Silica-Shelled Single Quantum Dot Micelles as Imaging Probes with Dual or Multimodality

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• 作者：Rumiana Bakalova ; Zhivko Zhelev ; Ichio Aoki ; Hideki Ohba ; Yusuke Imai ; Iwao Kanno
• 刊名：Analytical Chemistry
• 出版年：2006
• 出版时间：August 15, 2006
• 年：2006
• 卷：78
• 期：16
• 页码：5925 - 5932
• 全文大小：682K
• 年卷期：v.78,no.16(August 15, 2006)
• ISSN：1520-6882

文摘

The present study describes a stabilization of singlequantum dot (QD) micelles by a "hydrophobic" silicaprecursor and an extension of a silica layer to form a silicashell around the micelle using "amphiphilic" and "hydrophilic" silica precursors. The obtained product consists of ~92% single nanocrystals (CdSe, CdSe/ZnS, orCdSe/ZnSe/ZnS QDs) into the silica micelles, coated witha silica shell. The thickness of the silica shell varies,starting from 3-4 nm. Increasing the shell thicknessincreases the photoluminescence characteristics of QDsin an aqueous solution. The silica-shelled single CdSe/ZnS QD micelles possess a comparatively high quantumyield in an aqueous solution, a controlled small size, sharpphotoluminescence spectra (fwhm ~30 nm), an absenceof aggregation, and a high transparency. The surface ofthe nanoparticles is amino-functionalized and ready forconjugation. A comparatively good biocompatibility isdemonstrated. The nanoparticles show ability for intracellular delivery and are noncytotoxic during long-termincubation with viable cells in the absence of light exposure, which makes them appropriate for cell tracing anddrug delivery. The presence of the hydrophobic layerbetween the QD and silica-shell ensures an incorporationof other hydrophobic molecules with interesting properties (e.g., hydrophobic paramagnetic substances, hydrophobic photosensitizers, membrane stabilizers, lipid-soluble antioxidants or prooxidants, other hydrophobicorganic dyes, etc.) in the close proximity of the nanocrystal. Thus, it is possible to combine the characteristics ofhybrid materials with the priority of small size. The silica-shelled single QD micelles are considered as a basis forfabrication of novel hybrid nanomaterials for industrialand life science applications, for example, nanobioprobeswith dual modality for simultaneous application in different imaging techniques (e.g., fluorescent imaging andfunctional magnetic resonance imaging).