Synthesis, theoretical calculations and laser flash photolysis studies of selected amphiphilic porphyrin derivatives used as biofilm photodegradative materials
- Openda, Yolande I, Ngoy, Bokolombe P, Muva, Jules T, Nyokong, Tebello
- Authors: Openda, Yolande I , Ngoy, Bokolombe P , Muva, Jules T , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/190589 , vital:45008 , xlink:href="https://doi.org/10.1039/D1NJ02651H"
- Description: Photodynamic antimicrobial activities of gallium and indium porphyrins as well as their quaternized derivatives have been investigated against S. aureus and E. coli biofilms, as well as on their planktonic (free floating) cells using a light emitting diode lamp at 415 nm. The studied photosensitizers show considerable ability to generate singlet oxygen and the quaternized molecules 2a and 3a are potential photodynamic antimicrobial chemotherapy (PACT) agents with log10 colony forming units >9 for E. coli and S. aureus planktonic cells. The quaternized derivatives are found to have higher ability to significantly suppress the biofilms of both S. aureus and E. coli in vitro. Therefore, this demonstrates that they are potentially suitable photosensitive agents for PACT use. The TD-B3LYP/LanL2DZ calculations were performed to evaluate the singlet excitation energies of quaternized and non-quaternized porphyrins in vacuo. Our study shows excellent agreement between time-dependent density-functional theory (TD-DFT) excited energies and experimental S1 > S0 excitation energies. The small deviation observed between the calculated and experimental spectra arises from the solvent effect. The excitation energies observed in these UV-visible spectra mostly originated from electron promotion between the highest occupied molecular orbital (HOMO) for the less intense band and the HOMO−1 for the most intense band of the ground states to the lower unoccupied molecular orbital (LUMO) of the excited states.
- Full Text:
- Date Issued: 2021
- Authors: Openda, Yolande I , Ngoy, Bokolombe P , Muva, Jules T , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/190589 , vital:45008 , xlink:href="https://doi.org/10.1039/D1NJ02651H"
- Description: Photodynamic antimicrobial activities of gallium and indium porphyrins as well as their quaternized derivatives have been investigated against S. aureus and E. coli biofilms, as well as on their planktonic (free floating) cells using a light emitting diode lamp at 415 nm. The studied photosensitizers show considerable ability to generate singlet oxygen and the quaternized molecules 2a and 3a are potential photodynamic antimicrobial chemotherapy (PACT) agents with log10 colony forming units >9 for E. coli and S. aureus planktonic cells. The quaternized derivatives are found to have higher ability to significantly suppress the biofilms of both S. aureus and E. coli in vitro. Therefore, this demonstrates that they are potentially suitable photosensitive agents for PACT use. The TD-B3LYP/LanL2DZ calculations were performed to evaluate the singlet excitation energies of quaternized and non-quaternized porphyrins in vacuo. Our study shows excellent agreement between time-dependent density-functional theory (TD-DFT) excited energies and experimental S1 > S0 excitation energies. The small deviation observed between the calculated and experimental spectra arises from the solvent effect. The excitation energies observed in these UV-visible spectra mostly originated from electron promotion between the highest occupied molecular orbital (HOMO) for the less intense band and the HOMO−1 for the most intense band of the ground states to the lower unoccupied molecular orbital (LUMO) of the excited states.
- Full Text:
- Date Issued: 2021
Photophysical properties and photodynamic therapy activity of a meso-tetra (4-carboxyphenyl) porphyrin tetramethyl ester–graphene quantum dot conjugate
- Managa, Muthumuni, Ngoy, Bokolombe P, Nyokong, Tebello
- Authors: Managa, Muthumuni , Ngoy, Bokolombe P , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187533 , vital:44669 , xlink:href="https://doi.org/10.1039/C8NJ06175K"
- Description: Novel meso-tetra(4-carboxyphenyl)porphyrin tetramethyl ester metal derivatives were synthesised and characterized. These derivatives were interacted with graphene quantum dots (GDQs). Spectroscopic evidence that was obtained showed that the resultant conjugates were stable due to the strong π–π stacking interaction between the GQDs and the porphyrins. The fluorescence and singlet oxygen generating behaviour of the porphyrins and the nanoconjugates were investigated following incorporation. The dark toxicity and photodynamic therapy activities of the porphyrins and the nanoconjugates were successfully studied using MCF-7 breast cancer cells. Cell viability for the dark toxicity was more than 90% for all complexes. The PDT activities at the highest concentration of 120 μg ml−1 showed a decrease in cell viability down to 15.2% for the GaClTMPP–GQDs.
- Full Text:
- Date Issued: 2019
- Authors: Managa, Muthumuni , Ngoy, Bokolombe P , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187533 , vital:44669 , xlink:href="https://doi.org/10.1039/C8NJ06175K"
- Description: Novel meso-tetra(4-carboxyphenyl)porphyrin tetramethyl ester metal derivatives were synthesised and characterized. These derivatives were interacted with graphene quantum dots (GDQs). Spectroscopic evidence that was obtained showed that the resultant conjugates were stable due to the strong π–π stacking interaction between the GQDs and the porphyrins. The fluorescence and singlet oxygen generating behaviour of the porphyrins and the nanoconjugates were investigated following incorporation. The dark toxicity and photodynamic therapy activities of the porphyrins and the nanoconjugates were successfully studied using MCF-7 breast cancer cells. Cell viability for the dark toxicity was more than 90% for all complexes. The PDT activities at the highest concentration of 120 μg ml−1 showed a decrease in cell viability down to 15.2% for the GaClTMPP–GQDs.
- Full Text:
- Date Issued: 2019
Synthesis and photophysical properties of BODIPY-decorated graphene quantum dot–phthalocyanine conjugates
- Nwahara, Nnamdi, Nkhahle, Reitumetse, Ngoy, Bokolombe P, Mack, John, Nyokong, Tebello
- Authors: Nwahara, Nnamdi , Nkhahle, Reitumetse , Ngoy, Bokolombe P , Mack, John , Nyokong, Tebello
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/233409 , vital:50088 , xlink:href="https://doi.org/10.1039/C8NJ00758F"
- Description: This work reports on the synthesis and characterisation of novel supramolecular hybrids containing BODIPY-decorated graphene quantum dots (BODIPY@GQDs) and zinc phthalocyanine. Graphene quantum dots (GQDs) were functionalized with L-glutathione (GSH) in order to assist coupling to the BODIPY dye. {2,9(10)16(17)23(24)-Tetrakis-[3-(diethylamino)phenoxy]phthalocyaninato}zinc(II) (1) was immobilized via π–π stacking interaction on the BODIPY-decorated GQDs and pristine GQDs to form the supramolecular hybrids 1-BODIPY@GQDs and 1-GQDs, respectively. The photophysical and photochemical properties of these conjugates were investigated. Energy transfer occurred from the (i) GQDs to BODIPY, (ii) GQDs to 1, and (iii) BODIPY@GQDs to 1via fluorescence resonance energy transfer (FRET). The highest FRET efficiency was observed for the BODIPY@GQDs (0.93). The introduction of the BODIPY core to the GQD structure resulted in higher triplet, and singlet oxygen quantum yields for the resultant Pc/GQD hybrid (1-BODIPY@GQDs). The zeta potential values obtained imply a high colloidal stability for the supramolecular hybrids. The results suggest that such hybrids may be applied in fields such as photodynamic therapy (PDT), where a high singlet oxygen quantum yield is desired.
- Full Text:
- Date Issued: 2018
- Authors: Nwahara, Nnamdi , Nkhahle, Reitumetse , Ngoy, Bokolombe P , Mack, John , Nyokong, Tebello
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/233409 , vital:50088 , xlink:href="https://doi.org/10.1039/C8NJ00758F"
- Description: This work reports on the synthesis and characterisation of novel supramolecular hybrids containing BODIPY-decorated graphene quantum dots (BODIPY@GQDs) and zinc phthalocyanine. Graphene quantum dots (GQDs) were functionalized with L-glutathione (GSH) in order to assist coupling to the BODIPY dye. {2,9(10)16(17)23(24)-Tetrakis-[3-(diethylamino)phenoxy]phthalocyaninato}zinc(II) (1) was immobilized via π–π stacking interaction on the BODIPY-decorated GQDs and pristine GQDs to form the supramolecular hybrids 1-BODIPY@GQDs and 1-GQDs, respectively. The photophysical and photochemical properties of these conjugates were investigated. Energy transfer occurred from the (i) GQDs to BODIPY, (ii) GQDs to 1, and (iii) BODIPY@GQDs to 1via fluorescence resonance energy transfer (FRET). The highest FRET efficiency was observed for the BODIPY@GQDs (0.93). The introduction of the BODIPY core to the GQD structure resulted in higher triplet, and singlet oxygen quantum yields for the resultant Pc/GQD hybrid (1-BODIPY@GQDs). The zeta potential values obtained imply a high colloidal stability for the supramolecular hybrids. The results suggest that such hybrids may be applied in fields such as photodynamic therapy (PDT), where a high singlet oxygen quantum yield is desired.
- Full Text:
- Date Issued: 2018
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