Structural and Antioxidative Features of Chlorogenic Acid

This work contributes to the structure clarification of chlorogenic acid (5-O-caffeoylquinic acid, 5CQA) by comparing the experimental and simulated IR, Raman, 1H-NMR, 13C-NMR, and UV-vis spectra. The lowest-energy conformers in the gas-phase and solution were used for all calculations. Very good agreement between all experimental and simulated spectra indicates correct arrangement of the atoms in the 5CQA molecule. In addition, the bond dissociation enthalpies, proton affinities, electron transfer enthalpies, ionization potentials, and proton dissociation enthalpies for 5CQA were used for thermodynamic consideration of the major antioxidative mechanisms: HAT (Hydrogen Atom Transfer), SPLET (Sequential Proton-Loss Electron-Transfer), and SET-PT (Single Electron Transfer – Proton Transfer). It was found that HAT may be the predominant mechanism in nonpolar solvents, while HAT and SPLET are competitive pathways in polar media. All quantum-chemical calculations were carried out by means of the MN12-SX method. Its performance is similar to those of the B3LYP-D2, B3LYP-D3, and M06-2X functionals. This work is licensed under a Creative Commons Attribution 4.0 International License

Plasmon induced enhancement of photoinduced antibacterial activity of graphene quantum dots

Due to the exponential growth of bacterial infection as well as resistance toward most antibiotics, the development of new materials for treatment is urgently needed. In recent years, graphene quantum dots (GQDs) have been identified as promising carbon nanomaterial for eco-friendly antibacterial applications due to their optical and chemical stability, non-toxicity, and biocompatibility. One of the reported GQD’s antimicrobial mechanisms is the photo-induced production of singlet oxygen (1O2). Under light exposure, GQDs transfer the energy to molecular oxygen from the surrounding medium. Oxygen molecules transform to their excited form 1O2, which causes oxidative stress in bacterial cells and reduces their viability. In this study, pristine GQDs were produced in an easy, one-step electrochemical top-down approach using graphite electrodes as a starting material. Carboxyl groups of GQDs are modified using a carbodiimide coupling reaction catalyzed by 1-ethyl-3- (3-dimethylaminopropyl)carbodiimide (EDC), with ethylenediamine (EDA) as an amine. In the next step, these NH2 terminated dots were decorated with gold nanoparticles (AuNPs) by the same EDC coupling procedure. Abillity of GQDs-AuNP nanocomposite to generate singlet oxygen upon blue light (470 nm) was investigated by UV-Vis spectroscopy and 9,10- anthracenediylbis-(methylene)dimalonic acid (ABDA) as selective 1O2 traping agent. After 2 hours of blue light illumination, the band at 420 nm charachterisic for ABDA was completly disaperided only in the presence of the GQD-AuNPs indicating good prooxidative potential of composite. Photoinduced antibacterial effects of GQD-AuNPs were studied using minimum inhibitory concentration (MIC) test which showed great antibacterial activity against several bacterial strains.Twenty-First Young Researchers’ Conference - Materials Science and Engineering: Program and the Book of Abstracts; November 29 – December 1, 2023, Belgrade, Serbi

Proizvodnja sadnica žute lincure (Gentiana lutea L.) za rasad i gajenje u uslovima suvog ratarenja u planinama Srbije

This paper deals with development of yellow gentian nursery plants in the open winter beds established in the mountainous region of Serbia at 1000 m a.s.l. Number, weight and size of one-, two- and three-year-old nursery plants were measured in succession for two years. The one-year-old nursery plants had an average 1.5 g fresh weight and 0.4 g dry weight, while the average length and width of the thickened root parts were 6.0 cm and 0.4 cm, respectively. The average fresh and dry root weights of the two-year-old nursery plants were 4.9 g and 1.4 g, respectively, with the length and width of the thickened root part 10.8 cm and 1.2 cm, respectively. The average root weights of the three-year-old plantlets were 15.6 g (fresh weight) and 4.7 g (dry weight), but they were too branchy and difficult for transplanting into the field. The average number of yellow gentian nursery plants per m2 of the open winter bed, following the first, second and third growing year were 714, 243 and 95, respectively. Two-year-old nursery plants proved to be the most suitable for establishing large-scale plantations for the production of yellow gentian root under dry farming conditions in the mountains of Serbia.U radu je prikazan razvoj sadnica žute lincure u rasadniku u otvorenim zimskim lejama zasnovanim u planinskom regionu Srbije na 1000 m nadmorske visine. Meren je broj, masa i veličina sadnica jednogodišnje, dvogodišnje i trogodišnje starosti u sukcesiji tokom dve godine. Sadnice jednogodišnje starosti imale su prosečnu masu 1,5 g (svežu) odnosno 0,4 g (suvu) i prosečnu dužinu zadebljalog dela korena 6,0 cm sa prosečnom debljinom 0,4 cm. Prosečna masa svežeg korena sadnica dvogodišnje starosti je bila 4,9 g a suvog korena 1,4 g uz dužinu zadebljalog dela korena 10,8 cm i debljinu vrata korena 1,2 cm. Prosečne mase korena trogodišnjih sadnica su iznosile 15,6 g (sveža), odnosno 4,7 g (suva), ali je koren ovih sadnica bio previše razgranat i stoga nepodesan za plantažnu sadnju. Prosečan broj dobijenih sadnica po m2 leje na kraju prve godine je iznosio 714, na kraju druge 243 i treće 95. Dvogodišnje sadnice žute lincure proizvedene u otvorenim zimskim lejama, po svojim karakteristikama se se pokazale kao najpogodnije za zasnivanju plantaža lincure za proizvodnju korena u uslovima suvog ratarenja u planinama Srbije

Application of graphene quantum dots in heavy metals and pesticides detection

Graphene Quantum Dots (GQDs) were produced using electrochemical oxidation of graphite rods. Obtained GQDs were gamma-irradiated in the presence of the N atoms source, ethylenediamine. Both structural and morphological changes were investigated using UV-Vis, X-ray photoelectron and photoluminescence (PL) spectroscopy as well as atomic force microscopy. The ability of both types of dots to change PL intensity in the presence of pesticides such as malathion and glyphosate, as well as copper (II) ions was detected. These preliminary results indicated a high potential of produced GQDs to be applied as non-enzymatic PL sensors for the detection of selected pesticides and metal ions

N-doped graphene quantum dots for detection of palladium(II) ions and carbofuran

We produced Graphene Quantum Dots (GQDs) by electrochemical oxidation of graphite rods and exposed them to gamma irradiation at a dose of 200 kGy, in the presence of ethylenediamine. Before irradiation, oxygen was removed from the GQDs dispersion by purging with Ar. These conditions induced both chemical reduction as well as the incorporation of N atoms in the structure of GQDs. Thus, N-doped GQDs were produced. The morphology of dots was investigated using atomic force microscopy. UV-Vis and photoluminescence spectroscopy were used to investigate the optical properties of modified GQDs. The changes in the intensities of PL emission spectra were studied in the presence of different concentrations of Pd2+ and pesticide carbofuran. We observed promising results for the application of N-doped GQDs for non-enzymatic PL detection of selected metal ions and molecules of pesticide

Amino functionalized graphene quantum dots - new fluorescent sensor for Co2+ ions

Graphene quantum dots (GQDs) were fabricated by simple electrochemical oxidation of graphite electrodes. Modified GQDs were obtained by gamma irradiation of GQDs, EDA, and IPA mixture at a dose of 25 kGy. In this approach, GQDs with the amino groups were produced (25γ-GQDs). These GQDs have shown a high uniformity, good dispersibility in water, and strong photoluminescence in the blue part of the electromagnetic spectrum. Modified GQDs were studied in the optical detection of Co2+ ions. The PL intensities of GQDs were measured in the presence of Co2+ ions in the concentration range 0-7.5 µmol L-1 . It was demonstrated that PL intensities decreased linearly in the concentration range 0-2.5 µmol L-1 . The value of the coefficient of determination (R2= 0.95949) indicates the potential of 25γ-GQDs for application in optical sensing of Co2+ ions

Sustainability of chemical soil quality in Southern Morava river valley in correlation with the flooding

Land as the main edaphic factor, plays a very important role in the production of various field crops, fruit and vine crops. Its role is reflected in the fertility and productivity. Soil fertility includes content available nutrients, such as individual elements, pH and humus. The study of soil quality leads to conclusions about what the land is suitable for cultivation of what kind of culture. This paper presents the results of investigation of changes in soil quality in the South Morava river valley, in correlation with the floods. Different results of pH, humus, nitrogen, phosphorus and potassium, are obtain in the function of time, within the research conducted. Experiment was implemented two years ago, immediately after the flood and six months after the floods, which occurred in May 2014 in the region South Serbia. The methods that were used for the analysis of the soil are: colorimetric, photometric, potentiometric and spectrophotometry. Results show a high degree of sustainability of quality of land intended for the cultivation of field crops. The conclusion is that the soil relatively quickly regenerate their properties after floods

Samopovređivanje osoba sa težim oblicima intelektualne ometenosti

The results of the study indicate the presence of higher prevalence of selfinjury in individuals with more severe forms of intellectual disability. Data on prevalence is uneven as a result of different methodological approaches in the participating studies. The aim is to display the available and relevant research whose case involves examination various indicators of the phenomenon of self-injury in individuals with more severe forms of intellectual disability (prevalence, manifestations, function of self-injury and treatment). Analysis of the 52 available studies led to several conclusions: the incidence of self-injury linearly increases with decreasing levels of intellectual functioning, so the highest incidence registered in individuals with profound intellectual disability; risk factors for the occurrence of self-injury are deficits in the quality of adaptive and communication skills, disturbances in sensory development and the presence of other types of behavioral disorders; data on the prevalence self-injury ranging from 4% to 82%; the most common forms of self-injury are hitting on the head, or hitting head on the other objects and biting; self-injury is often in the function of social avoidance tasks/activities and self-stimulation; self-injury can be treated with a variety of behavioral techniques that are based on reinforcement and extinction.Rezultati studija ukazuju na prisustvo veće prevalencije samopovređivanja kod osoba sa težim oblicima intelektualne ometenosti. Podaci o prevalenciji su neujednačeni što je posledica različitog metodološkog pristupa u obuhvaćenim studijama. Cilj rada je prikaz dostupnih i relevantnih istraživanja čiji se predmet odnosi na ispitivanje različitih pokazatelja fenomena samopovređivanja kod osoba sa težim oblicima intelektualne ometenosti (prevalencija, manifestacije, funkcija samopovređujućeg ponašanja i tretman). Analizom 52 dostupne studije došlo se do nekoliko zaključaka: učestalost samopovređivanja linearno raste sa opadanjem nivoa intelektualnog funkcionisanja, pa je tako najveća učestalost registrovana kod osoba sa dubokom intelektualnom ometenošću; faktori rizika za pojavu samopovređivanja su i deficiti u kvalitetu adaptivnih i komunikativnih veština, smetnje u senzornom razvoju i prisustvo drugih tipova poremećaja u ponašanju; podaci o prevalenciji samopovređivanja se kreću u rasponu od 4% do 82%; najučestaliji oblici samopovređivanja su: udaranje po glavi, ili udaranje glavom o druge objekte i ujedanje; samopovređivanje je najčešće u funkciji socijalnog izbegavanja zadataka/aktivnosti i autostimulacije; samopovređivanje se može tretirati različitim bihejvioralnim tehnikama koje su zasnovane na potkrepljenju i ekstinkciji

Innovative modifications of graphene quantum dots for improved photodynamic therapy in antibacterial treatment

Considering the rising concern of antibiotic resistance, developing advanced antibacterial solutions is highly needed. The ability of graphene quantum dots (GQDs) to generate reactive oxygen species (ROS) upon light exposure made them promising candidates as agents in photodynamic therapy for combatting infections, including antibiotic-resistant strains. GQDs show versatile chemical, physical, and biological properties such as high fluorescent activity, resistance to photo-bleaching, low toxicity, excellent solubility, and biocompatibility. This research focused on exploring the ability of GQDs to produce singlet oxygen under blue light exposure. We used two singlet oxygen probes, 9,10-anthracenediylbis(methylene) dimalonic acid and 1,3-diphenylisobenzofuran to study photoinduced production radicals from several GQDs. To tune the ability of GQDs to generate ROS, we used gamma irradiation in two different media, the presence of L-cysteine and cyclopentanone. The results showed improvements in singlet oxygen production in both cases. However, the modification conducted with cyclopentanol showed notably higher efficacy in promoting singlet oxygen production. This research demonstrates the increasing significance of GQDs in discovering new methods to combat bacteria. The modification of GQDs with gamma irradiation leads to increased production of singlet oxygen enhancing the effectiveness of photodynamic therapy for treating infections.Twenty-First Young Researchers’ Conference - Materials Science and Engineering: Program and the Book of Abstracts; November 29 – December 1, 2023, Belgrade, Serbi

Supplementary data for article: Marković, V.; Markovic, S.; Janicijevic, A.; Rodić, M.; Leovac, V. M.; Todorović, N.; Trifunović, S. S.; Joksović, M. D. Mechanistic Investigation and DFT Calculation of the New Reaction between S-Methylisothiosemicarbazide and Methyl Acetoacetate. Structural Chemistry 2013, 24 (6), 2127–2136. https://doi.org/10.1007/s11224-013-0223-3

Supplementary material for: [https://doi.org/10.1007/s11224-013-0223-3]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/1455