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

Abstract

Thermal engineering at the microscale, such as the regulation and precise evaluation of the temperature within cellular environments, is a major challenge for basic biological research and biomaterials development. We engineered a polymeric nanoparticle having a fluorescent temperature sensory dye and a photothermal dye embedded in the polymer matrix, named nanoheater-thermometer ( nanoHT ). When nanoHT is illuminated with a near-infrared laser at 808 nm, a subcellular-sized heat spot is generated in a live cell. Fluorescence thermometry allows the temperature increment to be read out concurrently at individual heat spots. Within a few seconds of an increase in temperature by approximately 11.4 °C from the base temperature (37 °C), we observed the death of HeLa cells. The cell death was observed to be triggered from the exact local heat spot at the subcellular level under the fluorescence microscope. Furthermore, we demonstrate the application of nanoHT for the induction of muscle contraction in C2C12 myotubes by heat release. We successfully showed heat-induced contraction to occur in a limited area of a single myotube based on the alteration of protein–protein interactions related to the contraction event. These results demonstrate that even a single heat spot provided by a photothermal material can be extremely effective in altering cellular functions.

A palette of site-specific organelle fluorescent thermometers

“…The laser irradiation during 15 ​s increases the temperature of the local heat spot, and then the generated heat is transmitted from graphite to the surrounding cells, causing a temperature gradient from the heating center (high temperature) to the surrounding area (low temperature). For reference, photothermal heating during such a short time scarcely caused critical damage to HeLa cells unless the temperature increment does not reach approximately 11 ​°C from the base temperature of 37 ​°C, which was supported by previous literature [ 39 ]. Using such a microscopic set-up, ETG, MTG, LTG, GTG, PTG and NTG were evaluated in HeLa cells, while DTG was tested in brown adipocytes due to its large lipid droplets.…”

A biomimetic nanoplatform for customized photothermal therapy of HNSCC evaluated on patient-derived xenograft models

“…4a, b ), a temperature that could induce cell damage. 38

Fig. 4 Photothermal anti-cancer performance in orthotopic tongue tumor mouse models.

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“…4a, b), a temperature that could induce cell damage. 38 Tumor signals were present in the tongue of the mice that merely received laser irradiation. While in the mice treated with Au@C-CCM6 plus laser irradiation, fluorescence signals disappeared on the 7th day without relapse for 30 days of observation (Fig.…”

Intracellular Magnetic Control over the Reversible Assembly of Silica-Based Magnetic Composite Particles for Photothermal Therapy

“…The MCPs, with an enhanced cellular uptake and high mobility in cell, can be applicable to optical and magnetic heating technologies at the cellular level. Several mechanisms for heat-induced cell death have been reported: the perturbation of electron transport chain in mitochondria; , the heat-induced endoplasmic reticulum stress; and so on . In addition, a successful accumulation of Fe in cell would lead ferroptosis. − By controlling the size of MCPs, the cellular uptake of particles can be enhanced, and such internalized particles can be utilized for local heating.…”