Sandile P. Songca

Applications of functionalized nanomaterials in photodynamic therapy

Specially designed functionalized nanomaterials such as superparamagnetic iron oxide, gold, quantum dots and up- and down-conversion lanthanide series nanoparticles have consistently and completely revolutionized the biomedical environment over the past few years due to their specially inferring properties, such as specific drug delivery, plasmonic effect, optical and imaging properties, therapeutic thermal energy productionand excellent irresistible cellular penetration. These properties have been used to improve many existing disease treatment modalities and have led to the development of better therapeutic approaches for the advancement of the treatment of critical human diseases, such as cancers and related malaise. In photodynamic therapy, for example, where the delivery of therapeutic agents should ideally avoid toxicity on nearby healthy cells, superparamagnetic iron oxide nanoparticles have been shown to be capable of making photodynamic therapy (PDT) prodrugs and their associative targeting moieties tumor-specific via their unique response to an external magnetic fields. In this review, the nanomaterials commonly employed for the enhancement of photodynamic therapy are discussed. The review further describes the various methods of synthesis and characterization of these nanomaterials and highlights challenges for improving the efficacy of PDT in the future.

Biosynthesis of silver nanoparticles from Acacia mearnsii De Wild stem bark and its antinociceptive properties

ABSTRACT The biosynthesis of silver nanoparticles (Ag-NPs) using the hydrosol extract of the dry stem bark of Acacia mearnsii as reducing and capping agents, and their antinociceptive properties are hereby reported. By varying the temperature and reaction time, the temporal evolution of the optical and morphological properties of the as-synthesized material was investigated. The NPs were characterized by UV–visible absorption spectroscopy, transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDS) and x-ray diffractometry (XRD) The optical analyses show that the position of the maximum surface plasmon resonance (SPR) peak is red-shifted as the reaction temperature decreased. The TEM micrographs show that the as-synthesized Ag-NPs are spherical while the X-ray diffraction shows that the material is highly crystalline with face-centered cubic structures. The anti-inflammatory efficacy, analyzed by the formalin model, indicates that the as-synthesized Ag-NPs are very effective, with an inhibition rate of about 76%. GRAPHICAL ABSTRACT

Photodynamic therapy evaluation of methoxypolyethyleneglycol-thiol-SPIONs-gold-meso-tetrakis(4-hydroxyphenyl)porphyrin conjugate against breast cancer cells

Magnetic field enhanced photodynamic therapy is an effective non-invasive technique for the eradication of cancer diseases. In this report, magnetic field enhancement of the photodynamic therapy (PDT) efficacy of a novel methoxypolyethyleneglycol-thiol-SPIONs-gold-meso-tetrakis(4-hydroxyphenyl)porphyrin conjugate (nano-drug) against MCF-7 breast cancer cells was evaluated. The nano-drug exhibited excellent blue and red emissions under suitable ultraviolet (380 nm) and visible (430 nm) excitations and was well taken up by the cells without any significant dark cytotoxicity after 24 h post-incubation. However, after exposure of cells to light for about 15 min, high rate of cell death was observed in a dose-dependent manner. In addition, the cells that were exposed to external magnetic field displayed higher phototoxicity than the non-exposed cells. Altogether, these results suggest that the nano-porphyrin drug system can function as a new promising magnetic-field targeting agent for theranostic photodynamic eradication of cancer diseases.

Facile Green Synthesis and Characterization of Water Soluble Superparamagnetic Iron Oxide-Gold Porphyrin Conjugate for Improved Photodynamic Therapy

Porphyrin has been proven to be an efficient photosensitizer for photodynamic therapy (PDT). However, the problem of undesired localization in non-tumour environments has lowered its therapeutic efficacy. To make porphyrin tumour specific, we have successfully conjugated a meso-substituted symmetric 4-hydroxyphenyl porphyrin (THPP) to superparamagnetic iron oxide nanoparticles-gold core-shell nanostructure (SPIONs-Au). The magnetic porphyrin conjugate (MPC) was characterized using UV-Visible spectrophotometry (UV-Vis), Photoluminescence spectroscopy (PL) and Fourier Transform infrared spectroscopy (FT-IR). The as-synthesized MPC exhibited strong attraction towards external magnetic field and high singlet oxygen quantum yield sufficient for the eradication of cancer cells in vitro.