Photodynamic antimicrobial chemotherapy against Staphylococcus aureus and Escherichia coli sensitized using indium (III) cationic porphyrins linked to core-shell magnetic nanoparticles
- Authors: Makola, Lekgowa Collen
- Date: 2021-04
- Subjects: Photochemotherapy , Photosensitizing compounds , Staphylococcus aureus , Escherichia coli , Indium , Porphyrins , Magnetic nanoparticles , Quaternize
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/177225 , vital:42801
- Description: Photodynamic antimicrobial chemotherapy (PACT) is a well-known antimicrobial therapy technique used against multi-drug resistant pathogens. In this study, the syntheses, characterization, photophysicochemical properties, and the applications of symmetrically and asymmetrically substituted cationic indium (III) porphyrins linked to silver/copper ferrite core-shell (Ag/CuFe2O4) magnetic nanoparticles (MNPs) as potential photosensitizers for PACT are reported. The synthesized complexes include axially modified porphyrins quaternized through an axial ligand. All the asymmetrically substituted porphyrins were linked to the NPs via an ester bond and the symmetrically substituted porphyrins were linked (peripherally and /or axially) via self-assembly (Ag-S and/or Ag-N). The impact of axial modification, peripheral substituents, conjugation to the NPs, the number of positive charges, and the chain length of the alkyl halides quaternizing agents on PACT efficacy and photophysicochemical properties of porphyrins were studied. High singlet oxygen quantum yields and antimicrobial log reductions were observed. Lipophilicity and hydrophilicity of the porphyrins were also studies, where the complexes quaternized with methyl iodide showed relatively high hydrophilicity character. Upon in vitro PACT studies, the quaternized complexes were observed to have 0% viable colony, signifying their effectiveness. Moreover, the highest log reductions of 9.27 were observed against S. aureus and 9.58 were observed against E. coli. The findings from this work delineate that singlet oxygen generation alone is not a distinct factor on the PACT efficacy of the porphyrin complexes, since some of the complexes have practically the same singlet oxygen quantum but different PACT activity. However, other contributing factors including water solubility play a significant role. , Thesis (MSc) -- Faculty of Science, Department of Chemistry, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Makola, Lekgowa Collen
- Date: 2021-04
- Subjects: Photochemotherapy , Photosensitizing compounds , Staphylococcus aureus , Escherichia coli , Indium , Porphyrins , Magnetic nanoparticles , Quaternize
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/177225 , vital:42801
- Description: Photodynamic antimicrobial chemotherapy (PACT) is a well-known antimicrobial therapy technique used against multi-drug resistant pathogens. In this study, the syntheses, characterization, photophysicochemical properties, and the applications of symmetrically and asymmetrically substituted cationic indium (III) porphyrins linked to silver/copper ferrite core-shell (Ag/CuFe2O4) magnetic nanoparticles (MNPs) as potential photosensitizers for PACT are reported. The synthesized complexes include axially modified porphyrins quaternized through an axial ligand. All the asymmetrically substituted porphyrins were linked to the NPs via an ester bond and the symmetrically substituted porphyrins were linked (peripherally and /or axially) via self-assembly (Ag-S and/or Ag-N). The impact of axial modification, peripheral substituents, conjugation to the NPs, the number of positive charges, and the chain length of the alkyl halides quaternizing agents on PACT efficacy and photophysicochemical properties of porphyrins were studied. High singlet oxygen quantum yields and antimicrobial log reductions were observed. Lipophilicity and hydrophilicity of the porphyrins were also studies, where the complexes quaternized with methyl iodide showed relatively high hydrophilicity character. Upon in vitro PACT studies, the quaternized complexes were observed to have 0% viable colony, signifying their effectiveness. Moreover, the highest log reductions of 9.27 were observed against S. aureus and 9.58 were observed against E. coli. The findings from this work delineate that singlet oxygen generation alone is not a distinct factor on the PACT efficacy of the porphyrin complexes, since some of the complexes have practically the same singlet oxygen quantum but different PACT activity. However, other contributing factors including water solubility play a significant role. , Thesis (MSc) -- Faculty of Science, Department of Chemistry, 2021
- Full Text:
- Date Issued: 2021-04
In vitro susceptibility of Staphylococcus aureus to porphyrin-silver mediated photodynamic antimicrobial chemotherapy
- Authors: Shabangu, Samuel Malewa
- Date: 2020
- Subjects: Porphyrins , Nanoparticles , Photochemotherapy , Drug resistance in microorganisms , Staphylococcus aureus
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/167476 , vital:41484
- Description: This work reports on the syntheses and characterization of symmetrical and unsymmetrical porphyrin complexes namely, 5,10,15,20-tetra(4-pyridyl)-porphyrinato zinc(II) (1), 5,10,15,20-tetrathienyl porphyrinato zinc(II) (2), 5-(4-hydroxyphenyl)-10, 15, 20-tris(2-thienyl) porphyrinato zinc(II) (3), 5-(4-carboxyphenyl)-10,15,20-tris(pentafluorophenyl)- porphyrinato zinc(II) (4), 5-(4-carboxyphenyl)-10,15,20-triphenyl-porphyrinato zinc(II) (5) and 5-(4-carboxyphenyl)-10, 15, 20-tris(2-thienyl)-porphyrinato zinc(II) (6). The synthesis of silver nanoparticles (AgNPs) was also undertaken in this research work. Complexes 1, 2, 3 and 6 were linked to oleic acid/oleylamine functionalized nanoparticles via self-assembly and 4-6 were linked via covalent interaction through an amide bond to glutathione capped AgNPs. The effect of nature of bond along with symmetry were investigated, of interest were the five membered thienyl substituents. The photophysical and photochemical behaviour of the complexes and their conjugates with AgNPs were investigated in dimethylformamide. The porphyrin and AgNPs conjugates afforded an increase in singlet oxygen quantum yield. Complexes 1-6 and their conjugates were used for photodynamic antimicrobial chemotherapy of Staphylococcus aureus. The antimicrobial studies were done in two different concentrations of 0.36 and 2.0 μg/mL. The thienyl substituted porphyrin complexes and their conjugates gave better photodynamic activity as compared to phenyl analogues
- Full Text:
- Date Issued: 2020
- Authors: Shabangu, Samuel Malewa
- Date: 2020
- Subjects: Porphyrins , Nanoparticles , Photochemotherapy , Drug resistance in microorganisms , Staphylococcus aureus
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/167476 , vital:41484
- Description: This work reports on the syntheses and characterization of symmetrical and unsymmetrical porphyrin complexes namely, 5,10,15,20-tetra(4-pyridyl)-porphyrinato zinc(II) (1), 5,10,15,20-tetrathienyl porphyrinato zinc(II) (2), 5-(4-hydroxyphenyl)-10, 15, 20-tris(2-thienyl) porphyrinato zinc(II) (3), 5-(4-carboxyphenyl)-10,15,20-tris(pentafluorophenyl)- porphyrinato zinc(II) (4), 5-(4-carboxyphenyl)-10,15,20-triphenyl-porphyrinato zinc(II) (5) and 5-(4-carboxyphenyl)-10, 15, 20-tris(2-thienyl)-porphyrinato zinc(II) (6). The synthesis of silver nanoparticles (AgNPs) was also undertaken in this research work. Complexes 1, 2, 3 and 6 were linked to oleic acid/oleylamine functionalized nanoparticles via self-assembly and 4-6 were linked via covalent interaction through an amide bond to glutathione capped AgNPs. The effect of nature of bond along with symmetry were investigated, of interest were the five membered thienyl substituents. The photophysical and photochemical behaviour of the complexes and their conjugates with AgNPs were investigated in dimethylformamide. The porphyrin and AgNPs conjugates afforded an increase in singlet oxygen quantum yield. Complexes 1-6 and their conjugates were used for photodynamic antimicrobial chemotherapy of Staphylococcus aureus. The antimicrobial studies were done in two different concentrations of 0.36 and 2.0 μg/mL. The thienyl substituted porphyrin complexes and their conjugates gave better photodynamic activity as compared to phenyl analogues
- Full Text:
- Date Issued: 2020
Effect of fluoroquinolones antibiotics on vancomycin and oxacillin resistant staphylococcus species in Eastern Cape Province
- Authors: Soyege, Oludotun
- Date: 2012
- Subjects: Staphylococcus aureus , Quinolone antibacterial agents , Fluoroquinolones
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/25349 , vital:64212
- Description: This study shows the susceptibility profile of some Staphylococcus species isolated from commensal Staphylococci in Nkonkobe municipality, South Africa. A total number of 120 Staphylococcal isolates were screened for their susceptibilities to various classes of antibiotics such as Aminoglycoside (Gentamycin), Aminoglycoside (Kanamycin), Macrolide (Erythromycin), Tetracycline (Minocycline), Anti-tuberculous (Rifampicin), Lincosamides (Clindamycin), Cephalosporin and Fluoroquinolones in general. During the study, 32 (26percent) the test organisms were susceptible to both methicillin and vancomycin, while 12 (10percent) had co-resistance to the antibiotics. Furthermore, Gentamycin (an Aminoglycoside) had a relatively high potency against the isolates with 107 (89.17percent) of the bacteria being susceptible to it, while 10 (8.33percent) were resistant. On the other hand, Erythromycin (a Macrolide) was active against 72 (60percent) of the isolates, while 5 (4.17percent) and 74 (61.67percent) of the isolates yielded intermediate and resistant responses respectively. In addition , 51 (42.5percent) of the isolates were susceptible to rifampicin, while 1 (0.83percent) and 17 (14.17percent) were intermediate and resistant respectively. Ten percent of the isolates screened for their antibiotic susceptibility pattern in this study were positive for mecA gene among the vancomycin-oxacillin resistant strains while van gene was not detected in any of the isolates. This shows how the synergy of both vancomycin and oxacillin contribute to some resistance nature of Staphylococci. In order to overcome this resistance attributes of Staphylococci, to the commonly used antibiotics as discussed under this context, various types of fluoroquinolones were tested. The result shows that less than 10percent of the isolates were generally resistant to the fluoroquinolones except against Nalidix acid to which all the isolates were resistant. Other antibiotics had relatively higher resistance patterns as observed for minocycline (39.51percent), clindamycin (12.75percent), gentamycin (12.31percent) and vancomycin (12.3percent). The new generation fluoroquinolones including Gatifloxacin, Levofloxacin, Moxifloxacin and Ciprofloxacin to which less than 5percent of the bacteria are resistant gives some clinical advantage over the Methicillin and Vancomycin resistant strains. About 31percent of the isolates had multiple antibiotic resistance index of ≥1 and suggests animals in the community as potential reservoirs of antibiotic resistance determinants in the environment. Data obtained in this study is of epidemiological importance and valuable for disease control. , Thesis (MSc) -- Faculty of Science and Agriculture, 2012
- Full Text:
- Date Issued: 2012
- Authors: Soyege, Oludotun
- Date: 2012
- Subjects: Staphylococcus aureus , Quinolone antibacterial agents , Fluoroquinolones
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/25349 , vital:64212
- Description: This study shows the susceptibility profile of some Staphylococcus species isolated from commensal Staphylococci in Nkonkobe municipality, South Africa. A total number of 120 Staphylococcal isolates were screened for their susceptibilities to various classes of antibiotics such as Aminoglycoside (Gentamycin), Aminoglycoside (Kanamycin), Macrolide (Erythromycin), Tetracycline (Minocycline), Anti-tuberculous (Rifampicin), Lincosamides (Clindamycin), Cephalosporin and Fluoroquinolones in general. During the study, 32 (26percent) the test organisms were susceptible to both methicillin and vancomycin, while 12 (10percent) had co-resistance to the antibiotics. Furthermore, Gentamycin (an Aminoglycoside) had a relatively high potency against the isolates with 107 (89.17percent) of the bacteria being susceptible to it, while 10 (8.33percent) were resistant. On the other hand, Erythromycin (a Macrolide) was active against 72 (60percent) of the isolates, while 5 (4.17percent) and 74 (61.67percent) of the isolates yielded intermediate and resistant responses respectively. In addition , 51 (42.5percent) of the isolates were susceptible to rifampicin, while 1 (0.83percent) and 17 (14.17percent) were intermediate and resistant respectively. Ten percent of the isolates screened for their antibiotic susceptibility pattern in this study were positive for mecA gene among the vancomycin-oxacillin resistant strains while van gene was not detected in any of the isolates. This shows how the synergy of both vancomycin and oxacillin contribute to some resistance nature of Staphylococci. In order to overcome this resistance attributes of Staphylococci, to the commonly used antibiotics as discussed under this context, various types of fluoroquinolones were tested. The result shows that less than 10percent of the isolates were generally resistant to the fluoroquinolones except against Nalidix acid to which all the isolates were resistant. Other antibiotics had relatively higher resistance patterns as observed for minocycline (39.51percent), clindamycin (12.75percent), gentamycin (12.31percent) and vancomycin (12.3percent). The new generation fluoroquinolones including Gatifloxacin, Levofloxacin, Moxifloxacin and Ciprofloxacin to which less than 5percent of the bacteria are resistant gives some clinical advantage over the Methicillin and Vancomycin resistant strains. About 31percent of the isolates had multiple antibiotic resistance index of ≥1 and suggests animals in the community as potential reservoirs of antibiotic resistance determinants in the environment. Data obtained in this study is of epidemiological importance and valuable for disease control. , Thesis (MSc) -- Faculty of Science and Agriculture, 2012
- Full Text:
- Date Issued: 2012
Azadipyrromethenes for applications in photodynamic antimicrobial chemotherapy, photodynamic therapy and optical limiting
- Authors: Dubazana, Nadine
- Date: 2020
- Subjects: Dyes and dyeing -- Chemistry , Photochemotherapy , Cancer -- Photochemotherapy , Anti-infective agents , Staphylococcus aureus , Nonlinear optics , Azadipyrromethenes , BODIPY
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/166150 , vital:41333
- Description: Azadipyrromethenes, azaBODIPYs and zinc azadipyrromethene complexes were prepared and characterised to examine the effect on their photophysical properties of incorporating phenyl groups at the 1,3,5,7-positions with electron-donating and withdrawing groups at the para-positions. To enhance their ability to generate singlet oxygen, appropriate structural modifications were made through the addition of a Zn(II) ion or halogenation at the 2,6 positions. In vitro photodynamic therapy (PDT) studies targeting MCF-7 human breast cancer cells were carried out. To evaluate and understand the effectiveness of the dyes as photosensitisers, cellular uptake, phototoxicity and the half-maximal inhibitory concentration (IC50) values were analysed. Photodynamic antimicrobial chemotherapy (PACT) studies were also carried out to study the effectiveness of the dyes against Staphylococcus aureus (S. aureus). Dyes with donor-π-acceptor (D-π-A) properties were synthesised and tested against the second harmonic of the Nd:YAG laser in optical limiting (OL) studies. The second-order hyperpolarisability, third-order susceptibility and nonlinear absorption coefficient values were determined. The results suggest that 1,3,5,7-azaBODIPY dyes may be less suitable for use in this context than analogous D-π-A 3,5-distyrylBODIPY dyes. Molecular modelling was carried out to identify the structure-property relationships of the synthesised dyes by analysing trends in the energies of the frontier molecular orbitals (MOs) and spectroscopic properties.
- Full Text:
- Date Issued: 2020
- Authors: Dubazana, Nadine
- Date: 2020
- Subjects: Dyes and dyeing -- Chemistry , Photochemotherapy , Cancer -- Photochemotherapy , Anti-infective agents , Staphylococcus aureus , Nonlinear optics , Azadipyrromethenes , BODIPY
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/166150 , vital:41333
- Description: Azadipyrromethenes, azaBODIPYs and zinc azadipyrromethene complexes were prepared and characterised to examine the effect on their photophysical properties of incorporating phenyl groups at the 1,3,5,7-positions with electron-donating and withdrawing groups at the para-positions. To enhance their ability to generate singlet oxygen, appropriate structural modifications were made through the addition of a Zn(II) ion or halogenation at the 2,6 positions. In vitro photodynamic therapy (PDT) studies targeting MCF-7 human breast cancer cells were carried out. To evaluate and understand the effectiveness of the dyes as photosensitisers, cellular uptake, phototoxicity and the half-maximal inhibitory concentration (IC50) values were analysed. Photodynamic antimicrobial chemotherapy (PACT) studies were also carried out to study the effectiveness of the dyes against Staphylococcus aureus (S. aureus). Dyes with donor-π-acceptor (D-π-A) properties were synthesised and tested against the second harmonic of the Nd:YAG laser in optical limiting (OL) studies. The second-order hyperpolarisability, third-order susceptibility and nonlinear absorption coefficient values were determined. The results suggest that 1,3,5,7-azaBODIPY dyes may be less suitable for use in this context than analogous D-π-A 3,5-distyrylBODIPY dyes. Molecular modelling was carried out to identify the structure-property relationships of the synthesised dyes by analysing trends in the energies of the frontier molecular orbitals (MOs) and spectroscopic properties.
- Full Text:
- Date Issued: 2020
- «
- ‹
- 1
- ›
- »