Effects of ionic strength on the antimicrobial photodynamic efficiency of methylene blue

Abstract

Antimicrobial photodynamic therapy (APDT) may become a useful clinical tool to treat microbial infections, and methylene blue (MB) is a well-known photosensitizer constantly employed in APDT studies, and although MB presents good efficiency in antimicrobial studies, some of the MB photochemical characteristics still have to be evaluated in terms of APDT. This work aimed to evaluate the role of MB solvent's ionic strength regarding dimerization, photochemistry, and photodynamic antimicrobial efficiency. Microbiological survival fraction assays on Escherichia coli were employed to verify the solution's influence on MB antimicrobial activity. MB was evaluated in deionized water and 0.9% saline solution through optical absorption spectroscopy; the solutions were also analysed via dissolved oxygen availability and reactive oxygen species (ROS) production. Our results show that bacterial reduction was increased in deionized water. Also we demonstrated that saline solution presents less oxygen availability than water, the dimer/monomer ratio for MB in saline is smaller than in water and MB presented a higher production of ROS in water than in 0.9% saline. Together, our results indicate the importance of the ionic strength in the photodynamic effectiveness and point out that this variable must be taken into account to design antimicrobial studies and to evaluate similar studies that might present conflicting results.

Real-time evaluation of two light delivery systems for photodynamic disinfection of Candida albicans biofilm in curved root canals

“…Furthermore, Tavares et al showed the importance of type II PDT mechanism, whereas a direct transference of energy occurs from the photosensitizer to the molecular oxygen [38]. Nunez et al also pointed out the importance of molecular oxygen availability for antimicrobial photodynamic damage [39]. Therefore, for predictable results in endodontic APDT, the oxygen tension inside all the anatomic features from different root canal areas should be also evaluated, and the method of irradiation may contribute to balance the oxygen consumption.…”

Role of Bio-Fertilizers in Sustainable Agriculture

“…General use of chemicals as a fertilizers can full fell the demand of fast growth and high amount of food supply but obviously those leads to damage the environment (damaging microbial biota, killing friendly insects and increase in pH). However the use of chemicals fertilizers make the crops susceptible to disease and also results in decease soil fertility (5,20) It has been estimated the in 2020 the world population will we more than 8 billon and to feed them we need 28.8 million tons of food and nutrients and we estimated the only 21.6 million tons will be available to community of the world ) (21) To feed the world population we have to increase the amount of agriculture and increase the productivity in such a way the it is useful and also show no bad effect on either environment, Human, beneficial insects etc. for this purpose we have to increase agriculture productions using chemical fertilizers, pesticides, herbicides, fungicides, and insecticides (22) As already discussed due to hazardous effect we are moving towards other sources rather the chemicals which have to be more safe and more effective and ecologically safe and cost effective as well, all these properties are present in bio-fertilizers (23).…”

“…Azospirillum are gram negative bacteria with ability of nitrogen fixation belong to spirilaceae family (2) This genus include mant sp like Azospirillum amazonense, Azospirillum halopraeferens, andAzospirillum brasilense, but among them the most beneficial sp are Azospirillum lipoferum and A. brasilense (21) They make associated symbiosis with the plants especially with those which have C4 dicarboxylic pathway of photosynthesis (56) They produce plant regulators like IAA, GA and cytokinin with work as root development due to which plants are able to uptake large amount of nutrients. (57) The major advantage of these bacteria is that they full, fell the requirement of nitrogen in paddy, sorghum and sunflower up to 25%.…”

“…These type of bacteria are found in different type of crops such as rice, maize, sugarcane, vegetables (Azobactor play important role in production of some other vitamins such as riboflavin and thiamin (59) Azolla and Blue-green algae: Azolla contain sp Azolla caroliniana, Azolla microphylla, Azolla filiculoides, and Azolla mexicana (21). These are present in large amount in paddy field belonging to eight different types of families and enhance the growth of plant by producing different type of hormones such as Indole acetic acid, Gibberellic acid (21). To increase the productivity Nitrogen is essential mineral for that and that nitrogen is provided to rice plant by means of biological nitrogen fixation (4,60) 4-5% of nitrogen is present in Azolla on dry basis and 0.2-0.4% is present on wet basis.…”

“…To increase the productivity Nitrogen is essential mineral for that and that nitrogen is provided to rice plant by means of biological nitrogen fixation (4,60) 4-5% of nitrogen is present in Azolla on dry basis and 0.2-0.4% is present on wet basis. Azolla is very important means of organic fertilizer as it provide nitrogen to rice plant (21) It also has the ability to decompose the soil fastly and also provide the plant important minerals like phosphorus, potassium iron, zinc and other micro elements, (61)…”