Effects of a new photoactivatable cationic porphyrin on ciliated protozoa and branchiopod crustaceans, potential components of freshwater ecosystems polluted by pathogenic agents and their vectors

Abstract

The increasing use of photosensitized processes for disinfection of microbiologically polluted waters requires a precise definition of the factors controlling the degree of photosensitivity in target and non-target organisms. In this regard, tests with protozoa and invertebrates which have a natural habitat in such waters may be used as first screening methods for the assessment of possible hazards for the ecosystem. A new cationic porphyrin, namely meso-tri(N-methyl-pyridyl)mono(N-dodecyl-pyridyl)porphine (C12), is tested in this work on the protozoan Ciliophora Colpoda inflata and Tetrahymena thermophila and the Crustacea Branchiopoda Artemia franciscana and Daphnia magna. The protocol involved 1 h incubation with porphyrin doses in the 0.1-10.0 μM range and subsequent irradiation with visible light at a fluence rate of 10 mW cm(-2). The results indicate that C12 porphyrin has a significant affinity for C. inflata and T. thermophila; this is also shown by fluorescence microscopic analyses. C. inflata cysts were resistant to the phototreatment up to a porphyrin dose of 0.6 μM. The effects of C12 on cysts have been evaluated at 3 and 24 h after the end of the phototreatment; a delay in the excystment process was observed. T. thermophila was fairly resistant to the phototreatment with C12 porphyrin. The data obtained with the two crustaceans indicated that the effects of dark- and photo-treatment with C12 need to be closely examined for every organism. A. franciscana is more resistant, probably owing to its ability to adapt to extreme conditions, while the high level of photosensitivity displayed by Daphnia magna represents a potential drawback, as this organism is often selected as a reference standard for assessing the environmental safety. Thus, while C12 photosensitisation can represent a useful tool for inducing a microbicidal or larvicidal action on polluted waters, the irradiation protocols must be carefully tailored to the nature of the specific water basin, and in particular to its biotic characteristics.

Potential applications of porphyrins in photodynamic inactivation beyond the medical scope

“…The resistance of A. franciscana to the phototreatment was explained by the very low amount of the ingested PS along with its ability to adapt to extreme conditions. These findings emphasized the need for carefully tailored irradiation protocols, taking into account the nature of the specific water basin, particularly in what refers to its biotic characteristics [52].…”

“…Tri-Py + -C 12 -Py + -Me, already mentioned as an effective photoactivated antimicrobial agent for aquaculture [69] and diseasetransmitting insect vectors [50], has also been tested on the protozoan Ciliophora Colpoda inflata and Tetrahymena thermophile and on the Crustacea Branchiopoda Artemia franciscana and Daphnia magna, which are used in routine toxicity assessment in freshwater ecosystems [52]. Following incubation with Tri-Py + -C 12 -Py + -Me for 60 min (0.1-10 M range) the organisms were irradiated with visible light (10 mW cm −2 ) for 60 min as well.…”

“…No [47] No [50,52,69] On filter paper [82] On cotton fabric [86,108] On polysilsesquioxane plastic films [61] On cotton fabric [87] On azide-modified cellulose nanocrystals [43,75] On chloroacetyl cellulose ester chlorides [78] On cellulose laurate esters plastic films [79] No [71] No [93] No [49,71,93,110] and Tri-Py + -Me-PF on silica coated Fe3O4 nanoparticles [70] and also on CoFe2O4 nanoparticles [111] No [81] No [105] No [36,37,71,74,81,105]; Tetra-Py + -Me was entrapped into microporous silica gels [88] and into three alkylene-bridged polysilsesquioxanes [89] On optically transparent indium tin oxide electrodes [63] On chitosan membranes [72] Pd(II) TetraTPPCO2H On a polyurethane matrix [83] No [105] In hydrophilic polycaprolactone and polyurethane (TecophilicH) nanofibers [60]; on electrospun polymeric nanofiber materials polyurethane Larithane TM , polystyrene, polycaprolactone, and polyamide 6 [76]; into three alkylene-bridged polysilsesquioxanes [89]; and in a silica-gel supported antimony porphyrin complex SbTPP [97,98] No [44,…”

Spray layer-by-layer films for photodynamic inactivation

“…A PDI experiment is performed by placing a PS in contact with a microorganism 1 (bacteria, virus, fungi protozoa, and pathogenic algae) [16,17], followed by local light 2 irradiation of the PS with the wavelength at the absorption maximum [18]. In addition to 3 the parameters associated with the light, such as its wavelength and fluence, and the PS 4 concentration, another important factor for PDI is the process of PS administration to the 5 microorganism.…”

Synthesis and Studies of New Fluorescein‐Porphyrin Dyads: A Theoretical and Experimental Approach

“…They have also been studied in agronomy, in which environment preservation related to health safety is a major challenge of this century. Due to their capacity to produce reactive oxygen species (ROS) after photoactivation, porphyrins are good candidates as potential photoactivable herbicides,, pesticides and insecticides;, precluding the drawbacks associated with such agents, including groundwater contamination.…”