Fujioka Kouki, Hiruoka Masaki, Sato Keisuke, Manabe Noriyoshi, Miyasaka Ryosuke, Hanada Sanshiro, Hoshino Akiyoshi, Tilley Richard D, Manome Yoshinobu, Hirakuri Kenji, Yamamoto Kenji
International Clinical Research Centre, Research Institute, International Medical Centre of Japan, Japan. Institute of DNA Medicine, Research Centre for Medical Sciences, Jikei University School of Medicine, Japan.
Nanotechnology. 2008 Oct 15;19(41):415102. doi: 10.1088/0957-4484/19/41/415102. Epub 2008 Sep 3.
Semiconductor quantum dots (QDs) hold some advantages over conventional organic fluorescent dyes. Due to these advantages, they are becoming increasingly popular in the field of bioimaging. However, recent work suggests that cadmium based QDs affect cellular activity. As a substitute for cadmium based QDs, we have developed photoluminescent stable silicon quantum dots (Si-QDs) with a passive-oxidation technique. Si-QDs (size: 6.5 ± 1.5 nm) emit green light, and they have been used as biological labels for living cell imaging. In order to determine the minimum concentration for cytotoxicity, we investigated the response of HeLa cells. We have shown that the toxicity of Si-QDs was not observed at 112 µg ml(-1) and that Si-QDs were less toxic than CdSe-QDs at high concentration in mitochondrial assays and with lactate dehydrogenase (LDH) assays. Especially under UV exposure, Si-QDs were more than ten times safer than CdSe-QDs. We suggest that one mechanism for the cytotoxicity is that Si-QDs can generate oxygen radicals and these radicals are associated with membrane damages. This work has demonstrated the suitability of Si-QDs for bioimaging in lower concentration, and their cytotoxicity and one toxicity mechanism at high concentration.
半导体量子点（QDs）相对于传统有机荧光染料具有一些优势。由于这些优势，它们在生物成像领域越来越受欢迎。然而，最近的研究表明，基于镉的量子点会影响细胞活性。作为基于镉的量子点的替代品，我们采用被动氧化技术开发了光致发光稳定的硅量子点（Si-QDs）。Si-QDs（尺寸：6.5±1.5纳米）发出绿光，并已被用作活细胞成像的生物标记物。为了确定细胞毒性的最低浓度，我们研究了HeLa细胞的反应。我们发现，在112微克/毫升的浓度下未观察到Si-QDs的毒性，并且在线粒体检测和乳酸脱氢酶（LDH）检测中，高浓度下Si-QDs的毒性低于CdSe-QDs。特别是在紫外线照射下，Si-QDs比CdSe-QDs安全十倍以上。我们认为细胞毒性的一种机制是Si-QDs可以产生氧自由基，这些自由基与膜损伤有关。这项工作证明了低浓度下Si-QDs适用于生物成像，以及它们在高浓度下的细胞毒性和一种毒性机制。
