Development of new types of antimicrobial coatings is of utmost importance due to increasing problems with pathogen transmission from various infectious surfaces to human beings. In this study, new ...types of highly potent antimicrobial polyurethane composite films encapsulated by hydrophobic riboflavin-based carbon polymer dots are presented. Detailed structural, optical, antimicrobial, and cytotoxic investigations of these composites were conducted. Low-power blue light triggered the composites to eradicate
in 30 min, whereas the same effect toward
was reached after 60 min. These composites also show low toxicity against MRC-5 cells. In this way, RF-CPD composites can be used for sterilization of highly touched objects in the healthcare industry.
Nowadays, it is a great challenge to develop new medicines for treating various infectious diseases. The treatment of these diseases is of utmost interest to further prevent the development of ...multi-drug resistance in different pathogens. Carbon quantum dots, as a new member of the carbon nanomaterials family, can potentially be used as a highly promising visible-light-triggered antibacterial agent. In this work, the results of antibacterial and cytotoxic activities of gamma-ray-irradiated carbon quantum dots are presented. Carbon quantum dots (CQDs) were synthesized from citric acid by a pyrolysis procedure and irradiated by gamma rays at different doses (25, 50, 100 and 200 kGy). Structure, chemical composition and optical properties were investigated by atomic force microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, UV-Vis spectrometry and photoluminescence. Structural analysis showed that CQDs have a spherical-like shape and dose-dependent average diameters and heights. Antibacterial tests showed that all irradiated dots had antibacterial activity but CQDs irradiated with dose of 100 kGy had antibacterial activity against all seven pathogen-reference bacterial strains. Gamma-ray-modified CQDs did not show any cytotoxicity toward human fetal-originated MRC-5 cells. Moreover, fluorescence microscopy showed excellent cellular uptake of CQDs irradiated with doses of 25 and 200 kGy into MRC-5 cells.
The cost of treatment of antibiotic-resistant pathogens is on the level of tens of billions of dollars at the moment. It is of special interest to reduce or solve this problem using antimicrobial ...coatings, especially in hospitals or other healthcare facilities. The bacteria can transfer from medical staff or contaminated surfaces to patients. In this paper, we focused our attention on the antibacterial and antibiofouling activities of two types of photodynamic polyurethane composite films doped with carbon polymerized dots (CPDs) and fullerene C
. Detailed atomic force, electrostatic force and viscoelastic microscopy revealed topology, nanoelectrical and nanomechanical properties of used fillers and composites. A relationship between the electronic structure of the nanocarbon fillers and the antibacterial and antibiofouling activities of the composites was established. Thorough spectroscopic analysis of reactive oxygen species (ROS) generation was conducted for both composite films, and it was found that both of them were potent antibacterial agents against nosocomial bacteria (
,
,
,
,
and
). Antibiofouling testing of composite films indicated that the CPDs/PU composite films eradicated almost completely the biofilms of
and
and about 50% of
biofilms.
The cost of treatment of antibiotic-resistant pathogens is on the level of tens of billions of dollars at the moment. It is of special interest to reduce or solve this problem using antimicrobial ...coatings, especially in hospitals or other healthcare facilities. The bacteria can transfer from medical staff or contaminated surfaces to patients. In this paper, we focused our attention on the antibacterial and antibiofouling activities of two types of photodynamic polyurethane composite films doped with carbon polymerized dots (CPDs) and fullerene Csub.60. Detailed atomic force, electrostatic force and viscoelastic microscopy revealed topology, nanoelectrical and nanomechanical properties of used fillers and composites. A relationship between the electronic structure of the nanocarbon fillers and the antibacterial and antibiofouling activities of the composites was established. Thorough spectroscopic analysis of reactive oxygen species (ROS) generation was conducted for both composite films, and it was found that both of them were potent antibacterial agents against nosocomial bacteria (Klebsiela pneumoniae, Proteus mirabilis, Salmonela enterica, Enterococcus faecalis, Enterococcus epidermis and Pseudomonas aeruginosa). Antibiofouling testing of composite films indicated that the CPDs/PU composite films eradicated almost completely the biofilms of Pseudomonas aeruginosa and Staphylococcus aureus and about 50% of Escherichia coli biofilms.
Abstract 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 LC3B 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.
: Upper endoscopy is considered the gold standard for screening and diagnosis of esophageal varices (EV). Non-invasive methods for predicting EV have become a research hotspot in recent years. The ...aim of this study was to assess the role of non-invasive scores in predicting the presence of EV in patients with liver cirrhosis, and to determine the value of these scores in predicting the outcome of patients with cirrhosis presenting with acute variceal bleeding.
: A total of 386 patients with liver cirrhosis were included. The model for end-stage liver disease (MELD), aspartate aminotransferase (AST) to alanine aminotransferase (ALT) ratio (AST/ALT), AST to platelet ratio index (APRI), fibrosis-4-index (FIB-4), fibrosis index (FI), King's Score, albumin-bilirubin (ALBI) score, and platelet-albumin-bilirubin (PALBI) score were calculated. The discriminatory capacities of the examined scores in predicting the presence of esophageal varices were tested using receiver operating characteristic (ROC) curves.
: The ROC curve analysis showed (area under the curve) AUC values of ALBI and PALBI of 0.603, and 0.606, respectively, for the prediction of EV. APRI, MELD, PALBI, King's, FIB-4, and ALBI scores showed statistically significant correlation with EV bleeding (
< 0.05). AUC of APRI and MELD for predicting EV bleeding were 0.662 and 0.637, respectively. The AUC value of MELD in short-term mortality was 0.761.
: ALBI and PALBI scores had modest diagnostic accuracy of EVs in liver cirrhosis. APRI and MELD can be used as a reference index for the EV bleeding, and MELD score is best associated with short-term outcome in cirrhotic patients.
Due to their low cost and possible green synthesis, high stability and resistance to photobleaching, graphene quantum dots (GQDs) can be considered as one of the class of carbon nanomaterials which ...may have great potential as an agent for photosensitized oxygen activation. In such a way, GQDs can be used as a theranostic agent in photodynamic therapy. In this work pristine GQDs, GQDs irradiated with gamma rays and GQDs doped with N and N, S atoms are produced using a simple, green approach. By using different techniques (AFM, HR-TEM, SEM-EDS, FTIR, XRD, PL and UV–Vis) we investigated structural and optical properties of the new types of GQDs. We showed that GQDs functionalized with thiourea (GQDs-TU) completely lost the ability to produce singlet oxygen (1O2) upon photoexcitation while functionalization with urea (GQDs-U) improves the capability of GQDs to produce 1O2 upon the same conditions. Thus, presented GQDs modification with urea seems like a promising approach for the production of the efficient photosensitizer. On the opposite, GQDs-TU are efficient OH quencher. Due to high singlet oxygen production and low cytotoxicity below 100 μg/mL against HeLa cells, GQDs-U is a good candidate as an agent in photodynamic therapy at this concentration.
Display omitted
•GQD structure was modified by thermal with urea and thiourea.•GQDs functionalized with thiourea are efficient OH quencher.•Urea improves the capability of GQDs to produce 1O2 upon photoexcitation.•Low toxicity toward HeLa cells in dark candidates them as photosensitizers.
Semiconductor Zn-Mn-O crystallites were synthesized by a solid state reaction method starting from the thermal decomposition of the appropriate oxalates. Samples were thermally treated in air at ...temperatures ranging from 400 to 900?C. The nominal concentrations of manganese werex = 0.01, 0.02, 0.04 and 0.10. The samples were investigated by the X-ray powder diffraction method, magnetization measurements and by electron paramagnetic resonance. X-ray diffractgrams show a dominant wurtzite structure of Zn-Mn-O. Room temperature ferromagnetism was observed in Zn-Mn-O samples with manganese concentrations x ? 0.04, thermally treated at low temperature (500?C). The saturation magnetiza?tion for the sample with x = 0.01 was 0.05 ?B/Mn. The room temperature ferromagnetism seems to be due to the diffusion of Zn into the Mn-oxides grains.
Ispitivani su poluprovodnicki Zn-Mn-O kristali dobijeni metodom sinteze u cvrstom stanju - termickom dekompozicijom odgovarajucih oksalata i termickim tretmanom. Termicki tretman je izvrsen u vazduhu na razlicitim temperaturama u intervalu od 400 do 900?C. Nominalne koncentracije mangana su x = 0,01; 0,02; 0,04 i 0,10. Uzorci su ispitivani metodom difrakcije X-zraka na prahu, merenjem magnetizacije i metodom elektronske paramagnetne rezonance. Analiza difraktograma ukazuje na dominantnu vurcitnu kristalnu strukturu sintetisanog Zn-Mn-O materijala. Feromagnetizam na sobnoj temperaturi je uocen na uzorcima Zn-Mn-O sa koncentracijom mangana x ? 0,04 termicki tretiranim na nizim temperaturama (500?C). Magnetizacija zasicenja u uzorku x = 0,01 iznosi 0,05 ?B/Mn. Ferromagnetna faza je verovatno posledica difuzije Zn u neki manganov oksid.
Luminescence of monoclinic lithium metatitanate (Li2TiO3) powders activated with different quantities of Mn4+ is studied in detail. Its strong deep‐red emission arising from the Mn4+ 2Eg → 4A2g spin ...forbidden transition is centered at around 688 nm and is suitable for luminescence thermometry. Structural and electron paramagnetic resonance analyses show that Mn4+ ions are equally distributed in two almost identical Ti4+ sites in which they are octahedrally coordinated by six oxygen ions. Calculations based on the exchange charge model of the crystal field provided values of Racah parameters (B=760 cm−1, C= 2993 cm−1), crystal‐field splitting Dq= 2043 cm−1, and the nephelauxetic parameter β1=0.9775. The maximal quantum efficiency of 24.1% at room temperature is found for 0.126% Mn4+ concentration. Temperature quenching of emission occurs by a cross‐over via 4T2 excited state of the Mn4+ ions with T1/2=262 K and is quite favorable for the application in the lifetime‐based luminescence thermometry since relative changes in emission decay values are exceptionally‐large (around 3.21% at room temperature). We derived theoretical expressions for the temperature dependence of the absolute and relative sensitivities and discuss the influence of host material properties on lifetime sensitivities.
The luminescence of Mn4+ activated Li2TiO3 deep‐red phosphor provides the high‐performance temperature sensing with temperature resolution better than 30 mK over the wide temperature range. The engineering of the Mn4+ activated materials for the high‐precision luminescence thermometry via the control of the energies of 4T2g level and phonon coupling is shown.
The present study reports the synthesis and spectroscopic characterization of dinuclear silver(I) complexes, {Ag(X-O)(phtz-N)2(µ-phtz-N,N')2} (X = NO3 - (Ag1) and CF3SO3 - (Ag2), and phtz is ...phthalazine). The interaction of these two complexes with calf thymus DNA (ct-DNA) and bovine serum albumin (BSA) was investigated to assess their binding affinity to these biomolecules. The binding constants of complexes Ag1 and Ag2 to BSA are found to be higher than those for ct-DNA, being in accordance with their higher affinity toward the studied protein. The values of partition coefficient (logP) for the investigated complexes indicate higher cellular uptake efficiency of Ag1 than Ag2. The in vivo toxicity of the complexes Ag1 and Ag2 against the model organism, Caenorhabditis elegans, was studied to check their therapeutic potential.
PDF
