Determination Of Singlet Oxygen Research Articles

In-vitro investigation of green synthesized gold nanoparticle’s role in combined photodynamic and radiation therapy of cancerous cells

Gold nanoparticles (AuNPs) have been introduced for increasing the effectiveness of various cancer treatments such as radiation and photodynamic therapy. Instead of toxic chemicals, various natural compounds have been introduced for AuNPs synthesis. Here, gallic acid-coated AuNPs (Ga@AuNPs) with the average diameter of 17.9 ± 10 nm and surface charge of −16.2 ± 3.2 mV have been synthesised through easy and single-step chemical route and were characterised with transmission electron microscopy (TEM), dynamic light scattering (DLS) and UV–Vis spectroscopy. The interaction of Ga@AuNPs and methylene blue (MB) photosensitisers was confirmed through various techniques such as FTIR spectroscopy, zeta potential investigation, and UV–vis spectroscopy. Based on our results, methylene blue was adsorbed to the surface of Ga@AuNPs through various amine and thiol functional groups. Upon laser radiation, a release of singlet oxygen species (ROS) from nanoformulation of methylene blue was more gradual than free methylene blue based on the determination of singlet oxygen in the present of 1,3-diphenylisobenzofuran (DPBF) radical scavenger. The Ga@AuNPs nanoparticles were not representing significant toxic effects toward cells. However, the synthesised nanoparticles could increase the effectiveness of radiation therapy or combined treatment of methylene blue mediated photodynamic and radiation therapy in an in-vitro investigation.

In Vitro Cytotoxicity and Morphological Assessments of GO-ZnO against the MCF-7 Cells: Determination of Singlet Oxygen by Chemical Trapping.

Graphene-based materials have attracted considerable interest owing to their distinctive characteristics, such as their biocompatibility in terms of both their physical and intrinsic chemical properties. The use of nanomaterials with graphene as a biocompatible agent has increased due to an uptick in dedication from biomedical investigators. Here, GO-ZnO was characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), ultraviolet-visible (UV-Vis) spectroscopy, energy dispersive X-ray analysis (EDAX), and Raman spectroscopy for structural, morphological, and elemental analysis. The toxic extent of GO-ZnO was noted by a methyl-thiazole-tetrazolium (MTT), while cellular morphology was observed towards the MCF-7 cells using an inverted microscope at magnification 40×. The cytotoxic effect of GO-ZnO investigated the cell viability reduction in a dose-dependent manner, as well as prompted the cell demise/destruction in an apoptotic way. Moreover, statistical analysis was performed on the experimental outcomes, with p-values < 0.05 kept as significant to elucidate the results. The generation of reactive oxygen species (ROS) demonstrated the potential applicability of graphene in tumor treatment. These key results attest to the efficacy of GO-ZnO nanocomposites as a substantial candidate for breast malignancy treatment.

Determination of Singlet Oxygen and Electron Transfer Mediated Mechanisms of Photosensitized Protein Damage by Phosphorus(V)porphyrins.

The mechanism of photosensitized protein damage byphosphorus(V) tetraphenylporphyrin derivatives (P(V)TPPs) wasquantitatively clarified. P(V)TPPs bound to human serum albumin(HSA), a water-soluble protein, and damaged its tryptophan residueduring photoirradiation. P(V)TPPs photosensitized singlet oxygen ((1)O(2))generation, and the contribution of (1)O(2) to HSA damage was confirmedby the inhibitory effect of sodium azide, a (1)O(2) quencher. However,sodium azide could not completely inhibit HSA damage, suggesting thecontribution of an electron transfer mechanism to HSA damage. Thedecrement in the fluorescence lifetime of P(V)TPPs by HSA supportedthe electron transfer mechanism. The contribution of these processes could be determined by the kinetic analysis of the effect ofsodium azide on the photosensitized protein damage by P(V)TPPs.

Determination of singlet oxygen quenching and antioxidant activity of Bieckols isolated from the brown alga Eisenia bicyclis

In this study, we determined 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radical scavenging activities as well as the reducing power for screening of antioxidant activity of bieckols in Eisenia bicyclis (Kjellamn) Setchell (E. bicyclis). The compounds 6,6′-bieckol, 6,8′-bieckol and 8,8′-bieckol are representative members of the phlorotannins family. The isolated bieckols displayed markedly strong DPPH and ABTS radical scavenging effects when compared to those of positive controls (BHA and Trolox). These bieckols were also found to have significant reducing power. The isolated bieckols (6,6′-bieckol, 6,8′-bieckol and 8,8′-bieckol) were found to effectively suppress the detrimental effects of 1O2 on type-II photosensitization. The concentrations required to exert a 50 % quenching effect on 1O2 (QC50) were found to be 30.7, 35.7 and 49.4 μM for 6,6′-bieckol, 6,8′-bieckol and 8,8′-bieckol, respectively. Interestingly, all these bieckols were found to be superior to histidine (5.9 mM), a well-known 1O2 quencher. These results suggested that brown algae phlorotannins, and bieckols in particular, may play an important role in protecting marine organisms against sunlight damage by eliminating 1O2. This knowledge may contribute to the development of natural bioactive products with potential applications in reducing photo-produced oxidative damage involving reactive oxygen species in living organisms.

Quantitative Determination of Singlet Oxygen By Laser Deflection Calorimetry

ABSTRACT A sensitive method for the quantitative determination of singlet oxygen based on a low-cost laser deflection calorimeter (LDC) apparatus is presented. The heat released from the singlet oxygen generation and its nonradiative decay in an aqueous phase causes the formation of a thermally driven refractive index gradient in an adjacent organic phase. This effect, which is proportional to the amount of singlet oxygen generated, is monitored by the deflection of a laser beam. Limits of detection (LOD) obtained were in the sub-μmol level which is one order of magnitude lower than the LOD obtained by measuring the “dimol” emission at 633 run. This method should be specially designed for studying chemical and biochemical processes at interfaces by measuring low amounts of heat released.