Dataset Information

Functional characterization and axonal transport of quantum dot labeled BDNF.

ABSTRACT: Brain derived neurotrophic factor (BDNF) plays a key role in the growth, development and maintenance of the central and peripheral nervous systems. Exogenous BDNF activates its membrane receptors at the axon terminal, and subsequently sends regulation signals to the cell body. To understand how a BDNF signal propagates in neurons, it is important to follow the trafficking of BDNF after it is internalized at the axon terminal. Here we labeled BDNF with bright, photostable quantum dots (QD-BDNF) and followed the axonal transport of QD-BDNF in real time in hippocampal neurons. We showed that QD-BDNF was able to bind BDNF receptors and activate downstream signaling pathways. When QD-BDNF was applied to the distal axons of hippocampal neurons, it was observed to be actively transported toward the cell body at an average speed of 1.11 ± 0.05 ?m s(-1). A closer examination revealed that QD-BDNF was transported by both discrete endosomes and multivesicular body-like structures. Our results showed that QD-BDNF could be used to track the movement of exogenous BDNF in neurons over long distances and to study the signaling organelles that contain BDNF.

SUBMITTER: Xie W

PROVIDER: S-EPMC3462492 | biostudies-literature | 2012 Aug

REPOSITORIES: biostudies-literature

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Functional characterization and axonal transport of quantum dot labeled BDNF.

Xie Wenjun W Zhang Kai K Cui Bianxiao B

Integrative biology : quantitative biosciences from nano to macro 20120706 8

Brain derived neurotrophic factor (BDNF) plays a key role in the growth, development and maintenance of the central and peripheral nervous systems. Exogenous BDNF activates its membrane receptors at the axon terminal, and subsequently sends regulation signals to the cell body. To understand how a BDNF signal propagates in neurons, it is important to follow the trafficking of BDNF after it is internalized at the axon terminal. Here we labeled BDNF with bright, photostable quantum dots (QD-BDNF) a ...[more]

PMID: 22772872

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Project description:Charge transfer processes with semiconductor quantum dots (QDs) have generated much interest for potential utility in energy conversion. Such configurations are generally nonbiological; however, recent studies have shown that a redox-active ruthenium(II)-phenanthroline complex (Ru2+-phen) is particularly efficient at quenching the photoluminescence (PL) of QDs, and this mechanism demonstrates good potential for application as a generalized biosensing detection modality since it is aqueous compatible. Multiple possibilities for charge transfer and/or energy transfer mechanisms exist within this type of assembly, and there is currently a limited understanding of the underlying photophysical processes in such biocomposite systems where nanomaterials are directly interfaced with biomolecules such as proteins. Here, we utilize redox reactions, steady-state absorption, PL spectroscopy, time-resolved PL spectroscopy, and femtosecond transient absorption spectroscopy (FSTA) to investigate PL quenching in biological assemblies of CdSe/ZnS QDs formed with peptide-linked Ru2+-phen. The results reveal that QD quenching requires the Ru2+ oxidation state and is not consistent with Förster resonance energy transfer, strongly supporting a charge transfer mechanism. Further, two colors of CdSe/ZnS core/shell QDs with similar macroscopic optical properties were found to have very different rates of charge transfer quenching, by Ru2+-phen with the key difference between them appearing to be the thickness of their ZnS outer shell. The effect of shell thickness was found to be larger than the effect of increasing distance between the QD and Ru2+-phen when using peptides of increasing persistence length. FSTA and time-resolved upconversion PL results further show that exciton quenching is a rather slow process consistent with other QD conjugate materials that undergo hole transfer. An improved understanding of the QD-Ru2+-phen system can allow for the design of more sophisticated charge-transfer-based biosensors using QD platforms.

Dataset Information

Functional characterization and axonal transport of quantum dot labeled BDNF.

Publications

Functional characterization and axonal transport of quantum dot labeled BDNF.

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