Abstract
Aluminum phthalocyanine nanoparticles (NP AlPc) possess the features that make them a promising photosensitizer. In particular, AlPc NPs do not fluoresce in free nanoform, fluoresce weakly in normal tissue, strongly in tumors and very strongly in macrophages. Also, such particles fluoresce and become phototoxic when contacting certain biocomponents. The type of biocomponents that bind to AlPc NPS defines intensity, lifetime, and spectral distribution of the fluorescence. This study aimed to investigate the peculiarities of nanophotosensitizer capturing in 3D models of cell cultures. The data obtained demonstrate that AlPc NPs are captured by cells inside the spheroid in the course of the first hour, as the fluorescent signal's growth shows. Having analyzed the fluctuations of the fluorescence signal of AlPc NPs inside a spheroid, we have also discovered that the cellular 3D models are heterogeneous. Laser irradiation (two-photon excitation at λ = 780/390 nm) resulted in photobleaching of fluorescence, which is probably associated with AlPc NP deactivation. Thus, the created model comprised of a 3D cell culture and AlPc NPs provides a better insight into metabolic processes in cells than monolayer 2D cell cultures. Besides, the model allows to evaluate the photodynamic effect depending on phenotypic properties of various areas in the heterogeneous 3D-structure.
Highlights
Nanoparticles (NPs), which are based on molecular nanocrystals of photosensitizer (PS), are promising agents for the fluorescence diagnostics (FD) and treatment by the photodynamic therapy (PDT)
Aluminium phthalocyanine (AlPc) NPs uptake in spheroids was evaluated at different times during 1 hour
The time and spatial dynamic of AlPc NPs uptake described above could be explained by the heterogeneity of cells in 3D model in temrs of different metabolic processes and phenotypes
Summary
Обнаружена гетерогенность клеточных 3D-моделей по анализу изменения сигнала флуоресценции НЧ AlPc внутри сфероида. Aluminium phthalocyanine (AlPc) nanocrystals have an advantage over the molecular PS used in clinic settings due to the significantly higher accumulation selectivity of nanoscale materials [1,2,3,4] They are able to fluoresce only in monomeric form upon the interaction of nanocrystals with biological structures, hereby providing appropriate FD detection efficiency [1, 2]. Three-dimensional (3D) cell cultures are considered as a more accurate and reproducible model for performing in vitro drug screening This model displays several features of in vivo tumor tissues such as presence of extracellular matrix, intercellular interaction, hypoxia, drug penetration and resistance [8,9,10]. Thereby, we have chosen 3D multicellular spheroids as a model to study accumulation, distribution and PDT efficiency of AlPc NPs in HeLa cells
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