Dual-Emitting Quantum Dot/Quantum Rod-Based Nanothermometers with Enhanced Response and Sensitivity in Live Cells

Abstract

Temperature is a key parameter in physiological processes, and probes able to detect small changes in local temperature are necessary for accurate and quantitative physical descriptions of cellular events. Several have recently emerged that offer excellent temperature sensitivity, spatial resolution, or cellular compatibility, but it has been challenging to realize all of these properties in a single construct. Here, we introduce a luminescent nanocrystal-based sensor that achieves this with a 2.4% change/°C ratiometric response over physiological temperatures in aqueous buffers, with a precision of at least 0.2 °C. Thermoresponsive dual emission is conferred by a Förster resonant energy transfer (FRET) process between CdSe-CdS quantum dot-quantum rods (QD-QRs) as donors and cyanine dyes as acceptors, which are conjugated to QD-QRs using an amphiphilic polymer coating. The nanothermometers were delivered to live cells using a pH-responsive cationic polymer colloid, which served to both improve uptake and release nanocrystals from endosomal confinement. Within cells, they showed an unexpected enhancement in their temperature response and sensitivity, highlighting the need to calibrate these and similar probes within the cell.

Ho,Yb:KLu(WO4)2 Nanoparticles: A Versatile Material for Multiple Thermal Sensing Purposes by Luminescent Thermometry

“…However, in the latter case, the synthesis procedure was complex, the temperature range explored was very narrow, and it was not indicated at which wavelength the quantum dots/organic dye system was pumped. 76 Also Eu-doped SiO 2 submicrometric spheres exhibit a higher sensitivity in a shorter temperature range, 13 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 these systems operated in the green region of the electromagnetic spectrum. Thus, our nanoparticles offer an alternative luminescence range that can be used for thermometric applications when interferences arise in the green range of wavelengths.…”

Temperature-Dependent Exciton and Trap-Related Photoluminescence of CdTe Quantum Dots Embedded in a NaCl Matrix: Implication in Thermometry

“…It also reduces the impact of external factors that alter absolute intensities (fl uctuation of excitation intensity, detection effi ciency, and optical occlusion) and offers a self-referencing luminescent thermometry method which does not require calibration. [ 9,33,34,66 ] The CdTe QDs@NaCl powders feature an intrinsic dual-emission temperature-dependent luminescence, which enables their use in self-referencing luminescent thermometry. The ratio of the integrated PL intensity of the excitonic (core) band for the sample with d QDs = 2.3 nm relative to that of the trap-related (surface) band shows a monotonic decrease with falling temperature (Figure 8 …”

“…[33][34][35][36][37][38] QDs in the solid state provide an ease of processability, robustness, and good thermal stability. However, several problems in the application of QD-based luminescent temperature sensors are not yet solved.…”

Fluorescent nanoparticle interactions with biological systems: What have we learned so far?

“…This effect most likely arises from the formation of a biomolecular corona around the internalized AuNCs that modifies their photophysical properties. Such a dramatic difference also suggests that the effects of nano-bio interactions have to be thoroughly considered when designing fluorescent NPs for bio-applications [18] .…”