Synthesis and application of luminescent single CdS quantum dot encapsulated silica nanoparticles directed for precision optical bioimaging

Abstract

This paper presents the synthesis of aqueous cadmium sulfide (CdS) quantum dots (QDs) and silica-encapsulated CdS QDs by reverse microemulsion method and utilized as targeted bio-optical probes. We report the role of CdS as an efficient cell tag with fluorescence on par with previously documented cadmium telluride and cadmium selenide QDs, which have been considered to impart high levels of toxicity. In this study, the toxicity of bare QDs was efficiently quenched by encapsulating them in a biocompatible coat of silica. The toxicity profile and uptake of bare CdS QDs and silica-coated QDs, along with the CD31-labeled, silica-coated CdS QDs on human umbilical vein endothelial cells and glioma cells, were investigated. The effect of size, along with the time-dependent cellular uptake of the nanomaterials, has also been emphasized. Enhanced, high-specificity imaging toward endothelial cell lines in comparison with glioma cells was achieved with CD31 antibody-conjugated nanoparticles. The silica-coated nanomaterials exhibited excellent biocompatibility and greater photostability inside live cells, in addition to possessing an extended shelf life. In vivo biocompatibility and localization study of silica-coated CdS QDs in medaka fish embryos, following direct nanoparticle exposure for 24 hours, authenticated the nanomaterials' high potential for in vivo imaging, augmented with superior biocompatibility. As expected, CdS QD-treated embryos showed 100% mortality, whereas the silica-coated QD-treated embryos stayed viable and healthy throughout and after the experiments, devoid of any deformities. We provide highly cogent and convincing evidence for such silica-coated QDs as a model nanoparticle in practice, to achieve in vitro and in vivo precision targeted imaging.

Removal of Pb(ii) and Cd(ii) from wastewater using arginine cross-linked chitosan–carboxymethyl cellulose beads as green adsorbent

“…the adsorption results from the coordination of Pb(II) and Cd(II) species by the guanidine moiety of the crosslinker arginine. 33,34 Adsorption studies…”

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

“…Due to their unique optical and chemical properties, i.e., their broad absorption spectra, narrow fluorescence emission, intense fluorescence, and photo bleaching resistance [2,3], QDs were proposed as nanoprobes which were able to replace the conventional organic dyes and fluorescent proteins [4]. The use of different core material combinations and appropriate nanocrystal sizes has rendered QDs useful in biosensing [5], energy transfer [6], in vivo imaging [7], drug delivery [8], and diagnostic and cancer therapy applications [9]. …”

“…Interestingly, efforts to reduce QD toxicity include the encapsulation in a SiO 2 shell [7,12], with silicon-based QDs being expected to be less toxic than heavy metal-containing ones. 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].…”

Multifunctional Cu2−xTe Nanocubes Mediated Combination Therapy for Multi-Drug Resistant MDA MB 453

“…With remarkably diverse physicochemical properties, nanomaterials have tremendous prospects in medical treatment options. The integration of multiple functionalities such as specific cell targeting, fluorescent monitoring, drug/biomolecule accommodation, signature signal based sensing etc., in a single nano-entity offers a plethora of opportunities in strengthening the current anti-cancer therapeutic regimes 8 9 10 11 12 13 14 15 16 17 18 19 . Inorganic nanoparticles as gold, metal sulfides etc., hold high-extinction coefficients in converting near-infrared (NIR) light to heat, and have been examined for photothermal therapy.…”