Effect of Polyethylenimine, a Cell Permeabilizer, on the Photosensitized Destruction of Algae by Methylene Blue and Nuclear Fast Red

Abstract

The present study reports the effect a cell permeabilizer, polyethylenimine (PEI) has on the photodynamic effect of methylene blue (MB) and nuclear fast red (NFR) in the presence of hydrogen peroxide (H2O2). The photosensitized destruction of the algae Chlorella vulgaris under irradiation with visible light is examined. The photodynamic effect was investigated under aerobic and anaerobic conditions. The presence of a permeabilizer during the photosensitized destruction of C. vulgaris does not enhance the activity of the MB, MB/H2O2 system or the NFR, NFR/H2O2 system under aerobic conditions. However under anaerobic conditions we have determined that when a cell permeabilizer was added to the MB/H202 system, the photosensitized destruction of C. vulgaris proceeded via a combination of Type I and Type II mechanisms. The presence of PEI enforces MB/H2O2 to be active toward the destruction of C. vulgaris whether oxygen is present or absent. Under aerobic and anaerobic conditions the activity of NFR was suppressed in the presence of PEI as a result of electrostatic interactions between the photosensitizer and the cell permeabilizer. The decrease in fluorescence recorded is indicative of destruction of the chlorophyll a pigment.

Photosensitized Destruction of Chlorella vulgaris by Methylene Blue or Nuclear Fast Red Combined with Hydrogen Peroxide under Visible Light Irradiation

“…The presence of H2O2 adds to the lifetime of singlet oxygen, and the increased lifetime of the radical species present leads to the increased destruction of C. vulgaris observed. This result is contrary to our previous work where we reported that the photosensitized destruction of the cyanobacteria S. leopolienis by a MB/H2O2 system proceeded via a Type I mechanism (43). The difference in the two species is that S. leopoliensis is a prokaryote while C. vulgaris is a eukaryote.…”

Self-assembled graphene quantum dots induced by cytochrome c: a novel biosensor for trypsin with remarkable fluorescence enhancement

“…The red-shi of the FL indicates that self-assembled aggregation of GQDs is induced by Cyt c, and the aggregation of GQDs is driven by electrostatic attraction. Cyt c is a cationic polyelectrolyte with a neutral pH 34,[44][45][46][47][48] and thus readily forms complexes with anionic GQDs. The large amount of carboxyl groups at the edge of GQDs are considered as restraining the p-p intermolecular interactions, which eventually leads to the self-assembled packing with a specic J-type aggregation induced by Cyt c. 49 The self-assembled aggregation of GQDs is further proven by transmission electron microscopy (TEM).…”

A new generation of biocides for control of crustacea in fish farms

“…We have previously reported the use of methylene blue (MB) and nuclear fast red (NFR) as biocides in the treatment of algae and cyanobacteria [24][25][26].…”