Matolwandile M. Mtotywa

Bio: Matolwandile M. Mtotywa is an academic researcher from Mintek. The author has contributed to research in topics: Medicine & Quality (philosophy). The author has an hindex of 1, co-authored 1 publications receiving 17 citations.

Gold(I) and silver(I) complexes of 2,3-bis(diphenylphosphino)maleic acid: Structural studies and antitumour activity

Abstract: The 2:1 and 1:2 adducts of Au(I) and 1:2 adducts of Ag(I) with the diphosphine 2,3-bis(diphenylphosphino)maleic acid (dpmaa) have been prepared in high yields. Crystal structures have been determined for the neutral digold complex (AuCl)2(dpmaa) · 2thf (1) and the bis-chelated complex [Au(dpmaa)2]Cl · H2O · CH3OH (2). For 1, conformational rigidity imposed by the ethylenic bridge facilitates the formation of short intramolecular Au–Au contacts with no evidence of similar intermolecular contacts. Complex 2 crystallizes with [Au(dpmaa)2]+ cations hydrogen bonded through the carboxyl groups to a water molecule and chloride anion to form a H-bonded chain along the a axis. 31P NMR titration of 1 with dpmaa in acetone shows conversion to 2 at Au:P–P ratios less than 1:1 indicating similar high thermodynamic and kinetic stabilities to other bis-chelated [Au(P–P)2]+ complexes containing 5- or 6-membered chelate rings. The ionic Au(I) complex 2 and the analogous Ag(I) complex [Ag(dpmma)2]NO3 (3) are highly water soluble. The in vitro cytotoxic activity of 2 was assessed against eight different cell lines and no significant activity was found. The solubility properties and solution behaviour of the complexes are compared to the analogous 1,2-bis(diphenylphosphino)ethane (dppe) complexes and the potential significance of these results to the antitumour properties of chelated 1:2 Au(I)diphosphine complexes are discussed.

Developing a Quality 4.0 Maturity Index for Improved Business Operational Efficiency and Performance

Abstract: Purpose: Technological advances and increased environmental turbulence require a transition in quality management. The study aimed at developing a Quality 4.0 maturity index for improved business operational efficiency and performance. Methodology/Approach: This conceptual paper introduces a theoretical business evaluative model that allows an integrated analysis of technology-driven, quality management dimensions. The model is based on theoretical and empirical information and describes Quality 4.0 business analysis by a theoretical central business dimensional concept, formal statistical analytical methods and uses these data to assign a maturity index score to the business. Findings: The study builds the Quality 4.0 maturity index following the analysis of seven continuous quality improvement dimensions. The maturity of these dimensions in the business is assessed with a five-point maturity level. The effectiveness of the index should be confirmed with fit as covariation and a composite score for the level of Quality 4.0 maturity. Research Limitation/Implication: The research is based on theory and has not been validated with empirical data. It is recommended that a validation study be conducted based on the approach and guidelines provided in the paper. Originality/Value of paper: The study helped develop a theoretical aspect of total quality management during an era of the fourth industrial revolution. It also aimed at practically benefiting a business by focussing on improved business capacity and capability to mitigate the environmental turbulence associated with pandemics. The paper provides novel work, as it describes one of the first Quality 4.0 maturity index models that may be used to improve business.

Diagnostic Assessment of Post-COVID-19 Operations for Business Model Reconfiguration Decision

Abstract: The current study develops a diagnostics assessment model of post-COVID-19 operations for business model reconfiguration decision referred to as the Pakade model. For this purpose, it identified seven diagnostic factors namely business operations disruptions, loss of human resources, changing cost structure due to safety requirements, work structure and culture change, disruption of supply chain and logistics, changing customer requirement and behaviour, and consequences of interventions on sustainability. The assessment was conducted using a 29-item scale scored on a 7-point scale representing the level of impact on the respective firm’s business model. The proposed model assesses the composite score and relative importance index for each business factor, highlights the approach for investigating the validity and reliability of this multidimensional model, and makes short- and long-term impact evaluation with multiple linear regression and difference-in-difference (DiD) method, respectively. Diagnostics assessment determines the form and extent of business model reconfiguration. It can either be an adjustment driven by the introduction or enhancement of world class work practices, a business re-engineering, or a complete change of the business model. This model can be applied to both the primary and secondary economic sectors to determine the changes required in the business model of a firm.

Factors influencing quality and performance of cloud computing platforms defined by personal users in South Africa

Abstract: Cloud computing changed our way of doing things because we now maintain our systems and data on global online platforms. The research aimed to investigate the predictive factors determining the quality of personal users' cloud computing and their effect on platform performance. The study adopted a cross-sectional, descriptive, quantitative design conducted within South African communities and received 254 responses, a response rate of 66.1%. The measurement model (SRMR = 0.071) results demonstrated that cost-effectiveness, reliability, flexibility, availability, security effectiveness, and scalability collectively define the quality of cloud computing platforms utilized by personal users. AVE (0.575 – 0.694), CR (0.844 – 0.901), Fornell-Larcker criterion, and cross-loadings confirmed convergent validity, reliability, and discriminant validity. Security effectiveness, scalability, and reliability have a statistically significant effect on platform performance with small to medium effect sizes. The theoretical implication is an enhanced domestication theory of technology based on cloud computing, thus providing insights into the needs required to fit within the prevailing environment and context. In addition, it helped understand the personal users' decisions on cloud computing. The study enhances cloud computing at a personal level through understanding that the decision and value may differ from well-researched organizational levels.

Post COVID-19 online shopping in South Africa: A mediation analysis of customer satisfaction on e-service quality and purchase intention

Abstract: The study investigated the dynamics of online shopping focusing on mediation analysis of customer satisfaction on e-service quality and purchase intention. The study used a cross-sectional quantitative method where 324 responses were collected through a self-administered online survey questionnaire from South African consumers. The findings revealed that system availability, efficiency, responsiveness, fulfilment, privacy and compensation can be collectively used to measure electronic service dimensions in online shopping. These dimensions have a statistically significant relationship with purchase intention, while customer satisfaction has a mediation effect on the relationship. Customer satisfaction has a full mediation effect on the relationship between electronic service quality dimensions, compensation and privacy and trust with purchase intention and partial mediation between electronic service quality dimensions, responsiveness, efficiency and system availability with purchase intention. These findings inform businesses that are using online shopping platforms and assist them in prioritizing their resources. The contribution of the research is the use of the value-percept paradigm that is enhanced by importance-analysis within customer satisfaction as a mediator on e-service quality and purchase intention. This underpins the importance of customers' values and, more importantly, a 'customized' customer, where 'one size fit all' is diminishing during the time of technological advances.

Targeting the mitochondrial cell death pathway with gold compounds

Abstract: There is much recent evidence showing that mitochondria play a critical role in the regulation of apoptosis (programmed cell death), making them an attractive target for the design of new anticancer drugs. A variety of different strategies targeting mitochondria for cancer therapy have been described in recent literature. Several different classes of gold-based compounds (in both Au(I) and Au(III) oxidation states) have attracted interest as potential antitumour agents and there is evidence that many act by mechanisms involving mitochondrial cell death pathways. Two distinct classes of Au(I) phosphine complexes display antitumour properties, these having either linear two-coordinate, or tetrahedral four-coordinate geometries. Both classes appear to target mitochondria, but different mechanisms are likely to be involved, related to their differing propensity to undergo ligand exchange reactions with biological ligands. The anti-arthritic Au(I) phosphine drug, auranofin, has been shown to induce apoptosis via selective inhibition of the mitochondrial isoform of thioredoxin reductase, an enzyme which has emerged as a potential new drug target. Gold(I) compounds are among the most potent known inhibitors of thioredoxin reductase, attributable to binding of Au(I) to the redox-active selenocysteine residue. On the other hand [Au(dppe) 2 ] + , and related tetrahedral Au(I) phosphine complexes, do not undergo ligand exchange reactions as readily as two-coordinate linear Au(I) complexes. Their antitumour activity may stem from the lipophilic, cationic properties, as for other delocalised lipophilic cations that accumulate in mitochondria. Examples from our own recent work on different types of Au(I) phosphine and N -heterocyclic carbene compounds under investigation as potential mitochondrial targeting antitumour agents are reported here. We also review recent related literature on auranofin and a variety of Au(III) antitumour compounds which either inhibit mitochondrial thioredoxin reductase, or induce apoptosis by other mitochondrial cell death pathways.

Anti-cancer potential of gold complexes

Abstract: A full range of gold compounds is currently being investigated for their potential as anti-tumor agents. Gold(I) compounds related to the anti-arthritic drug $${\rm Auranofin}^\circledR$$ continue to attract attention, especially those carrying biologically active molecules with anti-tumor activity in their own right. Tetrahedrally coordinated gold(I) compounds, that possibly target mitochondria, are under development with a particular focus upon moderating their hydrophilicity. A resurgence of interest in square-planar gold(III) compounds has occurred in the last decade. A wide variety of species: mono- and di-nuclear, neutral and charged, coordination and organometallic, etc. are being developed. Supporting many investigations are studies of mechanistic aspects of gold compounds but a clear understanding of the mechanism of action of these compounds has yet to be delineated.

Gold(I) N-heterocyclic carbene based initiators for bulk ring-opening polymerization of l-lactide

Abstract: Synthesis, structures, and catalysis studies of gold(I) complexes of N-heterocyclic carbenes namely, a di-O-functionalized [1-(2-hydroxy-cyclohexyl)-3-(acetophenone)imidazol-2-ylidene], a mono-O-functionalized [1-(2-hydroxy-cyclohexyl)-3-(benzyl)imidazol-2-ylidene] and a non-functionalized [1,3-di- i -propyl-benzimidazol-2-ylidene], are reported. Specifically, the gold complexes, [1-(2-hydroxy-cyclohexyl)-3-(acetophenone)imidazol-2-ylidene]AuCl ( 1c ), [1-(2-hydroxy-cyclohexyl)-3-(benzyl)imidazol-2-ylidene]AuCl ( 2c ), and [1,3-di- i -propyl-benzimidazol-2-ylidene]AuCl ( 3b ), were prepared from the respective silver complexes 1b , 2b , and 3a by treatment with (SMe 2 )AuCl in good yields following the commonly used silver carbene transfer route. The silver complexes 1b , 2b , and 3a were synthesized from the respective imidazolium halide salts by the reactions with Ag 2 O. The N-heterocyclic carbene precursors, 1-(2-hydroxy-cyclohexyl)-3-(acetophenone)imidazolium chloride ( 1a ) and 1-(2-hydroxy-cyclohexyl)-3-(benzyl)imidazolium chloride ( 2a ), were synthesized by the direct reactions of cyclohexene oxide and imidazole with chloroacetophenone and benzyl chloride respectively. The gold ( 1c , 2c , and 3b ) and the silver ( 3a ) complexes along with a new O-functionalized imidazolium chloride salt ( 1a ) have been structurally characterized by X-ray diffraction. The structural studies revealed that geometries around the metal centers were almost linear in these gold and silver complexes. The gold ( 1c , 2c , and 3b ) complexes efficiently catalyze ring-opening polymerization (ROP) of l -lactide under solvent-free melt conditions producing polylactide polymer of moderate to low molecular weights with narrow molecular weight distributions.

Polynuclear Ruthenium, Osmium and Gold Complexes. The Quest for Innovative Anticancer Chemotherapeutics

Abstract: Polynuclear compounds are a relatively new and successful approach in metal-based cancer chemotherapy as typified by the trinuclear Pt compound BBR3464 which was evaluated in clinical trials. In this review, we discuss newer developments of polynuclear ruthenium, osmium and gold complexes, focusing on their anticancer activity. The compounds presented are often supposed to exert their anticancer activity by different modes of action as compared to established drugs, including newly proposed mechanisms such as enzyme inhibition, crosslinking of biomacromolecules or through photo-activation, though many of the examples are also capable of binding to DNA nucleobases. Important metabolization and chemical characteristics of such compounds are discussed, and if the appropriate data is available, molecular modes of action are highlighted.

Supramolecular assembly of molecular gold(I) compounds: An evaluation of the competition and complementarity between aurophilic (Au⋯Au) and conventional hydrogen bonding interactions

Abstract: A bibliographic review of the crystallographic literature has been conducted on gold(I) compounds bearing functional groups capable of forming conventional hydrogen bonding interactions, namely, primary amide, secondary amide and carboxylic acid. The clear majority of structures featured hydrogen bonding interactions leading to well defined zero- or one-dimensional supramolecular architectures; rarely were two-dimensional architectures formed. Conversely, aurophilic, Au⋯Au, were the exception rather than the rule. This observation is correlated with steric hindrance: small atoms associated via directional hydrogen bonding compared with encumbered gold-atom environments (due to bulky ligands). Amide-{⋯HNCO}2 and carboxylic acid-{⋯HOCO}2 synthons featured in significantly more of the gold(I) structures compared with all-organic systems, particularly for non-ionic structures where charged-assisted hydrogen bonding precluded the formation of these cyclic synthons. This suggests a crystal engineering strategy of functionalising metal complexes with hydrogen bonding potential to improve opportunities of rational design of crystal structures.