Regularities of complexation of indotricarbocyanine dyes with human blood serum proteins

Abstract

Photodynamic therapy is one of the most minimally invasive methods of treating malignant neoplasms of various localisations [1–3]. Further development of the method continues by improving the parameters of the used photosensitisers (PS). According to modern concepts, an ideal PS should exhibit a pronounced photo- dynamic effect when activated by radiation in the transparency window of biological tissues, have a high se- lectivity of accumulation in target tissues, biocompatibility, an effective pharmacokinetic profile, be eliminated from the body relatively quickly, and fluoresce with sufficient efficiency for diagnostic purposes [3; 4]. In re- cent years, there has been an increase in research interest in polymethine dyes as promising photosensitisers for photodynamic therapy of malignant neoplasms [5]. According to the results of complex studies of the photophysical properties of a number of indotricarbocyanine dyes in model media and tumors of experimental animals in vivo, a dye was chosen that largely satisfies the specified requirements [6]. It is based on an indotricarbocyanine dye with a chlorine-substituted orthophenylene bridge in the polymethine chain. Polyethylene glycols with a molecular weight of 300 g/mol (PEG300), covalently linked at the end groups, provided the new PS with high water solubility and biocompatibility. The effectiveness of PS largely depends on the selectivity of its accumulation in tumor tissues. Therefore, studies aimed at developing new methods of targeted drug delivery are relevant. One way to solve this problem is to use complexes of PS molecules with carriers, which provide efficient accumulation in tumor cells. In this regard, blood plasma components, proteins and lipoproteins, have special attention as endogenous carriers [7; 8]. On the contrary, blood serum is an available model medium for studying the photophysical properties of a PS under the conditions in which it is found in vivo.