Local thermal activation of individual living cells and measurement of temperature gradients in microscopic volumes

The review is focused on a new, unique and promising method of creating a precision local temperature gradient in the micro- and nanovolumes, allowing to heat a single cell and to explore exogenous and endogenous intracellular processes. Retrospective analysis and systematization of advanced developments in the study of intracellular temperature have been carried out. A device is described in detail consisting of an optical nanoheater, which uses metallic nanoparticles or water warming up with infrared laser beam, enabling setting a stationary temperature gradient of up to 70°C at a distance of 20 μm from the heat source, and a fluorescent microthermometer, which can measure temperature in microvolumes with millisecond resolution. Special attention is paid to the physical, in particular, thermodynamic description of temperature as а parameter of macro-, micro- and nanosystems and to the description of the ultralocal temperature gradient induction mechanism. The results are collected on the implementation of the local heating on living cell and on the thermoinduction of intracellular processes, among which the growth rate of neurites, of about 10 μm/min in a thermal gradient is the most impressive; absolutely new prospects opened by “thermal manipulation” of a living cell are highlighted.