Asymmetrical zinc (II) phthalocyanines cobalt tungstate nanomaterial conjugates for photodegradation of methylene blue
- Authors: Mgidlana, Sithi , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184991 , vital:44314 , xlink:href="https://doi.org/10.1016/j.jphotochem.2021.113421"
- Description: Herein, we present syntheses of three asymmetrical zinc(II) phthalocyanine (ZnPc) complexes and hydrothermal synthesis of cobalt tungstate nanoparticles. The ZnPc derivatives were covalently linked to cobalt tungstate nanoparticles. Photophysical and photochemical behaviour of Pcs and nanoconjugates were investigated. The nanoconjugates generated higher triplet quantum yield and singlet oxygen quantum yield than the ZnPcs alone. Furthermore, in this paper photocatalytic efficiencies of ZnPc complexes and nanoconjugates were investigated for the degradation of methylene blue and higher photocatalytic behaviour was observed for the conjugates. The kinetic model was used to study photocatalytic behaviour of all the prepared photocatalysts.
- Full Text:
- Date Issued: 2021
Ball-type phthalocyanines and reduced graphene oxide nanoparticles as separate and combined corrosion inhibitors of aluminium in HCl
- Authors: Nnaji, Nnaemeka , Nawji, Njemuwa , Mack, John , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185421 , vital:44385 , xlink:href="https://doi.org/10.1016/j.molstruc.2021.130279"
- Description: Corrosion inhibition performances and adsorption behaviour at the aluminum-HCl solution interface were investigated for reduced graphene oxide nanosheets (rGONS), tetrakis-[4,4′-((4-(benzo[d]thiazol-2-yl)-1,2-bis(phenoxy)] (diphthalocyaninato gallium (III) chloride) (2) and tetrakis-4-(hexadecane-1,2-dioxyl)-bis(phthalocyaninato gallium(III) chloride) (1). Corrosion inhibition effects of rGONS, 1 and 2 were evaluated alone and in combination in 1.0 M hydrochloric acid solution using electrochemical techniques. The mechanism of aluminum corrosion inhibition revealed predominantly anodic character for rGONS and predominantly cathodic character for 1, 2, and conjugates with rGONS . The polarization technique gave inhibition efficiency values of 96.5% and 96.9% respectively for 1 and 2, which increased in the presence of rGONS to 97.4% and 98.1%, respectively, for the highest concentrations of 1 and 2. Scanning electron microscopy revealed effective metal surface protection by the inhibitors by formation of protective films.
- Full Text:
- Date Issued: 2021
Borneol-triarylcorrole hybrids with chiral-optical response and anticancer behaviours
- Authors: Fu, Bo , Wang, Lin , Yu, Xiaoxiao , Fang, Xianying , Mack, John , Dingiswayo, Somila , Nyokong, Tebello , Liang, Xu , Xu, Haijun
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185294 , vital:44362 , xlink:href="https://doi.org/10.1016/j.dyepig.2021.109699"
- Description: A series of four multifunctional A2B type H3corroles with meso-borneol substituents at the B position have been synthesized and characterized. A detailed analysis of the optical properties was carried out, and a comparison was made with theoretical calculations to identify the key trends in the structure-property relationships. The meso-borneol substituent couples with the corrole core leading to clear CD signals in the B band region. Enhanced anti-cancer properties are observed in vitro relative to (−)-borneol with cell inhibition rates of up to 94%.
- Full Text:
- Date Issued: 2021
Effect of ultrasonic frequency and power on the sonodynamic therapy activity of cationic Zn (II) phthalocyanines
- Authors: Nene, Lindokuhle C , Sindelo, Azole , Britton, Jonathan , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185737 , vital:44419 , xlink:href="https://doi.org/10.1016/j.jinorgbio.2021.111397"
- Description: We report on the sonodynamic activity of cationic phthalocyanines (Pcs) and the effect of the variation of two parameters: ultrasound frequency and power (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)) on the efficiency of their reactive oxygen species generation and cancer eradication in vitro thereof. Where Par stands for the various combinations of these parameters. Four Pcs were investigated with substituents bearing diethylamine, ortho- and para-pyridine and morpholine groups. Overall, the para-pyridine and morpholine Pcs showed substantial sono-activity in the various ultrasound parameters with Par I and IV generally showing better singlet oxygen and hydroxyl radicals generation confirmed by electron paramagnetic resonance spectroscopy. In some cases, very high hydroxyl radicals' generation was observed at Par II. Furthermore, the fragmentation of the Pcs after Par II treatments was confirmed using UV–vis and magnetic circular dichroism spectroscopy. The reactive species generation efficacy decreased at Par III for all samples. Ultrasound assisted cytotoxicity of the Pcs was confirmed in vitro using the human (Michigan Cancer Foundation-7) breast cancer cell line.
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- Date Issued: 2021
Electrocatalytic activity of manganese tetra 4-aminophenyl porphyrin in the presence of graphene quantum dots
- Authors: Jokzai, Mbulelo , Mpeta, Lekhetho S , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/231443 , vital:49888 , xlink:href="https://doi.org/10.1016/j.molstruc.2015.02.040"
- Description: A manganese tetra 4-aminophenyl porphyrin (MnTAPP) was synthesized and attached to graphene quantum dots (GQDs) via covalent and π-π interaction to give MnTAPP@GQDs and MnTAPP--GQDs, respectively. There was an increase (using dynamic light scattering and transmission electron microscopy) in size of the GQDs in the presence of the porphyrin due to aggregation. The porphyrins in the absence and presence of GQDs were then adsorbed onto a glassy carbon electrode using drop and dry method. The electrochemical behavior was tested by cyclic voltammetry and chronoamperometry towards hydrazine. Both methods of combining MnTAPP with GQDs improved the activity of the electrocatalysis compared to individual components. MnTAPP@GQDs showed better catalytic rate constant of 4.36 × 102 Ms−1 and lowest LoD of 0.0023 mM followed by MnTAPP--GQDs. Furthermore, the sensor showed good selectivity in the presence of interfering analytes. All probes showed good stability.
- Full Text:
- Date Issued: 2021
Electrocatalytic activity of Schiff base containing copper phthalocyanines towards the detection of catechol
- Authors: Ndebele, Nobuhle , Sen, Pinar , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/231410 , vital:49885 , xlink:href="https://doi.org/10.1016/j.poly.2021.115518"
- Description: In this study, four new copper phthalocyanine complexes were synthesised and studied as electrocatalysts for the detection of catechol. Two of these complexes were derived from a symmetrical benzaldehyde phthalocyanine complex via the condensation of the benzaldehyde substituents with amine reagents. The electrocatalysts proved to be highly stable towards the detection of catechol. The oxidation peaks obtained using cyclic voltammetry range from 0.20 to 0.38 V. Detection limits were obtained via chronoamperometry and are as low as 0.16 µM with fairly high sensitives being obtained. Overall all four copper complexes exhibited excellent electrocatalytic activity towards the electrooxidation of catechol.
- Full Text:
- Date Issued: 2021
Electrochemical detection of dopamine using phthalocyanine-nitrogen-doped graphene quantum dot conjugates
- Authors: Ndebele Nobuhle , Sen, Pinar , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185724 , vital:44418 , xlink:href="https://doi.org/10.1016/j.jelechem.2021.115111"
- Description: Two cobalt phthalocyanine molecules were synthesized, a symmetrically substituted CoPc (1) and an unsymmetrically substituted CoPc (2). These CoPcs were π-π stacked onto nitrogen-doped graphene quantum dots (NGQDs). The CoPcs, NGQDs and their respective conjugates were used as electro-catalytic probes in the electrochemical oxidation of dopamine. The molecules were adsorbed onto a glassy carbon electrode (GCE) using the drop dry method, the GCE was used to support those catalysts. The electrooxidation of dopamine was studied using cyclic voltammetry and chronoamperometry. An improvement in the sensitivity and limit of detection was observed upon conjugation.
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- Date Issued: 2021
Electrografting of isophthalic acid monolayer and covalent attachment of antibody onto carbon surfaces
- Authors: Mwanza, Daniel , Phal, Sereilakhena , Nyokong, Tebello , Tesfalidet, Solomon , Mashazi, Philani N
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/231345 , vital:49879 , xlink:href="https://doi.org/10.1016/j.electacta.2021.139360"
- Description: In this study, a 5-diazonium isophthalic acid was synthesized and electrografted onto glassy carbon (GCE) and screen-printed carbon (SPCE) electrodes. SPCE was used to demonstrate fabrication of a miniature device and to compare with conventional glassy carbon electrodes. The isophthalic acid (IPA) electrografted thin film was used for the immobilization of anti-methotrexate antibody (Ab) using carbodiimide activation chemistry to form antibody modified surfaces, GCE-IPA-Ab and SPCE-IPA-Ab. The GCE -IPA-Ab and SPCE-IPA-Ab surfaces were used as capacitive biosensors for the detection of methotrexate (MTX) in phosphate buffer (pH 7.4) using capacitive electrochemical impedance spectroscopy (EIS). The EIS data was analyzed using singular value decomposition (SVD). Principal component regression analysis gave R2 values of 0.99 for both the GCE-IPA-Ab and SPCE-IPA-Ab surfaces. The detection limit from the calibration curve of the GCE-IPA-Ab and SPCE-IPA-Ab was calculated to be 7.0 pmol.L−1 and 5.5 pmol.L−1, respectively.
- Full Text:
- Date Issued: 2021
Enhanced photo-ablation effect of positively charged phthalocyanines-detonation nanodiamonds nanoplatforms for the suppression of Staphylococcus aureus and Escherichia coli planktonic cells and biofilms
- Authors: Openda, Yolande I , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185712 , vital:44417 , xlink:href="https://doi.org/10.1016/j.jphotochem.2021.113200"
- Description: Photodynamic antimicrobial therapy (PACT) is a powerful technic recommended to eliminate life-threatening pathogens that cause localized and superficial infections as pathogens cannot develop resistance to it. For this reason, new positively charged chalcone substituted zinc (3a) and indium (4a) metalated phthalocyanines (Pcs) were synthesized and were π-π interacted with detonation nanodiamonds (DNDs) nanoparticles to form new water soluble nanoplatfoms 3a@DNDs and 4a@DNDs. The conjugates generated high singlet oxygen quantum yields (ΦΔ) in water (1% DMSO, used for PACT studies) with values of 0.46 and 0.47 for 3a@DNDs and 4a@DNDs, respectively. Hence, they were tested for PACT against biofilms of S. aureus and E. coli, as well as their planktonic cells. The quaternized Pcs alone 3a and 4a as well as their nanoconjugates 3a@DNDs and 4a@DNDs were effective PACT agents with log10 CFU > 9 for E. coli and S. aureus. The quaternized derivatives were found to have higher ability to completely suppress both planktonic and biofilms of S. aureus and E. coli in vitro. Therefore, they could be used as appropriate photosensitive agents.
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- Date Issued: 2021
Enhanced upconversion emission of Er3+-Yb3+ co-doped Ba5 (PO4) 3OH powder phosphor for application in photodynamic therapy
- Authors: Mokoena, Puseletso P , Poluwole, David O , Nyokong, Tebello , Swart, Hendrik C , Ntwaeaborwa, Odireleng M
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185035 , vital:44318 , xlink:href="https://doi.org/10.1016/j.sna.2021.113014"
- Description: Er3+-Yb3+ co-doped Ba5(PO4)3OH nanoparticle powder phosphors were successfully synthesized by urea combustion method. The resulting powder phosphors were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), high resolution scanning electron microscopy (HRSEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS) and photoluminescence spectroscopy (PL). XRD data confirmed crystallization of pure hexagonal phase of Ba5(PO4)3OH and HRSEM images showed formation of ellipsoidal particles. XPS data combined with EDS analysis confirmed the materials composition that corresponds with identification of all the chemical elements constituting the materials. The in vitro dark cytotoxicity of the particles confirmed lack of cytocidal behaviour in the absence of light, but considerable photodynamic therapy (PDT) activity was observed upon illumination. Upon excitation using a 980 nm laser, multiple emission peaks in the green and red regions corresponding to the optical transitions of Er3+ ion were observed. Upon co-doping with Yb3+, upconverted red emission was detected and this was attributable to non-radiative energy transfer from Yb3+ to Er3+. The proposed mechanism of upconversion photoluminescence is discussed.
- Full Text:
- Date Issued: 2021
Folic acid-modified phthalocyanine-nanozyme loaded liposomes for targeted photodynamic therapy
- Authors: Nwahara, Nnamdi , Abrahams, Garth , Prinsloo, Earl , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/231369 , vital:49881 , xlink:href="https://doi.org/10.1016/j.pdpdt.2021.102527"
- Description: The hypoxic tumour microenvironment and poor spatiotemporal localization of photosensitizers are two significant obstacles that limit practical applications of photodynamic therapy. In response, a biocompatible, light-activatable liposome integrated with both a zinc phthalocyanine photodynamic component and Pt nanoparticles-decorated with MnO2 catalase-mimicking component are engineered. This multifunctional system was rationally designed using unsaturated phospholipids to achieve on-demand drug release following light irradiation. Specificity was achieved by folic acid functionalization resulting in folate-modified liposomes (FTLiposomes). We demonstrated its specific uptake by fluorescence imaging using folate receptor (FR) overexpressing HeLa and MCF-7 cells as in vitro models. This multifunctional liposome exhibits superior hypoxic anti-tumour effects and holds the potential to reduce side effects associated with untargeted therapy. Fluorescence of the constituent ZnPc and folate-receptor targeting could enable tracking and permit spatiotemporal regulation for improved cancer treatment.
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- Date Issued: 2021
Impact of axial ligation on photophysical and photodynamic antimicrobial properties of indium (III) methylsulfanylphenyl porphyrin complexes linked to silver-capped copper ferrite magnetic nanoparticles
- Authors: Makola, Collen L , Nyokong, Tebello , Amuhaya, Edith K
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185942 , vital:44450 , xlink:href="https://doi.org/10.1016/j.poly.2020.114882"
- Description: Photodynamic antimicrobial chemotherapy (PACT) is a well-known technique used against bacteria that have developed resistance towards antibiotics. We herein report the synthesis, photophysical properties, and PACT activity of 2-hydroxypyridine axial ligated indium 5,10,15,20-tetrakis-(4-phenylmethylthio) porphyrin (3) and quaternized 2-hydroxypyridine axial ligated indium 5,10,15,20-tetrakis-(4-phenylmethylthio) porphyrin (4). The porphyrin complexes (3 and 4) were further linked to oleyamine (OLM)/oleic acid (OLA) capped Ag/CuFe2O4 and also 6-mercapto-1-hexanol functionalized (MCH-Ag/CuFe2O4) nanoparticles through silver - sulphur (Ag-S) and silver-nitrogen (Ag-N); self-assembly. The PACT studies were carried out using Staphylococcus aureus. While all the synthesized porphyrins demonstrated PACT activity, the quaternized complex and its conjugate showed the highest PACT activity with 0% cell viability after irradiation for 25 min, resulting in a log reduction of 8.31.
- Full Text:
- Date Issued: 2021
Nanohybrid electrocatalyst based on cobalt phthalocyanine-carbon nanotube-reduced graphene oxide for ultrasensitive detection of glucose in human saliva
- Authors: Adeniyi, Omotayo , Nwahara, Nnamdi , Mwanza, Daniel , Nyokong, Tebello , Mashazi, Philani N
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/231356 , vital:49880 , xlink:href="https://doi.org/10.1016/j.snb.2021.130723"
- Description: The current diabetes management systems require collecting blood samples via an invasive and painful finger pricking leading to the formation of callus, scarring and loss of sensibility to patients due to continuous monitoring. Therefore, a non-invasive and painless method of determining glucose levels would be desirable to diabetes patients who need constant monitoring. Saliva glucose measurement is a non-invasive alternative for diabetes management. A highly sensitive, stable, and selective non-enzymatic electrochemical sensor that can accurately quantify saliva glucose is required. A single-walled carbon nanotube/reduced graphene oxide/cobalt phthalocyanines nanohybrid modified glassy carbon electrode (GCE-SWCNT/rGO/CoPc) has been fabricated for the non-enzymatic determination of glucose in human saliva. The SWCNT/rGO/CoPc was characterized using various spectroscopic, microscopic, and electrochemical techniques. The synergistic effect between SWCNT, rGO, and CoPc facilitated excellent electron transfer process that improved the sensor sensitivity. The GCE-SWCNT/rGO/CoPc sensor exhibited two linear responses in the 0.30 μM to 0.50 mM and 0.50–5.0 mM glucose concentration ranges, and the detection limit was 0.12 μM. The sensor had an excellent saliva glucose detection sensitivity of 992.4 μA·mM−1·cm−2 and high specificity for glucose in the presence of other coexisting analytes. In addition, it showed good storage stability, reusability, and a fast response time of about 1.2 s. The GCE-SWCNT/rGO/CoPc nanohybrid electrode showed excellent potential for developing accurate, non-invasive, and painless glucose sensing.
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- Date Issued: 2021
Photo-sonodynamic combination activity of cationic morpholino-phthalocyanines conjugated to nitrogen and nitrogen-sulfur doped graphene quantum dots against MCF-7 breast cancer cell line in vitro
- Authors: Nene, Lindokhule Cindy , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/231334 , vital:49878 , xlink:href="https://doi.org/10.1016/j.pdpdt.2021.102573"
- Description: In this work, we explore the reactive oxygen species (ROS) generation abilities of cationic morpholino-substituted-phthalocyanine (Pc) conjugated to nitrogen (NGQDs) and nitrogen-sulfur (NSGQDs) doped-graphene quantum dots upon irradiation with light for photodynamic therapy (PDT), ultrasound for sonodynamic therapy (SDT) and the combination of both in photo-sonodynamic therapy (PSDT). The in vitro cytotoxicity studies were conducted using the Michigan Cancer Foundation-7 breast cancer cell lines (MCF-7 cells). For PDT treatments, only the 1O2 was detected for all the sensitizers, whereas both the 1O2 and •OH radicals were evident after SDT and PSDT treatments. An increase in the 1O2 generation was observed for the conjugates compared to the GQDs and the Pc alone. However, the •OH radicals were reduced in the conjugates compared to the GQDs and the Pc alone. The NGQDs generally showed better ROS generation efficacy compared to the NSGQDs, alone and in the conjugates. The combination therapy also shows improved efficacy compared to the monotherapies for the Pcs and Pc-GQDs conjugates.
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- Date Issued: 2021
Photocatalytic and solar radiation harvesting potential of a free-base porphyrin-zinc (II) phthalocyanine heterodyad functionalized polystyrene polymer membrane for the degradation of 4-chlorophenol
- Authors: Mafukidze, Donovan M , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185772 , vital:44422 , xlink:href="https://doi.org/10.1016/j.jphotochem.2021.113142"
- Description: In this work a novel porphyrin-phthalocyanine heterodyad (complex 4) was synthesized and embedded in polystyrene polymer membranes. The singlet oxygen generation of 4 improved in comparison to the parent porphyrin and phthalocyanine complexes giving singlet oxygen quantum yields of 0.67 and 0.51 (in dimethyl sulfoxide) where the porphyrin and phthalocyanine complementarily absorb respectively. Successful Buchwald-Hartwig coupling of complex 4 to amine functionalized polystyrene ((NH2)PS) gave a complex loading of 24.6 mg complex/g 4-PS. Embedding of 4-PS in polystyrene polymer membrane yielded the photoactive 4-memb which proved to be capable of degrading 4-chlorophenol at reaction rates of at least 1.12 × 10−7 molL-1 min-1 and half-life of 193 min in a pseudo first order reaction at an initial concentration of 3.10 × 10-5. Also, light harvesting experiments proved 4-memb to be active in the whole 300–700 nm wavelength range with the greatest activity being under white light.
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- Date Issued: 2021
Photocatalytic desulfurization of dibenzothiophene using asymmetrical zinc (II) phthalocyanines conjugated to silver-magnetic nanoparticles
- Authors: Mgidlana, Sithi , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185953 , vital:44451 , xlink:href="https://doi.org/10.1016/j.ica.2020.119970"
- Description: Asymmetrical Zn(II) phthalocyanines: mono (4-carboxy phenoxy) tris (phenylazo phenoxy) (1), mono (4-amino phenoxy) tris (phenylazo phenoxy) (2), mono (4-propanoic acid phenoxy) tris (phenylazo phenoxy) (3) zinc(II) phthalocyanines are synthesized and covalently linked to mercaptohexanol (mph) or mercaptopropionic acid (mpa) functionalized dimerized silver-magnetic nanoparticles (Ag-M). Complexes 1 and 3 are covalently linked to nanomaterials via ester bond whereas complex 2 is covalently linked to nanoparticles (NPs) via amide bond. The conjugates of complexes 1–3 with NPs gave higher singlet oxygen quantum than the Pcs alone. Electrospun fibers were fabricated from polystyrene (PS) solutions containing complexes 1 to 3 and their conjugates. The functionalized PS fibers were used for the phototransformation of dibenzothiophene. The increase in photocatalytic properties of phthalocyanines was observed in the presence of Ag-M with 3 alone and its conjugate with mph capped silver-magnetic nanoparticles showing the larger catalytic activity towards the transformation of dibenzothiophene.
- Full Text:
- Date Issued: 2021
Photocatalytic desulfurization of dibenzothiophene using methoxy substituted asymmetrical zinc (II) phthalocyanines conjugated to metal tungstate nanomaterials
- Authors: Mgidlana, Sithi , Nwahara, Nnamdi , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185760 , vital:44421 , xlink:href="https://doi.org/10.1016/j.poly.2021.115053"
- Description: We report on the syntheses of three asymmetrical zinc(II) phthalocyanine endowed with benzoic acid, phenylpropanoic acid, and phenylacetic acid units: (1), (2), and (3), respectively. Metal tungstate nanoparticles, capped with glutathione were prepared and characterized using analytical techniques. Complexes were covalently linked to nickel tungstate (NiWO4) and bismuth tungstate (Bi2WO6) through an amide bond. The complexes and the conjugates with nanomaterial were evaluated for singlet oxygen generating ability. Complexes 1–2 and their conjugates generate higher singlet oxygen compared to 3 and its corresponding conjugates. The conjugates show degradation of dibenzothiophene (DBT) in fuel with shorter half-lives and greater initial rate values compared to phthalocyanines alone.
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- Date Issued: 2021
Photocytotoxicity of heavy-atom-free thiobarbituric acid functionalized pyrene derivatives against MCF-7 cancer cells
- Authors: Babu, Balaji , Ali, Thaslima A , Ochappan, Thivagar , Mack, John , Nyokong, Tebello , Sethuraman, Mathur G
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/190556 , vital:45005 , xlink:href="https://doi.org/10.1016/j.pdpdt.2020.102102"
- Description: Two thiobarbituric acid-functionalized pyrene derivatives (P1, P2) have been synthesized to explore the photophysical properties and photodynamic activity of dyes of this type. Both compounds exhibit an intense intramolecular charge transfer (ICT) band at ca. 470 nm, which is absent in the spectra of the precursor. P1 and P2 exhibit singlet oxygen generation on irradiation with light with moderate singlet oxygen yields of 0.36 and 0.32, respectively, in DMSO. P1 showed better photodynamic activity against MCF-7 cells with an IC50 value of 18.3 μM under illumination at 455 nm for 60 min with a Thorlabs M455L3 LED (330 mW.cm−2).
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- Date Issued: 2021
Photodynamic inactivation of Staphylococcus Aureus with Schiff base substituted Zinc phthalocyanines through conjugation to silver nanoparticles
- Authors: Sen, Pinar , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185688 , vital:44415 , xlink:href="https://doi.org/10.1016/j.molstruc.2021.130012"
- Description: We present the preparation of Schiff base substituted neutral phthalocyanines derived from aldehyde-substituted phthalocyanine which are conjugated to silver nanoparticles through covalent-like strong interactions. The photophysicochemical properties of the nanoconjugates and the Pcs alone were studied comparatively. The photodynamic antimicrobial chemotherapy (PACT) activities. of prepared photosensitizers was investigated against Gram-positive bacterium (Staphylococcus aureus). Unlike Pcs alone, conjugated phthalocyanines to silver nanoparticles showed excellent photodynamic antimicrobial activity with the 100% reduction percentage upon illumination.
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- Date Issued: 2021
Photophysicochemical behaviour of phenoxy propanoic acid functionalised zinc phthalocyanines when grafted onto iron oxide and silica nanoparticles: Effects in photodynamic antimicrobial chemotherapy
- Authors: Dube, Edith , Soy, Rodath , Shumba, Mumyaradzi , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185465 , vital:44389 , xlink:href="https://doi.org/10.1016/j.jlumin.2021.117939"
- Description: This work reports on the covalent linkage of (3-aminopropyl)triethoxysilane (APTES) functionalised iron oxide (IONPs–APTES) and silica (SiNPs–APTES) nanoparticles with zinc(II) tetra–([3–(4–phenoxy) propanoic acid) phthalocyanine] (1) and zinc(II) mono–([3–(4–phenoxy) propanoic acid) phthalocyanine (2) via an amide bond to form the conjugates, 1–IONPs-APTES, 1–SiNPs–APTES, 2-IONPs-APTES and 2-SiNPs-APTES). The photophysicochemical behaviour of the conjugates was investigated. These were characterized by a decrease in the fluorescence quantum yields and lifetimes, and an increase in the triplet quantum yield and singlet oxygen quantum yield when compared to complex 1 and 2 alone. The conjugates to IONPs-APTES displayed higher ΦT than those of SiNPs-APTES probably due to the heavy atom effect of iron compared to silica and the high loading capacity of the relatively smaller iron oxide NPs, however, there was no significant difference in the ΦΔ values of 2-IONPs-APTES (ΦΔ=0.59) and 2-SiNPs-APTES (ΦΔ=0.58), suggesting that the energy transfer process between the excited triplet state of 2-IONPs-APTES and ground state molecular oxygen was not effective. Photodynamic antimicrobial chemotherapy (PACT) studies showed that linkage of Pcs to NPs improves their photoinactivation capability against Staphylococcus aureus and Escherichia coli. IONPs-APTES and its conjugates generally displayed the highest log reductions than SiNPs-APTES and its conjugates except for studies after 75 min of irradiation for S. Aureus where the log reductions are the same. 2-IONP-APTES was recovered using a magnet after each photodegradation cycle and its stability after 3 cycles confirmed re-usability.
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- Date Issued: 2021