"Knowing With": New Rhodes Board Navigates Collaboration, Intimacy, and Solidarity
- Baasch, Rachel M, Fọlárànmí, Stephen, Koide, Emi, Kakande, Angelo, Simbao, Ruth K
- Authors: Baasch, Rachel M , Fọlárànmí, Stephen , Koide, Emi , Kakande, Angelo , Simbao, Ruth K
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/147514 , vital:38645 , https://doi.org/10.1162/afar_a_00523
- Description: Rhodes University (or UCKAR), based in Makhanda, South Africa, joined the African Arts editorial consortium in 2016 and its first journal issue—vol. 50, no. 2—was published in 2017. Initially the board was run by Ruth Simbao, with the aim of developing collaborations with other scholars, particularly those based on the African continent and within the global south (Simbao 2017: 1). For the second Rhodes issue (Summer 2018), Simbao worked with Guest Board Member Amanda Tumusiime from Makerere University, and for the third Rhodes issue (Summer 2019) she collaborated with Stephen Folárànmí from Obáfémi Awólówò University, Ilé-Ifè, Nigeria, who at the time was a Postdoctoral Fellow at Rhodes.
- Full Text:
- Authors: Baasch, Rachel M , Fọlárànmí, Stephen , Koide, Emi , Kakande, Angelo , Simbao, Ruth K
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/147514 , vital:38645 , https://doi.org/10.1162/afar_a_00523
- Description: Rhodes University (or UCKAR), based in Makhanda, South Africa, joined the African Arts editorial consortium in 2016 and its first journal issue—vol. 50, no. 2—was published in 2017. Initially the board was run by Ruth Simbao, with the aim of developing collaborations with other scholars, particularly those based on the African continent and within the global south (Simbao 2017: 1). For the second Rhodes issue (Summer 2018), Simbao worked with Guest Board Member Amanda Tumusiime from Makerere University, and for the third Rhodes issue (Summer 2019) she collaborated with Stephen Folárànmí from Obáfémi Awólówò University, Ilé-Ifè, Nigeria, who at the time was a Postdoctoral Fellow at Rhodes.
- Full Text:
Bodies, buildings, and borders: navigating the divided nation through contemporary South African and Palestinian art practice
- Authors: Baasch, Rachel M
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/145897 , vital:38476 , https://0-doi.org.wam.seals.ac.za/10.1162/afar_a_00401
- Description: This paper navigates the phenomenon of the divided nation through the work of contemporary South African artists Th¬ando Mama, Sikhumbuzo Makandula, and Ndikhumbule Ngqinambi. I position the work of these artists practicing in a post-apartheid nation-state alongside the work of contemporary Palestinian artists Larissa Sansour and Khaled Jarrar, who respond to the ongoing struggle of the stateless Palestinian nation divided by colonialism and Israeli apartheid. Each of these artists critiques the construction of the modern nation-state using symbols such as the national flag, the national anthem, the passport and postage stamp, and physical walls and buildings.
- Full Text:
- Authors: Baasch, Rachel M
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/145897 , vital:38476 , https://0-doi.org.wam.seals.ac.za/10.1162/afar_a_00401
- Description: This paper navigates the phenomenon of the divided nation through the work of contemporary South African artists Th¬ando Mama, Sikhumbuzo Makandula, and Ndikhumbule Ngqinambi. I position the work of these artists practicing in a post-apartheid nation-state alongside the work of contemporary Palestinian artists Larissa Sansour and Khaled Jarrar, who respond to the ongoing struggle of the stateless Palestinian nation divided by colonialism and Israeli apartheid. Each of these artists critiques the construction of the modern nation-state using symbols such as the national flag, the national anthem, the passport and postage stamp, and physical walls and buildings.
- Full Text:
Guarded visions: walls, watchtowers and warped perspectives in the Israeli occupied West Bank Palestinian territory
- Authors: Baasch, Rachel M
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/147281 , vital:38611 , https://0-hdl.handle.net.wam.seals.ac.za/10520/EJC176318
- Description: This paper examines the relationship between Israel's fortification of physical space and narratives of division in the Israeli occupied Palestinian West Bank Territory. I argue that the fortification and separation of physical space deepens segregation, and increases fear, hostility and disconnection between people living in this context. Furthermore, I suggest that this relationship between narratives of division and insecurity and structural mechanisms of control within the West Bank influences and impacts on individuals such that personal perspectives become guarded and defensive. The mediation of subjects through a defensive lens can prevent individuals from forming connections that acknowledge the permeability of seemingly impenetrable distinctions between inside and outside, or self and an-other. The looking, recording and representation of people in a place that is guarded and framed from a position of insecurity reduces the capacity of individuals to locate openings that traverse restrictive boundaries. In order to contextualise my discussion, I have included personal documentation of defensive structures photographed in the West Bank between 2013 and 2014. I position my observations and analyses in relation to discussions about the Oush Grab Military Base presented by the Decolonizing Architecture Art Residency (DAAR) in their recent publication Architecture after revolution (2013).
- Full Text:
- Authors: Baasch, Rachel M
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/147281 , vital:38611 , https://0-hdl.handle.net.wam.seals.ac.za/10520/EJC176318
- Description: This paper examines the relationship between Israel's fortification of physical space and narratives of division in the Israeli occupied Palestinian West Bank Territory. I argue that the fortification and separation of physical space deepens segregation, and increases fear, hostility and disconnection between people living in this context. Furthermore, I suggest that this relationship between narratives of division and insecurity and structural mechanisms of control within the West Bank influences and impacts on individuals such that personal perspectives become guarded and defensive. The mediation of subjects through a defensive lens can prevent individuals from forming connections that acknowledge the permeability of seemingly impenetrable distinctions between inside and outside, or self and an-other. The looking, recording and representation of people in a place that is guarded and framed from a position of insecurity reduces the capacity of individuals to locate openings that traverse restrictive boundaries. In order to contextualise my discussion, I have included personal documentation of defensive structures photographed in the West Bank between 2013 and 2014. I position my observations and analyses in relation to discussions about the Oush Grab Military Base presented by the Decolonizing Architecture Art Residency (DAAR) in their recent publication Architecture after revolution (2013).
- Full Text:
Between a cushion and a risky conversation: ARTS LOUNGE reviewed
- Authors: Baasch, Rachel M
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/147703 , vital:38662 , https://doi.org/10.1080/00043389.2011.11877155
- Description: On the fringe of the National Arts Festival, at a point of transition between Rhodes University campus and the commercial side of Grahamstown, the walls of a former home and former horse-stable, now a research house, reverberate with the strain of cross-disciplinary, site-specific collaboration. The ARTS LOUNGE made its first official appearance at the Grahamstown National Arts Festival (ViPPA Research Center, Rhodes University) from 30 June to 9 July 2011. The ten-day event was organised by the Visual and Performing Arts of Africa Research (ViPPA) team in collaboration with musicians, artists, writers, performers and members of the public.
- Full Text:
- Authors: Baasch, Rachel M
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/147703 , vital:38662 , https://doi.org/10.1080/00043389.2011.11877155
- Description: On the fringe of the National Arts Festival, at a point of transition between Rhodes University campus and the commercial side of Grahamstown, the walls of a former home and former horse-stable, now a research house, reverberate with the strain of cross-disciplinary, site-specific collaboration. The ARTS LOUNGE made its first official appearance at the Grahamstown National Arts Festival (ViPPA Research Center, Rhodes University) from 30 June to 9 July 2011. The ten-day event was organised by the Visual and Performing Arts of Africa Research (ViPPA) team in collaboration with musicians, artists, writers, performers and members of the public.
- Full Text:
Thien-2-yl substituted chlorins as photosensitizers for photodynamic therapy and photodynamic antimicrobial chemotherapy
- Babu, Balaji, Sindelo, Azole, Mack, John, Nyokong, Tebello
- Authors: Babu, Balaji , Sindelo, Azole , Mack, John , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/190578 , vital:45007 , xlink:href="https://doi.org/10.1016/j.dyepig.2020.108886"
- Description: The synthesis and characterization of meso-tetra(thien-2-yl)chlorin (1) and meso-tetra(5-bromothien-2-yl)chlorin (2) is reported. These dyes have red-shifted absorption maxima compared to those of the analogous meso-tetraphenylchlorin (3). 1 and 2 have Q bands at 660 and 664 nm, respectively, singlet oxygen quantum yields of 0.60 and 0.64 and exhibit good photostability. The triplet states were found to have lifetimes of 8.6 μs in N2 purged DMF. Time-dependent cellular uptake of chlorins reached a maximum in MCF-7 cancer cells after 12 h. Upon irradiation with a Thorlabs M660L3 LED (280 mW cm−2), 2 exhibited better photocytotoxicity with an IC50 value of 2.7 μM against MCF-7 cells. The 2ʹ,7ʹ-dichlorodihydrofluorescein diacetate (DCFDA) assay provided evidence for intracellular generation of reactive oxygen species. Photodynamic inactivation of bacteria by the chlorins was also studied. 2 exhibits better activity with log reduction values of 7.42 and 8.34 towards Staphylococcus aureus and Escherichia coli, respectively, under illumination for 60 min at 660 nm with a Thorlabs M660L3 LED (280 mW cm−2). These results demonstrate that 2 is a promising candidate for future in vivo experiments and merits further in-depth investigation.
- Full Text:
- Authors: Babu, Balaji , Sindelo, Azole , Mack, John , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/190578 , vital:45007 , xlink:href="https://doi.org/10.1016/j.dyepig.2020.108886"
- Description: The synthesis and characterization of meso-tetra(thien-2-yl)chlorin (1) and meso-tetra(5-bromothien-2-yl)chlorin (2) is reported. These dyes have red-shifted absorption maxima compared to those of the analogous meso-tetraphenylchlorin (3). 1 and 2 have Q bands at 660 and 664 nm, respectively, singlet oxygen quantum yields of 0.60 and 0.64 and exhibit good photostability. The triplet states were found to have lifetimes of 8.6 μs in N2 purged DMF. Time-dependent cellular uptake of chlorins reached a maximum in MCF-7 cancer cells after 12 h. Upon irradiation with a Thorlabs M660L3 LED (280 mW cm−2), 2 exhibited better photocytotoxicity with an IC50 value of 2.7 μM against MCF-7 cells. The 2ʹ,7ʹ-dichlorodihydrofluorescein diacetate (DCFDA) assay provided evidence for intracellular generation of reactive oxygen species. Photodynamic inactivation of bacteria by the chlorins was also studied. 2 exhibits better activity with log reduction values of 7.42 and 8.34 towards Staphylococcus aureus and Escherichia coli, respectively, under illumination for 60 min at 660 nm with a Thorlabs M660L3 LED (280 mW cm−2). These results demonstrate that 2 is a promising candidate for future in vivo experiments and merits further in-depth investigation.
- Full Text:
Photodynamic activity of Sn (IV) tetrathien-2-ylchlorin against MCF-7 breast cancer cells
- Babu, Balaji, Mack, John, Nyokong, Tebello
- Authors: Babu, Balaji , Mack, John , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185920 , vital:44448 , xlink:href="https://doi.org/10.1039/d0dt03958f"
- Description: A new readily-synthesized Sn(IV) tetraarylchlorin with thien-2-yl substituents (SnC) has been prepared and fully characterized by various spectroscopic techniques and its photophysical and photochemical properties, such as the singlet oxygen quantum yield (ΦΔ), fluorescence quantum yield (ΦF), triplet lifetime (τT) and photostability, have been evaluated. SnC has an unusually high ΦΔ value of 0.89 in DMF. Studies on the photodynamic activity against MCF-7 breast cancer cells exhibited a very low IC50 value of 0.9 μM and high phototoxicity (dark versus light) indices of >27.8 after irradiation with a 660 nm Thorlabs LED (280 mW cm−2). The results demonstrate that Sn(IV) tetraarylchlorins of this type are suitable candidates for further in-depth PDT studies.
- Full Text:
- Authors: Babu, Balaji , Mack, John , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185920 , vital:44448 , xlink:href="https://doi.org/10.1039/d0dt03958f"
- Description: A new readily-synthesized Sn(IV) tetraarylchlorin with thien-2-yl substituents (SnC) has been prepared and fully characterized by various spectroscopic techniques and its photophysical and photochemical properties, such as the singlet oxygen quantum yield (ΦΔ), fluorescence quantum yield (ΦF), triplet lifetime (τT) and photostability, have been evaluated. SnC has an unusually high ΦΔ value of 0.89 in DMF. Studies on the photodynamic activity against MCF-7 breast cancer cells exhibited a very low IC50 value of 0.9 μM and high phototoxicity (dark versus light) indices of >27.8 after irradiation with a 660 nm Thorlabs LED (280 mW cm−2). The results demonstrate that Sn(IV) tetraarylchlorins of this type are suitable candidates for further in-depth PDT studies.
- Full Text:
Naked Eye and Colorimetric Detection of Cyanide with a 1, 3‐Diethyl‐2‐thiobarbituric Acid Substituted Ferrocene Chemosensor
- Babu, Balaji, Mack, John, Nyokong, Tebello
- Authors: Babu, Balaji , Mack, John , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/190567 , vital:45006 , xlink:href="https://doi.org/10.1002/slct.202100163"
- Description: A 1,3-diethyl-2-thiobarbituric-acid-substituted ferrocene (FET) has been evaluated for its cyanide sensing ability by UV-visible absorption spectroscopy and other characterization methods. FET provides a ratiometric colorimetric chemosensor for the CN− anion detection in 1 : 1 DMSO/H2O (v/v) solution. The addition of CN− results in an immediate color change from dark blue to pale orange that is visible to the naked eye. Mechanism studies and molecular modelling with TD-DFT calculations demonstrate that nucleophilic addition of CN− to an electrophilic sp2-hybridized carbon atom blocks charge transfer from the ferrocene ring complex to the thiobarbituric acid moiety. The FET sensor exhibits excellent selectivity for CN− and a limit of detection of 0.2 μM.
- Full Text:
- Authors: Babu, Balaji , Mack, John , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/190567 , vital:45006 , xlink:href="https://doi.org/10.1002/slct.202100163"
- Description: A 1,3-diethyl-2-thiobarbituric-acid-substituted ferrocene (FET) has been evaluated for its cyanide sensing ability by UV-visible absorption spectroscopy and other characterization methods. FET provides a ratiometric colorimetric chemosensor for the CN− anion detection in 1 : 1 DMSO/H2O (v/v) solution. The addition of CN− results in an immediate color change from dark blue to pale orange that is visible to the naked eye. Mechanism studies and molecular modelling with TD-DFT calculations demonstrate that nucleophilic addition of CN− to an electrophilic sp2-hybridized carbon atom blocks charge transfer from the ferrocene ring complex to the thiobarbituric acid moiety. The FET sensor exhibits excellent selectivity for CN− and a limit of detection of 0.2 μM.
- Full Text:
Photocytotoxicity of heavy-atom-free thiobarbituric acid functionalized pyrene derivatives against MCF-7 cancer cells
- Babu, Balaji, Ali, Thaslima A, Ochappan, Thivagar, Mack, John, Nyokong, Tebello, Sethuraman, Mathur G
- Authors: Babu, Balaji , Ali, Thaslima A , Ochappan, Thivagar , Mack, John , Nyokong, Tebello , Sethuraman, Mathur G
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/190556 , vital:45005 , xlink:href="https://doi.org/10.1016/j.pdpdt.2020.102102"
- Description: Two thiobarbituric acid-functionalized pyrene derivatives (P1, P2) have been synthesized to explore the photophysical properties and photodynamic activity of dyes of this type. Both compounds exhibit an intense intramolecular charge transfer (ICT) band at ca. 470 nm, which is absent in the spectra of the precursor. P1 and P2 exhibit singlet oxygen generation on irradiation with light with moderate singlet oxygen yields of 0.36 and 0.32, respectively, in DMSO. P1 showed better photodynamic activity against MCF-7 cells with an IC50 value of 18.3 μM under illumination at 455 nm for 60 min with a Thorlabs M455L3 LED (330 mW.cm−2).
- Full Text:
- Authors: Babu, Balaji , Ali, Thaslima A , Ochappan, Thivagar , Mack, John , Nyokong, Tebello , Sethuraman, Mathur G
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/190556 , vital:45005 , xlink:href="https://doi.org/10.1016/j.pdpdt.2020.102102"
- Description: Two thiobarbituric acid-functionalized pyrene derivatives (P1, P2) have been synthesized to explore the photophysical properties and photodynamic activity of dyes of this type. Both compounds exhibit an intense intramolecular charge transfer (ICT) band at ca. 470 nm, which is absent in the spectra of the precursor. P1 and P2 exhibit singlet oxygen generation on irradiation with light with moderate singlet oxygen yields of 0.36 and 0.32, respectively, in DMSO. P1 showed better photodynamic activity against MCF-7 cells with an IC50 value of 18.3 μM under illumination at 455 nm for 60 min with a Thorlabs M455L3 LED (330 mW.cm−2).
- Full Text:
A heavy-atom-free π-extended N-confused porphyrin as a photosensitizer for photodynamic therapy
- Babu, Balaji, Mack, John, Nyokong, Tebello
- Authors: Babu, Balaji , Mack, John , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185909 , vital:44447 , xlink:href="https://doi.org/10.1039/d1nj00112d"
- Description: The synthesis and characterization of a novel 1,3-diethyl-2-thiobarbituric-acid-substituted N-confused porphyrin (NCP-TB) is reported, along with a study of its photodynamic activity against MCF-7 cells using 530 (110 mW cm−2) and 660 nm (280 mW cm−2) Thorlabs light-emitting diodes for 30 min. The singlet oxygen quantum yield for NCP-TB is 0.38 compared to 0.23 for the parent unsubstituted N-confused porphyrin (NCP) due to the presence of a sulfur atom. NCP-TB exhibits enhanced PDT activity compared to NCP at both wavelengths. A significantly lower IC50 value of 5.2 μM was obtained at 530 nm (14.7 μM at 660 nm) despite a smaller light dose, due to a large red shift of the intense B band into the green region of the spectrum. 2′,7′-Dichlorofluorescein diacetate (DCFDA) assays demonstrate that there is intracellular generation of reactive oxygen species upon exposure to light.
- Full Text:
- Authors: Babu, Balaji , Mack, John , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185909 , vital:44447 , xlink:href="https://doi.org/10.1039/d1nj00112d"
- Description: The synthesis and characterization of a novel 1,3-diethyl-2-thiobarbituric-acid-substituted N-confused porphyrin (NCP-TB) is reported, along with a study of its photodynamic activity against MCF-7 cells using 530 (110 mW cm−2) and 660 nm (280 mW cm−2) Thorlabs light-emitting diodes for 30 min. The singlet oxygen quantum yield for NCP-TB is 0.38 compared to 0.23 for the parent unsubstituted N-confused porphyrin (NCP) due to the presence of a sulfur atom. NCP-TB exhibits enhanced PDT activity compared to NCP at both wavelengths. A significantly lower IC50 value of 5.2 μM was obtained at 530 nm (14.7 μM at 660 nm) despite a smaller light dose, due to a large red shift of the intense B band into the green region of the spectrum. 2′,7′-Dichlorofluorescein diacetate (DCFDA) assays demonstrate that there is intracellular generation of reactive oxygen species upon exposure to light.
- Full Text:
A Sn (iv) porphyrin with mitochondria targeting properties for enhanced photodynamic activity against MCF-7 cells
- Babu, Balaji, Mack, John, Nyokong, Tebello
- Authors: Babu, Balaji , Mack, John , Nyokong, Tebello
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/230897 , vital:49829 , xlink:href="https://doi.org/10.1039/D2NJ00350C"
- Description: Two readily synthesized Sn(IV) porphyrins (SnP, SnPH) have been prepared with and without the cationic triphenylphosphonium moiety (TPP+), which have high singlet oxygen quantum yields (ca. 0.72) and long triplet state lifetimes. The Sn(IV) porphyrin with a TPP+ moiety (SnPH) exhibits favorable photodynamic activity against MCF-7 cells with IC50 values of 2.9 μM. SnPH exhibits higher cellular uptake than SnP in MCF-7 cells. A Rhodamine 123 (Rh123) assay showed that SnPH targets mitochondria and induces apoptosis by generating reactive oxygen species. The results demonstrate that this structural modification strategy merits further in-depth study.
- Full Text:
- Authors: Babu, Balaji , Mack, John , Nyokong, Tebello
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/230897 , vital:49829 , xlink:href="https://doi.org/10.1039/D2NJ00350C"
- Description: Two readily synthesized Sn(IV) porphyrins (SnP, SnPH) have been prepared with and without the cationic triphenylphosphonium moiety (TPP+), which have high singlet oxygen quantum yields (ca. 0.72) and long triplet state lifetimes. The Sn(IV) porphyrin with a TPP+ moiety (SnPH) exhibits favorable photodynamic activity against MCF-7 cells with IC50 values of 2.9 μM. SnPH exhibits higher cellular uptake than SnP in MCF-7 cells. A Rhodamine 123 (Rh123) assay showed that SnPH targets mitochondria and induces apoptosis by generating reactive oxygen species. The results demonstrate that this structural modification strategy merits further in-depth study.
- Full Text:
An octabrominated Sn (iv) tetraisopropylporphyrin as a photosensitizer dye for singlet oxygen biomedical applications
- Babu, Balaji, Mack, John, Nyokong, Tebello
- Authors: Babu, Balaji , Mack, John , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186679 , vital:44524 , xlink:href="https://doi.org/10.1039/D0DT01915A"
- Description: Two novel Sn(IV) tetraisopropylphenylporphyrins have been synthesized to explore the effect of octabromination at the β-pyrrole positions on their photophysical properties and photodynamic activity. The lower energy Q band of an octabrominated complex lies at 675 nm well within the therapeutic window. The octabrominated dye has a relatively high singlet oxygen quantum yield of 0.78 in DMF and exhibits favorable photodynamic activity against MCF-7 cells with an IC50 value of 10.7 μM and a 5.74 log reduction value (5 μM) towards S. aureus under illumination at 660 nm for 60 min with a Thorlabs M660L3 LED (280 mW cm−2).
- Full Text:
- Authors: Babu, Balaji , Mack, John , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186679 , vital:44524 , xlink:href="https://doi.org/10.1039/D0DT01915A"
- Description: Two novel Sn(IV) tetraisopropylphenylporphyrins have been synthesized to explore the effect of octabromination at the β-pyrrole positions on their photophysical properties and photodynamic activity. The lower energy Q band of an octabrominated complex lies at 675 nm well within the therapeutic window. The octabrominated dye has a relatively high singlet oxygen quantum yield of 0.78 in DMF and exhibits favorable photodynamic activity against MCF-7 cells with an IC50 value of 10.7 μM and a 5.74 log reduction value (5 μM) towards S. aureus under illumination at 660 nm for 60 min with a Thorlabs M660L3 LED (280 mW cm−2).
- Full Text:
Sn (iv) N-confused porphyrins as photosensitizer dyes for photodynamic therapy in the near IR region
- Babu, Balaji, Mack, John, Nyokong, Tebello
- Authors: Babu, Balaji , Mack, John , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186648 , vital:44521 , xlink:href="https://doi.org/10.1039/D0DT03296D"
- Description: The utility of Sn(IV) N-confused porphyrin (SnNCP) for use as photosensitizer dyes in photodynamic therapy is investigated. SnNCP has an unusually high singlet oxygen quantum yield of 0.72 in DMSO. IC50 values of 1.6 and 12.8 μM were obtained against MCF-7 cells upon irradiation with 660 and 780 nm LEDs.
- Full Text:
Sn (iv) N-confused porphyrins as photosensitizer dyes for photodynamic therapy in the near IR region
- Authors: Babu, Balaji , Mack, John , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186648 , vital:44521 , xlink:href="https://doi.org/10.1039/D0DT03296D"
- Description: The utility of Sn(IV) N-confused porphyrin (SnNCP) for use as photosensitizer dyes in photodynamic therapy is investigated. SnNCP has an unusually high singlet oxygen quantum yield of 0.72 in DMSO. IC50 values of 1.6 and 12.8 μM were obtained against MCF-7 cells upon irradiation with 660 and 780 nm LEDs.
- Full Text:
Preparation of NIR absorbing axial substituted tin (iv) porphyrins and their photocytotoxic properties
- Babu, Balaji, Amuhaya, Edith K, Oluwole, David O, Prinsloo, Earl, Mack, John, Nyokong, Tebello
- Authors: Babu, Balaji , Amuhaya, Edith K , Oluwole, David O , Prinsloo, Earl , Mack, John , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/234592 , vital:50211 , xlink:href="https://doi.org/10.1039/C8MD00373D"
- Description: Sn(IV) porphyrins ([Sn(IV)TTP(3PyO)2] (5) and [Sn(IV)TPP(3PyO)2] (6) [tetrathienylporphyrin (TTP), tetraphenylporphyrin (TPP), and pyridyloxy (PyO)]) were prepared and characterized and their photocytotoxicity upon irradiation with 625 nm light has been studied. The presence of the 3PyO axial ligands was found to limit the aggregation and enhance the solubility of 5 and 6 in DMF/H2O (1 : 1). The photophysical properties and photodynamic therapy (PDT) activity of the meso-2-thienyl and meso-phenyl-substituted Sn(IV) porphyrins are compared. 5 and 6 were found to be photocytotoxic in MCF-7 cancer cells when irradiated with a Thorlabs M625L3 LED at 625 nm but remained nontoxic in the dark. The PDT activity of Sn(IV) meso-tetra-2-thienylporphyrin 5 was found to be significantly enhanced relative to its analogous tetraphenylporphyrin 6. There is a marked red-shift of the Q00 band of 5 into the therapeutic window due to the meso-2-thienyl rings, and 5 has an unusually high singlet oxygen quantum yield value of 0.83 in DMF. The results demonstrate that readily synthesized axially ligated Sn(IV) meso-arylporphyrins are potentially suitable for use as singlet oxygen photosensitizers in biomedical applications and merit further in depth investigation in this context.
- Full Text:
- Authors: Babu, Balaji , Amuhaya, Edith K , Oluwole, David O , Prinsloo, Earl , Mack, John , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/234592 , vital:50211 , xlink:href="https://doi.org/10.1039/C8MD00373D"
- Description: Sn(IV) porphyrins ([Sn(IV)TTP(3PyO)2] (5) and [Sn(IV)TPP(3PyO)2] (6) [tetrathienylporphyrin (TTP), tetraphenylporphyrin (TPP), and pyridyloxy (PyO)]) were prepared and characterized and their photocytotoxicity upon irradiation with 625 nm light has been studied. The presence of the 3PyO axial ligands was found to limit the aggregation and enhance the solubility of 5 and 6 in DMF/H2O (1 : 1). The photophysical properties and photodynamic therapy (PDT) activity of the meso-2-thienyl and meso-phenyl-substituted Sn(IV) porphyrins are compared. 5 and 6 were found to be photocytotoxic in MCF-7 cancer cells when irradiated with a Thorlabs M625L3 LED at 625 nm but remained nontoxic in the dark. The PDT activity of Sn(IV) meso-tetra-2-thienylporphyrin 5 was found to be significantly enhanced relative to its analogous tetraphenylporphyrin 6. There is a marked red-shift of the Q00 band of 5 into the therapeutic window due to the meso-2-thienyl rings, and 5 has an unusually high singlet oxygen quantum yield value of 0.83 in DMF. The results demonstrate that readily synthesized axially ligated Sn(IV) meso-arylporphyrins are potentially suitable for use as singlet oxygen photosensitizers in biomedical applications and merit further in depth investigation in this context.
- Full Text:
Synthesis, characterization and photodynamic activity of Sn (iv) triarylcorroles with red-shifted Q bands
- Babu, Balaji, Prinsloo, Earl, Mack, John, Nyokong, Tebello
- Authors: Babu, Balaji , Prinsloo, Earl , Mack, John , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187521 , vital:44668 , xlink:href="https://doi.org/10.1039/C9NJ03391B"
- Description: Two Sn(IV) triarylcorroles were synthesised and characterized. The absorption spectrum of a meso-thien-2-yl substituted tin(IV)corrole (1-Sn) is red shifted compared to its phenyl analogue (2-Sn) and shows no sign of aggregation in solution. 1-Sn and 2-Sn exhibited singlet oxygen quantum yields of 0.87 and 0.54 in DMF, and have a triplet lifetime of 31 and 50 μs, respectively. Time dependent cellular uptake in MCF-7 cells for 1-Sn reached a peak at 24 h, and 1-Sn was found to be more lipophilic than 2-Sn. 1-Sn showed good photo-cytotoxicity on exposure to a Thorlabs 625 nm LED with an IC50 value of 3.2 μM and remained inactive in the dark.
- Full Text:
- Authors: Babu, Balaji , Prinsloo, Earl , Mack, John , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187521 , vital:44668 , xlink:href="https://doi.org/10.1039/C9NJ03391B"
- Description: Two Sn(IV) triarylcorroles were synthesised and characterized. The absorption spectrum of a meso-thien-2-yl substituted tin(IV)corrole (1-Sn) is red shifted compared to its phenyl analogue (2-Sn) and shows no sign of aggregation in solution. 1-Sn and 2-Sn exhibited singlet oxygen quantum yields of 0.87 and 0.54 in DMF, and have a triplet lifetime of 31 and 50 μs, respectively. Time dependent cellular uptake in MCF-7 cells for 1-Sn reached a peak at 24 h, and 1-Sn was found to be more lipophilic than 2-Sn. 1-Sn showed good photo-cytotoxicity on exposure to a Thorlabs 625 nm LED with an IC50 value of 3.2 μM and remained inactive in the dark.
- Full Text:
Non-aggregated lipophilic water-soluble tin porphyrins as photosensitizers for photodynamic therapy and photodynamic antimicrobial chemotherapy:
- Babu, Balaji, Soy, Rodah C, Mack, John, Nyokong, Tebello
- Authors: Babu, Balaji , Soy, Rodah C , Mack, John , Nyokong, Tebello
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/158241 , vital:40165 , DOI: 10.1039/d0nj01564d
- Description: Two readily synthesized water-soluble Sn(IV) porphyrins have been prepared with quaternized pyridyl nitrogens and 2-naphthalato trans-axial ligands. Methyl and hexyl groups were attached to the quaternized nitrogens to form lipophilic dyes with high singlet oxygen quantum yields (ca. 0.90) and unusually long triplet state lifetimes. The dyes exhibit good photodynamic activity against MCF-7 cells with IC50 values of 14.3 and 8.5 μM, respectively. The hexyl quaternized dye exhibited a 9.69 log reduction value (0.5 μM) towards S. aureus under illumination for 90 min (250 mW cm−2). The results demonstrate that this set of structural modification strategies for photosensitizer dyes merits further in depth study.
- Full Text:
- Authors: Babu, Balaji , Soy, Rodah C , Mack, John , Nyokong, Tebello
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/158241 , vital:40165 , DOI: 10.1039/d0nj01564d
- Description: Two readily synthesized water-soluble Sn(IV) porphyrins have been prepared with quaternized pyridyl nitrogens and 2-naphthalato trans-axial ligands. Methyl and hexyl groups were attached to the quaternized nitrogens to form lipophilic dyes with high singlet oxygen quantum yields (ca. 0.90) and unusually long triplet state lifetimes. The dyes exhibit good photodynamic activity against MCF-7 cells with IC50 values of 14.3 and 8.5 μM, respectively. The hexyl quaternized dye exhibited a 9.69 log reduction value (0.5 μM) towards S. aureus under illumination for 90 min (250 mW cm−2). The results demonstrate that this set of structural modification strategies for photosensitizer dyes merits further in depth study.
- Full Text:
The uses of Chrysomya megacephala (Fabricius, 1794)(Diptera: Calliphoridae) in forensic entomology:
- Badenhorst, Rozane, Villet, Martin H
- Authors: Badenhorst, Rozane , Villet, Martin H
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/140631 , vital:37905 , DOI: 10.1080/20961790.2018.1426136
- Description: Chrysomya megacephala (Fabricius, 1794) occurs on every continent and is closely associated with carrion and decaying material in human environments. Its abilities to find dead bodies and carry pathogens give it a prominence in human affairs that may involve prosecution or litigation, and therefore forensic entomologists. The identification, geographical distribution and biology of the species are reviewed to provide a background for approaches that four branches of forensic entomology (urban, stored-product, medico-criminal and environmental) might take to investigations involving this fly.
- Full Text:
- Authors: Badenhorst, Rozane , Villet, Martin H
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/140631 , vital:37905 , DOI: 10.1080/20961790.2018.1426136
- Description: Chrysomya megacephala (Fabricius, 1794) occurs on every continent and is closely associated with carrion and decaying material in human environments. Its abilities to find dead bodies and carry pathogens give it a prominence in human affairs that may involve prosecution or litigation, and therefore forensic entomologists. The identification, geographical distribution and biology of the species are reviewed to provide a background for approaches that four branches of forensic entomology (urban, stored-product, medico-criminal and environmental) might take to investigations involving this fly.
- Full Text:
An experimental test of the allotonic frequency hypothesis to isolate the effects of light pollution on bat prey selection:
- Bailey, Lauren A, Brigham, R Mark, Bohn, Shelby J, Boyles, Justin G, Smit, Ben
- Authors: Bailey, Lauren A , Brigham, R Mark , Bohn, Shelby J , Boyles, Justin G , Smit, Ben
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/158309 , vital:40171 , https://0-doi.org.wam.seals.ac.za/10.1007/s00442-019-04417-w
- Description: Artificial lights may be altering interactions between bats and moth prey. According to the allotonic frequency hypothesis (AFH), eared moths are generally unavailable as prey for syntonic bats (i.e., bats that use echolocation frequencies between 20 and 50 kHz within the hearing range of eared moths) due to the moths’ ability to detect syntonic bat echolocation. Syntonic bats therefore feed mainly on beetles, flies, true bugs, and non-eared moths. The AFH is expected to be violated around lights where eared moths are susceptible to exploitation by syntonic bats because moths’ evasive strategies become less effective. The hypothesis has been tested to date almost exclusively in areas with permanent lighting, where the effects of lights on bat diets are confounded with other aspects of human habitat alteration. We undertook diet analysis in areas with short-term, localized artificial lighting to isolate the effects of artificial lighting and determine if syntonic and allotonic bats (i.e., bats that use echolocation frequencies outside the hearing range of eared moths) consumed more moths under conditions of artificial lights than in natural darkness.
- Full Text:
- Authors: Bailey, Lauren A , Brigham, R Mark , Bohn, Shelby J , Boyles, Justin G , Smit, Ben
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/158309 , vital:40171 , https://0-doi.org.wam.seals.ac.za/10.1007/s00442-019-04417-w
- Description: Artificial lights may be altering interactions between bats and moth prey. According to the allotonic frequency hypothesis (AFH), eared moths are generally unavailable as prey for syntonic bats (i.e., bats that use echolocation frequencies between 20 and 50 kHz within the hearing range of eared moths) due to the moths’ ability to detect syntonic bat echolocation. Syntonic bats therefore feed mainly on beetles, flies, true bugs, and non-eared moths. The AFH is expected to be violated around lights where eared moths are susceptible to exploitation by syntonic bats because moths’ evasive strategies become less effective. The hypothesis has been tested to date almost exclusively in areas with permanent lighting, where the effects of lights on bat diets are confounded with other aspects of human habitat alteration. We undertook diet analysis in areas with short-term, localized artificial lighting to isolate the effects of artificial lighting and determine if syntonic and allotonic bats (i.e., bats that use echolocation frequencies outside the hearing range of eared moths) consumed more moths under conditions of artificial lights than in natural darkness.
- Full Text:
On location: Narratives of the South African city of the late 1940s and 1950s in film and literature
- Authors: Baines, Gary F
- Date: 2009
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125397 , vital:35779 , https://doi.10.1080/02582470308671922
- Description: This article is about narratives, about the forms and meanings constructed by South African storytellers, especially writers and filmmakers. It examines the relationships between examples of these two different narrative forms of literature (fiction and non-fiction) and feature film. Following Turner, the point of departure is that the study of narrative has the potential to provide a framework within which such a two pronged approach can be undertaken. This is not to say that the production of meaning takes place within an exclusive literary or cinematic context. Rather, this approach will allow us to obtain a fuller picture of the narrative of the South African city than is possible by concentrating on one medium. It is based on the premise that narratives are ultimately produced by culture; thus these cultural constructions generate meanings, take on a significance, and assume forms that are articufations of the values, beliefs -the ideology - of the culture.' Literature and film offer specific forms for such narratives. By adopting an interdisciplinary approach which borrows insights from literary and film studies, this article attempts to make a contribution to the fledgling field of South African cultural studies.
- Full Text:
On location: Narratives of the South African city of the late 1940s and 1950s in film and literature
- Authors: Baines, Gary F
- Date: 2009
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125397 , vital:35779 , https://doi.10.1080/02582470308671922
- Description: This article is about narratives, about the forms and meanings constructed by South African storytellers, especially writers and filmmakers. It examines the relationships between examples of these two different narrative forms of literature (fiction and non-fiction) and feature film. Following Turner, the point of departure is that the study of narrative has the potential to provide a framework within which such a two pronged approach can be undertaken. This is not to say that the production of meaning takes place within an exclusive literary or cinematic context. Rather, this approach will allow us to obtain a fuller picture of the narrative of the South African city than is possible by concentrating on one medium. It is based on the premise that narratives are ultimately produced by culture; thus these cultural constructions generate meanings, take on a significance, and assume forms that are articufations of the values, beliefs -the ideology - of the culture.' Literature and film offer specific forms for such narratives. By adopting an interdisciplinary approach which borrows insights from literary and film studies, this article attempts to make a contribution to the fledgling field of South African cultural studies.
- Full Text:
[Post] Colonial Histories: Trauma, Memory and Reconciliation in the Context of the Angolan Civil War
- Authors: Baines, Gary F
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125752 , vital:35814 , https://doi.10.1080/03612759.2019.1587342
- Description: In 2007, a former South African Defence Force (SADF) paratrooper, Marius van Niekerk, embarked on a journey to confront his shameful memories relating to his role in the Angolan Civil War. From Sweden (where he had gone into exile), Van Niekerk returned to Angola, where he had been deployed during the mid-1980s, and recruited three other veterans of the war to join his party: Patrick Johannes, who had been coerced to fight for the Popular Armed Forces for the Liberation of Angola (FAPLA); Samuel Machado Amaru, who was forcefully enlisted by the National Union for the Total Independence of Angola (UNITA); and Mario Mahonga, who had fought for the Portuguese colonial army before he was recruited by the SADF to fight against the Popular Movement for the Liberation of Angola (MPLA) regime. Van Niekerk had been conscripted at the age of seventeen, and the others had been coerced into their respective militias at more tender ages. It is not clear how the three Angolans were induced to participate in the project, whose objectives they evidently did not share.
- Full Text:
[Post] Colonial Histories: Trauma, Memory and Reconciliation in the Context of the Angolan Civil War
- Authors: Baines, Gary F
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125752 , vital:35814 , https://doi.10.1080/03612759.2019.1587342
- Description: In 2007, a former South African Defence Force (SADF) paratrooper, Marius van Niekerk, embarked on a journey to confront his shameful memories relating to his role in the Angolan Civil War. From Sweden (where he had gone into exile), Van Niekerk returned to Angola, where he had been deployed during the mid-1980s, and recruited three other veterans of the war to join his party: Patrick Johannes, who had been coerced to fight for the Popular Armed Forces for the Liberation of Angola (FAPLA); Samuel Machado Amaru, who was forcefully enlisted by the National Union for the Total Independence of Angola (UNITA); and Mario Mahonga, who had fought for the Portuguese colonial army before he was recruited by the SADF to fight against the Popular Movement for the Liberation of Angola (MPLA) regime. Van Niekerk had been conscripted at the age of seventeen, and the others had been coerced into their respective militias at more tender ages. It is not clear how the three Angolans were induced to participate in the project, whose objectives they evidently did not share.
- Full Text:
The saga of South African POWs in Angola, 1975-82
- Authors: Baines, Gary F
- Date: 2012
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/69882 , vital:29592 , http://dx.doi.org/10.5787/40-2-999
- Description: This article narrates the story of nine soldiers captured during and shortly after Operation Savannah, the codename for the South African Defence Force invasion of Angola in 1975–6. Eight of these soldiers were captured in Angola in three separate incidents by Angolan and/or Cuban forces, whereas the last was abducted from northern Namibia by SWAPO (the South West Africa Peoples’ Organisation). The article then provides a chronological account of the sequels to this story that interweaves a number of threads: first, the account relates the South African government’s attempts to suppress press coverage of these stories for fear of the political ‘fall-out’ that the matter might cause amongst the white electorate and in case it jeopardised secret negotiations to secure the release of the prisoners; and second, it uncovers the role played by intermediaries, especially the International Committee of the Red Cross (ICRC), in the sensitive and fraught negotiation process. It will be shown that the South African authorities adopted divergent approaches when dealing with SWAPO and the Angolans/Cubans to secure the release of prisoners of war (POWs). This is because the South African authorities regarded the former as involved in an internal insurrection whereas the latter were members of the military forces of sovereign states. Accordingly, they paid lip service to the Geneva Conventions in the case of Angolan and Cuban POWs but treated captured SWAPO cadres as ‘terrorists’ or ‘criminals’.
- Full Text:
- Authors: Baines, Gary F
- Date: 2012
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/69882 , vital:29592 , http://dx.doi.org/10.5787/40-2-999
- Description: This article narrates the story of nine soldiers captured during and shortly after Operation Savannah, the codename for the South African Defence Force invasion of Angola in 1975–6. Eight of these soldiers were captured in Angola in three separate incidents by Angolan and/or Cuban forces, whereas the last was abducted from northern Namibia by SWAPO (the South West Africa Peoples’ Organisation). The article then provides a chronological account of the sequels to this story that interweaves a number of threads: first, the account relates the South African government’s attempts to suppress press coverage of these stories for fear of the political ‘fall-out’ that the matter might cause amongst the white electorate and in case it jeopardised secret negotiations to secure the release of the prisoners; and second, it uncovers the role played by intermediaries, especially the International Committee of the Red Cross (ICRC), in the sensitive and fraught negotiation process. It will be shown that the South African authorities adopted divergent approaches when dealing with SWAPO and the Angolans/Cubans to secure the release of prisoners of war (POWs). This is because the South African authorities regarded the former as involved in an internal insurrection whereas the latter were members of the military forces of sovereign states. Accordingly, they paid lip service to the Geneva Conventions in the case of Angolan and Cuban POWs but treated captured SWAPO cadres as ‘terrorists’ or ‘criminals’.
- Full Text: