Upconverting Carbon Nanodots from Ethylenediaminetetraacetic Acid (EDTA) as Near-Infrared Activated Phototheranostic Agents.

This work describes the synthesis of nitrogen-doped carbon nanodots (CNDs) synthesized from ethylenediaminetetraacetic acid (EDTA) as a precursor and their application as luminescent agents with a dual-mode theranostic role as near-infrared (NIR) triggered imaging and photodynamic therapy agents. Interestingly, these fluorescent CNDs are more rapidly and selectively internalized by tumor cells and exhibit very limited cytotoxicity until remotely activated with a NIR illumination source. These CNDs are excellent candidates for phototheranostic purposes, for example, simultaneous imaging and therapy can be carried out on cancer cells by using their luminescent properties and the in situ generation of reactive oxidative species (ROS) upon excitation in the NIR range. In the presence of CNDs, NIR remote activation induces the in vitro killing of U251MG cells. Through the use of flow imaging cytometry, we have been able to successfully map and quantify the different types of cell deaths induced by the presence of intracellular superoxide anions (. O2 - ) and hydrogen peroxide (H2 O2 ) ROS generated in situ upon NIR irradiation.

Polymer functionalized gold nanoparticles as nonviral gene delivery reagents.

BACKGROUND: In the present study, we investigated the ability of polyethylene glycol (PEG) functionalized gold nanoparticles to function as nonviral vectors in the transfection of different cell lines, comparing them with commercial lipoplexes. METHODS: Positively-charged gold nanoparticles were synthesized using polyethylenimine (PEI) as a reducing and stabilizer agent and its cytotoxicity was reduced by its functionalization with PEG. We bound the nanoparticles to three plasmids with different sizes (4-40 kpb). Vector internalization was evaluated by confocal and electronic microscopy. Its transfection efficacy was studied by fluorescence microscopy and flow cytometry. The application of the resulting vector in gene therapy was evaluated indirectly using ganciclovir in HeLa cells transfected to express the herpes virus thymidine kinase. RESULTS: An appropriate ratio between the nitrogen from the PEI and the phosphorous from the phosphate groups of the DNA, together with a reduced size and an elevated electrokinetic potential, are responsible for an increased nanoparticle internalization and enhanced protein expression when carrying plasmids of up to 40 kbp (plasmid size close to the limit of the DNA-carrying capacity of viral vectors). Compared to a commercial transfection reagent, an equal or even higher expression of reporter genes (on HeLa and Hek293t) and a suicide effect on HeLa cells transfected with the herpes virus thymidine kinase gene were observed when using this novel nanoparticulated vector. CONCLUSIONS: Nonviral vectors based on gold nanoparticles covalently coupled with PEG and PEI can be used as efficient transfection reagents showing expression levels that are the same or greater than those obtained with commercially available lipoplexes.

Nitrogen-Induced Transformation of Vitamin†C into Multifunctional Up-converting Carbon Nanodots in the Visible-NIR Range.

Water-soluble, biocompatible, and photoluminescent carbon nanodots have been obtained from the rationalized carbonization of vitamin C, a well-known antioxidant molecule in the presence of an amine co-reactant. Herein, we describe the positive influence of N-doping to induce a unique pH-dependent lifetime decay response that would be potentially attractive in biological backgrounds with intrinsic fluorescence fluctuations. In addition, the selectivity and sensitivity of the N-containing carbon nanoprobes towards the detection of copper ions at ppm levels is critically enhanced in comparison with the un-doped counterpart, especially in the near-infrared (NIR) range. Finally, the up-converting properties have been also successfully applied to image tumor cells in the visible range and remarkably, in the NIR region in which minimal tissue or water absorption and maximum penetration depth are expected.