Quantum dots versus organic dyes as fluorescent labels

Resch‐Genger, Ute; Grabolle, Markus; Cavaliere, Sara; Nitschke, Roland; Nann, Thomas

doi:10.1038/nmeth.1248

Cited by 3,462 publications

(2,808 citation statements)

References 120 publications

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“…The lifetime is inversely proportional to the overlap between the electron and hole wave functions, τ r ∝ |〈ψ e |ψ h 〉| −2 , and typically ranges between 10 and 100 ns, several times that of organic dyes and fluorescent proteins, which typically have lifetimes of ~1-10 ns. 23 We found the wave functions for the electron and hole by treating them as distinct particles moving in a three-dimensional potential well and with different effective masses, and (Supporting Information). The particles' energies are inversely proportional to their effective masses, which are intrinsic properties of the semiconductor.…”

Section: Semiconductor Nanocrystals Have Voltage-dependent Photophysimentioning

confidence: 99%

Optical Strategies for Sensing Neuronal Voltage Using Quantum Dots and Other Semiconductor Nanocrystals

Marshall

Schnitzer

2013

ACS Nano

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Biophysicists have long sought optical methods capable of reporting the electrophysiological dynamics of large-scale neural networks with millisecond-scale temporal resolution. Existing fluorescent sensors of cell membrane voltage can report action potentials in individual cultured neurons, but limitations in brightness and dynamic range of both synthetic organic and genetically encoded voltage sensors have prevented concurrent monitoring of spiking activity across large populations of individual neurons. Here we propose a novel, inorganic class of fluorescent voltage sensors: semiconductor nanoparticles, such as ultrabright quantum dots (qdots). Our calculations revealed that transmembrane electric fields characteristic of neuronal spiking (~10 mV/nm) modulate a qdot's electronic structure and can induce ~5% changes in its fluorescence intensity and ~1 nm shifts in its emission wavelength, depending on the qdot's size, composition, and dielectric environment. Moreover, tailored qdot sensors composed of two different materials can exhibit substantial (~30%) changes in fluorescence intensity during neuronal spiking. Using signal detection theory, we show that conventional qdots should be capable of reporting voltage dynamics with millisecond precision across several tens or more individual neurons over a range of optical and neurophysiological conditions. These results unveil promising avenues for imaging spiking dynamics in neural networks and merit in-depth experimental investigation. Toward addressing these challenges, we studied whether tools from nanotechnology, specifically, bright, multifunctional semiconductor quantum dots (qdots), 22,23 might be useful for imaging neuronal membrane potentials. Qdots are known to possess voltagesensitive optical properties, including a red-shifting of the qdot's fluorescence emission peak, spectral broadening, and a decrease in the intensity of fluorescence emission ( Figure 1C,D). [24][25][26][27] Qdots also are highly resistant to photobleaching and exhibit large quantum yields and absorption cross sections for one-(σ 1 ) and two-photon (σ 2 ) excitation. For example, CdSe qdots with radius R ~ 3 nm exhibit cross sections of σ 1 > 1 nm 2 and σ 2 > 3 × 10 4 GM, as compared to σ 1 ~ 10 −2 nm 2 and σ 2 ~ 3 × 10 2 GM for green fluorescent protein. 28,29 Marshall and Schnitzer Page 2 ACS Nano. Author manuscript; available in PMC 2017 December 15. Graphical Abstract HHMI Author Manuscript HHMI Author Manuscript HHMI Author ManuscriptTo evaluate the spike detection capabilities of qdot indicators quantitatively, we applied a theoretical approach that incorporates the physical, biophysical, and statistical components of the problem. We calculated the effect of applied electric fields on the qdot's electronic structure and examined how this modulates a qdot's fluorescence intensity and emission spectra. We also studied nonspherical, nonhomogenous qdots, which we refer to more generally as semiconductor nanocrystals, and found that these nanoparticles can demonstrate muc...

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Section: Semiconductor Nanocrystals Have Voltage-dependent Photophysimentioning

confidence: 99%

Optical Strategies for Sensing Neuronal Voltage Using Quantum Dots and Other Semiconductor Nanocrystals

Marshall

Schnitzer

2013

ACS Nano

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“…Compared with the traditional organic dyes, QDs have excellent optical properties: a wider absorption band and a narrower emission band of mostly symmetric shape [53]. In 2003, Peng's research group [54] proposed that semiconductor NCs can be used as the gas sensing material, because gas can cause a weak change of chemical or physical properties on NCs surface, and it thus changes the optical properties.…”

Section: Sensorsmentioning

confidence: 99%

Exploration of nano-surface chemistry for spectral analysis

Liu

Lü

et al. 2013

Chin. Sci. Bull.

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The applications of nano-surface chemistry in the field of spectral analysis have attracted growing interest in recent years. In this article, we reviewed the applications of nanomaterials-based chemical reactions for spectral analysis, including the development in plasma-catalysis, surface-enhanced spectroscopy, separation and preconcentration, chemical vapor generation, labeling and signal amplification. Introduction of nano-surface chemistry to spectral analysis not only improves the sensitivity and selectivity, broadens the application range of spectral analysis, but also affords analytical community special characterization tools.surface chemistry, nanomaterial, plasma, separation, chemical vapor generation, opticle gas sensors, atomic spectrometry Citation:Li C H, Liu R, Lü Y, et al. Exploration of nano-surface chemistry for spectral analysis.

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“…Optical detection often requires bulky components and fluorescent labeling that increases the complexity and cost of the system [3]. Quenching of labels and sterical interference with molecular binding are other drawbacks of fluorescent labeling techniques [4]. Although, optical systems can detect droplets at very high rates (on the order of kHz), these systems are not scalable [5].…”

Section: Introductionmentioning

confidence: 99%

Microfluidic droplet content detection using integrated capacitive sensors

Isgor

Marçalı

Keser

et al. 2015

Sensors and Actuators B: Chemical

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a b s t r a c tMicrofluidic capacitive sensors have been used for detection of droplets, however they have been lacking the sensitivity required for detecting the content of droplets. In this study, we developed a scalable, portable, robust and high sensitivity capacitive microdroplet content detection system using coplanar electrodes with nanometer thick silicon dioxide (SiO 2 ) passivation layer and off-the-shelf capacitive sensors. The microfluidic chip we have designed provides easy and rapid modification of droplet content by mixing two aqueous liquids at any given ratio. The change in dielectric constant of the droplet content leads to the change in capacitive signal. The dielectric content of droplets was modified continuously while corresponding capacitance signal was measured. The resolution of the system was measured as 3 dielectric permittivity units. The results were verified using a semiconductor parameter analyzer. The application specific integrated circuit used in this work enables a portable, low-cost detection system and matches the performance of bench-top analyzers. Automated and precise measurement of dielectric content in droplets for biochemical assay monitoring is a major application of the presented system.

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Quantum dots versus organic dyes as fluorescent labels

Cited by 3,462 publications

References 120 publications

Optical Strategies for Sensing Neuronal Voltage Using Quantum Dots and Other Semiconductor Nanocrystals

Optical Strategies for Sensing Neuronal Voltage Using Quantum Dots and Other Semiconductor Nanocrystals

Exploration of nano-surface chemistry for spectral analysis

Microfluidic droplet content detection using integrated capacitive sensors

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