Selective cell injection of fluorescence particle sensor encapsulated in fusogenic liposome using optical manipulation and control of surface potential using photochromic chemical

We developed selective injection of a single particle sensor into a specific cell by optically-regulated cell adhesion and membrane fusion of liposome for intracellular measurement. Fluorescence sensor encapsulated in fusogenic liposome is fabricated by spontaneous transfer method. The liposome is consists of neural lipids and spiropyran (SP). SP is a photochromic chemical and used to control the surface potential of the liposome. The surface potential of the liposome is neutral under VIS illumination. On the other hand, the surface potential becomes positive by UV-induced photoisolation of the SP. Charged liposome adheres to the cell membrane by coulomb´s force since the surface potential of the membrane is negative. The estimated coulomb´s force is approximately several hundred pN. The particle sensor can contain various fluorescence indicators such as Rhodmaine B as temperature sensor. The sensor is manipulated by optical tweezers and contacted to the cell membrane. We evaluated encapsulation efficiency of the single sensor into the liposome and adhesion efficiency to cell membrane under UV illumination. We demonstrated the optically-controlled adhesion of the sensor to MDCK cell and observed the injected sensor by laser confocal fluorescence method. As results, we succeeded in injection of particle sensor into the cell cytoplasm and nucleus.