A comparative study of the effect of different stabilizers on the critical quality attributes of self-assembling nano co-crystals
- Authors: Witika, Bwalya A , Smith, Vincent J , Walker, Roderick B
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/183224 , vital:43931 , xlink:href=" https://doi.org/10.3390/pharmaceutics12020182"
- Description: Lamivudine (3TC) and zidovudine (AZT) are antiviral agents used orally to manage HIV/AIDS infection. A pseudo one-solvent bottom-up approach was used to develop and produce nano co-crystals of 3TC and AZT. Equimolar amounts of 3TC dissolved in de-ionized water and AZT in methanol were rapidly injected into a pre-cooled vessel and sonicated at 4 °C. The resultant suspensions were characterized using a Zetasizer. The particle size, polydispersity index and Zeta potential were elucidated. Further characterization was undertaken using powder X-ray diffraction, Raman spectroscopy, Fourier transform infrared spectroscopy, differential scanning calorimetry, and energy dispersive X-ray spectroscopy scanning electron microscopy. Different surfactants were assessed for their ability to stabilize the nano co-crystals and for their ability to produce nano co-crystals with specific and desirable critical quality attributes (CQA) including particle size (PS) less than 1000 nm, polydispersity index (PDI) less than 0.500 and Zeta potential (ZP) less than −30 mV. All surfactants produced co-crystals in the nanometer range. The PDI and PS are concentration-dependent for all nano co-crystals manufactured while only ZP was within specification when sodium dodecyl sulfate was used in the process.
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- Date Issued: 2020
Co-loading of isoniazid-grafted phthalocyanine-in-cyclodextrin and rifampicin in crude soybean lecithin liposomes: Formulation, spectroscopic and biological characterization
- Authors: Nkanga, Christian I , Roth, Michael , Walker, Roderick B , Noundou, Xavier S , Krause, Rui W M
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/183481 , vital:43999 , xlink:href="https://doi.org/10.1166/jbn.2020.2880"
- Description: An inclusion complex of isoniazid-grafted phthalocyanine with gamma-cyclodextrin (Complex) was co-encapsulated with rifampicin (RIF) in crude soybean lecithin liposomes using a heating method. The encapsulation efficiency (%EE) of the Complex-RIF co-loaded liposomes (Rif-Complex-Lips) was determined using UV-Vis spectrophotometry. Rif-Complex-Lips formulations were evaluated using dynamic light scattering, transmission electron microscopy (TEM), 1H-NMR, absorption and emission spectroscopy. Dialysis was used for drug release study in two different media, pH 6.4 and 7.4. HeLa cells were used to assess potential cytotoxicity, and the uptake by lung fibroblasts and epithelial cells was investigated using fluorescence microscopy. The particle size and Zeta potential of Rif-Complex-Lips were approximately 594 nm and –50 mV. Spectroscopic analyses demonstrated molecular distribution of the cargo within the lipid core, and encapsulation efficiency of 58% for Complex and 86% for RIF. TEM analysis unveiled the existence of spherical nanoparticles in our samples, indicating the presence of liposomes. Rif-Complex-Lips exhibited much higher release rates for both INH and RIF at pH 6.4 compared to those tested at pH 7.4. In addition, there was no cytotoxicity on HeLa cells, but remarkable Rif-Complex-Lips internalization by peripheral lung fibroblasts and epithelial cells. Hence, Rif-Complex-Lips are promising vehicles for intracellular delivery of antimicrobial drugs.
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- Date Issued: 2020
Formulation optimization of smart thermosetting lamotrigine loaded hydrogels using response surface methodology, box benhken design and artificial neural networks
- Authors: Melamane, Siyabonga , Walker, Roderick B , Khamanga, Sandile M
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/183265 , vital:43936 , xlink:href="https://doi.org/10.1080/03639045.2020.1791163"
- Description: The aim of this research was to develop lamotrigine containing thermosetting hydrogel for intranasal administration to manage and treat generalized epilepsy. Thermosetting hydrogels were prepared using different ratios of poloxamer 407 (L127), poloxamer 188 (L68) and CarbopolVR 974 P NF (C974) using the cold production process. The in situ thermosetting hydrogel was optimized using Box Behken design. Co-solvency approach was used to increase the solubility of lamotrigine by dissolving it in propylene glycol and polyethylene glycol 400 (0.2: 0.8) and the resultant solution was incorporated in the hydrogel to manufacture an LTG hydrogel. The presence of a higher amount of L127 resulted in higher viscosity at 22 0C and 34 0C and decreased the overall release of LTG. An increase in the amount of C974 resulted in a decrease in the pH of the hydrogel. The results show that formulations F10, F12, F13, F14, F15, F16 and F17 exhibited acceptable thermosetting behavior, pH and released adequate Lamotrigine above the minimum effective concentration to treat generalized epilepsy. The optimized formulation exhibited acceptable thermosetting behavior, pH and lamotrigine release but formed a stiff gel at 22 0C. The average LTG content of the optimized hydrogel was 5.00 ± 0.0225mg/ml with % recovery of 99.17%. The amount of LTG released at 12 h from the optimized hydrogel was 3.21 ± 0.0155mg and will be therapeutically effective in the brain after absorption via the olfactory region in the nasal cavity.
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- Date Issued: 2020
Reimagining academic identities in response to research demands at Universities of Technology
- Authors: Gumbi, Thobani , McKenna, Sioux
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185897 , vital:44446 , xlink:href="https://doi.org/10.14426/cristal.v8i1.234"
- Description: In the last volume of this journal, Garraway and Winberg called for a reimagination of Universities of Technology (UoT) within the South African higher education system. This article continues that conversation by looking at the implications that the formation of the UoT had for academics’ identities. Technikon lecturers’ identities were closely tied to workplace expertise, but demands for research in UoTs have changed this. A social realist analysis of interviews with fifteen academics at three UoTs finds that research remains a contested issue. Interviewees understood research to take the form of acquiring postgraduate qualifications, rather than as an ongoing activity tied to their identities. Echoing Garraway and Winberg’s study, the bureaucratic nature of the institutional culture was referred to as a constraint. There was also a view that for this programme, Dental Technology, a demand for research was needed from industry if this was to be a valued aspect of academics’ identities.
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- Date Issued: 2020
The photodynamic antimicrobial chemotherapy of Stapphylococcus aureus using an asymmetrical zinc phthalocyanine conjugated to silver and iron oxide based nanoparticles
- Authors: Mapukata, Sivuyisiwe , Nwahara, Nnamdi , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186078 , vital:44461 , xlink:href="https://doi.org/10.1016/j.jphotochem.2020.112813"
- Description: The synthesis and characterisation of asymmetrical zinc(II) 2(3)-mono-isophthalic acid-9(10),16(17),23 (24)-tri (tert-butylphenoxy) phthalocyanine (complex 4) are reported. The phthalocyanine is conjugated to cysteamine capped silver nanoparticles (Cys-Ag NPs), amine functionalised iron oxide magnetic nanoparticles (NH2-Fe3O4 NPs) and a core-shell composite of the two (Cys-Fe3O4@Ag) via amide bonds. The photo-physico-chemical properties of complex 4 and its respective nanoconjugates (4-Ag, 4-Fe3O4 NPs and 4-Fe3O4@Ag NPs) are also reported. The nanoconjugates showed improved triplet and singlet oxygen quantum yields compared to complex 4. The antibacterial activity of complex 4 and its nanoconjugates were also evaluated on S. aureus wherein their activity was found to be mainly visible light driven with the best catalyst being 4-Fe3O4@Ag. The work therefore demonstrates the feasibility of phthalocyanine-nanoparticle based compounds as potential agents in real life antibacterial treatment
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- Date Issued: 2020
Theoretical and photodynamic therapy characteristics of heteroatom doped detonation nanodiamonds linked to asymmetrical phthalocyanine for eradication of breast cancer cells
- Authors: Matshitse, Refilwe , Tshiwawa, Tendamudzimu , Managa, Muthumuni , Nwaji, Njemuwa , Lobb, Kevin A , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186089 , vital:44462 , xlink:href="https://doi.org/10.1016/j.jlumin.2020.117465"
- Description: An amide mono substituted benzothiozole phthalocyanine: zinc(II) 3-(4-((3,17,23-tris(4-(benzo [d]thiazol-2-yl)phenoxy)-9-yl)oxy) phenyl)amide phthalocyanine (NH2BzPc) was covalently linked to undoped and heteroatom doped detonation nanodiamonds (DNDs): B@DNDs, P@DNDs, S@DNDs, N@DNDs, and SandN@DNDs There is a drastic decrease in highest occupied molecular orbital (HOMO) – lowest unoccupied molecular orbital (LUMO) energy gaps for nanoconjugates compared to DNDs alone. B@DNDs-NH2BzPc, SandN@DNDs-NH2BzPc, and P@DNDs-NH2BzPc showed superior photodynamic therapy (PDT) effects. DNDs-NH2BzPc also had a small HOMO-LUMO gap, but did not show improved PDT activity compared to the Pc alone, suggesting doping of DNDs is important. This study shows improved PDT effect on Michigan Cancer Foundation-7 breast cancer lines at 7.63%, 7.62% and 6.5% cell viability for P@DNDs-NH2BzPc, SandN@DNDs-NH2BzPc and B@DNDs-NH2BzPc, respectively.
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- Date Issued: 2020
Understanding the context of multifaceted collaborations for social-ecological sustainability: A methodology for cross-case analysis
- Authors: Cockburn, Jessica J , Schoon, Michael , Cundill, Georgina , Robinson, Cathy , Aburto, Jamie A , Alexander, Steve M , Baggio, Jacopo A , Barnaud, Cecile , Chapman, Mollie , Llorente, Marina G , Garcia-Lopez, Gustavo A , Hill, Rosemary , Speranza, Chinwe I , Lee, Jean , Meek, Chanda L , Rosenberg, Eureta , Schultz, Lisen , Thondhlana, Gladman
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/370725 , vital:66371 , xlink:href="https://doi.org/10.5751/ES-11527-250307"
- Description: There are limited approaches available that enable researchers and practitioners to conduct multiple case study comparisons of complex cases of collaboration in natural resource management and conservation. The absence of such tools is felt despite the fact that over the past several years a great deal of literature has reviewed the state of the science regarding collaboration. Much of this work is based on case studies of collaboration and highlights the importance of contextual variables, further complicating efforts to compare outcomes across case-study areas and the likely failure of approaches based on one size fits all generalizations. We expand on the standard overview of the field by identifying some of the challenges associated with managing complex systems with multiple resources, multiple stakeholder groups with diverse knowledges/understandings, and multiple objectives across multiple scales, i.e., multifaceted collaborative initiatives. We then elucidate how a realist methodology, within a critical realist framing, can support efforts to compare multiple case studies of such multifaceted initiatives. The methodology we propose considers the importance and impact of context for the origins, purpose, and success of multifaceted collaborative natural resource management and conservation initiatives in social-ecological systems.
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- Date Issued: 2020