Activated carbon-decorated polyacrylonitrile fibers and their porphyrin-immobilized composites for removal of methylene blue dye and Ciprofloxacin in water
- Authors: Oyim, James , Amuhaya, Edith , Nyokong, Tebello
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/${Handle} , vital:65077 , xlink:href="https://doi.org/10.1080/10601325.2023.2183868"
- Description: Photocatalyst adsorbents are an appealing group of materials for environmental applications. Herein, we study a new simple, inexpensive, yet very effective adsorbent photocatalyst based on porphyrin immobilized activated carbon-decorated polyacrylonitrile, InP(PAN/AC), for removal of methylene blue dye and Ciprofloxacin in water under Xe-lamp and sunlight irradiation (the latter for Ciprofloxacin only). Our results shed light on developing the most effective and sustainable adsorbent photocatalysts that can easily be industrialized due to the ease of preparation through electrospinning coupled with the readily available preparation materials. After five cycles, the InP(PAN/AC) maintained high methylene dye removal efficiency and structural integrity. Significantly, we propose the coordinated contribution of singlet oxygen and hydroxyl radical in the photodegradation process and highlight the importance of such an integrated system with adsorption and photodegradation capabilities for water treatment.
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- Date Issued: 2023
Asymmetrical zinc phthalocyanine conjugated to various nanomaterials for applications in phototransformation of organic pollutants and photoinactivation of bacteria
- Authors: Mgidlana, Sithi , Openda, Yolande Ikala , Nyokong, Tebello
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/360344 , vital:65081 , xlink:href="https://doi.org/10.1016/j.molstruc.2022.134850"
- Description: Zinc phthalocyanine (ZnPc) complexes are linked to metallic nanoparticles covalently via amide and ester bonds. The photocatalytic activity of the conjugates of ZnPc complexes with NiWO4, Ag2WO4, CoWO4 and Ag-Fe3O4 nanoparticles are evaluated for photodegradation of methylene blue, tetracycline, and dibenzothiophene. The photocatalytic efficiencies of the prepared phthalocyanine complexes increased in the presence of nanoparticles. This work also reports on the photodynamic antimicrobial chemotherapy activity of these materials against Staphylococcus aureus (S. aureus) bacteria. The results indicate that Ag2WO4 based nanoconjugates exhibit high antimicrobial activity with higher log reduction compared to NiWO4, CoWO4 and Ag-Fe3O4 based materials.
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- Date Issued: 2023
Co phthalocyanine mediated electrochemical detection of the HER2 in the presence of Au and CeO2 nanoparticles and graphene quantum dots
- Authors: Centane, Sixolile , Nyokong, Tebello
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/360372 , vital:65083 , xlink:href="https://doi.org/10.1016/j.bioelechem.2022.108301"
- Description: In this work, cobalt tetra phenoxy acetic acid phthalocyanine (CoTAPc) is investigated as an electron mediator, immobilization platform for an HB5 aptamer and to enhance the electrochemical signal for the detection of human epidermal growth factor receptor 2 (HER2). Furthermore, the CoTAPc was combined individually with sulphur/nitrogen doped graphene quantum dots (SNGQDs), gold nanoparticles (AuNPs) and cerium oxide nanoparticles (CeO2NPs), on a glassy carbon electrode (GCE) via sequential adsorption. The CoTAPc and SNGQDs were also π-π stacked, used for electrode modification similarly to the rest of the other surfaces and applied towards the electrochemical detection of HER2. The designed sensors were characterized using electrochemical impedance spectroscopy (EIS). The designed aptasensors showed detection limits as low as 6.0 pg/mL. The real life applicability of the designed aptasensors was tested in human serum samples. The aptasensors showed great storage stability, sensitivity and specificity towards HER2, implying great potential for applications in early diagnosis of breast cancer.
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- Date Issued: 2023
Combination of photodynamic antimicrobial chemotherapy and ciprofloxacin to combat S. aureus and E. coli resistant biofilms
- Authors: Openda, Yolande Ikala , Nyokong, Tebello
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/360384 , vital:65084 , xlink:href="https://doi.org/10.1016/j.pdpdt.2022.103142"
- Description: Photodynamic antimicrobial chemotherapy (PACT) coupled with an antibiotic, ciprofloxacin (CIP), was investigated using two indium metallated cationic photosensitizers, a porphyrin (1) and a phthalocyanine (2). Applying PACT followed by the antibiotic treatment led to a remarkable reduction in the biofilm cell survival of two antibiotic-resistant bacterial strains, S. aureus (Gram-positive) and E. coli (Gram-nenative). Treating both bacteria strains with PACT alone showed no significant activity at 32 µM with 15 min irradiation, while CIP alone exhibited a minimum biofilm inhibition concentration (MBIC) at 4 and 8 µg/mL on S. aureus and E. coli, respectively following 24 h incubation. The combined treatment resulted in the complete eradication of the matured biofilms with high log10 reduction values of 7.05 and 7.20 on S. aureus and E. coli, respectively, at low concentrations. It was found that 15 min PACT irradiation of 8 µM of complexes (1 and 2) combined with 2 µg/mL of CIP have a 100% reduction of the resistant S. aureus biofilms. Whereas the total killing of E. coli was obtained when combining 8 µM of complex 1 and 16 µM of complex 2 both combined with 4 µg/mL of CIP.
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- Date Issued: 2023
Development of a translation device for axiological-semantic density in political news articles: Wording and charging
- Authors: Siebörger, Ian , Adendorff, Ralph D
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/385311 , vital:68006 , xlink:href="https://doi.org/10.1515/text-2020-0156"
- Description: The concept of axiological-semantic density from Legitimation Code Theory (LCT) is extremely helpful in analysing political knowledge-building, as it describes the strength of relations between various people, political stances and moral judgements, enabling these to be positioned in relation to each other. We present a multi-level translation device designed to identify strengths of axiological-semantic density in political news articles from the Daily Sun, South Africa’s most popular tabloid newspaper. This translation device was devised through analysis of selected texts from a corpus of 516 articles published between January and June 2015. It was developed through a collaborative process involving the first author and a team of student research assistants. The final translation device has five tools, of which two, the wording and charging tools, are described in this article, and then illustrated using an example analysis of a Daily Sun political news article. Both tools reveal insights into South African political discourses and ways in which axiological-semantic density can be enacted in future research. Making axiological-semantic density visible using such a translation device also has practical applications in assisting readers to understand the ways in which publications such as the Daily Sun position political parties, enabling them to engage more constructively in discussions on the country’s future.
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- Date Issued: 2023
Dual action of asymmetrical zinc (II) phthalocyanines conjugated to silver tungstate nanoparticles towards photodegradation of tetracycline and inactivation of Staphylococcus aureus bacteria
- Authors: Mgidlana, Sithi , Sen, Pinar , Nyokong, Tebello
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/360400 , vital:65085 , xlink:href="https://doi.org/10.1016/j.jphotochem.2022.114444"
- Description: Asymmetric (A3B) Zn(II) phthalocyanines containing dimethoxy phenoxy as the dominant substituent and (phenoxy) propanoic acid (1), (phenoxy) acetic acid (2), and (phenoxy) acrylic acid (3) as the other substituents were synthesized and linked to silver tungstate nanoparticles (Ag2WO4 NPs). The photocatalytic activities of the prepared complexes 1–3 and nanoconjugates were evaluated for the photodegradation of tetracycline (TC) under visible-light irradiation and for photodynamic antimicrobial chemotherapy (PACT) activity against S. aureus. The results revealed that complex 3 had the best photocatalytic and PACT performance compared to 1 and 2, corresponding to the higher singlet oxygen quantum yield of the former in dimethyl sulfoxide. The photodegradation reaction was also examined using EPR and a mechanism for generation of singlet oxygen under visible light was confirmed. Photoinactivation of S. aureus improved in the presence of TC, when the two are applied together.
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- Date Issued: 2023
Electrocatalytic Behavior of Manganese and Cobalt Porphyrins Attached to Graphene Quantum Dots
- Authors: Jokazi, Mbulelo , Mpeta, Lekhetho S , Nyokong, Tebello
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/360411 , vital:65086 , xlink:href="https://doi.org/10.1002/elan.202200222"
- Description: Manganese and cobalt metalated 5, 10, 15-tris(aminophenyl)-20-(4-carboxyphenyl) porphyrins (ClMnTA3CPP and CoTA3CPP) were synthesized and attached to graphene quantum dots (GQDs) via π-π interaction and electrostatic interaction. The electrochemical oxidation of hydrazine was performed via cyclic voltammetry and chronoamperometry. The CoTA3CPP showed good electrocatalytic activity towards the oxidation of hydrazine in terms of catalytic rate constants and limits of detection (LoD). ClMnTA3CPP showed lower overpotential 0.60 V. The introduction of GQDs improved the electrocatalytic ability when combined with CoTA3CPP and ClMnTA3CPP with the lowest LoD (0.0025 mM CoTA3CPP–GQDs) followed by ClMnTA3CPP–GQDs with 0.0033 mM.
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- Date Issued: 2023
Evaluation of the antibacterial activity of gallic acid anchored phthalocyanine-doped silica nanoparticles towards Escherichia coli and Staphylococcus aureus biofilms and planktonic cells
- Authors: Magadla, Aviwe , Openda, Yolande Ikala , Mpeta, Lekhetho S , Nyokong, Tebello
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/360424 , vital:65087 , xlink:href="https://doi.org/10.1016/j.pdpdt.2023.103520"
- Description: In this work, we have described the synthesis of phthalocyanine complexes Zn(II) tetrakis 4-(5-formylpyridin-2-yl)oxy) phthalocyanine (2), Zn(II) tetrakis-1 butyl 4-(2-(6- (tetra-phenoxy)pyridin-3-yl) vinyl)pyridin-1-ium phthalocyanine (3) and Zn(II) tetrakis 1 butyl 5-(2-(1-butylpyridin-1-ium-4-yl)vinyl)-2-(tetra-phenoxy)pyridin-1-ium phthalocyanine (4). The effect of a varying number of charges when the Pc complexes are alone or grafted in gallic acid (GA) tagged silica nanoparticles on photodynamic antimicrobial chemotherapy (PACT) is investigated toward Staphylococcus aureus (S.aureus) and Escherichia coli (E.coli) in both planktonic and biofilm forms. Complex 4, bearing a total of 8 cationic charges, displayed the highest activity with log CFU (colony forming units) values of 8.60 and 6.42 against E.coli and S.aureus biofilms, respectively. The surface stability of E.coli and S.aureus biofilms in the presence of 4 and its conjugate was analyzed using cyclic voltammetry. Scanning electron microscopy (SEM) and Raman spectra are also used to study the conformational and biochemical changes within biofilm upon subjecting them to PACT.
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- Date Issued: 2023
Photoantimicrobial activity of Schiff-base morpholino phthalocyanines against drug resistant micro-organisms in their planktonic and biofilm forms
- Authors: Sindelo, Azole , Sen, Pinar , Nyokong, Tebello
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/360437 , vital:65088 , xlink:href="https://doi.org/10.1016/j.pdpdt.2023.103519"
- Description: Antimicrobial photodynamic inactivation (aPDI) is a treatment for the eradication of drug-resistant micro-organisms. One of the advantages of this technique, is that there is minimal possibility of microbial resistance. Hence, herein, the preparation and characterization of novel neutral and cationic morpholine containing Schiff base phthalocyanines are reported. The cationic complexes gave moderate singlet oxygen quantum yields (ΦΔ) of ∼0.2 in aqueous media. Conversely, the neutral complexes generated very low ΦΔ values making them very poor candidates for antimicrobial studies. The cationic phthalocyanines showed excellent photodynamic activity against planktonic cells of all micro-organisms (Candida albicans, Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus, Salmonella enterica subspecies enterica serovar Choleraesuis, vancomycin-resistant Enterococcus faecium, and methicillin-resistant Staphylococcus aureus). The efficiency of aPDI was shown to be both concentration and light-dose-dependent. Mono biofilms were susceptible when treated with 200 µM of cationic Pcs at 108 J/cm2. However, ∼10% of the mixed biofilm survived after treatment.
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- Date Issued: 2023
Photodynamic inactivation of methicillin-resistant Staphylococcus aureus using pyrrolidinium containing Schiff base phthalocyanines
- Authors: Sindelo, Azole , Sen, Pinar , Nyokong, Tebello
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/360449 , vital:65089 , xlink:href="https://doi.org/10.1016/j.jphotochem.2022.114535"
- Description: New tetra-substituted zinc and indium Schiff base phthalocyanines (ZnPc and InPc, respectively) are synthesized and characterized herein. The ethyl pyrrolidine (ZnPc-2, InPc-2) and propyl pyrrolidine (ZnPc-3, InPc-3) substituted Schiff base Pcs were reacted with methyl iodide to form their cationic derivatives (ZnPc-2Q, InPc-2Q, ZnPc-3Q, and InPc-3Q, respectively). The photophysical and photochemical properties of the Pcs were studied. The cationic Pcs generated higher singlet oxygen quantum yield in aqueous media than the neutral Pcs. The photoinactivation of Methicillin-resistant Staphylococcus aureus (MRSA) and Methicillin-sensitive Staphylococcus aureus (MSSA) strains was evaluated. 5 µM ZnPc-3Q and InPc-3Q inactivated 100 % of the MSSA and MRSA while 5 µM ZnPc-2Q and InPc-2Q eradicated 100 % for MSSA and 97.2 % and 98.7 % (respectively) of the MRSA. The photodynamic antimicrobial chemotherapy studies depended on singlet oxygen ability, the charges, and the extension of the alkyl groups.
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- Date Issued: 2023
The in-vitro proliferation-suppression of MCF-7 and HeLa cell lines mediated by differently substituted ionic phthalocyanines in sonodynamic therapy supplemented-photodynamic therapy
- Authors: Nene, Lindokuhle Cindy , Nyokong, Tebello
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/360461 , vital:65090 , xlink:href="https://doi.org/10.1016/j.jinorgbio.2022.112084"
- Description: This work focuses on the study of the effects of the ultrasonic frequency (MHz) and power (W.cm−2) on the stability, reactive oxygen species yields and cytotoxicity activities of differently substituted ionic phthalocyanines (Pcs) in sonodynamic therapy (SDT). Four ultrasonic parameters were investigated: Par I (1 MHz: 1 W.cm−2), Par II (1 MHz: 2 W.cm−2), Par III (3 MHz: 1 W.cm−2) and Par IV (3 MHz: 2 W.cm−2). A higher degradation of the Pcs was observed with increasing power at the Par II. Two reactive oxygen species (ROS) were detected in the ultrasound treated Pcs: singlet oxygen and hydroxyl radicals. Due to minimal degradation of most Pcs, Par I was chosen for SDT, photodynamic therapy (PDT), and photo-sonodynamic therapy (PSDT) against Michigan Cancer Foundation-7 and Henrietta Lacks cancer cell lines. PSDT generally showed improved therapeutic efficacies of the Pcs compared to the SDT and PDT mono treatments.
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- Date Issued: 2023
Women farmers leading and co-learning in an agroecology movement at the intersections of gender and climate
- Authors: Chanyau, Ludwig , Rosenberg, Eureta
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/373873 , vital:66730 , xlink:href="https://doi.org/10.1080/10130950.2023.2239313"
- Description: This study, carried out in the Eastern Cape Province of South Africa, was particularly interested in women farmers’ access to social learning spaces for expanding their knowledge about farming in the context of climate change. Small-scale women and peasant farmers face historical intersectional inequalities as a result of the colonial and apartheid past which has continued to disadvantage women in the present through exclusion, limited or no access to finance, insecure or no land tenure, little bargaining power and unequal access to water. The gender prejudices and unequal access to resources experienced by women is brought into sharp relief by climate change. The article provides a case study of an agroecology movement led by women farmers that promotes climate-appropriate, low-cost farming practices using community and home gardens. The practices are tried out and further developed by women farmers themselves, relying on agroecology-informed extension services, open dialogue and the support of communities of practice. Unlike traditional top-down approaches to farmer learning common in public extension services, extension officers in the movement participate in creating conditions for co-learning and co-construction of new knowledge − that is, social learning − thus responding directly to their needs as farmers. The lead researcher joined in and observed farming and learning activities following an ethnographic approach. Farmers and other movement members were engaged in semi-structured interviews which explored the value derived from social learning (Wenger-Trayner and Wenger-Trayner Citation2020). The article concludes that the movement is responding to many of the intersectional challenges that women farmers in the Eastern Cape face. Further, its social learning approach holds potential for expanding women farmers’ ability to provide for themselves and their communities and inform their climate change adaptation.
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- Date Issued: 2023
A laminated, emergentist view of skills ecosystems
- Authors: Ramsarup, Presha , Lotz-Sisitka, Heila , McGrath, Simon
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/370074 , vital:66295 , xlink:href="https://doi.org/10.1080/14767430.2022.2145768"
- Description: In this paper we present a model of vocational education and training (VET) that can be used to guide decisions relating to VET in Africa today. This model takes the critique of the neoclassical, neoliberal model of VET as its starting point. Guided by Bhaskar's Critical Naturalism, we use immanent critique to consider the adequacy of proposed alternatives to the neoclassical approach, such as: the heterodox approach, which foregrounds explanations based on human capital and political economy; and Hodgson and Spours' social ecosystem model, which addresses some of the limitations of the heterodox account by including, social and ecosystem elements. Finally, we offer a version of the social ecosystem model that, according to our analysis, explains more of the empirical evidence than previous models. Our version of the social ecosystem model differs from earlier versions in terms of its explicit reference to the critical realist ideas of position- practices and emergence.
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- Date Issued: 2022
A simple quinoline-thiophene Schiff base turn-off chemosensor for Hg2+ detection
- Authors: Musikavanhu, Brian , Muthusamy, Selvaraj , Zhu, Dongwei , Xue, Zhaoli , Yu, Qian , Chivumba, Choonzo N , Mack, John , Nyokong, Tebello , Wang, Shengjun , Zhao, Long
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/230362 , vital:49771 , xlink:href="https://doi.org/10.1016/j.saa.2021.120338"
- Description: A new Schiff base probe (QT) consisting of 8-aminoquinoline (Q) and thiophene-2-carboxaldehyde (T) moieties has been synthesized. QT undergoes chelation-enhanced fluorescence quenching when exposed to Hg2+ due to coordination by the sulfur and nitrogen atoms of QT thus forming a facile “turn-off” sensor. The formation of the chelation complex was confirmed by UV–visible absorption and emission spectral measurements, 1H NMR titration and density functional theory calculations. These studies revealed that the probe exhibits high selectivity and sensitivity towards Hg2+ in the presence of other common metal ions. A low detection limit of 23.4 nM was determined and a Job plot confirmed a 2:1 stoichiometry between QT and Hg2+. The potential utility of QT as a sensor for Hg2+ ions in human HeLa cells was determined by confocal fluorescence microscopy, and its suitability for use in the field with environmental samples was tested with Whatman filter paper strips.
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- Date Issued: 2022
A Sn (iv) porphyrin with mitochondria targeting properties for enhanced photodynamic activity against MCF-7 cells
- 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.
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- Date Issued: 2022
Application of gold and palladium nanoparticles supported on polymelamine microspheres in the oxidation of 1-phenylethanol and some other phenyl substituted alcohols
- Authors: Storm, Ené , Maggott, Emile D , Mashazi, Philani N , Nyokong, Tebello , Malgas-Enus, Rehana , Mapolie, Selwyn F
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/299824 , vital:57858 , xlink:href="https://doi.org/10.1016/j.mcat.2022.112456"
- Description: Melamine formaldehyde and melamine resorcinol formaldehyde microspheres were decorated with Au and Pd nanoparticles and applied as heterogeneous catalysts in the oxidation of 1-phenylethanol. The catalysts showed similar activities irrespective of the support employed. Moderate conversion activities of 48–50% were achieved when using acetonitrile as solvent; however, when employing water as solvent, the supported catalysts formed a three-phase, emulsion system which facilitated the catalytic conversion of 1-phenylethanol to acetophenone at much higher conversions of around 83%. The oxidant, TBHP, decomposed rapidly in acetonitrile, whilst it remained stable in aqueous solution, leading to the enhanced activities observed when using water as solvent. These systems also proved to be recyclable for up to five cycles, with only slight loss of activity observed; this can be attributed to the physical loss of catalyst during the workup procedure conducted between each cycle.
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- Date Issued: 2022
Aptamer versus antibody as probes for the impedimetric biosensor for human epidermal growth factor receptor
- Authors: Centane, Sixolile , Nyokong, Tebello
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/229884 , vital:49720 , xlink:href="https://doi.org/10.1016/j.jinorgbio.2022.111764"
- Description: In the present work, the performance of aptamer and antibody bioreceptors for the detection of the human epidermal growth factor receptor (HER2) cancer biomarker on a glassy carbon electrode is reported. The carboxylic acid group rich graphene quantum dots (GQDs) modified with gold nanoparticles and a porphyrin binuclear framework (CoP-BNF) were used to modify the glassy carbon electrode. The aptamer and antibody were both amine functionalized and attached to GQDs and CoP-BNF through an amide bond. The designed immunosensors and aptasensors in this work were characterized using electrochemical impedance spectroscopy. The aptasensors, compared to the immunosensors gave better limit of detection values. The aptasensor outperforms the immunosensor in terms of its reusability and storability, while the immunosensor could not be regenerated for subsequent experiments. The potential applicability of all sensors in this work was also investigated, by detection of HER2 in spiked human serum with acceptable results.
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- Date Issued: 2022
Assessing the electrocatalytic activity of a localized push-pull system in cobalt phthalocyanine/graphene quantum dot hybrids
- Authors: Nkhahle, Reitumetse , Nyokong, Tebello
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/229909 , vital:49722 , xlink:href="https://doi.org/10.1016/j.matchemphys.2022.125842"
- Description: In this study, two cobalt phthalocyanines (asymmetric complex 1) and symmetric (complex 2) were synthesized and conjugated to nitrogen-doped graphene quantum dots (NGQDs) through covalent and non-covalent means to create Co phthalocyanine (CoPc)-NGQDs hybrid systems. The CoPcs and conjugates were applied as electrode modifiers on a glassy carbon electrode in the electrochemical sensing of nitrite. Of the CoPcs alone, complex 1 performed better than complex 2 regarding the limits of detection (LoD) recorded (5.74 μM for 1 and 15.1 μM for 2). Regarding the conjugates/nanocomposites, the π-π stacked conjugate derived from complex 2 (2πNGQDs) demonstrated highly favourable electrochemical potential with an LoD value of 0.70 μM. The nanocomposites fashioned from complex 1 were marred by a reduced loading which rendered the conjugates poor electrochemical sensors. These observations however do not disqualify GQDs as complementary nanomaterials to phthalocyanines but rather shed light on seeking alternative routes to increasing the Pc loading in conjugates (more so in π-π stacked conjugates).
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- Date Issued: 2022
Asymmetrical zinc (II) phthalocyanines conjugated to metal tungstate nanoparticles for photoinactivation of Staphylococcus aureus
- Authors: Mgidlana, Sithi , Managa, Muthumuni , Nyokong, Tebello
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/295718 , vital:57372 , xlink:href="https://doi.org/10.1080/00958972.2022.2090837"
- Description: In this study, we report for the first time on the photodynamic antimicrobial chemotherapy (PACT) of asymmetrical zinc(II) phthalocyanines and their conjugates with nickel tungstate (NiWO4), cobalt tungstate (CoWO4) and bismuth tungstate (Bi2WO6) nanoparticles. CoWO4, NiWO4 and Bi2WO6 were capped with glutathione and covalently linked to three asymmetrical zinc(II) phthalocyanines for PACT. The plate count method was used to investigate the effect of covalently linking asymmetrical zinc(II) phthalocyanines to nanoparticles under light (for PACT against Staphylococcus aureus) and in the dark. Both Pc complexes and the conjugates indicated minimum dark-toxicity. The conjugates showed greater antimicrobial activity against a gram-positive and drug resistant bacteria, Staphylococcus aureus, than Pc complexes alone.
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- Date Issued: 2022
Characterising the shared genetic influences between schizophrenia and subcortical brain regions
- Authors: Wooton, Olivia , Campbell, Megan , Jahanshad, Neda , Thompson, Paul , Stein, Dan , Dalvie, Shareefa
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/302450 , vital:58197 , xlink:href="https://doi.org/10.1016/j.euroneuro.2022.07.533"
- Description: Background: Abnormalities in brain structural volumes are well established in schizophrenia (SZ) and have been proposed as an endophenotype for the disorder. Despite increasing interest in the genetic relationship between brain structural volumes and SZ, our knowledge of the genetic overlap between the phenotypes is limited. This study aims to extend our current understanding of the shared genetic influences between SZ and subcortical brain volumes using data from the latest genome-wide association studies for the respective phenotypes (GWAS) and novel statistical approaches. Additionally, we will explore whether the association between schizophrenia and abnormal regional brain volumes is causal in nature. Methods: Summary statistics were obtained from the largest Psychiatric Genomic Consortium (PGC)-SZ GWAS (Ncase = 69,369, Ncontrol = 236,642) and the CHARGEENIGMA-UKBB GWAS of volumetric measures for eight subcortical brain regions (the nucleus accumbens, amygdala, brainstem, caudate nucleus, hippocampus, globus pallidus, putamen, and thalamus), and total intracranial volume (N = 30,983 - 40,380). Single nucleotide polymorphism (SNP) effect concordance analysis (SECA) was used to assess pleiotropy and concordance. Genetic correlation was assessed using linkage disequilibrium score regression (LDSR) and the pleiotropy informed conditional FDR approach was applied to identify SNPs associated with SZ conditional on their association with subcortical brain volumes. Mendelian randomization (MR) was used to test for causal association between SZ and each brain region. Results: There was evidence of global pleiotropy between SZ, and all examined subcortical brain regions. Inverse concordance between the genetic determinants of SZ and volumes of the nucleus accumbens, amygdala, brainstem, hippocampus, and thalamus was observed. Increased statistical power to detect SZ risk loci was shown when conditioning on subcortical brain volumes. There was no significant evidence for a causal effect of any of the examined brain regions on schizophrenia risk. Discussion: These data confirm the shared genetic basis of SZ and specific intracranial and subcortical brain volumes and provide evidence for negative concordance between SZ and volumes of the nucleus accumbens, amygdala, brainstem, hippocampus, and thalamus. Leveraging the genetic overlap between SZ and subcortical brain volumes has the potential to provide novel insights into the biological basis of the disorder.
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- Date Issued: 2022