Quantum-dot optical temperature probes

Abstract

The steady-state photoluminescence (PL) properties of cadmium selenide quantum dots (QDs) with a zinc sulfide overlayer [(CdSe)ZnS] can be strongly dependent on temperature in the range from 100 to 315 K. The PL intensity from 50 to 55 Å (CdSe)ZnS QDs in poly(lauryl methacrylate) matrices increases by a factor of ∼5 when the temperature is decreased from 315 to 100 K, and the peak of the emission band is blueshifted by 20 nm over the same range. The change in PL intensity is appreciable, linear, and reversible (−1.3% per °C) for temperatures close to ambient conditions. These properties of (CdSe)ZnS dots are retained in a variety of matrices including polymer and sol–gel films, and they are independent of excitation wavelength above the band gap. The significant temperature dependence of the luminescence combined with its insensitivity to oxygen quenching establishes (CdSe)ZnS dots as optical temperature indicators for temperature-sensitive coatings.

Optimum quantum dot size for highly efficient fluorescence bioimaging

“…For this "critical" size, the QY scales up to 0.47, in reasonable agreement with previous works that report on QY values ranging from 0.25 up to 0.6 for CdTe QDs. 11,23,35 At this point, it should be noted that a small variation in synthesis conditions may result in a large difference in quantum efficiency, even with the same experimental conditions, but different batches. Nevertheless, we ruled out this possibility by repeating the measurements, using completely different batches provided by the same company.…”

“…8 In addition, recent works have demonstrated the ability of QDs to act as nano-thermometers based on the thermal sensitivity of their fluorescence bands. [9][10][11][12][13][14] Based on all these outstanding properties, QDs have been successfully used to mark specific receptors in cell membranes, to measure intracellular temperature, and to label living embryos at different stages. 9,[15][16][17] Most of the QD-based bio-images reported up to now were obtained by using either CdSe or CdTe QDs, since both are currently commercially available with a high degree of quality.…”

Temperature Sensor Based on Colloidal Quantum Dots–PMMA Nanocomposite Waveguides

“…These multicomponent materials are known as nanocomposites. Walker et al first characterized the temperature response of the photo-luminescence (PL) of colloidal QDs immobilized inside a polylaurylmethacrylate (PLMA) matrix [10] proving the suitability of QDs as temperature references for PL-based sensing applications. Other authors have also reported the use of different host polymers such as polystyrene (PS) [11] or polymethylmethacrylate (PMMA) [12] to embed QDs, and even coupling the light with the aid of optical fibers [13].…”

Synthesis kinetics of CdSe quantum dots in trioctylphosphine oxide and in stearic acid

“…This versatility leads to numerous photonic applications, such as optical fiber amplifiers, 1,2 color displays using light-emitting diode arrays, 3 optical temperature probes, 4 and biomedical imaging. 5 Conjugation of QDs with antibodies yields biomarkers that compete with traditional organic fluorescent tags in terms of biocompatibility, excitation and filtering simplicity, and photostability.…”