Visible light responsive TiO2-graphene oxide nanosheets-Zn phthalocyanine ternary heterojunction assisted photoelectrocatalytic degradation of Orange G
- Nwahara, Nnamdi, Adeniyi, Omotayo, Mashazi, Philani N, Nyokong, Tebello
- Authors: Nwahara, Nnamdi , Adeniyi, Omotayo , Mashazi, Philani N , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185446 , vital:44387 , xlink:href="https://doi.org/10.1016/j.jphotochem.2021.113291"
- Description: Herein, we report on the successful fabrication of a visible light-responsive TiO2 - graphene oxide nanosheets – Zn phthalocyanine (TiO2@GONS@ZnPc) ternary structure for the photoelectrochemical degradation of Orange G azo dye. The characterization of TiO2@GONS@ZnPc composite was achieved using various spectroscopic and microscopic techniques. Our results show that the TiO2@GONS@ZnPc surface hybrid heterojunction promotes charge separation and electron migration, significantly improving the degradation efficiency with an applied potential. For the first time, we show the existence of a non-radical activation route for persulfate (PS) using such π electron-rich ZnPc-GONS catalysts. The degradation kinetics were found to follow pseudo first order kinetics. Electron spin resonance analyses suggested that neither hydroxyl radicals nor sulfate radicals were produced therein, and therefore were not responsible for the persulfate-driven oxidation of the OG dye. These findings suggest that both which GONS and ZnPc play a critical role in mediating the eventual charge transfer mediated PS activation. The results illustrate the remarkable capacity of the TiO2@GONS@ZnPc composite to rapidly degrade Orange G by a coupled TiO2@GONS@ZnPc-persulfate system.
- Full Text:
- Authors: Nwahara, Nnamdi , Adeniyi, Omotayo , Mashazi, Philani N , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185446 , vital:44387 , xlink:href="https://doi.org/10.1016/j.jphotochem.2021.113291"
- Description: Herein, we report on the successful fabrication of a visible light-responsive TiO2 - graphene oxide nanosheets – Zn phthalocyanine (TiO2@GONS@ZnPc) ternary structure for the photoelectrochemical degradation of Orange G azo dye. The characterization of TiO2@GONS@ZnPc composite was achieved using various spectroscopic and microscopic techniques. Our results show that the TiO2@GONS@ZnPc surface hybrid heterojunction promotes charge separation and electron migration, significantly improving the degradation efficiency with an applied potential. For the first time, we show the existence of a non-radical activation route for persulfate (PS) using such π electron-rich ZnPc-GONS catalysts. The degradation kinetics were found to follow pseudo first order kinetics. Electron spin resonance analyses suggested that neither hydroxyl radicals nor sulfate radicals were produced therein, and therefore were not responsible for the persulfate-driven oxidation of the OG dye. These findings suggest that both which GONS and ZnPc play a critical role in mediating the eventual charge transfer mediated PS activation. The results illustrate the remarkable capacity of the TiO2@GONS@ZnPc composite to rapidly degrade Orange G by a coupled TiO2@GONS@ZnPc-persulfate system.
- Full Text:
What are social-ecological systems and social-ecological systems research
- Biggs, Reinette, Clements, Hayley, de Vos, Alta, Folke, Carl, Manyani, Amanda, Maciejewski, Kristine, Martin-Lopez, Berta, Preiser, Rika, Selomane, Odirilwe, Schluter, Maja
- Authors: Biggs, Reinette , Clements, Hayley , de Vos, Alta , Folke, Carl , Manyani, Amanda , Maciejewski, Kristine , Martin-Lopez, Berta , Preiser, Rika , Selomane, Odirilwe , Schluter, Maja
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/433900 , vital:73008 , ISBN 9781000401516 , https://library.oapen.org/handle/20.500.12657/49560
- Description: The period since the Second World War has been marked by rapid and accelerating changes to many aspects of human society and the environment (Clark, Crutzen, and Schellnhuber 2004; Steffen et al. 2011; Steffen et al. 2015a). There is accumulating evidence and rising concern about the potential consequences these changes hold for key Earth system processes at a global scale, and human well-being and prosperity into the future (Krausmann et al. 2013; Steffen et al. 2015b). The Anthropocene, as this new era of extensive human impact on the Earth has come to be known (Crutzen 2006), manifests in a closely intertwined set of social and ecological changes. Technological advances, increasing human population, rising levels of wealth and consumption, and the institutional arrangements we have developed to govern our economies and societies interplay with one another, and drastically affect the Earth’s climate, biological diversity, fresh-water and biogeochemical flows, and levels of novel pollutants in the environment (Steffen et al. 2015a). These environmental changes, in turn, contribute to increasingly frequent and severe droughts (Dai 2013; Trenberth et al. 2014), floods (Milly et al. 2002; Nicholls 2004), heatwaves (Guo et al. 2018; Oliver et al. 2018) and the emergence of novel pathogens such as SARS-CoV-2 (Everard et al. 2020; O ’Callaghan-Gordo and Antò 2020; Schmeller, Courchamp, and Killeen 2020) that can lead to massive societal disruption and hardship, especially among the poor (Wheeler and Von Braun 2013; Barbier and Hochard 2018).
- Full Text:
- Authors: Biggs, Reinette , Clements, Hayley , de Vos, Alta , Folke, Carl , Manyani, Amanda , Maciejewski, Kristine , Martin-Lopez, Berta , Preiser, Rika , Selomane, Odirilwe , Schluter, Maja
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/433900 , vital:73008 , ISBN 9781000401516 , https://library.oapen.org/handle/20.500.12657/49560
- Description: The period since the Second World War has been marked by rapid and accelerating changes to many aspects of human society and the environment (Clark, Crutzen, and Schellnhuber 2004; Steffen et al. 2011; Steffen et al. 2015a). There is accumulating evidence and rising concern about the potential consequences these changes hold for key Earth system processes at a global scale, and human well-being and prosperity into the future (Krausmann et al. 2013; Steffen et al. 2015b). The Anthropocene, as this new era of extensive human impact on the Earth has come to be known (Crutzen 2006), manifests in a closely intertwined set of social and ecological changes. Technological advances, increasing human population, rising levels of wealth and consumption, and the institutional arrangements we have developed to govern our economies and societies interplay with one another, and drastically affect the Earth’s climate, biological diversity, fresh-water and biogeochemical flows, and levels of novel pollutants in the environment (Steffen et al. 2015a). These environmental changes, in turn, contribute to increasingly frequent and severe droughts (Dai 2013; Trenberth et al. 2014), floods (Milly et al. 2002; Nicholls 2004), heatwaves (Guo et al. 2018; Oliver et al. 2018) and the emergence of novel pathogens such as SARS-CoV-2 (Everard et al. 2020; O ’Callaghan-Gordo and Antò 2020; Schmeller, Courchamp, and Killeen 2020) that can lead to massive societal disruption and hardship, especially among the poor (Wheeler and Von Braun 2013; Barbier and Hochard 2018).
- Full Text:
Why decolonialising feminist psychology may fail, and why it mustn't: The politics of signification and the case of' teenage pregnancy'
- Macleod, Catriona I, Masuko, Diemo, Feltham-King, Tracey
- Authors: Macleod, Catriona I , Masuko, Diemo , Feltham-King, Tracey
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/446327 , vital:74490
- Description: The calls to decolonise psychology and feminisms are a demand for action in overcoming past and current (neo) colonial injustices. Decolonisation has, however, been complex owing to the plurality, mutation, and masking of (neo)colonial systems. Within this context, decolonialising feminist psychology may fail. Homing in on the politics of signification, we argue that the colonial roots of many signifiers that serve to perpetuate gendered power relations are masked through their taken-for-granted status within psychology. We illustrate the latter through discussion of "adolescence", a signifier premised on colonialist thinking regarding individual and societal development. While gross forms of colonialist thinking regarding adolescence have disappeared, the "threat of degeneration" implicit in the concept remains. Drawing on critical work on "teenage pregnancy" in South Africa, we show how young womxn's reproductive health is impacted by the entrenchment of the threat of degeneration in educational and health responses. This discussion illustrates why decolonising feminist psychology must not fail. Alternative signifiers that serve the purpose of social justice and care should be foregrounded. These joint tasks (critique of (neo)colonialist signifiers and the enactment of transformation through foregrounding alternative signifiers) should underpin decolonising feminist psychology praxis.
- Full Text:
- Authors: Macleod, Catriona I , Masuko, Diemo , Feltham-King, Tracey
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/446327 , vital:74490
- Description: The calls to decolonise psychology and feminisms are a demand for action in overcoming past and current (neo) colonial injustices. Decolonisation has, however, been complex owing to the plurality, mutation, and masking of (neo)colonial systems. Within this context, decolonialising feminist psychology may fail. Homing in on the politics of signification, we argue that the colonial roots of many signifiers that serve to perpetuate gendered power relations are masked through their taken-for-granted status within psychology. We illustrate the latter through discussion of "adolescence", a signifier premised on colonialist thinking regarding individual and societal development. While gross forms of colonialist thinking regarding adolescence have disappeared, the "threat of degeneration" implicit in the concept remains. Drawing on critical work on "teenage pregnancy" in South Africa, we show how young womxn's reproductive health is impacted by the entrenchment of the threat of degeneration in educational and health responses. This discussion illustrates why decolonising feminist psychology must not fail. Alternative signifiers that serve the purpose of social justice and care should be foregrounded. These joint tasks (critique of (neo)colonialist signifiers and the enactment of transformation through foregrounding alternative signifiers) should underpin decolonising feminist psychology praxis.
- Full Text:
Youth Attitudes and Participation in Climate Protest
- Prendergast, Kate, Hayward, Bronwyn, Aoyagi, Midori, Burningham, Kate, Hasan, Mehedi, Jackson, Tim, Jha, Vimlendu, Kuroki, Larissa, Lukianov, Anastasia, Mattar, Helio, Schudel, Ingrid J, Venn, Sue, Yoshida, Aya
- Authors: Prendergast, Kate , Hayward, Bronwyn , Aoyagi, Midori , Burningham, Kate , Hasan, Mehedi , Jackson, Tim , Jha, Vimlendu , Kuroki, Larissa , Lukianov, Anastasia , Mattar, Helio , Schudel, Ingrid J , Venn, Sue , Yoshida, Aya
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/294471 , vital:57224 , xlink:href="https://doi.org/10.3389/fpos.2021.696105"
- Description: This article examines youth participation the school climate strikes of 2018 and 2019 (also known as #Fridays4Future), through an exploratory study conducted in seven diverse cities. Despite the international nature of the climate strikes, we know little about the factors that influenced youth participation in these protests beyond the global North. This matters because youth of the global South are disproportionately impacted by climate change and there is growing concern that the climate movement is dominated by narratives that marginalize the voices and priorities of Indigenous communities and people of color. In this context, the exploratory research reported here aimed to compare the attitudes of climate protesters (n = 314) and their non-protester peers (n = 1,217), in diverse city samples drawn from a wider study of children and youth aged 12–24 years, living in Christchurch (New Zealand); Dhaka (Bangladesh); Lambeth, London (United Kingdom); Makhanda (South Africa); New Delhi (India); São Paulo (Brazil); and Yokohama (Japan). Using cross-sectional data (N = 1,531) and binary logistic regression models, researchers examined three common explanations for youth participation in protest: availability (biographical and structural), political engagement (reported individual and collective efficacy of strikers and non-strikers), and self-reported biospheric values amongst participants. Results indicate that even in diverse city samples, structural availability (civic skills and organizational membership) predicted strike participation across city samples, but not political engagement (self-efficacy and collective efficacy). Youth who reported that ‘living in harmony with nature and animals’ was important for their wellbeing, were also more likely to strike than their peers. Descriptive statistics indicated that the majority (85 percent) of all protestors in this study agreed climate change was a serious issue and a startling 65 percent said that they think about climate change “all the time”. Reported rates of youth climate protest participation varied across city samples as did the extent to which participants reported having friends take part or expecting climate change to have a personal impact. While the study is exploratory, it points to the need for more extensive research to understand the diversity of youth participation in ‘global climate strikes’.
- Full Text:
- Authors: Prendergast, Kate , Hayward, Bronwyn , Aoyagi, Midori , Burningham, Kate , Hasan, Mehedi , Jackson, Tim , Jha, Vimlendu , Kuroki, Larissa , Lukianov, Anastasia , Mattar, Helio , Schudel, Ingrid J , Venn, Sue , Yoshida, Aya
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/294471 , vital:57224 , xlink:href="https://doi.org/10.3389/fpos.2021.696105"
- Description: This article examines youth participation the school climate strikes of 2018 and 2019 (also known as #Fridays4Future), through an exploratory study conducted in seven diverse cities. Despite the international nature of the climate strikes, we know little about the factors that influenced youth participation in these protests beyond the global North. This matters because youth of the global South are disproportionately impacted by climate change and there is growing concern that the climate movement is dominated by narratives that marginalize the voices and priorities of Indigenous communities and people of color. In this context, the exploratory research reported here aimed to compare the attitudes of climate protesters (n = 314) and their non-protester peers (n = 1,217), in diverse city samples drawn from a wider study of children and youth aged 12–24 years, living in Christchurch (New Zealand); Dhaka (Bangladesh); Lambeth, London (United Kingdom); Makhanda (South Africa); New Delhi (India); São Paulo (Brazil); and Yokohama (Japan). Using cross-sectional data (N = 1,531) and binary logistic regression models, researchers examined three common explanations for youth participation in protest: availability (biographical and structural), political engagement (reported individual and collective efficacy of strikers and non-strikers), and self-reported biospheric values amongst participants. Results indicate that even in diverse city samples, structural availability (civic skills and organizational membership) predicted strike participation across city samples, but not political engagement (self-efficacy and collective efficacy). Youth who reported that ‘living in harmony with nature and animals’ was important for their wellbeing, were also more likely to strike than their peers. Descriptive statistics indicated that the majority (85 percent) of all protestors in this study agreed climate change was a serious issue and a startling 65 percent said that they think about climate change “all the time”. Reported rates of youth climate protest participation varied across city samples as did the extent to which participants reported having friends take part or expecting climate change to have a personal impact. While the study is exploratory, it points to the need for more extensive research to understand the diversity of youth participation in ‘global climate strikes’.
- Full Text:
‘Bad choices’: Unintended pregnancy and abortion in nurses’ and counsellors’ accounts of providing pre-abortion counselling
- Mavuso, Jabulile M-J J, Macleod, Catriona I
- Authors: Mavuso, Jabulile M-J J , Macleod, Catriona I
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/444139 , vital:74195 , xlink:href="https://doi.org/10.1177/1363459320988873"
- Description: Little research tackles healthcare providers’ experiences in conducting pre-abortion counselling sessions in circumstances where pregnant persons may request an abortion. We report on a study conducted in South Africa, in which two nurses and two counsellors were asked about how they conduct these counselling sessions. Using a synthetic narrative approach, we present these health workers’ micro-narratives about their motivations for providing abortion services, the purpose of the counselling, their information-giving practices, and whether and how third parties are included in the counselling. We highlight how these micro-narratives are premised on discursive resources that problematise unintended pregnancy and abortion. These resources enable and justify directive counselling that undermines pregnant peoples’ reproductive autonomy. We locate such directiveness within dominant anti-abortion discourse and call for training to reframe normative understandings of abortion.
- Full Text:
- Authors: Mavuso, Jabulile M-J J , Macleod, Catriona I
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/444139 , vital:74195 , xlink:href="https://doi.org/10.1177/1363459320988873"
- Description: Little research tackles healthcare providers’ experiences in conducting pre-abortion counselling sessions in circumstances where pregnant persons may request an abortion. We report on a study conducted in South Africa, in which two nurses and two counsellors were asked about how they conduct these counselling sessions. Using a synthetic narrative approach, we present these health workers’ micro-narratives about their motivations for providing abortion services, the purpose of the counselling, their information-giving practices, and whether and how third parties are included in the counselling. We highlight how these micro-narratives are premised on discursive resources that problematise unintended pregnancy and abortion. These resources enable and justify directive counselling that undermines pregnant peoples’ reproductive autonomy. We locate such directiveness within dominant anti-abortion discourse and call for training to reframe normative understandings of abortion.
- Full Text:
‘Don't educate them out of educating themselves’
- Krueger, Anton, Wunder, Albert
- Authors: Krueger, Anton , Wunder, Albert
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/225481 , vital:49226 , xlink:href="https://doi.org/10.5920/pam.1005"
- Description: Al Wunder's biography, in his own words: I had four lucky breaks that precipitated my becoming a teacher of improvised movement theatre. Between the ages of eight and fourteen I broke my right leg four different times. In 1962, I began modern dance classes with Alwin Nikolais as a physical therapy. His choreography and improvisation sections of class inspired me to teach and perform professionally. I spent eight years studying, teaching, choreographing, and performing with Nikolais. 1970 saw me move to the San Francisco Bay area where I opened a dance studio teaching Nikolais dance technique and improvisation. In 1971, I joined forces with Terry Sendgraff and Ruth Zaporah creating The Berkeley Dance Theater and Gymnasium. My focus was to create a way to teach dance technique through improvisation. I met my Australian wife, Lynden Nicholls, in 1981 when she came to study Motivity at Terry’s studio in Berkeley. In 1982, I moved to Melbourne, Australia where Lynden and I set up a dance studio. My focus changed from teaching dance technique improvisationally to teaching improvised movement theatre performance
- Full Text:
- Authors: Krueger, Anton , Wunder, Albert
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/225481 , vital:49226 , xlink:href="https://doi.org/10.5920/pam.1005"
- Description: Al Wunder's biography, in his own words: I had four lucky breaks that precipitated my becoming a teacher of improvised movement theatre. Between the ages of eight and fourteen I broke my right leg four different times. In 1962, I began modern dance classes with Alwin Nikolais as a physical therapy. His choreography and improvisation sections of class inspired me to teach and perform professionally. I spent eight years studying, teaching, choreographing, and performing with Nikolais. 1970 saw me move to the San Francisco Bay area where I opened a dance studio teaching Nikolais dance technique and improvisation. In 1971, I joined forces with Terry Sendgraff and Ruth Zaporah creating The Berkeley Dance Theater and Gymnasium. My focus was to create a way to teach dance technique through improvisation. I met my Australian wife, Lynden Nicholls, in 1981 when she came to study Motivity at Terry’s studio in Berkeley. In 1982, I moved to Melbourne, Australia where Lynden and I set up a dance studio. My focus changed from teaching dance technique improvisationally to teaching improvised movement theatre performance
- Full Text:
The modulation of the photophysical and photodynamic therapy activities of a phthalocyanine by detonation nanodiamonds: Comparison with graphene quantum dots and carbon nanodots
- Matshitse, Refilwe, Managa, Muthumuni, Nyokong, Tebello
- Authors: Matshitse, Refilwe , Managa, Muthumuni , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186690 , vital:44525 , xlink:href="https://doi.org/10.1016/j.diamond.2019.107617"
- Description: A positively charged phthalocyanine (2,9,16,23-tetrakis[4-(N-methylpyridyloxy)]-phthalocyanine (ZnTPPcQ)) was non-covalently linked to carbon based nanoparticles: detonation nanodiamonds (DNDs), carbon dots (CDs) and graphene quantum dots (GQDs) to form nanosembles of DNDs-ZnTPPcQ, GQDs-ZnTPPcQ and CDs-ZnTPPcQ, respectively. Irrespective of its small size and the least number of Pcs (41.67 μg loading per milligram of DNDs), DNDs-ZnTPPcQ gave the highest singlet oxygen quantum yield (0.62) in dimethyl sulfoxide compared to the rest of the conjugates. This resulted in superior PDT activity against MCF7 breast cancer lines, with the lowest cell viability of 28% compared to ZnTPPcQ-CDs and ZnTPPcQ-GQDs at 30.1 ± 0.02% and 31.4 ± 0.23%, respectively.
- Full Text:
- Authors: Matshitse, Refilwe , Managa, Muthumuni , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186690 , vital:44525 , xlink:href="https://doi.org/10.1016/j.diamond.2019.107617"
- Description: A positively charged phthalocyanine (2,9,16,23-tetrakis[4-(N-methylpyridyloxy)]-phthalocyanine (ZnTPPcQ)) was non-covalently linked to carbon based nanoparticles: detonation nanodiamonds (DNDs), carbon dots (CDs) and graphene quantum dots (GQDs) to form nanosembles of DNDs-ZnTPPcQ, GQDs-ZnTPPcQ and CDs-ZnTPPcQ, respectively. Irrespective of its small size and the least number of Pcs (41.67 μg loading per milligram of DNDs), DNDs-ZnTPPcQ gave the highest singlet oxygen quantum yield (0.62) in dimethyl sulfoxide compared to the rest of the conjugates. This resulted in superior PDT activity against MCF7 breast cancer lines, with the lowest cell viability of 28% compared to ZnTPPcQ-CDs and ZnTPPcQ-GQDs at 30.1 ± 0.02% and 31.4 ± 0.23%, respectively.
- Full Text:
Electrocatalytic activity of a push pull Co (II) phthalocyanine in the presence of graphitic carbon nitride quantum dots
- Nxele, Siphesihle R, Oluwole, David O, Nyokong, Tebello
- Authors: Nxele, Siphesihle R , Oluwole, David O , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186746 , vital:44530 , xlink:href="https://doi.org/10.1016/j.electacta.2019.134978"
- Description: This work reports for the first time on the use of a conjugate of graphitic carbon nitride quantum dots (gCNQDs) with a push-pull asymmetrical cobalt phthalocyanine (CoPc) for electrochemical sensing. The nanocomposite is immobilized on a glassy carbon electrode (GCE) surface for the use in l-cysteine electrocatalysis. The nanocomposites were characterized using techniques such as X-ray diffractometry (XRD), Fourier transform infrared (FTIR) spectroscopy, UV-vis spectroscopy, transmission electron microscopy (TEM), energy dispersive X-ray (EDX) analysis, Raman spectroscopy and electrochemical methods. The nanocomposites were immobilized by the drop-dry method, sequentially or when premixed in solution. Good electrocatalytic oxidation of l-cysteine was observed, especially by the sequentially modified electrode surface, with the CoPc on top of gCNQDs. The sensitivity was determined as 3.5 μA.mM-1 and the limit of detection (LoD) as 101.3 μM for GCE-gCNQDs, 0.65 μA.mM-1 and 0.96 μM for GCE-CoPc, 23.41 μA.mM-1 and 0.41 μM for gCNQDs-CoPc (premixed) and 100.5 μA.mM-1 and 0.02 μM for gCNQDs-CoPc (sequential). The electrode surfaces also showed high stability by continuous cyclization.
- Full Text:
- Authors: Nxele, Siphesihle R , Oluwole, David O , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186746 , vital:44530 , xlink:href="https://doi.org/10.1016/j.electacta.2019.134978"
- Description: This work reports for the first time on the use of a conjugate of graphitic carbon nitride quantum dots (gCNQDs) with a push-pull asymmetrical cobalt phthalocyanine (CoPc) for electrochemical sensing. The nanocomposite is immobilized on a glassy carbon electrode (GCE) surface for the use in l-cysteine electrocatalysis. The nanocomposites were characterized using techniques such as X-ray diffractometry (XRD), Fourier transform infrared (FTIR) spectroscopy, UV-vis spectroscopy, transmission electron microscopy (TEM), energy dispersive X-ray (EDX) analysis, Raman spectroscopy and electrochemical methods. The nanocomposites were immobilized by the drop-dry method, sequentially or when premixed in solution. Good electrocatalytic oxidation of l-cysteine was observed, especially by the sequentially modified electrode surface, with the CoPc on top of gCNQDs. The sensitivity was determined as 3.5 μA.mM-1 and the limit of detection (LoD) as 101.3 μM for GCE-gCNQDs, 0.65 μA.mM-1 and 0.96 μM for GCE-CoPc, 23.41 μA.mM-1 and 0.41 μM for gCNQDs-CoPc (premixed) and 100.5 μA.mM-1 and 0.02 μM for gCNQDs-CoPc (sequential). The electrode surfaces also showed high stability by continuous cyclization.
- Full Text:
Photophysicochemical properties of nanoconjugates of zinc (II) 2 (3)-mono-2-(4-oxy) phenoxy) acetic acid phthalocyanine with cysteamine capped silver and silver–gold nanoparticles
- Oluwole, David O, Prinsloo, Earl, Nyokong, Tebello
- Authors: Oluwole, David O , Prinsloo, Earl , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188552 , vital:44764 , xlink:href="https://doi.org/10.1016/j.poly.2016.09.034"
- Description: A novel asymmetrical zinc(II) 2(3)-mono-2-(4-oxy)phenoxy)acetic acid phthalocyanine (complex 1) was synthesized and subsequently linked to cysteamine capped silver (AgNPs) and silver–gold (AgAuNPs) nanoparticles (NPs) via amide bonds. The photophysicochemical properties and in vitro photodynamic therapy activity of complex 1 and its nanoconjugates were investigated. The nanoconjugates showed improved photophysical properties compared to complex 1 alone. The fluorescence, triplet and singlet quantum yields of complex 1 were found to be 20%, 48%, and 43% respectively. Complex 1 showed in vitro dark cytotoxicity, but the dark toxicity was reduced for the combination of complex 1 with AgAuNPs, this combination also gave the best photodynamic therapy activity when compared to complex 1 and its conjugate with AgNPs without AuNPs.
- Full Text:
- Authors: Oluwole, David O , Prinsloo, Earl , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188552 , vital:44764 , xlink:href="https://doi.org/10.1016/j.poly.2016.09.034"
- Description: A novel asymmetrical zinc(II) 2(3)-mono-2-(4-oxy)phenoxy)acetic acid phthalocyanine (complex 1) was synthesized and subsequently linked to cysteamine capped silver (AgNPs) and silver–gold (AgAuNPs) nanoparticles (NPs) via amide bonds. The photophysicochemical properties and in vitro photodynamic therapy activity of complex 1 and its nanoconjugates were investigated. The nanoconjugates showed improved photophysical properties compared to complex 1 alone. The fluorescence, triplet and singlet quantum yields of complex 1 were found to be 20%, 48%, and 43% respectively. Complex 1 showed in vitro dark cytotoxicity, but the dark toxicity was reduced for the combination of complex 1 with AgAuNPs, this combination also gave the best photodynamic therapy activity when compared to complex 1 and its conjugate with AgNPs without AuNPs.
- Full Text: