Photo-induced inactivation of viruses: adsorption of methylene blue, thionine, and thiopyronine on Qbeta bacteriophage.

Abstract

The adsorption of cationic organic dyes (methylene blue, thionine, and thiopyronine) on Qf3 bacteriophage was studied by UV-visible and fluorescence spectroscopy. The dyes have shown a strong affinity to the virus and some have been used as sensitizers for photo-induced inactivation of virus. In the methylene blue concentration range of 0.1-5 ,uM and at high ratios of dye to virus (greater than 1000 dye molecules per virion), the dyes bind as aggregates on the virus. Aggregation lowers the efficiency of photoinactivation because of self-quenching of the dye. At lower ratios of dye to virus (lower than 500 dye molecules per virion), the dye binds to the virus as a monomer. Fluorescence polarization and time-resolved studies of the fluorescence support the conclusions based on fluorescence quenching. Increasing the ionic strength (adding NaCl) dissociates bound dye aggregates on the virus and releases monomeric dye into the bulk solution.Two broad techniques have been used for eliminating viral contamination in blood products: removal and inactivation. The former has been partially achieved by washing, filtration, or adsorption (1). The latter has utilized heat, intrinsically active chemical agents, photo-and y-irradiation without chemical addition, and photo-irradiation in the presence of sensitizing agents that are usually inactive until irradiated (2-6). For inactivation to preserve sensitive bystander molecules or cells, a very high degree of specificity for the virus must be obtained. In general, photo-irradiation in the presence of sensitizing agents is the only method that has yet approached the requisite specificity, in part because the sensitizer can be concentrated on the virus before it is activated. The sensitizing agent must have a high binding constant and bind specifically to a viral component: its lipid envelope (when present), its protein coat, or its genome. It must also have a path by which it can reach this component, as well as time to do so. Any coreactant (e.g., oxygen) must also have a path by which it can reach the reaction site. Inactivation may occur either because photoinduced damage renders the virus unable to enter a prospective host cell or because the virus is unable to replicate after entry because its genome has been rendered defective.We have selected methylene blue (MB) and its derivatives thionine (Th) and thiopyronine (TP) as prototype sensitizing agents ( Fig. 1) for virus inactivation. These dyes have high in vitro binding affinity to nucleic acids, a feature that appears to confer their microbiocidal and virucidal activity (7,8). MB is known as an antivirucidal compound, and it is at least competitive with other agents in minimizing undesirable effects. Its chemical and biological properties have been thoroughly studied (7), the optical absorption is optimum for the blood banking application, and it is currently being used clinically for photoinactivation of fresh frozen plasma in Europe (9). Inferring from the high binding affinity of MB, Th, and TP to nucleic acid...

Biophysical studies on the base specificity and energetics of the DNA interaction of photoactive dye thionine: Spectroscopic and calorimetric approach

“…1A), a tricyclic heteroaromatic molecule, has been studied for its intercalative interaction, photoinduced mutagenic actions on binding to DNA, photoinduced inactivation of viruses and as impedance based DNA biosensor [11][12][13][14]. Tuite and Kelly [15] suggested that thionine intercalated and also bound to the outside of linear duplex DNA.…”

Toxic interaction of thionine to deoxyribonucleic acids: Elucidation of the sequence specificity of binding with polynucleotides

“…1), a positively charged tricyclic heteroaromatic molecule, has been studied for its photoinduced mutagenic actions [13,14], toxic effects, damage on binding to DNA [15], photoinduced inactivation of viruses [16] and use as an impedance based DNA biosensor [16][17][18][19]. There have been several studies on the toxicity of thionine and many related phenothiazine dyes [20][21][22][23][24][25].…”

Well‐ordered structure of methylene blue monolayers on Au(111) surface: Electrochemical scanning tunneling microscopy studies

“…MB also has potential applications as a photoactive molecule in photodynamics therapy and for the selective killing of bacteria, viruses, and cancerous cells (Jockusch et al, 1996). It is also important to prepare well-ordered MB monolayers on a solid surface due to its potential application as a simple system to study basic aspects of the charge transfer process in enzymes, in high-density device for signal memory, and as templates for the advanced nanopatterning of surfaces.…”