Abstract
This paper describes the functionalization of poly(poly(ethylene glycol) methacrylate) (PPEGMA)-grafted CdTe (PPEGMA-g-CdTe) quantum dots (QDs) via surface-initiated reversible addition–fragmentation chain transfer (SI-RAFT) polymerization for immobilization of adenosine. Initially, the hydroxyl-coated CdTe QDs, synthesized using 2-mercaptoethanol (ME) as a capping agent, were coupled with a RAFT agent, S-benzyl S′-trimethoxysilylpropyltrithiocarbonate (BTPT), through a condensation reaction. Then, 2,2′-azobisisobutyronitrile (AIBN) was used to successfully initiate in situ RAFT polymerization to generate PPEGMA-g-CdTe nanocomposites. Adenosine-above-PPEGMA-grafted CdTe (Ado-i-PPEGMA-g-CdTe) hybrids were formed by the polymer shell, which had successfully undergone bioconjugation and postfunctionalization by adenosine (as a nucleoside). Fourier transform infrared (FT-IR) spectrophotometry, energy-dispersive X-ray (EDX) spectroscopy, thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy results indicated that a robust covalent bond was created between the organic PPEGMA part, cadmium telluride (CdTe) QDs, and the adenosine conjugate. The optical properties of the PPEGMA-g-CdTe and Ado-i-PPEGMA-g-CdTe hybrids were investigated by photoluminescence (PL) spectroscopy, and the results suggest that they have a great potential for application as optimal materials in biomedicine.
Highlights
Semiconductor nanocrystals, such as quantum dots (QDs), have recently attracted much attention in biological fields because of their advantageous properties, including high photostability, sharp emission, wide absorption, and especially high photoluminescence (PL) quantum yield [1–8]
After dried at 40 C under a vacuum oven to acquire the adenosine-above-poly(poly(ethylene glycol) methacrylate) (PPEGMA)-grafted cadmium telluride (CdTe) continuously stirring for 4 h, the samples were collected and washed several times with phosphate-buffered saline (PBS), (Ado-i-PPEGMA-g-CdTe) dried at 40 °C under a vacuum oven to acquire the adenosine-above-PPEGMA-grafted CdTe (Ado-iPPEGMA-g-CdTe) nanohybrids
Ado-i-PPEGMA-g-CdTe QDs was obtained by selectively initiating the last hydroxyl
Summary
Semiconductor nanocrystals, such as quantum dots (QDs), have recently attracted much attention in biological fields because of their advantageous properties, including high photostability, sharp emission, wide absorption, and especially high photoluminescence (PL) quantum yield [1–8]. The RAFT polymerization, when compared with other living polymerization techniques, is compatible with various functions (containing reactive functional groups) in monomers, making it an effective synthetic tool for potential tailored designs and in preparing polymers with fluorescent labels, polymer–drug conjugates, and novel polymeric bioconjugates. Many biocompatible polymers, such as poly(2-hydroxyethyl methacrylate) (PHEMA), poly(poly(ethylene glycol) methyl ether monomethacrylate) (PPEGMA), and poly(allyl methacrylate) (polyAMA), have been employed to decorate nanomaterials via RAFT polymerization in order to prepare new materials for different purposes [43–49]. Surface biocompatibility was ensured by attaching adenosine to one end of the PEG branches using the N,N 0 -disuccinimidyl carbonate (DSC) as a biofunctional linker
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