Design, synthesis, and spectroscopic profiling of novel coumarin dyes: Investigating solvent sensitivity and photophysical properties.

Coumarin dyes are highly versatile and widely employed as fluorescent chemosensors in a variety of fields, including molecular imaging, bioorganic chemistry, analytical chemistry, materials chemistry, biology, and medical science. Thanks to their outstanding photostability and high quantum yield, they represent an ideal choice for developing sensitive and selective sensing platforms. In this study, we successfully designed and synthesized four new dyes based on the coumarin dye molecular skeleton, investigating their solvent sensitivity and spectroscopic properties. Our novel coumarin dyes were synthesized by a straightforward approach, reacting coumarin-3-carboxylic acid succinimidyl ester derivatives with corresponding amines in 1,4-dioxane as a solvent. We carefully monitored the completion of the reactions using thin-layer chromatography (TLC) and characterized these dyes using spectral and elemental analyses. We further investigated the UV, fluorescence, time-correlated single photon counting (TCSPC) technique and time-resolved spectroscopy (TRES) of these dyes in different solvents and on polymer film poly(methyl methacrylate) (PMMA). The quantum yield of the synthesized dyes was determined, with values observed to range between 0.55 and 0.94. Most of the dye-solvent and dye-polymer combinations exhibited single exponential decay, with lifetimes ranging from 2.3 to 3 ns. Minor deviations from single exponential behavior were observed for most of the dyes in toluene, while significant deviations were observed for coumarin dyes with piperazine moiety. We have provided a rationalization of these results in terms of the chemical functionalities of the various dyes. Furthermore, we investigated the effect of interactions between 7-methoxy-2-oxo-N-(2-(piperazin-1-yl)ethyl)-2H-chromene-3-carboxamide and silica nanoparticles (Ludox) on the spectroscopic properties of these dyes, with charge transfer being one possible mechanism contributing to the behavior of the dyes. Additionally, we explored the effect of trifluoroacetic acid (TFA) on the dyes' emission intensity and fluorescence decay. Based on our UV and fluorescence measurements of the dyes in different solvents, we have concluded that these dyes can create excellent donor-acceptor pairs for our upcoming fluorescence resonance energy transfer (FRET) experiments.

A novel sinusoidal design for an electrocoagulation reactor followed by an electro-Fenton reaction and a porous ceramic filter for the treatment of polluted waters.

In this research work, a novel design of an electro-Fenton reactor for the treatment of polluted water was investigated. In addition to the reactor with iron electrodes, a ceramic filter was also used. An electrical circuit was designed to change the cathodes and anodes every 24 s via an electrical relay between the electrodes. The untreated water was sucked into the reactor with an air pump and entered the electrocoagulation chamber after filtration with a ceramic filter. Then, it flows to the polyethylene filter to separate the coagulated particles from the fresh water. To produce 12 L of clean water, the system consumed 100 W of energy. Analysis of a river sample showed a reduction in nephelometric turbidity units (NTUs), total suspended solids (TSS), biochemical oxygen demand (BOD), and chemical oxygen demand (COD). Turbidity reduction studies have shown that the system can improve water transparency by 95%, thereby improving water quality to acceptable levels. Further, this system reduced TSS by more than 86%. In addition, BOD was reduced by more than 84% and COD by more than 88%, as shown by the change in the ratio of BOD to COD from 0.44 to 0.625, indicating improved water quality. According to the results, the treatment system can clean polluted waters, particularly during floods and when industries discharge their effluents into rivers.

Nanoporous hydrogel absorbent based on salep: Swelling behavior and methyl orange adsorption capacity.

This study used the gas-blowing method to develop a nanoporous hydrogel using poly (3-sulfopropyl acrylate-co-acrylic acid-co-acrylamide) grafted onto salep. The synthesis of the nanoporous hydrogel was optimized by various parameters for maximum swelling capacity. The nanoporous hydrogel was characterized using FT-IR, TGA, XRD, TEM, and SEM analyses. Images from SEM showed numerous pores and channels in the hydrogel with an average size of about 80 nm, forming a honeycomb-like shape. The change in surface charge was investigated by zeta potential and revealed that the surface charge of the hydrogel ranged from 20 mV at acidic conditions to -25 mV at basic conditions. The swelling behavior of optimum superabsorbent hydrogel was determined under different environmental conditions, such as different pH values, ionic strengths of the environment, and solvents. In addition, the swelling kinetics and the absorbance under loading of the hydrogel sample in different environments were investigated. Moreover, Methyl Orange (MO) dye was removed from aqueous solutions using the nanoporous hydrogel as an adsorbent. The adsorption behavior of the hydrogel was examined under various conditions, and the adsorption capacity of the hydrogel was found tobe 400 mg g-1. The maximum water uptake was obtained under the following conditions: Salep weight = 0.01 g, AA = 60 µL, MBA = 300 µL, APS = 60 µL, TEMED = 90 µL, AAm = 600 µL, and SPAK = 90 µL. Lastly, the adsorption kinetics was studied by employing pseudo-first-order, pseudo-second-order, and intra-particle diffusion models.

Capability of novel fluorescence DNA-conjugated CdTe/ZnS quantum dots nanoprobe for COVID-19 sensing.

Urgent identification of COVID-19 in infected patients is highly important nowadays. Förster or fluorescence resonance energy transfer (FRET) is a powerful and sensitive method for nanosensing applications, and quantum dots are essential materials in FRET-based nanosensors. The QDs are conjugated to DNA or RNA and used in many applications. Therefore, in the present study, novel fluorescence DNA-conjugated CdTe/ZnS quantum dots nanoprobe designed for detection of Covid-19 after extracting their RNA from saliva of hesitant people. For achieving this purpose, the water-soluble CdTe/ZnS QDs-DNA prepared via replacing the thioglycolic acid (TGA) on the surface of QDs with capture DNA (thiolated DNA) throw a ligand-exchange method. Subsequently, by adding the different concentrations of complementary (target DNA) in a mixture of quencher DNA (BHQ2-labeled DNA) and the QDs-DNA conjugates at different conditions, sandwiched hybrids were formed. The results showed that the fluorescence intensity was decreased with increasing the concentration of target DNA (as a positive control). The linear equation and regression (Y = 40.302 X  + 1 and R2 = 0.98) were obtained by using the Stern-Volmer relationship. The Limit of detection (LOD) was determined 0.000823 µM. The achieved results well confirm the outcomes of the RT-PCR method in real samples.

Novel CMC-CdTe / ZnS QDs Nanosensor for the Detection of Anticancer Drug Epirubicin.

Epirubicin (EPI) is one of the standard anticancer drugs that apply for various cancers treatment. However, the accumulation of EPI in the human body can be highly toxic, and it causes inevitable harm to organs. As a result, the evaluation of low concentrations of this drug in body samples requires sensitive, rapid, and accurate analysis methods. The fluorescence method is an efficient way in comparison of the traditional methods such as liquid chromatography, capillary electrophoresis, and electrochemical methods. Herein, we synthesized a novel fluorescence nanosensor named CMC-CdTe/ZnS based on using quantum dots (QDs). The structure of the prepared nanosensor is confirmed by different analysis methods such as FT-IR, TGA, and TEM. Besides that, the fluorescence intensity response of CMC-CdTe/ZnS QDs in the presence of Epirubicin drug is investigated. Based on obtained results, not only this nanosensor developed, but also the fluorescence quenching was explained by the typical Stern-Volmer equation. The best linear quenching equation for entitled nanosensor in the presence of Epirubicin is F0/F = 0.0346Q + 1.08 (R2 = 0.99), and the detection limit of Epirubicin is around 0.04 × 10-6 mol/L at 25 °C. All of the results display that this method could be reliable and suitable approach for determination of Epirubicin in commercial samples as well.

Psychological Stress and Stressors Among Clinical Dental Students at Shiraz School of Dentistry, Iran.

OBJECTIVE: The purpose of this study was to assess the level of psychological stress and the perceived stressors among the undergraduate clinical dental students of Shiraz School of Dentistry. MATERIALS AND METHODS: This study was conducted during the second semester of the academic year 2018-2019 at Shiraz School of Dentistry, Shiraz University of Medical Sciences, Iran. The study group consisted of 150 dental clinical students. The participants were surveyed via the validated Depression, Anxiety, and Stress Scale (DASS-21) and the Dental Environment Stress (DES) questionnaires. One-way ANOVA, post hoc Tukey's test, repeated measure ANOVA, Holm-Sidak's test, and t-test were performed to analyze the data after the normality of the data was checked by Kolmogorov-Smirnov test. The P values of less than 0.05 were considered as statistically significant. RESULTS: No significant differences were observed among the dental students with different academic levels in terms of depression and anxiety scores (P=0.057 and 0.154, respectively). The lowest and highest stress scores were observed among the sixth- and fifth-year students, respectively (P values <0.05). The scores of the stressors associated with the academic factors were significantly higher than those of the other domains (P<0.05) except for that of the clinical education domain (P=0.070). The females showed significantly higher DES scores (P values <0.05). CONCLUSION: The highest and lowest stress levels were observed among the fifth- and sixth-year students, respectively. The primary sources of stress were academic factors and clinical education. The females expressed higher levels of stress in certain areas of dental training.

Knowledge of triage in the senior medical students in Shiraz University of Medical Sciences.

INTRODUCTION: Triage is a response to the problem of overcrowding in Emergency Departments (EDs) and accuracy of decisions made by the triage unit affects the ultimate outcome of EDs. This study was conducted to evaluate the knowledge of triage among last year medical students in Shiraz University of Medical Sciences. METHODS: This is a cross-sectional analytical study whose subjects were all the senior students of medicine (62) in the last year of medicine from January to June 2013 who attended emergency medicine course in the screen room of 2 University Hospitals. This questionnaire was designed in 3 sections including personal data, 15 questions on knowledge of triage and 10 case scenarios for triage decision making and completed by the students. Statistical analysis was performed in SPSS statistical software (version 14) using independent sample t-test, one way ANOVA, and Pearson correlation coefficient (p≤0.001). RESULTS: The total mean score of the participants was 10.6±1.5, ranging from 7 to 13. 58(93.5%) students had poor triage knowledge. In the scenario's section, the percentage of correct triage by students was 49.2% and those of over and under triage were 28.1% and 22.7%, respectively. There was a significant relationship between the triage accuracy and level of triage (ESI 4) (p≤0.001). CONCLUSION: The level of knowledge of triage in the last year medical students was poor, although most of them had passed a course in the screen room. It is recommended that medical students' educational courses should include sections on the knowledge of triage in emergency rooms.

Grafting chitosan and polyHEMA on carbon nanotubes surfaces: "grafting to" and "grafting from" methods.

We report a simple method for engineering chitosan (CS) functionalized multi-walled carbon nanotube (MWCNT) composites with a biomedically important polymer, poly-2-hydroxyethyl methacrylate (polyHEMA), by chemical grafting HEMA monomers via free radical polymerization. Functionalization of CS and polyHEMA occurred in three steps. First, using microwave irradiation, CS was grafted onto the surface and sidewall of the carbon nanotubes. Second, HEMA monomers were grafted onto the polymeric matrix surface. The final step involved free radical polymerization of HEMA monomers. Composite synthesis was confirmed by Fourier transform infrared (FTIR) spectroscopy. Moreover, the presence of polyHEMA on the surface of the CS functionalized carbon nanotubes was confirmed by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and thermo gravimetric analysis (TGA) analyses. Furthermore, in the aqueous phase, our novel composites exhibited higher dispersibility compared with pristine MWCNTs. Considering the biomedical importance of polyHEMA and CS polymers, we expect these materials to be useful in the pharmaceutical industry as novel biomaterial composites with potential applications in drug delivery.