Copolymerization and Synthesis of Multiply Binding Histamine Ligands for the Robust Functionalization of Quantum Dots

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• 作者：Anand Viswanath ; Yi Shen ; Alexandra N. Green ; Rui Tan ; Andrew B. Greytak ; Brian C. Benicewicz
• 刊名：Macromolecules
• 出版年：2014
• 出版时间：December 9, 2014
• 年：2014
• 卷：47
• 期：23
• 页码：8137-8144
• 全文大小：374K
• ISSN：1520-5835

文摘

The polymeric functionalization of quantum dots via ligand exchange is a robust method for the preparation of stable fluorescent particles with high quantum yields. For most biological applications of quantum dots, water solubility is a key requirement; to achieve biocompatibility, polymeric ligand systems that can provide water solubility as well as effective anchoring groups are advantageous. In this work, histamine functional polymers bearing poly(ethylene glycol) (PEG) side chains were prepared using RAFT polymerization. A versatile postmodification strategy using activated ester units of N-methacryloxysuccinimide (NMS) and poly(ethylene glycol) methacrylate in the polymer chain afforded copolymers ranging from 6K to 50K with low polydispersities, along with tailored composition of each monomer along the copolymer chain. By controlling the monomer ratio, PEGMA molecular weight, time, and temperature, the composition could be tuned to study its effect on quantum dot functionalization. Representative oleate-capped CdSe/Cd_xZn_1鈥?i>xS QDs purified by a recently established gel permeation chromatography (GPC) method were used to test the effectiveness of the histamine-bearing polymers for preparation of water-soluble QDs. Successful ligand exchange of the QDs was characterized by good dispersions in water, lack of aggregation between QDs, and good quantum yields in water. Overall, the synthetic method demonstrates a facile and robust postmodification strategy for the formation of multiply binding, histamine-bearing copolymers, which can be applied to nanomaterials for fundamental investigations and bioimaging/biodistribution studies.