. The results presented give evidence in favour of formation of an amide bond between the MTAPc and CdTe QDs. Both the linked ZnTAPc–QD complexes and the mixture of QDs and ZnTAPc (without chemical linking) showed Förster resonance energy transfer (FRET), though the linked showed less FRET, whereas the QD interactions with InTAPc yielded no evidence of FRET. Both MTAPcs quenched the QDs emission, with quenching constants of the order of 103–104M−1, binding constants of the order of 108-1010M-1 and the number of binding sites for the MTAPc upon the QD being 2. High energy transfer efficiencies were obtained (in some cases as high as 93%), due to the low donor to acceptor distances. Lastly, both MTAPc were shown to be poor optical limiters because their imaginary third-order susceptibility (Im[χ(3)]) was of the order of 10-17-10-16 (optimal range is 10-9-10-11), the hyperpolarizability (γ) of the order of 10-37-10-36 (optimal range is 10-29-10-34) and the k values were above one but below ten.
- Full Text:
- Date Issued: 2010
- Authors: Britton, Jonathan
- Date: 2010
- Subjects: Indium , Zinc , Quantum dots , Phthalocyanines , Photochemotherapy , Nonlinear optics , Nanocrystals
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4332 , http://hdl.handle.net/10962/d1004993 , Indium , Zinc , Quantum dots , Phthalocyanines , Photochemotherapy , Nonlinear optics , Nanocrystals
- Description: CdTe QDs capped with mercaptopropionic acid (MPA) and thioglycolic acid (TGA) were covalently linked to zinc and indium tetraaminophthalocyanines (TAPcs) using N-ethyl-N(3-dimethylaminopropyl) carbodiimide (EDC) and N-hydroxy succinimide (NHS) as the coupling agents. The results presented give evidence in favour of formation of an amide bond between the MTAPc and CdTe QDs. Both the linked ZnTAPc–QD complexes and the mixture of QDs and ZnTAPc (without chemical linking) showed Förster resonance energy transfer (FRET), though the linked showed less FRET, whereas the QD interactions with InTAPc yielded no evidence of FRET. Both MTAPcs quenched the QDs emission, with quenching constants of the order of 103–104M−1, binding constants of the order of 108-1010M-1 and the number of binding sites for the MTAPc upon the QD being 2. High energy transfer efficiencies were obtained (in some cases as high as 93%), due to the low donor to acceptor distances. Lastly, both MTAPc were shown to be poor optical limiters because their imaginary third-order susceptibility (Im[χ(3)]) was of the order of 10-17-10-16 (optimal range is 10-9-10-11), the hyperpolarizability (γ) of the order of 10-37-10-36 (optimal range is 10-29-10-34) and the k values were above one but below ten.
- Full Text:
- Date Issued: 2010
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