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

Abstract

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.

Recent development of silica nanoparticles as delivery vectors for cancer imaging and therapy

“…In 2012, Jun et al reported an ultrasensitive QDs-embedded SiNP for tumor fluorescence imaging (Figure 2a). 73 Compared to a single QD, the QDs-embedded SiNPs showed brighter fluorescence intensity and increased uptake by HeLa cells (Figure 2b). For in vivo fluorescence cell tracking, single QD labeled- or QDs-embedded SiNPs labeled-HeLa cells were injected into mice for long-term fluorescence imaging, and the results showed that even after 10 days, the QDs-embedded SiNPs emitted strong fluorescence for in vivo imaging (Figure 2c).…”

Interaction of silicon-based quantum dots with gibel carp liver: oxidative and structural modifications

“…Due to previously known benefits of silicon, like reduced elemental toxicity, its potential biodegradability to silicic acid and its abundance and low costs are adding to the promising results of recent investigations that indicate silicon use in in vivo imaging to be a good alternative to cadmium QDs [13,14]. Nanoporous and microparticulate forms of silicon have shown great promise in terms of compatibility and cytotoxicity [15]. Nonetheless, studies concerned with the biological and medical applications of silicon-based QDs are less numerous and still at preliminary stages [16-18].…”

Quantum dots decorated gold nanorod as fluorescent-plasmonic dual-modal contrasts agent for cancer imaging

“…The high efficient assembly of hydrophobic QDs with metal-affinity substrates via coordination chemistry (Lu et al, 2011), provides a promising alternative to improve QDs loading density and optical properties (Jun et al, 2012), compared with aqueous phase layer-by-layer assembly technics (Bakalova et al, 2008). Silicon, a versatile and biocompatible material for both substrates and coating layers on nano-objects (Jana et al, 2007;Foda et al, 2014), exhibits unique process ability that enabling facile incorporation of noble metal nanoparticles and a variable space between the plasmonic interior and surface attached fluorophores (Liu et al, 2006).…”