Iskanje po repozitoriju

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Opis: DNA intercalators are small molecules that insert between adjacent DNA base pairs and thus disturb DNA replication and transcription, which can lead to cell death. Certain metal complexes are excellent DNA intercalators, and have shown promise in chemotherapy. Here, a cyclodextrin porous polymer was prepared, characterized, exfoliated to form nanometer-sized particles, and used as a delivery vehicle for metal-free and Cu(II)-metalated anthraquinone-based DNA intercalators with a goal to minimize side effects of the highly toxic DNA intercalators. NMR experiments, including DOSY NMR, have shown the interaction between the cyclodextrin building block and the studied DNA intercalators. Porous nature of the delivery vehicle provided ample surface area for interaction with the drug candidates, resulting in encapsulation rates of up to 56%. Sustained cargo release from the polymer was achieved over eight days, and time-dependent cytotoxicity was observed. Furthermore, optical microscopy images indicated delivery vehicle internalization as well as disturbed cellular morphology within 24 hours of incubation. We anticipate that this study will stimulate further interest in the development of polymeric delivery systems for metal complexes.
Ključne besede: porous organic polymers, cyclodextrin, DNA intercalators, Cu(II) complexes, metal complexes
Objavljeno v RUNG: 10.11.2023; Ogledov: 774; Prenosov: 4
Celotno besedilo (5,10 MB)
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Ključne besede: multi-time resolution, source apportionment, submicronic particulate matter, positive matrix factorisation, PMF, multilinear engine, SoFi, ME2, organic sources, metals
Objavljeno v RUNG: 24.10.2023; Ogledov: 794; Prenosov: 6
Celotno besedilo (3,23 MB)
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Opis: 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.
Ključne besede: hypoxia, fluorescence, covalent organic frameworks, imaging, tumor cells
Objavljeno v RUNG: 19.09.2023; Ogledov: 880; Prenosov: 3
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Opis: Efficient enzyme immobilization is crucial for the successful commercialization of large-scale enzymatic water treatment. However, issues such as lack of high enzyme loading coupled with enzyme leaching present challenges for the widespread adoption of immobilized enzyme systems. The present study describes the development and bioremediation application of an enzyme biocomposite employing a cationic macrocycle-based covalent organic framework (COF) with hierarchical porosity for the immobilization of horseradish peroxidase (HRP). The intrinsic hierarchical porous features of the azacalix[4]arene-based COF (ACA-COF) allowed for a maximum HRP loading capacity of 0.76 mg/mg COF with low enzyme leaching (<5.0%). The biocomposite, HRP@ACA-COF, exhibited exceptional thermal stability (~200% higher relative activity than the free enzyme), and maintained ~60% enzyme activity after five cycles. LCMSMS analyses confirmed that the HRP@ACA-COF system was able to achieve >99% degradation of seven diverse types of emerging pollutants (2-mercaptobenzothiazole, paracetamol, caffeic acid, methylparaben, furosemide, sulfamethoxazole, and salicylic acid)in under an hour. The described enzyme-COF system offers promise for efficient wastewater bioremediation applications.
Ključne besede: covalent organic frameworks, enzymes, emerging pollutants, water purification, biocomposite
Objavljeno v RUNG: 11.08.2023; Ogledov: 946; Prenosov: 6
Celotno besedilo (1,45 MB)
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Opis: Porous organic polymers (POPs) and covalent organic frameworks (COFs) have gained significant attention in the scientific community for a wide array of applications because of their attractive physical and chemical properties. Porosity of these materials provides ample surface area for interaction with targets, while crystallinity allows for highly specific structural tuning. In this seminar, I will present two strategies of utilizing these features of newly prepared materials in biosensing. Firstly, a cationic POP was synthesized, deposited onto interdigitated electrode arrays via a nontraditional electrophoresis technique, and utilized for electrochemical sensing of bacterial cells. As the principle of detection relied on electrostatic interactions between the cationic POP and the anionic bacterial surface, the sensor operated for both Gram-positive and Gram-negative bacteria. Secondly, a small-molecule nitroimidazole target for hypoxia, a low oxygen environment present in tumors, was post-synthetically conjugated to the pores of a fluorescent COF. This material served as a useful hypoxia imaging agent in cancerous cells. The seminar will conclude with some future perspectives on POPs and COFs in biological applications followed by Q & A.
Ključne besede: Porous organic polymers, covalent organic frameworks, biosensors, hypoxia
Objavljeno v RUNG: 13.07.2023; Ogledov: 932; Prenosov: 0
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