Graduate School of Engineering, Tohoku University, 6-6-01 aza-Aoba Aoba, Sendai 980-8579, Japan.
Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo Bunkyo, Tokyo 113-0033, Japan.
Lab Chip. 2023 May 16;23(10):2411-2420. doi: 10.1039/d2lc01185a.
To understand the mechanism of intracellular thermal transport, thermal properties must be elucidated, particularly thermal conductivity and specific heat capacity. However, these properties have not been extensively studied. In this study, we developed a cellular temperature measurement device with a high temperature resolution of 1.17 m °C under wet conditions and with the ability to introduce intracellular local heating using a focused infrared laser to cultured cells on the device surface. Using this device, we evaluated the thermal properties of single cells based on their temperature signals and responses. Measurements were taken using on-chip-integrated microthermistors with high temperature resolution at varying surrounding temperatures and frequencies of local infrared irradiation on cells prepared on the sensors. Frequency spectra were used to determine the intensities of the temperature signals with respect to heating times. Signal intensities at 37 °C and a frequency lower than 2 Hz were larger than those at 25 °C, which were similar to those of water. The apparent thermal conductivity and specific heat capacity, which were determined at different surrounding temperatures and local heating frequencies, were lower than and similar to those of water at 37 °C and 25 °C, respectively. Our results indicate that the thermal properties of cells depend on both temperatures and physiological activities in addition to local heating frequencies.
为了理解细胞内热传输的机制，必须阐明热性质，特别是热导率和比热容。然而，这些性质尚未得到广泛研究。在这项研究中，我们开发了一种细胞温度测量设备，在湿条件下具有 1.17 m°C 的高温度分辨率，并且能够使用聚焦红外激光在设备表面上的培养细胞中引入细胞内局部加热。使用该设备，我们根据细胞的温度信号和响应评估了单个细胞的热性质。使用具有高温度分辨率的片上集成微热敏电阻在不同的周围温度和细胞局部红外辐照频率下进行测量，这些细胞在传感器上制备。使用频谱来确定相对于加热时间的温度信号的强度。在 37°C 和低于 2 Hz 的频率下的信号强度大于在 25°C 下的信号强度，这与水的信号强度相似。在不同的周围温度和局部加热频率下确定的表观热导率和比热容均低于 37°C 和 25°C 时水的值，并且与水的值相似。我们的结果表明，细胞的热性质不仅取决于局部加热频率，还取决于温度和生理活动。
