Optical spectroanalyzer with extended dynamic range for pharmacokinetic investigations of photosensitizers in biotissue

Abstract

Currently, the most promising method for the study of pharmacokinetics of drugs with fluorescent properties is the spectral-fluorescent method. In this article, we propose an algorithm for expanding the dynamic range of the spectrum analyzer by automatically monitoring the maximum spectral density in the recorded fluorescence spectrum and automatically controlled changes in the accumulation time depending on this value, followed by compensation of the output signal with regard to this change, as well as hardware circuit solutions that allow this algorithm.Testing of LESA-01-"Biospeс" spectrum analyzer, upgraded using the proposed approach, was carried out on photosensitizer dispersions based on tetra-3-phenylthiophthalocyanine hydroxyaluminium of various concentrations (from 0.01 mg/l to 50 mg/l), approximately corresponding to the concentrations realized in the process of studying pharmacokinetics in calibration samples and tissues of experimental animals.The proposed solutions that implement the algorithm for recording fluorescence spectra with automatic change of accumulation time depending on the signal level, ensured a significant expansion of the dynamic range of the spectrum analyzer (up to 3.5 orders of magnitude) and improved accuracy in pharmacokinetic studies.

Photodynamic inactivation of Escherichia coli bacteria by cationic photosensitizers

“…The rate of photo-bleaching of PS was estimated from the decrease in the intensity of their fluorescence depending on the light dose density. The intensity of their fluorescence was determined using spectra-analyzer LESA-01-BIOSPEC (Biospec, Moscow, Russia) with an extended dynamic range [23,24]. The irradiation was carried out in a cyclic mode, the fluorescence intensity was measured in the pauses between irradiation intervals under excitation with lasers with a light wavelength of 633 nm (MS, Cholosens) or 532 nm (derivatives of bacteriochlorin-tetra-cationic (3-PyBrE) 4 BCBr 4 and electro-neutral (3-PyBS) 4 BC).…”