Ultrasensitive, Biocompatible, Quantum-Dot-Embedded Silica Nanoparticles for Bioimaging

• Published in: Advanced functional materials 2012-05, Vol.22 (9), p.1843-1849
• Main Authors: Jun, Bong-Hyun, Hwang, Do Won, Jung, Heung Su, Jang, Jaeho, Kim, Hyunsoo, Kang, Homan, Kang, Taegyu, Kyeong, San, Lee, Hyeokjae, Jeong, Dae Hong, Kang, Keon Wook, Youn, Hyewon, Lee, Dong Soo, Lee, Yoon-Sik
• Format: Article
• Language: English
• Subjects: in vivo imaging; multishell quantum dots; quantum dots; silica nanoparticles; water-compatible nanoprobes
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.201102930

The successful development of highly sensitive, water‐compatible, nontoxic nanoprobes has allowed nanomaterials to be widely employed in various applications. The applicability of highly bright quantum dot (QD)‐based probes consisting of QDs on 120 nm silica nanoparticles (NPs) with silica shells is investigated. Their substantial merits, such as their brightness and biocompatibility, for effective bioimaging are demonstrated. Silica‐coated, QD‐embedded silica NPs (Si@QDs@Si NPs) containing QDs composed of CdSe@ZnS (core‐shell) are prepared to compare their structure‐based advantages over single QDs that have a similar quantum yield (QY). These Si@QDs@Si NPs exhibit approximately 200‐times stronger photoluminescence (PL) than single QDs. Cytotoxicity studies reveal that the Si@QDs@Si NPs are less toxic than equivalent numbers of silica‐free single quantum dots. The excellence of the Si@QDs@Si NPs with regard to in vivo applications is illustrated by significantly enhanced fluorescence signals from Si@QDs@Si‐NP‐tagged cells implanted in mice. Notably, a more advanced version of QD‐based silica NPs (Si@mQDs@Si NPs), containing multishell quantum dots (mQDs) composed of CdSe@CdS@ZnS, are prepared without significant loss of QY during surface modification. In addition, the Si@mQDs@Si NPs display a fivefold higher fluorescence activity than the Si@QDs@Si NPs. As few as 400 units of Si@mQDs@Si‐ NP‐internalized cells can be detected in the cell‐implanted mouse model. Very bright quantum dot (QD)‐based probes consisting of QDs on 120 nm silica nanoparticles with silica shells are investigated for effective bioimaging. Silica‐coated, QD‐embedded silica nanoparticles exhibit approximately 200‐times stronger photoluminescence (PL) than single QDs. The more advanced version of QD‐based silica nanoparticles containing multishell QDs can detect as few as 400 units of nanoparticle‐internalized cells in a cell‐implanted mouse model.