[Biological effect of photochemical hydrogen peroxide formation. 2. Intensification of the photodynamic effect of anthraquinone-2-sulfonic acid in the presence of glycerin and other hydrogen donors]

Electroporation of cell membranes supporting penetration of photodynamic active macromolecular chromophore dextrans

The aim is to demonstrate that macromolecular chromophore dextrans (Cibacron-dextran) acting as photosensitizers can be transported easily into cancer cells by electroporation of their membranes (short electric pulses on cell suspension between electrodes). There are two possibilities, either:(A)irradiation starts with the electropulse-showed with easily penetrating thiopyronin-yielding nearly 100% dead cells;(B)irradiation starts after a resealing time of membrane pores during which macromolecular photosensitizers can penetrate into cells. In this way, fractions of Cibacron-dextran with molecular weights (Mw) 3300, 10,900 and 500,000 are now able to kill. This combination of bioelectrochemistry and photobiology will be suitable also for other biopolymers, connected with photodynamic active chromophores (e.g. chromopeptides) to transport them through cell walls and membranes into cells and tissues. The human cancer cells U-935 and K-562 (pulsed by 1.15 kV/cm field strength) additionally or synergistically reach high rates of necrotic cells (colored by trypan blue) by this combination.

Photodynamic effect on cancer cells influenced by electromagnetic fields

The synergism of low-frequency electromagnetic field treatment and photodynamic effect on killing of human cancer cells is presented. The weak pulsating electromagnetic field (PEMF) generated by Helmholtz coils in the mT range influences the permeability of cell membranes for photosensitizers. Several types of sensitizers were excited by visible light during incorporation without and with two kinds of PEMF treatment. In the first part suitable photosensitizers were selected in the absorption range between 400 and 700 nm against human myeloid leukaemia K562 and human histiocytic lymphoma U937 cells by treatment of PEMF consisting of rectangular pulse groups. In the second part amplitude and frequency dependencies were measured using sinuous PEMF and white light with the result that after 12 min the PEMF treatment enhanced photodynamic effectivity by more than 40% over the control value. Taking into account the influence of many parameters, an additional optimization will be possible by photodynamic PEMF synergism for an increased drug delivery in general.