Antioxidative and Photo-Induced Effects of Different Types of N-Doped Graphene Quantum Dots

Due to the increasing number of bacterial infections and the development of resistivity toward antibiotics, new materials and approaches for treatments must be urgently developed. The production of new materials should be ecologically friendly considering overall pollution with chemicals and economically acceptable and accessible to the wide population. Thus, the possibility of using biocompatible graphene quantum dots (GQDs) as an agent in photodynamic therapy was studied. First, dots were obtained using electrochemical cutting of graphite. In only one synthetic step using gamma irradiation, GQDs were doped with N atoms without any reagent. Obtained dots showed blue photoluminescence, with a diameter of 19–89 nm and optical band gap of 3.23–4.73 eV, featuring oxygen-containing, amino, and amide functional groups. Dots showed antioxidative activity; they quenched •OH at a concentration of 10 μg·mL−1, scavenged DPPH• radicals even at 5 μg·mL−1, and caused discoloration of KMnO4 at 30 μg·mL−1. Under light irradiation, dots were able to produce singlet oxygen, which remained stable for 10 min. Photoinduced effects by GQDs were studied on several bacterial strains (Listeria monocytogenes, Bacillus cereus, clinical strains of Streptococcus mutans, S. pyogenes, and S. sangunis, Pseudomonas aeruginosa, and one yeast strain Candida albicans) but antibacterial effects were not noticed

Influence of pH value on the formation of chitosan/xanthan gum polyelectrolyte complexes and their properties as carriers for ibuprofen

Формирање полиелектролитних комплекса (ПЕК) заснива се на остваривању јаких али реверзибилних интеракција супротно наелектрисаних полиелектролита. pH вредност може утицати на степен јонизације и дистрибуцију наелектрисања, а тиме и на јачину електростатичких интеракција и карактеристике комплекса као носача лековитих супстанци.The formation of polyelectrolyte complexes (PECs) is based on the establishment of strong but reversible interactions between oppositely charged polyelectrolytes. pH value influences the ionization degree, charge distribution, strength of the electrostatic interactions, and the characteristics of complexes as drug carriers

Protected geoheritage sites as a touristic value of Srem

In the area of the smallest region of Autonomous Province of Vojvodina, which is, excluding Fruška gora, of very uniform geological structure, there is a significant number of geoheritage sites of different protection rank. The most of them are Natural Monuments, some individually protected, some protected as part of a larger entirety (National Park “Fruška gora”). There are two Special Nature Reserves and one Landascape of Exceptional Features. Except their significant importance for science and education, wishing to emphasize touristic value that these attractive objects of nature have, taking into account their number, we have segregated only those who are protected or in the protection procedure. Depending on the protection rank, they are mainly complementary touristic values, rarely interesting to broader spectrum of tourists. With development of appropriate programs (an example of “Leslend” in Inđija) and necessary investments, these natural objects could become an equal part of Srem rich touristic offer

High variability in SSU rDNA gene copy number among planktonic foraminifera revealed by single-cell qPCR

Metabarcoding has become the workhorse of community ecology. Sequencing a taxonomically informative DNA fragment from environmental samples gives fast access to community composition across taxonomic groups, but it relies on the assumption that the number of sequences for each taxon correlates with its abundance in the sampled community. However, gene copy number varies among and within taxa, and the extent of this variability must therefore be considered when interpreting community composition data derived from environmental sequencing. Here we measured with single-cell qPCR the SSU rDNA gene copy number of 139 specimens of five species of planktonic foraminifera. We found that the average gene copy number varied between of ~4 000 to ~50 000 gene copies between species, and individuals of the same species can carry between ~300 to more than 350 000 gene copies. This variability cannot be explained by differences in cell size and considering all plausible sources of bias, we conclude that this variability likely reflects dynamic genomic processes acting during the life cycle. We used the observed variability to model its impact on metabarcoding and found that the application of a correcting factor at species level may correct the derived relative abundances, provided sufficiently large populations have been sampled

Removal of trivalent chromium from aqueous solutions by natural clays: Valorization of saturated adsorbents as raw materials in ceramic manufacturing

Kaolinite/illite (KUb) and sepiolite (SEP) clays were used to study Cr(III) adsorption removal from aqueous solutions so that they could be utilized after saturation for ceramic manufacturing. SEP had a larger specific surface area and a higher PZC than KUb. The removal of Cr(III) was evaluated using a batch equilibration procedure at pHi = 4 and pHi = 6. Fast removal kinetics were observed for both clays. Maximum removal capacity was determined by changing the concentration of Cr(III) while keeping the concentration of clay constant and by altering the amount of clay while keeping the concentration of Cr(III) constant. In all situations, SEP had greater capacity than KUb, and capacity was greater for both clays at higher pHi. Not only did the pHi impact the removal capacity and efficiency, but so did the pH during adsorption and the initial concentration of Cr(III). Because of the higher PZC, the pHf for SEP was higher for the same pHi. The higher the pH and Cr(III) concentration, the higher the probability of Cr(OH)3 precipitation and the higher the removal capacity. Dried saturated clays were uniaxially pressed and sintered at 1000 °C for 2 h. The densities of the sintered materials were nearly identical to those of pure clay-based materials, but the compressive strengths were higher, which is significant for the use of saturated clays as raw materials in ceramic manufacturing. Leaching of Cr from SEP-based material was significantly higher than from KUb-based material probably due to the presence of CaCO3 in the SEP

Erythropoietin in Predicting Prognosis in Patients with Acute-on-Chronic Liver Failure

Background & Aims: Acute-on-chronic liver failure (ACLF) is characterized by a rapid progression to multiple organ failure and is associated with a very high mortality rate of 50-90%. Novel therapies are being investigated such as Erythropoietin (EPO). The aim of this prospective cohort study was to analyse the value of EPO in predicting prognosis and determine which patients may benefit most from EPO therapy. Methods: According to the EASL-CLIF criteria, 104 consecutive patients were diagnosed with ACLF, and separated into two groups based on the type of insult: bleeding (Group A=31) or non-bleeding (Group B=73). In addition to a complete biochemical work-up and calculation of relevant prognostic scores, levels of EPO were measured on admission and correlated to the type of insult and final outcome. Results: Fifteen patients from Group A (mean age 60.32 +/- 9.29 years) had a lethal outcome and higher values of EPO on admission (319.26 +/- 326.58 mIU/ml) (p lt 0.005), compared to the 37 patients from Group B (mean age 59.9 +/- 10.19 years) with EPO levels at admission of 29.88 +/- 34.6 mIU/mL. In Group B, a cut-off EPO value of 30.65 mIU/mL had a sensitivity of 87.5% and a specificity 57.4% in predicting lethal outcome with an AUROC of 0.823. In Group A, a cut-off value of 229.95 mlU/mL had a sensitivity and specificity of 53.3% and 92.7%, respectively. The AUROC for this cut-off was 0.847. Conclusions: Erythropoietin is superior to the standard prognostic scores in predicting 28-day mortality. Lower levels of EPO were detected in patients without bleeding as an insult indicating a possible therapeutic benefit in these patients

The role of modern imaging techniques in the diagnosis of malposition of the branch pulmonary arteries and possible association with microdeletion 22q11.2

Malposition of the branch pulmonary arteries is a rare malformation with two forms. In the typical form, pulmonary arteries cross each other as they proceed to their respective lungs. The "lesser form" is characterised by the left pulmonary artery ostium lying directly superior to the ostium of the right pulmonary artery, without crossing of the branch pulmonary arteries. Malposition of the branch pulmonary arteries is often associated with other congenital heart defects and extracardiac anomalies, as well as with 22q11.2 microdeletion. We report three infants with crossed pulmonary arteries and one adolescent with "lesser form" of the malformation. The results suggest that diagnosis of malposition of the branch pulmonary arteries could be challenging if based solely on echocardiography, whereas modern imaging technologies such as contrast computed tomography and magnetic resonance angiography provide reliable establishment of diagnosis. In addition, we performed the first molecular characterisation of the 22q11.2 region among patients with malposition of the branch pulmonary arteries and revealed a 3-megabase deletion in two out of four patients

Graphene quantum dots as autophagy-inducing photodynamic agents

The excellent photoluminescent properties of graphene quantum dots (GQD) makes them suitable candidates for biomedical applications, but their cytotoxicity has not been extensively studied. Here we show that electrochemically produced GQD irradiated with blue light (470 nm, 1 W) generate reactive oxygen species, including singlet oxygen, and kill U251 human glioma cells by causing oxidative stress. The cell death induced by photoexcited GQD displayed morphological and/or biochemical characteristics of both apoptosis (phosphatidylserine externalization, caspase activation. DNA fragmentation) and autophagy (formation of autophagic vesicles, LC3-I/LC3-II conversion, degradation of autophagic target p62). Moreover, a genetic inactivation of autophagy-essential LOB protein partly abrogated the photodynamic cytotoxicity of GQD. These data indicate potential usefulness of GQD in photodynamic therapy, but also raise concerns about their possible toxicity. (C) 2012 Elsevier Ltd. All rights reserved