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Compact Quantum Dots for Single-molecule Imaging
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Extremely high brightness from polymer-encapsulated quantum dots for two-photon cellular and deep-tissue imaging
Yanyan Fan1, Helin Liu2, Rongcheng Han3
11] State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China [2] Institute of Opto-electronic Materials and Technology, South China Normal University, Guangzhou 510631, China.
Scientific Reports
|April 25, 2015
Summary
Researchers developed polymer-encapsulated quantum dots (P-QDs) that enhance fluorescence quantum yield in water. These P-QDs offer superior brightness and stability for advanced imaging applications.
Area of Science:
- Materials Science
- Nanotechnology
- Biophotonics
Background:
- High two photon absorption (TPA) materials are crucial for applications like three-dimensional data storage, TPA microscopy (TPM), and photodynamic therapy (PDT).
- A significant challenge is the decrease in quantum yield (QY) when TPA materials are transferred to aqueous media.
- Optimizing TPA materials for TPM requires high TPA excitation (TPE) brightness, photostability, and low cytotoxicity.
Purpose of the Study:
- To develop a method for preparing polymer-encapsulated quantum dots (P-QDs) with enhanced properties for aqueous applications.
- To investigate the significant enhancement of QY in P-QDs compared to bare QDs in organic solvents.
- To evaluate the suitability of P-QDs as probes for high-quality cellular and tissue imaging.
Main Methods:
- Preparation of polymer-encapsulated quantum dots (P-QDs).
- Measurement of fluorescence quantum yield (QY) in tetrahydrofuran (THF) and water.
- Analysis of fluorescence decay lifetimes to understand QY enhancement mechanisms.
- Assessment of TPE brightness, photostability, colloidal stability, and cytotoxicity.
- Evaluation of P-QDs for cellular and tissue imaging using TPM.
Main Results:
- A convenient and efficient method for preparing P-QDs was established.
- QY of quantum dots (QDs) was significantly enhanced from 0.33 (in THF) to 0.84 (P-QD in water).
- Enhanced QY is attributed to the blocking of nonradiative decay pathways from surface trap states.
- P-QDs demonstrated high TPE brightness (σ × ϕ up to 6.2 × 10^6 GM), excellent photostability, and colloidal stability.
- Minimal cytotoxicity was observed for P-QDs.
- High-quality cellular TP imaging with a signal-to-background ratio > 100 and tissue imaging with a penetration depth of 2200 μm were achieved.
Conclusions:
- Polymer encapsulation effectively enhances the quantum yield of quantum dots in aqueous media.
- P-QDs exhibit superior brightness, photostability, and biocompatibility, making them ideal for TPM.
- The developed P-QDs are promising probes for advanced in vivo and in vitro imaging applications.
