Adhesion of photosensitizer to ferrofluids for use in photodynamic therapy

Ferrimagnetic particles of Fe3O4 were nanometrically synthesized by the coprecipitation method. These single-domain particles were stabilized by double surfactant layers in water-soluble fluids. The water-based ferrofluid was produced to deliver photosensitizing drugs to diseased tissue in photodynamic therapy. In order to coat photosensitizer on the magnetic particles, 5 x 10(-4) mol of haematoporphyrin was introduced into the fluid solution before, during, and after exposure to the first surfactant, and the adsorption reaction was conducted at 60, 70, and 80degreesC. The sample fluid included about 2 g of magnetite particles. The concentration of haematoporphyrin was obtained from the optical density of UV spectra. The amount of haematoporphyrin reacting with the dispersed fine particles increased with increasing temperature. The 5 x 10(-4) mol haematoporphyrin added to the fluid was coated on the particle surface with 3.8 x 10(-3) mol 1(-1) of ferrofluid when it reacted at 80degreesC after exposure to the first surfactant. In the thermogravimetric analysis measurement, the ferrofluid included 30.116 g l(-1) of dispersed particles. Therefore, 1.26 x 10(-4) mol g(-1) of the haematoporphyrin adhered to the magnetite particles, and its coating efficiency reached about 50% in the prepared ferrofluid. Also, a small-sized probe for photodynamic therapy using ferrofluid was designed in an integrated form so that it could be directly inserted into the tumour. (Some figures in this article are in colour only in the electronic version).