RESUMO
Liposomes are well-known cell simulators and are currently studied as drug delivery systems, for a targeted delivery of higher drug concentrations, in specific cells. Novel biophotonic techniques for manipulation and characterization of liposomes have been developed; among which are optical tweezers. In our work, we demonstrate a novel use of line optical tweezers to manipulate and cause liposome deformations. Optical forces induce tension on liposomes, which are stretched along the line optical trap. The method of dielectrophoresis, combined with optical tweezers, was used to measure the exerted optical forces. As a consequence, in the case of reversible liposome deformations, the value of the shear and bending moduli of liposomes was calculated. We anticipate that the selective manipulation of liposomes will help us toward a better understanding of the cellular-liposome interactions. Studying the biomechanical properties of liposomes will provide an insight into the mechanical behavior of individual living cells, which have recently been implicated in many aspects of human physiology and patho-physiology. The biomechanical properties of cells (i.e. deformability, stiffness and elasticity) can be useful biomarkers for various disease processes and changes of the cell state.
RESUMO
The current article presents the photobleaching properties of a group of pyrylium salts under ultrashort pulsed illumination. These pyrylium salts have the same basic chemical structure and differ only by a specific substituent. It is proven experimentally that two different mechanisms are simultaneously present to the photobleaching of all molecules studied (independently of their specific chemical structure). However, the particular parameters of each mechanism are influenced significantly by the substituent change. The experimental investigation of these parameters showed the presence of multiphoton interactions in the photobleaching of pyrylium salts depending essentially on the specific substituent.
