Design, synthesis, characterization and evaluation of Chitosan-based hydrogel for controlled drug delivery system
- Authors: Safari, Justin Bazibuhe
- Date: 2022-04
- Subjects: Chitosan , Drug delivery systems , Drugs Controlled release , Tenofovir , Colloids , Hepatitis B Chemotherapy , Hydrogel
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/232182 , vital:49969
- Description: Hepatitis B infection is a deadly infectious disease caused by the hepatitis B virus and is responsible for many deaths every year worldwide. Despite medication and vaccines against hepatitis B infection, it still presents high morbidity and mortality among populations. This is partly due to factors such as a long medication period of the existing treatments, resulting in poor patient compliance and leading to treatment failure. In addition, this situation can be responsible for the observed emerging drug resistance. Hence, novel drugs and drug delivery systems are needed to tackle this matter. Many strategies have been used to develop long-acting drug delivery systems treatment for several infectious diseases. Hydrogel drug delivery systems have shown interesting results as controlled drug delivery systems for several drugs. Therefore, the present study aimed to develop chitosan grafted poly (acrylamide-co-acrylic acid) hydrogel and apply it as a pH-sensitive controlled delivery system of tenofovir disoproxil fumarate (TDF). TDF is a nucleoside reverse transcriptase inhibitor used as first-line treatment of hepatitis B chronic infection and in the treatment of other viral infections. The free-radical polymerization method was utilized to modify chitosan by grafting acrylamide and acrylic acid and using N, N’-methylene bisacrylamide as the crosslinking agent to prepare the hydrogel, followed by an optimization of parameters that could affect the swelling capacity. The prepared chitosan-g-poly(acrylamide-co-acrylic acid) hydrogel was characterized using Fourier Transmission Infra-red spectroscopy (FTIR), X-Ray Diffraction (XRD), Thermal Gravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), Energy-dispersive X-ray spectroscopy (EDS), Scanning Electron Microscopy (SEM), and was evaluated for cytotoxicity using a HeLa cell assay. TDF was used as a drug model, it was loaded by the swelling equilibrium method, following by the investigation of the release profile of TDF-loaded hydrogel at pH 1.2 and 7.4. A successful synthesis of chitosan grafted poly(acrylamide-co-acrylic acid) hydrogel was confirmed by Fourier Transmission Infra-red spectroscopy (FTIR), X-Ray Diffraction Spectroscopy (XRD), Thermal Gravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), Energy-dispersive X-ray spectroscopy (EDS) and Scanning Electron Microscopy (SEM). Optimization results showed that the ratio of monomers impacted the swelling ratio of the hydrogel and both the concentration of the crosslinking agent, and the reaction initiator also affected the swelling ratio. The synthesized hydrogels were sensitive to pH and ionic strength. Hydrogel swelling was lower in acidic solutions and higher in neutral and basic solutions and decreased with the increasing ionic strength. Furthermore, SEM results revealed that hydrogel have a rough and fibrous surface structure with numerous pores. Cytotoxicity studies demonstrated that the hydrogel was non-cytotoxic at 50 μg/ml against HeLa cells which suggested a good biocompatibility of the material. TDF was loaded and released from the hydrogels and showed an encapsulation efficiency and drug loading percentage ranging from 81-96% and 8-10%, respectively. TDF release profile was found to be low in buffer solution of pH 1.2 (in the range of 5-10%) and much higher (38-53%) at pH 7.4 within 96 hours. TDF maintained its chemical integrity after release and the hydrogels can therefore be proposed as a new controlled-release drug delivery system for hepatitis B treatment. , Thesis (MSc) -- Faculty of Science, Chemistry, 2022
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Household food waste generation, disposal and minimisation in two South African towns
- Authors: Mtakati, Sinako
- Date: 2022-04
- Subjects: Food waste South Africa Cradock , Food waste South Africa Middelburg (Eastern Cape) , Sanitary landfills Environmental aspects South Africa , Greenhouse gases Environmental aspects South Africa , Income distribution South Africa , Socio-economic status South Africa , Waste minimization South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/232159 , vital:49967
- Description: Food waste is becoming an important issue considering greenhouse gas emissions from landfills. However, data on the quantities of food disposed remains limited, especially for developing, countries including South Africa. Global food waste estimates suggest that households in developed countries waste more food than those in developing countries. Further, research shows that lack of food waste management impacts negatively on the global efforts to combat food waste generation. I therefore set out to present primary data relating to household food waste generation and minimisation within a South African context. The case study covers two towns in the Eastern Cape province, namely Cradock and Middelburg, with a combined population of 55 352 people. Household food waste assessment and quantification was undertaken using two methods, 1) questionnaires to explore quantities of different types of food wasted by households, and 2) kitchen scales to measure the amounts of food discarded by households. Participating households in each suburb were selected randomly. Differences in shopping and household food waste behaviour in households from different income suburbs is vital to understand as it sets an effective approach to food waste interventions that might have a positive impact in minimising food waste generation. In this thesis, differences in shopping and household food waste behaviour across households in the affluent, middle and low-income suburbs is uncovered. A questionnaire was conducted and households in the affluent suburbs purchased food more frequently and had the highest percentage of respondents that used shopping list when buying food than those in the middle and low-income suburbs. The thesis also indicates that households in the low-income suburbs were more attracted to food special offers and had a higher proportion of respondents who could not distinguish between “Use by” and “Best before” dates than those in the affluent and middle- income suburbs. The reasons to food waste generation overlap between the towns. However, between the suburbs, the respondents from households in the affluent suburbs pointed that they were mainly generating and disposing food waste because they did not think it is an issue. Excessive cooking and food expiring before being consumed were found to be the most common reasons for food waste generation and disposal among households in the low and middle-income suburbs. The times which households are likely to generate more food waste were investigated. Nonetheless, only a few households indicated that there were times that they generated and disposed more food in the bins. The most cited times in the affluent suburbs were during Christmas (54%) and in summer (41%). Festive season (65%) and traditional ceremonies (37%) were the most cited times in the middle-income suburbs, while festive season (46%) and the summer season (36%) were the most cites among households in the low- income suburbs. The dimensions of shopping and household food waste behaviour is reflected in the types and quantities of food waste generated. The results reveal that vegetables were the most wasted food type in Cradock (26%) and in Middelburg (30%), while tinned food and dairy were the least discarded food types in both study towns with no significant differences in proportions of households discarding all six food types. One of the key results is that the average self-reported and weighed food waste generated per capita per annum for the two towns was 23.40±47.20 and 202.60±128.30 kg/capita/year, respectively as compared to the estimated 6-11 kg per annum in sub-Saharan Africa and South and Southeast Asia. Between the towns, Cradock generated more food waste (5.05±2.68 kg) than those in Middleburg (3.84±2.59 kg) in the previous 48 hours. It was also evident that each household and each person in Cradock generated more food waste at breakfast and the least at lunch, while in Middelburg the highest average amount of food waste generated was observed at supper and the least at lunch. The results indicate that household size and employment status were negatively correlated to food waste generation, while wealth status and gender were positively correlated to food waste generation. Majority of households (74% in Cradock and 73% in Middelburg) had no household food waste minimisation strategies implemented. The most cited strategies in place were cooking less frequently, cooking small portions and chopping and freezing vegetables as an anti-food waste strategy. Worth noting is that the small proportion of households with strategies in place are faced with a challenge of some household members showing unwillingness to effectively implement the strategies. The results also reveal that children wasted more food than adults, particularly girls. , Thesis (MSc) -- Faculty of Science, Environmental Science, 2022
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Recruitment disruptors: an exploratory study on the perception of artificial intelligence amongst selected Eastern Cape Province recruiters
- Authors: Sobekwa, Sinazo
- Date: 2022-04
- Subjects: Uncatalogued
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/232238 , vital:49974
- Description: Thesis (MA) -- Faculty of Humanities, Psychology, 2022
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