Recent progress on small molecular temperature‐sensitive fluorescent probes

Abstract

Temperature is an important biophysical parameter that is closely related with the metabolic activity in living cells. Therefore, the detection of intracellular temperature changes is crucial for exploring temperature‐related biological processes. Fluorescence probe is an ideal tool for observing temperature changes in cells, which has many advantages, such as high sensitivity, good selectivity, and noninvasive, and thus aroused the great interest of researchers. In this paper, we summarize the recent progress of organic small molecule temperature‐sensitive fluorescence probes in recent years was reviewed. Particularly, we describe the common response mode to the temperature and the practical applications of the probe in living cells and even animal models. Moreover, an outlook regarding temperature detection in clinical applications is discussed. The temperature‐sensitive fluorescent probe is a “black box” to many researchers. This review aims to open a window on the prospect of the noninvasive in vivo detection of temperature which is helpful to deeper understand this rich research area.

Photothermal Nanomaterials: A Powerful Light-to-Heat Converter

“…Briefly, the fluorescence intensity of small organic molecules generally decreases as the temperature is increased because of the thermal quenching effect. 401 Some specific molecules, such as green fluorescent proteins and organic dyes, possess temperature-dependent fluorescence polarization anisotropy; that is, the ratio of the emission intensities collected under different polarization states can vary with the environmental temperature. 402 Aggregation-induced emission (AIE) molecules have also been demonstrated to display temperature-responsive properties in terms of spectral position, fluorescence intensity, and fluorescence lifetime.…”

“…The selection of nanothermometers can cover a series of luminescent temperature-responsive probes, including fluorescent small molecules, fluorescent proteins, quantum dots (QDs), lanthanide-ion-doped UCNPs, vacancy-containing nanodiamonds, − carbon dots, , and polymeric nanoparticles . The operation of these nanothermometers mostly relies on the temperature-dependent fluorescence properties (Figure b), for example, the emission intensity, emission peak shifting, spectral ratio between the different fluorescence bands, lifetime, polarization anisotropy, and electron spin resonance or optically detected magnetic resonance (ODMR).…”

“…All of these signals allow for the real-time and noninvasive monitoring of local temperatures. Briefly, the fluorescence intensity of small organic molecules generally decreases as the temperature is increased because of the thermal quenching effect . Some specific molecules, such as green fluorescent proteins and organic dyes, possess temperature-dependent fluorescence polarization anisotropy; that is, the ratio of the emission intensities collected under different polarization states can vary with the environmental temperature .…”

Polarity-Independent Temperature-Induced Reversible Fluorescence Switching of Organic Nanoparticles: Application to Intracellular Temperature Imaging

“…Fluorescence measurements generally provide three important pieces of information: excitation wavelength (which depends on the absorbance of the fluorophore), fluorescence maximum (which is characteristic of the fluorophore, but independent of its concentration), and the intensity of the fluorescence (which depends on the concentration of the fluorophore and its quantum efficiency). Although fluorescent thermometers based on inorganic materials, such as quantum dots, oxides, or polymers have been known for a long time, small organic molecule-based fluorescent probes have rarely been explored . In general, thermoresponsive fluorescent probes exhibit a turn-off response at elevated temperatures due to radiationless decay processes initiated by thermal agitation.…”

“…Although fluorescent thermometers based on inorganic materials, such as quantum dots, oxides, or polymers have been known for a long time, small organic molecule-based fluorescent probes have rarely been explored. 12 In general, thermoresponsive fluorescent probes exhibit a turn-off response at elevated temperatures due to radiationless decay processes initiated by thermal agitation. Moreover, fluorescence properties of conventional organic fluorophores such as intensity and bandwidth are often affected by their residing environment, thereby limiting the sensitivity and accuracy of the measurement.…”