Carbon Nanocoil Based Flexible Tip for Live Cell Study of Mechanotransduction and Electro-physiological Characteristics
The responses of living cells to external mechanical and electrical stimulation play important roles in regulating their biological functions and behaviors, and the response mechanisms have attracted great attentions. Global stimulation on cells is generally used in traditional methods, but it is insufficient to investigate the mechanism of dynamic physiological response at the subcellular level. At present, there is still lack of a low-cost and easy-operated method to apply local mechanical force and electrical stimulation to living cells. In this work, an individual carbon nanocoil (CNC) is used as a microscale noninvasive tool for local stimulation on single cell, and a living cell imaging technology, fluorescence resonance energy transfer (FRET), is adopted to determine the responses of cells. After demonstrating that CNCs have low cytotoxicity to be applied in biological field, an individual CNC is used as a needle tip to apply local mechanical force on a single osteosarcoma cell, which is transfected with a Src FRET biosensor to explore the mechano-physiological response. A spatial increasing and polarized Src protein activation is observed on the stimulated cell. Moreover, a single CNC is also used as an electrode to exert periodic local electrical stimulation. Osteosarcoma cells transfected with calcium-FRET biosensors show notable spatial polarized FRET emission ratio distribution, then the FRET ratio shows a recoverable tendency towards the initial state after withdrawing the electrical stimulation. The cell biofunctions and structures are not damaged during the experiment process, which indicates CNC is a kind of non-invasive and bio-safe tip. The CNC tip is a powerful tool for exploring the mechanotransduction and electro-physiological characteristics of living cells.