Opto-thermal technologies for microscopic analysis of cellular temperature-sensing systems

Abstract

Could enzymatic activities and their cooperative functions act as cellular temperature-sensing systems? This review introduces recent opto-thermal technologies for microscopic analyses of various types of cellular temperature-sensing system. Optical microheating technologies have been developed for local and rapid temperature manipulations at the cellular level. Advanced luminescent thermometers visualize the dynamics of cellular local temperature in space and time during microheating. An optical heater and thermometer can be combined into one smart nanomaterial that demonstrates hybrid function. These technologies have revealed a variety of cellular responses to spatial and temporal changes in temperature. Spatial temperature gradients cause asymmetric deformations during mitosis and neurite outgrowth. Rapid changes in temperature causes imbalance of intracellular Ca2+ homeostasis and membrane potential. Among those responses, heat-induced muscle contractions are highlighted. It is also demonstrated that the short-term heating hyperactivates molecular motors to exceed their maximal activities at optimal temperatures. We discuss future prospects for opto-thermal manipulation of cellular functions and contributions to obtain a deeper understanding of the mechanisms of cellular temperature-sensing systems.

Modulation of Local Cellular Activities using a Photothermal Dye-Based Subcellular-Sized Heat Spot

“…This warrants further advances in heating methods that would have a potential to contribute to the analysis of thermodynamic factors in biology and accelerate the development of effective biomaterials. 4 , 5 While magnetic and optical heating for biospecimens have been established to induce heat at cellular and tissue levels, optical heating is superior in terms of spatiotemporal resolution. 1 , 6 , 7 An optical microscopic heating system, termed the infrared laser-evoked gene operator (IR-LEGO) system, having a near-infrared laser (1460 nm) has been fabricated to generate temperature increments at a localized spot by imparting vibration to water molecules.…”

“…Heating technology at the nano-/microscale has been indispensable in various research fields, such as material engineering and biological sciences. − More specifically, biological research pertaining to individual cells involves a huge variety of temperature-sensitive factors, such as chemical reactions, fluidity of cellular membranes, and flexibility of the structure of biomacromolecules. This warrants further advances in heating methods that would have a potential to contribute to the analysis of thermodynamic factors in biology and accelerate the development of effective biomaterials. , While magnetic and optical heating for biospecimens have been established to induce heat at cellular and tissue levels, optical heating is superior in terms of spatiotemporal resolution. ,, An optical microscopic heating system, termed the infrared laser-evoked gene operator (IR-LEGO) system, having a near-infrared laser (1460 nm) has been fabricated to generate temperature increments at a localized spot by imparting vibration to water molecules . However, the spatial resolution of the temperature distribution provided by the IR-LEGO system is limited by the size of the laser spot .…”

Thermal conductivity and conductance of protein in aqueous solution: Effects of geometrical shape

“…This remarkable observation has suggested a possibility that the intracellular temperature may play an important role as a biological signal, while a number of controversial issues such as “10 5 gap problem” 12–15 concerning the temperature relaxation remain. We then need further microscopic understanding of the biological roles of temperature and heat transfer at molecular level, whereas the experimental observations on the relationship between temperature and biomolecular behaviors are still difficult in spite of recent advances in experimental technologies 17–19 …”

“…Hence the use of molecular simulations may be promising to elucidate the microscopic mechanisms of thermal conduction at intracellular level. Substantial investigations have been carried out experimentally and computationally for both lipid membranes 24–29 and proteins 17–19,30–37 . Lipid membranes are usually in solid‐like state in the cell, thus being relatively easily investigated by conventional experimental and computational methods 20 .…”

“…We then need further microscopic understanding of the biological roles of temperature and heat transfer at molecular level, whereas the experimental observations on the relationship between temperature and biomolecular behaviors are still difficult in spite of recent advances in experimental technologies. 17 , 18 , 19 …”