In this study, hybrid carbon dots-plasmonic nanostructures including carbon dots/polyethyleneimine/gold (C-dots/PEI/Au), and carbon dots/polyethyleneimine/silver (C-dots/PEI/Ag) have been prepared using a microwave irradiation method. The prepared hybrid nanostructures have been characterized via optical spectroscopy, high resolution transmission electron microscopy (HRTEM), and X-ray diffraction (XRD).A remarkable enhancement in the optical parameters, such as absorptivity and quantum yield (QY), has been observed for the hybrid nanostructure compared to pure carbon dots. This plasmonic enhancement was more pronounced in the presence of silver (C-dots/PEI/Ag nanohybrid) than that of gold (C-dots/PEI/Au nanohybrid). This is referred to the low intrinsic loss and the degree of the overlap between the absorption spectra of silver nanoparticles and carbon dots. Furthermore, the biocompatibility assay and cellular response on epithelial kidney (Vero) normal cell has been investigated.The results showed that the optimal dose of treatment is about $200 mg ml À1 using both C-dots/PEI/Au or C-dots/PEI/Ag, nano-hybrids could be used safely in diagnostic bioimaging applications.

Culture filtrate of 2 actinomycetes extracted from marine sponge Crella cyathophora was used for the biosynthesis of AgNPs with a significant anti-microbial and biofilm activity. Also, AgNPs exhibited a low to moderate cytotoxicity against cells.

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Quantum dots (QDs) are a novel class of inorganic fluorophores which are gaining widespread recognition as a result of their exceptional photophysical properties and their applications as a biomarker and in molecular biomedical imaging. The aim of this study was to evaluate the in vivo genotoxicity in mice exposed to CdSe quantum dots of average size 5.0 ± 0.2 nm and CdSe doped with 1% cobalt ions of similar size. The quantum dots are surface modified using mercaptoacetic acid (MAA) in order to be biocompatible and water-soluble. The MAA-QDs were given to the mice orally at doses of 500, 1000, and 2000 mg/kg by weight of MAA-QDs. Bone marrow and liver samples were collected after two and seven days of treatment. The results indicated that after two days of treatment, the high dose of doped MAA-QDs was significantly able to induce DNA damage, formation of micronuclei (MNs), and generation of DNA adduct (8-hydroxy-2-deoxyguanosine, 8-OHdG). However, increasing DNA damage and the frequency of MNs formation as well as the generation of DNA adducts were observed with both the undoped MAA-QDs (2000 mg/kg) and doped MAA-QDs (1000 and 2000 mg/kg) after seven days of treatment. The results of our study indicate that exposure to high doses of pure MAA-QDs or MAA-QDs doped with cobalt has the potential to cause indirect in vivo genetic damage, which may be attributed to free radical-induced oxidative stress in mice.