Search query: Optical Molecular Sensing with Semiconductor Quantum Dots

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abstract: Semiconductor quantum dots (QDs) exhibit unique optical and photophysical properties. These features are implemented to develop optical molecular sensor systems. The review addresses the methods to functionalize the QDs with chemical capping layers that enable the use of the resulting hybrid structures for sensing, and discusses the photophysical mechanisms being applied in the different sensor systems. Different methods to design the chemically modified QDs hybrid structures for sensing low molecular weight substrates, metal ions, anions and gases are presented. These include the functionalization of the QDs with ligands that bind ions, the modification of the QDs with substrate specific ligands or receptor units, and the chemical modification of the QDs upon sensing. Specific emphasis is directed to describe the cooperative catalytic functions of the QDs in the sensing processes, and to address the function of sensing with logic gate operations.
author_names: Ronit Freeman

Itamar Willner
title: Optical molecular sensing with semiconductor quantum dots (QDs)
venue: Chemical Society reviews
year: 2012

author_names: Ronit Freeman

Itamar Willner
title: Optical Molecular Sensing with Semiconductor Quantum Dots (QDs)
year: 2012

abstract: Abstract Luminescent quantum dots (QDs) are colloidal semiconductor nanocrystals consisting of an inorganic core covered by a molecular layer of organic surfactants. Although QDs have been known for more than thirty years, they are still attracting the interest of researchers because of their unique size tunable optical and electrical properties arising from quantum confinement. Moreover, the controlled decoration of the QD surface with suitable molecular species enables the rational design of inorganic organic multicomponent architectures that can show a vast array of functionalities. This minireview highlights the recent progress in the use of surface modified QDs in particular, those based on cadmium chalcogenides as supramolecular platforms for light related applications such as optical sensing, triplet photosensitization, photocatalysis and phototherapy.
author_names: Marcello La Rosa

Emily H Payne

Alberto Credi
title: Semiconductor Quantum Dots as Components of Photoactive Supramolecular Architectures
venue: ChemistryOpen
year: 2020

abstract: Due to an internal error, the following article was added after the original publication of the special issue on Nanochemistry (11 12/2012) Semiconductor quantum dots (QDs) exhibit unique photophysical properties, turning these nanomaterials into ideal components for the development of optical or optoelectronic sensors and biosensors. Various methods and mechanisms of using QDs for sensing have been implemented, including the probing of recognition events by the luminescence of the QDs, their application in fluorescence resonance energy transfer (FRET) electron transfer (ET) chemiluminescence resonance energy transfer (CRET) and photoelectrochemical generation of photocurrents. These different mechanisms are exemplified by discussing the QD based sensing of low molecular weight substrates, chiroselective sensing of amino acids, probing of the catalytic activities of enzymes (casein kinase, tyrosinase, NAD+ dependent enzymes) and analysis of DNA and of aptamer substrate complexes. Specifically, the amplified QD based sensing of DNA using exonuclease III as target regeneration biocatalyst and the multiplexed detection of DNAs using differently sized QDs are discussed. Also, the implementation of the CRET process for the multiplexed analysis of DNA using differently sized QDs is addressed. Finally, the use of semiconductor QDs for the photoelectrochemical detection of DNA, aptamer substrate complexes and enzyme activities are discussed. Specifically, the use of QDs for photoelectrochemical sensors, using the CRET process as internal excitation light source, is described. The future applications of the various QD based sensors as analytical devices and as nanotools that probe intracellular processes are discussed.
author_names: Ronit Freeman

Julia Girsh

Bilha Willner

Itamar Willner
title: Sensing and Biosensing with Semiconductor Quantum Dots
year: 2012

abstract: Featuring size tunable electrical and optical properties, semiconductor quantum dots (QDs) are appealing intensive interests in developing ingenious luminescent materials for chemosensory and biological applications. The surface modification of QDs with functional ligands not only fine tunes the physiochemical properties and fluorescence emission behaviors, but also induces the designated interplay between analytes and probes for special determination. In this review, the fundamental principles guiding the rational design of high efficiency luminescent sensors with surface engineering are overviewed. The state of the art applications of QDs based probes are highlighted for the sensing of molecular substrates and ionic species as well as various biological applications, with the inherent recognition mechanisms elaborated for representative cases. The challenge and future research direction in this emerging and promising research field are also discussed.
author_names: Jie Zhou

Yun Liu

Jian Tang

Weihua Tang
title: Surface ligands engineering of semiconductor quantum dots for chemosensory and biological applications
year: 2017

abstract: Research on fluorescent semiconductor quantum dots (QDs, or nanocrystals) has been focused towards developing analytical applications for which their robust optical properties add value. To this end, the materials must be efficiently water solubilized and functionalized. This thesis details my research in this regard, starting with the development of a one step method to produce ~10 nm hydrodynamic diameter water soluble CdSe/ZnS quantum dots through ligand exchange with a near monolayer of organosilane caps. The samples are stable for months under benchtop conditions and have high quantum yields ~60% which is unprecedented for cap exchanged QDs. Furthermore, the procedure can be applied to CdS/ZnS, ZnSe/ZnMnS/ZnS, and CuInS2/ZnS QDs. While water solubilization is necessary for the development of analytical applications, the materials must be functionalized with chemical and biological vectors for sensing applications. In this regard, small molecular reagents that can efficiently functionalize water soluble CdSe/ZnS nanocrystals have been developed. These reagents do not cause quenching or precipitation of QDs as observed with commercially available activators. Last, a ratiometric fluorescent QD reporter for O2 levels in water created by attaching multiple pyrene functional chromophores to the surface of bright, water soluble semiconductor nanocrystals. These ligands have been used with both CdSe/CdZnS and AgInS2/ZnS nanocrystals, the latter of which represents a fluorescent QD sensor with significantly reduced toxicity.
author_names: Xi Zhang
title: Semiconductor Quantum Dots Water Solubilization, Functionalization, and Ratiometric Sensing of O2
year: 2014

abstract: Semiconductor quantum dots possess unique size dependent electronic properties and are of high potential interest for the construction of functional nanodevices. Photoinduced electron and energy transfer processes between quantum dots and surface bound molecular species open up attractive routes to implement chemical switching of luminescence, which is at the basis of luminescence sensing. In this article, we discuss the general principles underlying the rational design of this kind of multicomponent species. Successively, we illustrate a few prominent examples, taken from the recent literature, of luminescent chemosensors constructed by attaching molecular species to the surface of quantum dots.
author_names: Serena Silvi

Massimo Baroncini

Marcello La Rosa

Alberto Credi
title: Interfacing Luminescent Quantum Dots with Functional Molecules for Optical Sensing Applications
venue: Topics in Current Chemistry
year: 2016

abstract: Since its emergence, semiconductor nanoparticles known as quantum dots (QDs) have drawn considerable attention and have quickly extended their applicability to numerous fields within the life sciences. This is largely due to their unique optical properties such as high brightness and narrow emission band as well as other advantages over traditional organic fluorophores. New molecular sensing strategies based on QDs have been developed in pursuit of high sensitivity, high throughput, and multiplexing capabilities. For traditional biological applications, QDs have already begun to replace traditional organic fluorophores to serve as simple fluorescent reporters in immunoassays, microarrays, fluorescent imaging applications, and other assay platforms. In addition, smarter, more advanced QD probes such as quantum dot fluorescence resonance energy transfer (QD FRET) sensors, quenching sensors, and barcoding systems are paving the way for highly sensitive genetic and epigenetic detection of diseases, multiplexed identification of infectious pathogens, and tracking of intracellular drug and gene delivery. When combined with microfluidics and confocal fluorescence spectroscopy, the detection limit is further enhanced to single molecule level. Recently, investigations have revealed that QDs participate in series of new phenomena and exhibit interesting non photoluminescent properties. Some of these new findings are now being incorporated into novel assays for gene copy number variation (CNV) studies and DNA methylation analysis with improved quantification resolution. Herein, we provide a comprehensive review on the latest developments of QD based molecular diagnostic platforms in which QD plays a versatile and essential role.
author_names: Yi Zhang

Tza-Huei Wang
title: Quantum Dot Enabled Molecular Sensing and Diagnostics
venue: Theranostics
year: 2012

abstract: Quantum dots (QDs) are attractive semiconductor fluorescent nanomaterials with remarkable optical and electrical properties. The broad absorption spectra and high stability of QD transducers are advantageous for sensing and bioimaging. Molecular imprinting is a technique for manufacturing synthetic polymeric materials with a high recognition ability towards a target analyte. The high selectivity of the molecularly imprinted polymers (MIPs) is a result of the fabrication process based on the template tailored polymerization of functional monomers. The three dimensional cavities formed in the polymer network can serve as the recognition elements of sensors because of their specificity and stability. Appending specific molecularly imprinted layers to QDs is a promising strategy to enhance the stability, sensitivity, and selective fluorescence response of the resulting sensors. By merging the benefits of MIPs and QDs, inventive optical sensors are constructed. In this review, the recent synthetic strategies used for the fabrication of QD nanocrystals emphasizing various approaches to effective functionalization in aqueous environments are discussed followed by a detailed presentation of current advances in QD conjugated MIPs (MIP QDs) Frontiers in manufacturing of specific imprinted layers of these nanomaterials are presented and factors affecting the specific behaviour of an MIP shell are identified. Finally, current limitations of MIP QDs are defined and prospects are outlined to amplify the capability of MIP QDs in future sensing.
author_names: Monika Sobiech

Piotr Bujak

Piotr Lulinski

Adam Pron
title: Semiconductor nanocrystal polymer hybrid nanomaterials and their application in molecular imprinting.
venue: Nanoscale
year: 2019

abstract: Bright emitters with photoluminescence in the spectral region of 800 1600 nm are increasingly important as optical reporters for molecular imaging, sensing, and telecommunication and as active components in electrooptical and photovoltaic devices. Their rational design is directly linked to suitable methods for the characterization of their signal relevant properties, especially their photoluminescence quantum yield (Ph(f) Aiming at the development of bright semiconductor nanocrystals with emission >1000 nm, we designed a new NIR/IR integrating sphere setup for the wavelength region of 600 1600 nm. We assessed the performance of this setup by acquiring the corrected emission spectra and Ph(f) of the organic dyes Itrybe, IR140, and IR26 and several infrared (IR) emissive Cd(1 x)Hg(x)Te and PbS semiconductor nanocrystals and comparing them to data obtained with two independently calibrated fluorescence instruments absolutely or relative to previously evaluated reference dyes. Our results highlight special challenges of photoluminescence studies in the IR ranging from solvent absorption to the lack of spectral and intensity standards together with quantum dot specific challenges like photobrightening and photodarkening and the size dependent air stability and photostability of differently sized oleate capped PbS colloids. These effects can be representative of lead chalcogenides. Moreover, we redetermined the Ph(f) of IR26, the most frequently used IR reference dye, to 1.1 x 10( 3) in 1,2 dichloroethane DCE with a thorough sample reabsorption and solvent absorption correction. Our results indicate the need for a critical reevaluation of Ph(f) values of IR emissive nanomaterials and offer guidelines for improved Ph(f) measurements.
author_names: Soheil Hatami

Christian Wurth

Martin Kaiser

Susanne Leubner

Stefanie Gabriel

Lydia Bahrig

Vladimir Lesnyak

Jutta Pauli

Nikolai Gaponik

Alexander Eychmuller

Ute Resch-Genger
title: Absolute photoluminescence quantum yields of IR26 and IR emissive Cd(1 x)Hg(x)Te and PbS quantum dots method and material inherent challenges.
venue: Nanoscale
year: 2015