3D confined self-assembling of QD within super-engineering block copolymers as biocompatible superparticles enabling sti
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School of Materials and Energy, University of Electronic Science and Technology of China, Chengdu 611731, China The Avram and Stella Goldstein-Goren Department of Biotechnology Engineering, Ben-Gurion University of the Negev, Beer-Sheva 8410501, Israel 3 State Key Laboratory of Biotherapy, Sichuan University, Chengdu 610051, China 2
© Tsinghua University Press and Springer-Verlag GmbH Germany, part of Springer Nature 2020 Received: 7 July 2020 / Revised: 1 September 2020 / Accepted: 2 September 2020
ABSTRACT Eliminating colloidal toxicity and enabling its intrinsic fluorescence in aggressive environmental conditions are the key challenges for commercializing hydrophobic cadmium based quantum dots (QD). Polyarylene ether nitriles (PEN) are an example of super-engineering thermoplastics that possess a unique combination of thermal stability, intrinsic fluorescence, biocompatibility and distinct emulsion self-assembly feature. Herein, the co-self-assembly of amphiphilic PEN with hydrophobic CdSe@ZnS QD, confined in the three dimensional (3D) oil-in-water emulsion droplets, has been explored to fabricate fluorescent microparticles (FMP). It was found that these FMP demonstrated good biocompatibility (cell viability above 90%), while exhibiting a fluorescence emission in aqueous solution that was retained (intensity retention ratio above 80%) within the whole pH range of 1–14, as well as, after being subjected to autoclaving at 120 oC for 1 h. Interestingly, it was discovered that introduction of calcium ions in the emulsion self-assembly contributed to in-situ generation of phase changing nanoplates inside the FMP, which led to the photo-thermal modulated solid state fluorescence from drop-casted FMP film. Thanks to their versatile fluorescence, these FMP colloids were exploited as fluorescent probes for macrophages imaging, while micro-patterns with reversible changing of emission color were induced via thermal treatment and direct laser lithography.
KEYWORDS three dimensional (3D) confinement, self-assembly, quantum dots, amphiphilic polyarylene ether nitrile, stimulus responsive fluorescence
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Introduction
Cadmium-based quantum dots (QD) are small sized nanocrystals showing promising fluorescent properties, including sizedependent narrow emission, wide excitation wavelength range, nearly identical luminescence emission between single nanoparticle and ensemble of QD, high quantum yields, as well as, decent anti-photo bleaching [1, 2]. However, the intrinsic hydrophobicity and notorious toxicity of Cd-based QD have hindered their wider application, especially in biomedicine. Although there are published studies describing the phase transition of hydrophobic Cd-based QD via hydrophilic ligand exchange or direct synthesis of cadmium-free water soluble QD, their quantum yield and fluorescence stability remain inferior to those of classical hydrophobic Cd-based QD stabilized with oleic acid/amino ligands [3]. In addition to their diverse analytical and imaging applications in various aqueous scenarios, the research in
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