Abstract
BackgroundThe safe use in biomedicine of semiconductor nanoparticles, also known as quantum dots (QDs), requires a detailed understanding of the biocompatibility and toxicity of QDs in human beings. The biological characteristics and physicochemical properties of QDs entail new challenges regarding the management of potential adverse health effects following exposure. At certain concentrations, the synthesis of semiconductor nanoparticles of CdS using dextrin as capping agent, at certain concentration, to reduce their toxicity and improves their biocompatibility.ResultsThis study successfully synthesized and characterized biocompatible dextrin-coated cadmium sulfide nanoparticles (CdS-Dx/QDs). The results show that CdS-Dx/QDs are cytotoxic at high concentrations (>2 μg/mL) in HepG2 and HEK293 cells. At low concentrations (<1 μg/mL), CdS-Dx/QDs were not toxic to HepG2 or HeLa cells. CdS-Dx nanoparticles only induced cell death by apoptosis in HEK293 cells at 1 μg/mL concentrations. The in vitro results showed that the cells efficiently took up the CdS-Dx/QDs and this resulted in strong fluorescence. The subcellular localization of CdS-Dx/QDs were usually small and apparently unique in the cytoplasm in HeLa cells but, in the case of HEK293 cells it were more abundant and found in cytoplasm and the nucleus. Animals treated with 100 μg/kg of CdS-Dx/QDs and sacrificed at 3, 7 and 18 h showed a differential distribution in their organs. Intense fluorescence was detected in lung and kidney, with moderate fluorescence detected in liver, spleen and brain. The biocompatibility and toxicity of CdS-Dx/QDs in animals treated daily with 100 μg/kg for 1 week showed the highest level of fluorescence in kidney, liver and brain. Less fluorescence was detected in lung and spleen. There was also evident presence of fluorescence in testis. The histopathological and biochemical analyses showed that CdS-Dx/QDs were non-toxic for rodents.ConclusionsThe in vitro and in vivo studies confirmed the effective cellular uptake and even distribution pattern of CdS-Dx/QDs in tissues. CdS-Dx/QDs were biocompatible with tissues from rodents. The CdS-Dx/QDs used in this study can be potentially used in bio-imaging applications.
Highlights
The safe use in biomedicine of semiconductor nanoparticles, known as quantum dots (QDs), requires a detailed understanding of the biocompatibility and toxicity of QDs in human beings
The average size of the cadmiun sulfide (CdS)-Dx/QDs was determined to be of the order of 3 nm
The cadmium sulfide-dextrin (CdS-Dx)/QDs synthesized in this study had a size of 3–5 nm and we found them in all layers of the cerebral cortex, which strongly suggests that CdSDx/QDs entered the brain via the blood brain barrier (BBB)
Summary
The safe use in biomedicine of semiconductor nanoparticles, known as quantum dots (QDs), requires a detailed understanding of the biocompatibility and toxicity of QDs in human beings. The incorporation of QDs into biological systems often requires strategies for the manipulation of the ligands bound to the surface of the QDs surface in order to make them water-soluble and biocompatible–that is, compatible with living tissues or a living system by being neither toxic nor injurious or physiologically reactive [5]. Cadmium, which is the main component in the majority of QDs, is known to be acutely and chronically toxic to cells and organisms. In cells, it is taken into calcium membrane channels, where it accumulates [6,7,8]. The change in the physicochemical and structural properties of engineered QDs could be responsible for a number of material interactions that could have toxicological effects [10, 11]
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