María J. Hortigüela

MC3T3-E1 pre-osteoblast response and differentiation after graphene oxide nanosheet uptake

Nano-graphene oxide (GO) and its functionalized derivatives have aroused a great interest for drug delivery, tissue engineering and photothermal cancer therapy, but their biocompatibility has not yet been fully assessed. The aim of the present study was to evaluate the proliferation and differentiation of MC3T3-E1 pre-osteoblasts after the uptake of GO nanosheets (c.a. 400nm), functionalized with poly(ethylene glycol-amine) (PEG) and labelled with fluorescein isothiocyanate (FITC). Significant proliferation decrease and apoptosis increase were observed 3days after incorporation of FITC-PEG-GO by MC3T3-E1 cells. However, alterations on healthy pre-osteoblast differentiation into cells exhibiting osteoblast phenotype were not observed, as they showed normal alkaline phosphatase levels and matrix mineralization 12days after nanosheet uptake. The results suggest that 40μg/mL concentrations of these nanosheets would not affect the differentiation of healthy pre-osteoblasts, thus these PEG-GO nanosheets have potential to be used for biomedical applications after their internalization, as the induction of local hyperthermia on bone cancer.

Effect of samarium and vanadium co-doping on structure, ferroelectric and photocatalytic properties of bismuth titanate

We performed a systematic analysis of the structure, ferroelectric and photocatalytic activities of Sm and V co-doped Bi4Ti3O12 (SBVT) ceramics. The formation of 3-layered Aurivillius structure and chemically induced strain of SBVT were analyzed by SEM and HRTEM studies. From the results of structural refinements, temperature dependent XRD and Raman spectra we found that SBVT has a distorted orthorhombic structure and transforms to tetragonal in the temperature range of 475–600 °C. Raman modes of Bi sites experience the phase transition earlier compared to torsional bending modes of BO6 octahedra. From the results of polarization and piezoelectric strain measurements, we found that SBVT exhibits superior ferroelectric characteristics as well as improved S33 (0.02 × 10−3) compared to other rare-earth doped Bi4Ti3O12 materials reported in the literature. SBVT exhibited fatigue endurance up to 108 switching cycles. Such a behavior is attributed to the structural distortions due to the smaller ionic radius of Sm3+ and reduced oxygen vacancies. Local piezoresponse measurements demonstrated imprint characteristics of ferroelectric domains. Furthermore, we assessed the photocatalytic (PC) activity of SBVT – for the first time – in the gas–solid phase, monitoring the degradation of nitrogen oxides (i.e. NO + NO2). Results demonstrated that SBVT was photocatalytically active in the solar spectrum, being able to degrade NOx at ppb level concentration, and exhibited a very stable PC activity (five consecutive PC runs), proving itself suitable for reuse.

Eco-friendly profile of pegylated nano-graphene oxide at different levels of an aquatic trophic chain

Nanographene oxide (nGO) has been recently proposed as a new antitumoral therapeutic agent, drug delivery carrier and gene transfection vehicle, among others. Treatment is carried out by hyperthermia induced by infrared irradiation. After treatment, the nanosystems will be inevitably excreted and released to the environment. To understand the potential impacts of pegylated nGO (nGO-PEG), three key species from different trophic levels were used: the green micro-algae Raphidocelis subcapitata (growth inhibition test), the cladocera Daphnia magna (acute and chronic tests), and the fish Danio rerio (fish embryo test). Besides a regular standard procedure to assess toxicity, and considering the mode of action of nGO-PEG in cancer treatment, a simultaneous infrared lamp exposure was carried out for D. magna and D. rerio. Additionally, and taking advantage of the phenotypic transparency of D. magna, nGO-PEG was fluorescently tagged to evaluate the potential uptake of nGO-PEG. The R. subcapitata growth inhibition test showed effects during the first 48 h, recovering till the end of the test (96 h). No acute or chronic effects were observed for D. magna, under standard or infrared light exposures although confocal microscope images showed nGO-PEG uptake. Very small percentages of mortality and abnormalities were observed in D. rerio exposed with and without the infrared lamp. Although low hazard may be expected for nGO-PEG in aquatic ecosystems, further studies with species with different life traits should be accomplished, in order to derive more accurate conclusions.

Reply to Comment on “Highly Fluorescent Rhodamine B Nanoparticles Entrapped in Hybrid Glasses”

Rhodamine B (RB) nanoparticles entrapped in hybrid glasses show enhanced fluorescent emission (approximately 220-fold larger than that of single RB molecules) thanks to the configuration control of the self-assembled aggregates that form the supramolecular architecture of the nanoparticles. The fluorescence performance reported in this work is around 1 order of magnitude larger than that recently reported for fluorescent Nile Red nanoparticles. The fluorescence enhancement results from the use of a highly efficient fluorescent dye such RB and the formation of larger nanoparticles. Note that the later implies the presence of a large number of emitting centers involved in the fluorescence emission.