Thermal decomposition of citric acid is one of the most common synthesis methods for fluorescent carbon dots; the reaction pathway is, however, quite complex and the details are still far from being understood. For instance, several intermediates form during the process and they also give rise to fluorescent species. In the present work, the formation of fluorescent C‐dots from citric acid has been studied as a function of reaction time by coupling infrared analysis, X‐ray photoelectron spectroscopy, liquid chromatography/mass spectroscopy (LC/MS) with the change of the optical properties, absorption and emission. The reaction intermediates, which have been identified at different stages, produce two main emissive species, in the green and blue, as also indicated by the decay time analysis. C‐dots formed from the intermediates have also been synthesised by thermal decomposition, which gave an emission maximum around 450 nm. The citric acid C‐dots in water show short temporal stability, but their functionalisation with 3‐aminopropyltriethoxysilane reduces the quenching. The understanding of the citric acid thermal decomposition reaction is expected to improve the control and reproducibility of C‐dots synthesis.

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Genistein has been reported to have antioxidant and neuroprotective activity. Despite encouraging in vitro and in vivo results, several disadvantages such as poor water solubility, rapid metabolism, and low oral bioavailability limit the clinical application of genistein. The aim of this study was to design and characterize genistein-loaded chitosan nanoparticles for intranasal drug delivery, prepared by the ionic gelation technique by using sodium hexametaphosphate. Nanoparticles were characterized in vitro and their cytotoxicity was tested on PC12 cells. Genistein-loaded nanoparticles were prepared, and sodium hexametaphosphate was used as a valid alternative to well-known cross-linkers. Nanoparticle characteristics as well as their physical stability were affected by formulation composition and manufacturing. Small (mean diameters of 200–300 nm) and homogeneous nanoparticles were obtained and were able to improve genistein penetration through the nasal mucosa as compared to pure genistein. Nanoparticle dispersions showed a pH consistent with the nasal fluid and preserved PC12 cell vitality.

Graphene oxide/iron (III−VI) oxides nanocomposites have been produced with a fast and one-pot synthesis. K 2 FeO 4 (Fe(VI)-based compound), obtained from a dry synthesis, has been used as a green oxidant of graphite to produce graphene oxide, avoiding the use of the toxic permanganates. Graphene oxide flakes with a low oxidation degree and decorated with iron oxide have been obtained in one-step reaction. The material has been characterized by several techniques to investigate the structure (SEM, TEM analysis), the composition (X-ray fluorescence, XPS, FTIR, UV− visible, fluorescence, and Raman spectroscopy) and the performance (HPLC). The combined use of ferrate and graphene oxide/iron oxide is an efficient, cheap, and green alternative for water remediation. Real water samples containing different types of emerging pollutants (organic dyes, pesticides, and pharmaceutical drugs) have been efficiently decontaminated obtaining an abatement of 99% in a few minutes. The nanocomposite is paramagnetic and can be easily removed from water with a magnet after depollution. The materials have shown one of the best decontamination performance reported in the scientific literature so far.

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Malaria represents one of the most common infectious diseases which becoming an impellent public health problem worldwide. Antimalarial classical medications include quininebased drugs, like chloroquine, and artesunate, a derivative of artemisinin, a molecule found in the plant Artemisia annua. Such therapeutics are very effective but show heavy side effects like drug resistance. In this study, "green" silver nanoparticles (AgNPs) have been prepared from two Artemisia species (A. abrotanum and A. arborescens), traditionally used in folk medicine as a remedy for different conditions, and their potential antimalarial efficacy have been assessed. AgNPs have been characterized by UV-Vis, dynamic light scattering and zeta potential, FTIR, XRD, TEM and EDX. The structural characterization has demonstrated the spheroidal shape of nanoparticles and dimensions under 50 nm, useful for biomedical studies. Zeta potential analysis have shown the stability and dispersion of green AgNPs in aqueous medium without aggregation. AgNPs hemocompatibility and antimalarial activity have been studied in Plasmodium falciparum cultures in in vitro experiments. The antiplasmodial effect has been assessed using increasing doses of AgNPs (0.6 to 7.5 μg/ mL) on parasitized red blood cells (pRBCs). Obtained data showed that the hemocompatibility of AgNPs is related to their synthetic route and depends on the administered dose. A. abrotanum-AgNPs (1) have shown the lowest percentage of hemolytic activity on pRBCs, underlining their hemocompatibility. These results are in accordance with the lower levels of parasitemia observed after A. abrotanum-AgNPs (1) treatment respect to A. arborescens-AgNPs (2), and AgNPs (3) derived from a classical chemical synthesis. Moreover, after 24 and 48 hours of A. abrotanum-AgNPs (1) treatment, the parasite growth was locked in the ring stage, evidencing the effect of these nanoparticles to hinder the maturation of P. falciparum. The anti-malarial activity of A. abrotanum-AgNPs (1) on pRBCs was demonstrated to be higher than that of A. arborescens-AgNPs (2).

Ultrasonic imaging system is a non‐invasive medical imaging technique that has become one of the most widely used diagnostic tools in modern medicine for detecting prenatal anomalies and deep screening of biological tissues. One of the core components of the ultrasound system is represented by the probe where is located the transducer which produces mechanical energy in response to electrical signals, and conversely, produce electrical signals in response to mechanical stimulus. The ultrasound transducer in the probe is generally made of a piezoelectric ceramic material such as lead zirconate titanate (PZT), which present two important limitations as the presence of toxic material as the lead, and low acoustic impedance ascribable to its high density. For these reasons, it is necessary to focus the research on new eco‐friendly piezoelectric materials with properties comparable with PZT. Among them potassium sodium niobate is considered as a leading lead‐free candidate to replace lead‐based piezoceramics, resulting the most promising. In this review, the most relevant and advanced synthesis approaches and the unique properties of this class of lead‐free piezoceramics are presented in detail.

Enzyme-based sensors have emerged as important analytical tools with application in diverse fields, and biosensors for the detection of glucose using the enzyme glucose oxidase have been widely investigated. In this work, the preparation of biosensors by electrochemical polymerization of (poly)thiophenes, namely 2,2′-bithiophene (2,2′-BT) and 4,4′-bis(2-methyl-3-butyn-2-ol)-2,2′-bithiophene (4,4′-bBT), followed by immobilization of glucose oxidase on the films, is described. N-cyclohexyl-N′-(2-morpholinoethyl)carbodiimide metho-p-toluenesulfonate (CMC) was used as a condensing agent, and p-benzoquinone (BQ) was used as a redox mediator in solution. The glucose oxidase electrodes with films of 2,2′-BT and 4,4′-bBT were then tested for their ability in detecting glucose from synthetic and real samples (pear, apricot, and peach fruit juices).