41. In vitro tumor hypoxia imaging with fluorescent covalent organic frameworksTina Skorjanc, Dinesh Shetty, Damjan Makuc, Gregor Mali, Martina Bergant Marušič, Matjaž Valant, 2023, published scientific conference contribution abstract Abstract: Hypoxia refers to a condition where cells and tissues experience low, inadequate levels of O2. While healthy tissues are typically supplied with sufficient O2 (normoxia), cancerous tissues commonly face hypoxia due to the tumor’s extraordinarily high demand for oxygen. Various fluorescent small-molecule probes have been designed for selective detection of hypoxia in living cells, but few nanomaterials have been investigated for this type of bioimaging. Herein, we prepare a fluorescent covalent organic framework (COF) with β-ketoenamine linkages and post-synthetically modify it to conjugate hypoxia-sensitive nitroimidazole moieties
into its pores (NI-COF). Stacks of sheets in NI-COF observed under electron microscopy were exfoliated by ultrasonication, and dynamic light scattering measurements confirmed particle size of less than 200 nm. Thus-prepared material exhibited good stability in physiological conditions and low cytotoxicity in in vitro experiments. NI-COF also showed useful fluorescence properties with an emission peak at 490 nm (λex = 420 nm) at both neutral and mildly acidic pH levels that are characteristic of tumor tissues. Encouraged by the favorable properties of the material, we incubated HeLa cells pre-treated in either hypoxic or normoxic conditions with NI-COF. Fluorescence microscopy images demonstrated that the material was preferentially taken up by hypoxic cells, which showed higher fluorescence signal in their interior than cells cultured under normoxia conditions. It is anticipated that this study will stimulate further developments of COFs for imaging various biological conditions.
Keywords: hypoxia, fluorescence, covalent organic frameworks, imaging, tumor cells
Published in RUNG: 19.09.2023; Views: 1869; Downloads: 7
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42. Covalent organic frameworks for fluorescent imaging of hypoxiaTina Škorjanc, Dinesh Shetty, Gregor Mali, Damjan Makuc, Martina Bergant Marušič, Matjaž Valant, 2023, published scientific conference contribution abstract Keywords: hypoxia, covalent organic frameworks, imaging, fluorescence, post-synthetic modification
Published in RUNG: 06.06.2023; Views: 2240; Downloads: 3
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43. Nitroreductase-sensitive fluorescent covalent organic framework for tumor hypoxia imaging in cellsTina Škorjanc, Dinesh Shetty, Sushil Kumar, Damjan Makuc, Gregor Mali, Janez Volavšek, Martina Bergant Marušič, Matjaž Valant, 2023, original scientific article Keywords: covalent organic frameworks, imaging, hypoxia, fluorescence, cancer cells
Published in RUNG: 17.05.2023; Views: 2206; Downloads: 19
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44. Optical emission diagnosis of carbon nanoparticle incorporated chlorophyll for sensing applicationsMohanachandran Nair Sindhu Swapna, RAJ VIMAL, SARITHA DEVI H V, Sankararaman S, 2019, original scientific article Abstract: Chlorophyll fluorescence (Chl F) is widely used in sensing applications to understand terrestrial vegetation
and environmental and climatic variations. The increasing rates of industrialization and carbon emission
from internal combustion engines (ICEs) pose a threat to sustainable development. This study analyses
the impact of carbon nanoparticles (CNPs) from ICEs on the optical absorption and fluorescence emission of leaf pigments. Leaf pigments without and with CNPs were subjected to UV-visible and photo-luminescence (PL) spectroscopy analyses. The field emission scanning electron microscopy and high-resolution transmission electron microscopy images of CNPs showed their morphology. The Jablonski diagram of the CNP-incorporated chlorophyll system helped in understanding the fluorescence emission,internal conversion, and the exchange of energy between them. The variations in (i) total chlorophyll, (ii)
optical absorbance by total chlorophyll, (iii) PL emission peak (at 675 nm and 718 nm) intensities for different excitation wavelengths, and (iv) normalized absorbance at the PL emission peaks with different CNP concentrations were analysed by dividing into three regions. In Region I (0–0.625 mg ml−1 ), the
radiative component dominated the nonradiative component as a result of energy transfer from CNPs to chlorophyll. In Region II (0.625–1.2 mg ml−1 ), the increase in CNP concentration initiated diffusion into chloroplasts, resulting in the increase in the nonradiative part of total energy and decrease in PL peak
intensity. In Region III (1.2–2.5 mg ml−1
), the energy absorbed by the CNPs dissipated more nonradiatively, leading to a slow rate of increase in the radiative part. The visual response of PL emission, color purity,
and the distribution of the emitted energy over the spectrum studied with the help of CIE plots, power spectrum, and confocal fluorescence microscopy revealed the fluorescence emission in the red region. This study suggests the possibility of employing Chl F in agricultural, environmental, and biological fields
for sensing applications.
Keywords: carbon nanoparticle, optical emission, fluorescence
Published in RUNG: 05.07.2022; Views: 2007; Downloads: 0
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45. Tunable fluorescence from natural carbon source- PandanusMohanachandran Nair Sindhu Swapna, SARITHA DEVI H V, AMBADAS G, Sankararaman S, 2019, original scientific article Abstract: Carbon materials possessing photoluminescence properties are considered as potential candidates in a
wide range of photonic and optoelectronic applications. In this work, the cellulose derived from the natural source,
Pandanus, is autoclave-treated for the synthesis of fluorescent carbon. The natural fibres are greatly preferred
over synthetic ones due to their cost-effectiveness, easy processability, non-abrasivity, non-toxic and environment-friendly characteristics along with high mechanical strength and damage tolerance. These properties enable them
to be used as templates for synthesis, as important reinforcement materials for commercial thermoplastics and
for making value-added products. In this study, the synthesised sample is subjected to structural, morphological,
elemental and optical characterisations. These studies reveal that the sample can be used as a low-cost tunable
light-emitting source for photonic, biomedical and biosensing applications.
Keywords: Fluorescence, Pandanus, natural carbon, cellulose
Published in RUNG: 04.07.2022; Views: 2015; Downloads: 0
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46. From futile to fruitful: Diesel soot as white light emitterMohanachandran Nair Sindhu Swapna, Sankararaman S, 2018, original scientific article Abstract: The present work describes a solution for the effective use of the hazardous particulate matter (diesel soot) from the internal combustion engines (ICEs) as a potential material emitting white light for white light emitting diodes (WLEDs). The washed soot samples are subjected to Field Emission Scanning Electron Microscopy (FESEM), High- Resolution Transmission Electron Microscopy (HR-TEM), Energy Dispersive Spectroscopy (EDS), UV-Visible, Photoluminescent (PL) Spectroscopy and quantum yield measurements. The CIE plot and Correlated Color Temperature (CCT) reveals the white fluorescence on photoexcitation. The sample on ultraviolet (UV) laser excitation, provides a visual confirmation of white light emission from the sample. The diesel soot collected from public transport buses of different years of manufacture invariably exhibit white fluorescence at an excitation of 350 nm. The sample show a quantum yield of 47.09%. The study is significant in the context of pollution and search for low-cost, rare-earth phosphor free material for white light emission and thereby turning the hazardous, futile material into a fruitful material that can be used for potential applications in photonics and electronics.
Keywords: White light emitter, Diesel soot, CIE plot, Quantum yield, Fluorescence
Published in RUNG: 30.06.2022; Views: 2174; Downloads: 0
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47. Impact of microplastics on growth, photosynthesis and essential elements in Cucurbita pepo L.Ilaria Colzi, Luciana Renna, Elisabetta Bianchi, Maria Beatrice Castellani, Andrea Coppi, Sara Pignattelli, Stefano Loppi, Cristina Gonnelli, 2022, original scientific article Abstract: In this study, Cucurbita pepo L., one of the most cultivated, consumed and economically important crop worldwide, was used as model plant to test the toxic effects of the four most abundant microplastics identified in contaminated soils, i.e. polypropylene (PP), polyethylene (PE), polyvinylchloride (PVC), and polyethyleneterephthalate (PET). Cucurbita plants were grown in pots with increasing concentrations of the microplastics, then plant biometry, photosynthetic parameters and ionome of treated vs. untreated samples were compared to evaluate the toxicity of each plastic. All the pollutants impaired root and, especially, shoot growth. Specific and concentration-dependant effects of the different microplastics were found, including reduction in leaf size, chlorophyll content and photosynthetic efficiency, as well as changes in the micro- and macro-elemental profile. Among all the microplastics, PVC was identified as the most toxic and PE as the less toxic material. PVC decreased the dimensions of the leaf lamina, the values of the photosynthetic performance index and the plant iron concentration to a higher extent in respect to the other treatments. Microplastic toxicity exerted on the growth of C. pepo raises concerns about possible yield and economic loss, as well as for risks of a possible transfer into the food chain.
Keywords: microplastic toxicity, leaf traits, chlorophyll fluorescence, ionome, zucchini
Published in RUNG: 17.12.2021; Views: 3128; Downloads: 8
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48. Covalent Organic Polymers and Frameworks for Fluorescence-Based SensorsTina Škorjanc, Dinesh Shetty, Matjaž Valant, 2021, review article Keywords: fluorescence, sensors, covalent organic polymers, covalent organic frameworks, quenching, ions, explosives
Published in RUNG: 05.05.2021; Views: 3316; Downloads: 229
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49. Temperature-controlled airflow ventilation in operating rooms compared with laminar airflow and turbulent mixed airflowMalin Alsved, A. Civilis, P. Ekolind, Tina Šantl Temkiv, Jakob Löndahl, 2017, original scientific article Keywords: Surgical site infection, BioTrak, Fluorescence, Energy efficiency, Temperature-controlled ventilation, Air sampling
Published in RUNG: 04.01.2021; Views: 4710; Downloads: 0
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50. New air fluorescence detectors employed in the Telescope Array experimentH. Tokuno, Jon Paul Lundquist, 2012, original scientific article Abstract: Since 2007, the Telescope Array (TA) experiment, based in Utah, USA, has been observing ultra high energy cosmic rays to understand their origins. The experiment includes a surface detector (SD) array and three fluorescence detector (FD) stations. The FD stations, installed surrounding the SD array, measure the air fluorescence light emitted from extensive air showers (EASs) for precise determination of their energies and species. The detectors employed at one of the three FD stations were relocated from the High Resolution Fly's Eye (HiRes) experiment. At the other two stations, newly designed detectors were constructed for the TA experiment. An FD consists of a primary mirror and a camera equipped with photomultiplier tube pixels. To obtain the EAS parameters with high accuracy, understanding the FD optical characteristics is important. In this paper, we report the characteristics and installation of the new FDs and the performances of the FD components. The results of the monitored mirror reflectance during the observation time are also described in this report.
Keywords: Ultra high energy cosmic rays, Extensive air showers, Air fluorescence light detectors
Published in RUNG: 19.05.2020; Views: 3343; Downloads: 0
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