Stable Fluorescence of Green‐Emitting Carbon Nanodots as a Potential Nanothermometer in Biological Media

Abstract

1 of 7) 1600197Temperature measurement in biology and medical diagnostics is of great importance. Herein, a novel carbon nanodot (CND) based fluorescent nanothermometry device for spatially resolved temperature measurements is demonstrated. The fluorescence CNDs are prepared by a simple one-pot solvothermal method using sucrose as carbon source. Resultant CNDs show stable green fluorescence at 520 nm with high quantum yield (≈6%). The fluorescence of resultant CNDs exhibits a reversible linear response to temperature in a wide range of 20-85 °C. Moreover, the temperature resolution better than 0.5 °C and high sensitive variation of ≈1.3% °C −1 are observed in a broad physiological temperature range of 20-40 °C. Therefore, the as-prepared CNDs possess high water solubility, stable fluorescence, small size, and good biocompatibility, which make them promising candidate for thermometry and cell imaging in biological media. stability, serious toxicity, and high cost, have limited their further application.The carbon nanodots (CNDs), a new family member of carbon nanomaterials, are generally composed of sp 2 hybridized carbon atoms with abundant oxygenous and hydrogenous residues with sizes below 10 nm. [10,11] Compared to the conventional fluorescent nanomaterials (SQDs, metal nanoclusters, and organic fluorescent dyes), CNDs possess numerous superior features including easy preparation and functionalization, no/low toxicity, and high photostability, thus demonstrating a variety of potential applications, such as sensing, biomedicine, catalysis, and optoelectronic devices. [12][13][14][15] To date, many efforts have been done to study the preparations, properties, and applications of CNDs, but most of them show intense emission only in the blue-light region, and the long-wavelength (i.e., green-, yellow-, to red-light) emissions are usually very weak. [16][17][18] Such a drawback restricts further applications of CNDs, particularly in the biology-relevant fields because of the common blue autofluorescence of biological matrix and photodamage of biological tissues by ultraviolet excitation light. Furthermore, many CNDs-based nanosensors have been designed and played an important role in bio-analysts in vitro and vivo. [19][20][21][22] For example, Zhu et al. reported a facile and high output strategy for the fabrication of highly photoluminescent CNDs which could be utilized as a biosensor reagent for the detection of Fe 3+ in bio-systems; [19] Zhang group reported an effective fluorescent probe for sensing mercuric and iodide ions based on the nitrogen-doped CNDs; [20] Nie et al. applied the CNDs as an internal reference to construct a ratiometric pH sensor in living cells, [21] while few CNDs-based thermometers are reported. [23][24][25][26] More recently, our group used a hydrothermal route to prepare water-stable luminescent CNDs as nanosensors for the detection of pH and temperature; [23] then we also designed a "turn-on" chemosensor for detecting temperature through surface-modified CNDs and the carbon-dot-based...

Synthesis of highly fluorescent Cu/Au bimetallic nanoclusters and their application in a temperature sensor and fluorescent probe for chromium(iii) ions

“…This phenomenon might be attributed to thermal agitation of nonradiative processes, the molecule collision frequency and the nonradiative transition rate increase at high temperature, reducing the intensity of the emission from the excited state. [46][47][48] The linear relationship between the uorescence intensity and temperature was within the range of 20-70 C. As revealed in Fig. 4b, the linear equation was F ¼ À23.96T + 3149.2 (R ¼ 0.94).…”

Intracellular ratiometric temperature sensing using fluorescent carbon dots

“…Recently, carbon dot optical probes have been investigated for temperature sensing applications in vivo and in vitro. 9,16,23,24,[35][36][37] Yang et al 24 reported the synthesis of low cytotoxic biocompatible carbon dots with temperaturedependent uorescence intensity from 20 to 80 C and a thermal sensitivity of 0.85% C À1 . They extended their work to show temperature-dependent uorescence in an in vivo mouse model.…”

Graphene Quantum Dots as Intracellular Imaging-Based Temperature Sensors

“…This may explain the higher temperature sensitivity of the N-GQDs that are found in our works to have a high degree of functionalization [ 33 ]. Reversible temperature sensitivity been already observed with other carbon quantum dot based nanothermometers [ 17 , 35 , 37 , 44 ]. However, N-GQDs and RGQDs show a new variety of advantages including high biocompatibility evaluated previously via the thiazolyl blue tetrazolium bromide (MTT) and Luminescence assays, high visible quantum yields (N-GQDs) [ 33 ], simple and scalable synthesis, and potential for NIR temperature sensing (RGQDs) more applicable for in vivo studies [ 36 , 41 ].…”

“…It appears that the visible features of both N-GQDs and RGQDs experience monotonic decrease with temperature down to 19.3 and 16.8%, respectively, at 49 °C. Peak intensities quench linearly Recently, Kalytchuk et al suggested the mechanism behind this fluorescence intensity decrease due to a higher chance of obtaining non-radiative relaxation pathways from thermal effects [17,44]. Yang et al have also denoted that hydrogen bonds and oxygen-containing surface functional groups may play a role in the decrease of the fluorescence intensity with temperature enabling temperature-dependent excitation energy traps [33,37].…”