Currently, gold nanoparticles have found applications in engineering and medical sciences, taking advantage from their properties and characteristics. Surface plasmon resonance, for instance, is one of the main features for optical applications and other physical properties, like high density, that represents the key for cellular uptake. Among other applications, in the medical field, some diseases may be treated by using gene therapy, including monogenetic or polygenetic disorders and infections. Gene adding, suppression, or substitution is one of the many options for genetic manipulation. This work explores an alternative non-viral method for gene transfer by using gold nanoparticles functionalized with organic polymers; two routes of synthesis were used: one of them with sodium borohydride as reducing agent and the other one with chitosan oligosaccharide as reducing and stabilizing agent. Gold nanoparticles conjugated with chitosan, acylated chitosan and chitosan oligosaccharide, were used to evaluate transfection efficiency of plasmid DNA into cell culture (HEK-293). Physical and chemical properties of gold nanocomposites were characterized by using UV-Vis Spectroscopy, ξ-potential, and transmission electron microscopy. Furthermore, the interaction between gold nanoparticles and plasmid DNA was demonstrated by using agarose gel electrophoresis. Transfection tests were performed and evaluated by β-galactosidase activity and green fluorescence protein expression. The percentage of transfection obtained with chitosan, acylated chitosan, and chitosan oligosaccharide were of 27%, 33%, and 60% respectively.

The application of nanoscience and nanotechnology in medicine has been useful in the diagnosis, monitoring, and treatment of many diseases. Gold nanoparticles are commonly used for medical imaging studies, biosensors, drug delivery systems, and gene therapy. It has been reported that nanoparticles coated with specific polymers improve the biocompatibility and stability and decrease the cytotoxicity of the nanoparticles. In this work, we performed transfection studies of gold nanoparticles coated with polyethylene glycol, synthetized by two different methods, in a human embryonic kidney cell culture (HEK 293), by using plasmids pSV-β-Gal and pIRES2-EGFP. In addition, we also evaluated the cell uptake of a fluorescent drug (atorvastatin) using the synthetized gold nanoparticles as carriers. Furthermore, the study of cell viability after the interaction between these cells and the nanoparticles was performed. It was shown that the polyethylene glycol-coated gold nanoparticles presented transfection efficiency and cell uptake greater than 45% in each case. These results suggest that the synthetized gold nanoparticles coated with polyethylene glycol could be used successfully and safely as DNA and drug delivery systems.

Nanoparticles are rising worries because of recent reports about potential toxicity amid the incorporation of these emerging materials into consumer products, and industrial and scientific applications. New developments in the automotive industry are incorporating novel materials, which have increased the emission of nanoparticles into the atmosphere. To overcome the difficulty of detecting and characterizing atmospheric nanoparticles, alternative methods have been proposed, just as the indirect detection and characterization with bioindicators. We report the use of Taraxacum officinale as a sentinel organism to describe the effects of atmospheric nanostructured pollutants. ZnO and CuO nanoparticles (ZnO-NPs, CuO-NPs) were selected for this study, as they are two of the most present nanomaterials in the emerging automotive industry. The physiological effect on Taraxacum officinale exposure to ZnO-NPs and CuO-NPs was evaluated through growth rate, and total chlorophyll content; and comet assay was performed to evaluate the DNA damage. The exposure of plants was made by nebulizing dispersions of the nanoparticles. The exposure to ZnO-NPs presented the maximum DNA damage at a concentration of 100 mg/L. The DNA damage by both studied nanoparticles showed a significant difference against its bulk counterparts. Scanning electron microscopy (SEM) micrographs showed an accumulation of nanoparticles near the stomata. The study demonstrated the feasibility of T. officinale as a bioindicator of air-related nanoparticles toxicity, and the high sensitivity of the comet assay for this approach.

As nanoparticles are increasingly incorporated into consumer products and specialized areas, the need to study their toxicity and the importance of caution in their use are becoming more evident. The use of these novel materials in the automotive industry is causing increased nanoparticle emissions into the atmosphere, sparking concerns due to recent toxicology reports. Detecting and characterizing nanostructured atmospheric pollutants represent a complex task that alternative methods like genotoxic bioindicators may overcome. Ricinus communis was selected as a model plant to describe the genotoxic effect of air-dispersed nanostructured materials, using comet assay to evaluate the DNA damage by exposure to ZnO and CuO nanoparticles (ZnO-NPs, CuO-NPs), and total chlorophyll was determined to correlate the results. The plants were exposed for 1.25 h by nebulizing dispersions of the nanoparticles, and their effects were evaluated at 24 h and 5 days after exposure. Time was essential in demonstrating the DNA damage induced by lower levels of CuO-NPs and ZnO-NPs, which showed more significant damage after 5 days than bulk materials. In both compounds (CuO and ZnO), significant differences were observed in the comparison of their nanoscale and their bulk form, which confirms that the lower size of the nanoparticles presents a more significant genotoxic potential. In the scanning electron microscopy (SEM) micrographs, the accumulation of nanoparticles was observed near the stomata. The study demonstrated the viability of the comet assay as a sensitive tool both to assess DNA damage from ZnO-NPs and CuO-NPs on R. communis as a bioindicator and to investigate the potential risks of emerging nanomaterials, emphasizing the need for caution in their use.