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Förster Resonance Energy Transfer between Quantum Dot Donors and Quantum Dot Acceptors.

Chou KF, Dennis AM - Sensors (Basel) (2015)

Bottom Line: The unique optical properties of QDs provide certain advantages and also specific challenges with regards to sensor design, compared to other FRET systems.The fundamentals of FRET within a nominally homogeneous QD population as well as energy transfer between two distinct colors of QDs are discussed.Examples of successful sensors are highlighted, as is cascading FRET, which can be used for solar harvesting.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomedical Engineering, Boston University, Boston, MA 02215, USA. kfchou@bu.edu.

ABSTRACT
Förster (or fluorescence) resonance energy transfer amongst semiconductor quantum dots (QDs) is reviewed, with particular interest in biosensing applications. The unique optical properties of QDs provide certain advantages and also specific challenges with regards to sensor design, compared to other FRET systems. The brightness and photostability of QDs make them attractive for highly sensitive sensing and long-term, repetitive imaging applications, respectively, but the overlapping donor and acceptor excitation signals that arise when QDs serve as both the donor and acceptor lead to high background signals from direct excitation of the acceptor. The fundamentals of FRET within a nominally homogeneous QD population as well as energy transfer between two distinct colors of QDs are discussed. Examples of successful sensors are highlighted, as is cascading FRET, which can be used for solar harvesting.

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Schematic of surface-tethered induced aggregation, where the presence of a target nucleotide sequence would induce binding of a QD to a surface. The surface-tethered QD would have multiple additional binding sites available for further target binding and additional QDs labeled with complimentary sequences. Such a design is proposed as a means with which to take advantage of the multivalancy of both the donor and acceptor in QD-QD FRET. Schematic is not drawn to scale.
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sensors-15-13288-f015: Schematic of surface-tethered induced aggregation, where the presence of a target nucleotide sequence would induce binding of a QD to a surface. The surface-tethered QD would have multiple additional binding sites available for further target binding and additional QDs labeled with complimentary sequences. Such a design is proposed as a means with which to take advantage of the multivalancy of both the donor and acceptor in QD-QD FRET. Schematic is not drawn to scale.

Mentions: QDs present a large biochemically-active surface, resulting in multiple binding sites. This enables QDs to be successfully utilized as nanoscaffolds in hybrid systems, where multiple organic acceptors bind to a single QD donor, enhancing FRET efficiency (Equation (2), n > 1). In addition, the multivalency of the NP has enabled sensor designers to attach multiple labels, delivery sequences, or binding sequences to a single particle, providing for the development of complex multifunctional devices, all centered around one discrete hub. In the case of QD-QD FRET sensors, however, the presence of multiple binding sites on both the donor and acceptor QDs can facilitate significant aggregation, when the donor binds an acceptor, which binds or binds one or more donors, which bind one or more additional acceptors, etc. This form of clustering could be unpredictable and inhomogeneous, which may reduce the repeatability of assays built upon this platform. None of the sensors discussed in this review addressed this aggregation issue, so it is unclear to what extent this impacts sensor design or the reliability of QD-QD FRET-based assays. Solution-phase experiments could certainly be challenged if aggregation were induced to such an extent that colloidal stability was threatened. One could imagine, however, possible sensor designs where induced aggregation could be a significant advantage, for example by raising the local concentration of particles tethered to a surface due to ligand-induced clustering (Figure 15). A surface-tethered sensor could be highly useful for paper-based diagnostics, microfluidic sensors, or TIRF-based imaging, where the analyte-induced aggregation of donor and acceptor QDs could be used to both concentrate the analyte and enhance the detection signal and lower the detection limit.


Förster Resonance Energy Transfer between Quantum Dot Donors and Quantum Dot Acceptors.

Chou KF, Dennis AM - Sensors (Basel) (2015)

Schematic of surface-tethered induced aggregation, where the presence of a target nucleotide sequence would induce binding of a QD to a surface. The surface-tethered QD would have multiple additional binding sites available for further target binding and additional QDs labeled with complimentary sequences. Such a design is proposed as a means with which to take advantage of the multivalancy of both the donor and acceptor in QD-QD FRET. Schematic is not drawn to scale.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4507609&req=5

sensors-15-13288-f015: Schematic of surface-tethered induced aggregation, where the presence of a target nucleotide sequence would induce binding of a QD to a surface. The surface-tethered QD would have multiple additional binding sites available for further target binding and additional QDs labeled with complimentary sequences. Such a design is proposed as a means with which to take advantage of the multivalancy of both the donor and acceptor in QD-QD FRET. Schematic is not drawn to scale.
Mentions: QDs present a large biochemically-active surface, resulting in multiple binding sites. This enables QDs to be successfully utilized as nanoscaffolds in hybrid systems, where multiple organic acceptors bind to a single QD donor, enhancing FRET efficiency (Equation (2), n > 1). In addition, the multivalency of the NP has enabled sensor designers to attach multiple labels, delivery sequences, or binding sequences to a single particle, providing for the development of complex multifunctional devices, all centered around one discrete hub. In the case of QD-QD FRET sensors, however, the presence of multiple binding sites on both the donor and acceptor QDs can facilitate significant aggregation, when the donor binds an acceptor, which binds or binds one or more donors, which bind one or more additional acceptors, etc. This form of clustering could be unpredictable and inhomogeneous, which may reduce the repeatability of assays built upon this platform. None of the sensors discussed in this review addressed this aggregation issue, so it is unclear to what extent this impacts sensor design or the reliability of QD-QD FRET-based assays. Solution-phase experiments could certainly be challenged if aggregation were induced to such an extent that colloidal stability was threatened. One could imagine, however, possible sensor designs where induced aggregation could be a significant advantage, for example by raising the local concentration of particles tethered to a surface due to ligand-induced clustering (Figure 15). A surface-tethered sensor could be highly useful for paper-based diagnostics, microfluidic sensors, or TIRF-based imaging, where the analyte-induced aggregation of donor and acceptor QDs could be used to both concentrate the analyte and enhance the detection signal and lower the detection limit.

Bottom Line: The unique optical properties of QDs provide certain advantages and also specific challenges with regards to sensor design, compared to other FRET systems.The fundamentals of FRET within a nominally homogeneous QD population as well as energy transfer between two distinct colors of QDs are discussed.Examples of successful sensors are highlighted, as is cascading FRET, which can be used for solar harvesting.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomedical Engineering, Boston University, Boston, MA 02215, USA. kfchou@bu.edu.

ABSTRACT
Förster (or fluorescence) resonance energy transfer amongst semiconductor quantum dots (QDs) is reviewed, with particular interest in biosensing applications. The unique optical properties of QDs provide certain advantages and also specific challenges with regards to sensor design, compared to other FRET systems. The brightness and photostability of QDs make them attractive for highly sensitive sensing and long-term, repetitive imaging applications, respectively, but the overlapping donor and acceptor excitation signals that arise when QDs serve as both the donor and acceptor lead to high background signals from direct excitation of the acceptor. The fundamentals of FRET within a nominally homogeneous QD population as well as energy transfer between two distinct colors of QDs are discussed. Examples of successful sensors are highlighted, as is cascading FRET, which can be used for solar harvesting.

Show MeSH