Structural, optical, and bioimaging characterization of carbon quantum dots solvothermally synthesized from o-phenylenediamine

Carbon quantum dots as a novel type of carbon nanomaterials have attracted the attention of many researchers because of their unique optical, antibacterial, and anticancer properties as well as their biocompatibility. In this study, for the first time, carbon quantum dots were prepared from o-phenylenediamine dissolved in toluene by a solvothermal route. Subsequently, the prepared carbon quantum dots were encapsulated into polyurethane films by a swelling–encapsulation–shrink method. Analyses of the results obtained by different characterization methods (AFM, TEM, EDS, FTIR, photoluminescence, and EPR) indicate the significant influence of the precursor on structural, chemical, and optical properties. Antibacterial and cytotoxicity tests showed that these dots did not have any antibacterial potential, because of the low extent of reactive oxygen species production, and showed low dark cytotoxicity. By investigating the cellular uptake, it was established that these dots penetrated the HeLa cells and could be used as probes for bioimaging

Highly Efficient Antibacterial Polymer Composites Based on Hydrophobic Riboflavin Carbon Polymerized Dots

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 Escherichia coli in 30 min, whereas the same effect toward Staphylococcus aureus 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

Multi-Center Fetal Brain Tissue Annotation (FeTA) Challenge 2022 Results

Segmentation is a critical step in analyzing the developing human fetal brain. There have been vast improvements in automatic segmentation methods in the past several years, and the Fetal Brain Tissue Annotation (FeTA) Challenge 2021 helped to establish an excellent standard of fetal brain segmentation. However, FeTA 2021 was a single center study, and the generalizability of algorithms across different imaging centers remains unsolved, limiting real-world clinical applicability. The multi-center FeTA Challenge 2022 focuses on advancing the generalizability of fetal brain segmentation algorithms for magnetic resonance imaging (MRI). In FeTA 2022, the training dataset contained images and corresponding manually annotated multi-class labels from two imaging centers, and the testing data contained images from these two imaging centers as well as two additional unseen centers. The data from different centers varied in many aspects, including scanners used, imaging parameters, and fetal brain super-resolution algorithms applied. 16 teams participated in the challenge, and 17 algorithms were evaluated. Here, a detailed overview and analysis of the challenge results are provided, focusing on the generalizability of the submissions. Both in- and out of domain, the white matter and ventricles were segmented with the highest accuracy, while the most challenging structure remains the cerebral cortex due to anatomical complexity. The FeTA Challenge 2022 was able to successfully evaluate and advance generalizability of multi-class fetal brain tissue segmentation algorithms for MRI and it continues to benchmark new algorithms. The resulting new methods contribute to improving the analysis of brain development in utero.Comment: Results from FeTA Challenge 2022, held at MICCAI; Manuscript submitted. Supplementary Info (including submission methods descriptions) available here: https://zenodo.org/records/1062864

Characterization of alpha-synuclein transport in the digestive system

Sve više dokaza upućuje na probavni sustav kao važan etiopatogenetski čimbenik u Parkinsonovoj bolesti (PB). Simptomi vezani uz probavni sustav prevalentni su i javljaju se u prodromalnom stadiju bolesti, a patološki agregati alfa sinukleina (ɑS) u enteričkom živčanom sustavu (EŽS) opisani su prije nakupljanja u mozgu. Bakterijski i prehrambeni sinukleini mogli bi biti važan pokretač agregacije ɑS-a u EŽS-u, međutim, u ovom trenutku apsorpcija i translokacija luminalnog ɑS-a još uvijek nije istražena. Cilj ovog diplomskog rada bio je postaviti i validirati ex vivo model translokacije luminalnog ɑS-a kroz probavnu sluznicu miša i štakora te ispitati mehanizme translokacije. Istraživanja provedena u okviru ovog diplomskog rada pokazala su da ex vivo inkubacija fluorescentno obilježenog αS-a s probavnom sluznicom može poslužiti kao vrijedan model za proučavanje patofizioloških mehanizama povezanih sa sinukleinopatijama. Nakon luminalnog izlaganja, egzogeni αS u najvećoj mjeri nalazi se u epitelnim stanicama (uključujući i epitelne stanice odljuštene u lumen). Nakon toga, luminalni αS nakuplja se stanicama koje izražavaju biljege enteroendokrinih stanica i živčanih stanica, a najvažniji originalni doprinos ovog diplomskog rada je nakupljanje αS-a u enteroglijalnim stanicama što do ovog trenutka nije opisano u literaturi. Radni model postavljen na temelju provedenog istraživanja pretpostavlja translokaciju luminalnog αS kroz stanice probavnog epitela nakon čega dolazi do nakupljanja u nastavcima živčanih i enteroglijalnih stanica koje bi mogle biti ključni posrednici u prijenosu do spletova EŽS-a. Razumijevanje prijenosa αS-a u probavnom sustavu moglo bi doprinijeti razvoju novih ciljanih terapija koje bi mogle spriječiti nastanak i usporiti napredovanje PB-a.There is increasing evidence pointing to the digestive system as a key etiopathogenetic factor in Parkinson's disease (PD). Gastrointestinal symptoms are prevalent and occur during the prodromal stage of the disease, and pathological aggregates of alpha-synuclein (ɑS) in the enteric nervous system (ENS) have been observed before their accumulation in the brain. Bacterial and dietary synucleins could be important triggers for ɑS aggregation in the ENS; however, the absorption and translocation of luminal ɑS have not yet been thoroughly investigated. The aim of this thesis was to establish and validate an ex vivo model of luminal ɑS translocation through the digestive mucosa of mice and rats, and to examine the mechanisms of this translocation. The studies conducted as part of this thesis demonstrated that ex vivo incubation of fluorescently labeled αS with the digestive mucosa can serve as a valuable model for studying pathophysiological mechanisms related to synucleinopathies. Following luminal exposure, exogenous αS was predominantly found in epithelial cells (including epithelial cells shed into the lumen). Subsequently, luminal αS accumulates in cells expressing markers of enteroendocrine and neuronal cells. The most significant original contribution of this thesis is the accumulation of αS in enteroglial cells, a finding that has not been previously described in the literature. The working model proposed based on this research suggests the translocation of luminal αS through digestive epithelial cells, followed by accumulation in the extensions of neuronal and enteroglial cells, which could be key mediators in the transfer to ENS networks. Understanding the translocation of αS in the digestive system could contribute to the development of novel targeted therapies that may prevent the onset and slow the progression of PD

Photodynamic-active smart biocompatible material for an antibacterial surface coating

Here we present a new effective antibacterial material suitable for a coating, e.g., surface treatment of textiles, which is also time and financially undemanding. The most important role is played by hydrophobic carbon quantum dots, as a new type of photosensitizer, produced by carbonization of different carbon precursors, which are incorporated by swelling from solution into various polymer matrices in the form of thin films, in particular polyurethanes, which are currently commercially used for industrial surface treatment of textiles. The role of hydrophobic carbon quantum dots is to work as photosensitizers upon irradiation and produce reactive oxygen species, namely singlet oxygen, which is already known as the most effective radical for elimination different kinds of bacteria on the surface or in close proximity to such modified material. Therefore, we have mainly studied the effect of hydrophobic carbon quantum dots on Staphylococcus aureus and the cytotoxicity tests, which are essential for the safe handling of such material. Also, the production of singlet oxygen by several methods (electron paramagnetic spectroscopy, time-resolved near-infrared spectroscopy), surface structures (atomic force microscopy and contact angle measurement), and the effect of radiation on polymer matrices were studied. The prepared material is easily modulated by end-user requirements. © 2020 Elsevier B.V.Ministry of Education of the Slovak Republic; Slovak Academy of Sciences [VEGA 2/0051/20]; Czech Science FoundationGrant Agency of the Czech Republic [1916861S]; ERDF/ESF "Centre of Advanced Applied Sciences" [CZ.02.1.01/0.0/0.0/16_019/0000778

Enhanced visible light-triggered antibacterial activity of carbon quantum dots/polyurethane nanocomposites by gamma rays induced pre-treatment

Persistent microbial contamination of medical implant surfaces is becoming a serious threat to public health. This is principally due to antibiotic-resistant bacterial strains and the formation of bacterial biofilms. The development of novel antibacterial materials that will effectively fight both Gram-positive and Gram-negative bacteria and prevent biofilm formation represents a big challenge for researchers in the last few decades. In the present work, we report an antibacterial hydrophobic carbon quantum dots/polyurethane nanocomposite (hCQD-PU), with enhanced antibacterial properties induced by pre-treatment with gamma-irradiation. Hydrophobic quantum dots (hCQDs), which are capable of generating reactive oxygen species (ROS) upon irradiation with low-power blue light (470 nm), have been integrated into the polyurethane (PU) polymer matrix to form a photoactive nanocomposite. To modify its physical and chemical properties and improve its antibacterial efficacy, various doses of gamma irradiation (1, 10, and 200 kGy) in the air environment were applied to the formed nanocomposite. Gamma-irradiation pre-treatment significantly influenced the rise in ROS production, therefore, the prooxidative activity under the blue-light illumination of hCQD-PU was also significantly improved. The best antibacterial activity was demonstrated by the hCQD-PU nanocomposite irradiated with a dose of 200 kGy, with the complete eradication of Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Escherichia coli (E. coli) bacteria after 15 min of exposure to the blue lamp. © 2021 Elsevier LtdMinistry of Education, Science and Technological Development of the Republic of Serbia [451039/202114/200017]Ministarstvo Prosvete, Nauke i Tehnološkog Razvoja, MPNTR: 451-03-9/2021-14/20001

Corrigendum “antibacterial photodynamic activity of carbon quantum dots/polydimethylsiloxane nanocomposites against Staphylococcus aureus, Escherichia coli and Klebsiella pneumoniae” [photodiagnosis. photodyn. ther. 26 (2019) 342–349]

Despite great efforts, the design of antibacterial surfaces is still a challenge. In this work, results of structural, mechanical, cytotoxic and antibacterial activities of hydrophobic carbon quantum dots/polydimethylsiloxane surfaces are presented. Antibacterial action of this surface is based on the generation of reactive oxygen species which cause bacteria damage by oxidative stress. At the same time, this surface was not cytotoxic towards the NIH/3T3 cells. Swelling-encapsulation-shrink method is applied for encapsulation of hydrophobic carbon quantum dots in medical grade silicone-polydimethylsiloxane. XPS and photoluminescence spectroscopy analyses confirm that hydrophobic carbon quantum dots have been encapsulated successfully into polydimethylsiloxane polymer matrix. Based on stress-strain test the improvement of mechanical properties of these nanocomposites is established. It is shown by electron paramagnetic resonance spectroscopy and luminescence method that nanocomposite generates singlet oxygen initiated by 470 nm blue light irradiation. Antibacterial testing shows the nanocomposite in the form of foil kills Staphylococcus aureus, Escherichia coli and Klebsiella pneumoniae and is very effective after only a 15 min irradiation. © 2019 Elsevier B.V.Post-print version available at: [http://vinar.vin.bg.ac.rs/handle/123456789/8187]Link to the corrected article: [https://vinar.vin.bg.ac.rs/handle/123456789/8174

Antibacterial photodynamic activity of carbon quantum dots/polydimethylsiloxane nanocomposites against Staphylococcus aureus, Escherichia coli and Klebsiella pneumoniae

Despite great efforts, the design of antibacterial surfaces is still a challenge. In this work, results of structural, mechanical, cytotoxic and antibacterial activities of hydrophobic carbon quantum dots/polydimethylsiloxane surfaces are presented. Antibacterial action of this surface is based on the generation of reactive oxygen species which cause bacteria damage by oxidative stress. At the same time, this surface was not cytotoxic towards the NIH/3T3 cells. Swelling-encapsulation-shrink method is applied for encapsulation of hydrophobic carbon quantum dots in medical grade silicone-polydimethylsiloxane. XPS and photoluminescence spectroscopy analyses confirm that hydrophobic carbon quantum dots have been encapsulated successfully into polydimethylsiloxane polymer matrix. Based on stress-strain test the improvement of mechanical properties of these nanocomposites is established. It is shown by electron paramagnetic resonance spectroscopy and luminescence method that nanocomposite generates singlet oxygen initiated by 470 nm blue light irradiation. Antibacterial testing shows the nanocomposite in the form of foil kills Staphylococcus aureus, Escherichia coli and Klebsiella pneumoniae and is very effective after only a 15 min irradiation. © 2019 Elsevier B.V

Antibacterial photodynamic activity of carbon quantum dots/polydimethylsiloxane nanocomposites against Staphylococcus aureus, Escherichia coli and Klebsiella pneumoniae

Despite great efforts, the design of antibacterial surfaces is still a challenge. In this work, results of structural, mechanical, cytotoxic and antibacterial activities of hydrophobic carbon quantum dots/polydimethylsiloxane surfaces are presented. Antibacterial action of this surface is based on the generation of reactive oxygen species which cause bacteria damage by oxidative stress. At the same time, this surface was not cytotoxic towards the NIH/3T3 cells. Swelling-encapsulation-shrink method is applied for encapsulation of hydrophobic carbon quantum dots in medical grade silicone-polydimethylsiloxane. XPS and photoluminescence spectroscopy analyses confirm that hydrophobic carbon quantum dots have been encapsulated successfully into polydimethylsiloxane polymer matrix. Based on stress-strain test the improvement of mechanical properties of these nanocomposites is established. It is shown by electron paramagnetic resonance spectroscopy and luminescence method that nanocomposite generates singlet oxygen initiated by 470 nm blue light irradiation. Antibacterial testing shows the nanocomposite in the form of foil kills Staphylococcus aureus, Escherichia coli and Klebsiella pneumoniae and is very effective after only a 15 min irradiation. © 2019 Elsevier B.V.SASPRO Programme [1237/02/02-b]; People Programme (Marie Curie Actions) European Union's Seventh Framework Programme under REA [609427]; VEGA [2/0093/16]; Ministry of Education, Youth and Sports of the Czech Republic Program NPU I [LO1504]; Czech Science Foundation [19-09721S]; Ministry of Education, Science and Technological Development of the Republic of Serbia [172003]; bilateral project Serbia-Slovakia [SK-SRB-2016-0038]; multilateral scientific and technological cooperation in the Danube region [DS-2016-021