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Sustained delivery of Cu(II)-based DNA intercalators by nanometer-sized cyclodextrin-based porous polymers
Tina Škorjanc, Julian Heinrich, Damjan Makuc, Nora Kulak, Matjaž Valant, 2023, original scientific article

Abstract: 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.
Keywords: porous organic polymers, cyclodextrin, DNA intercalators, Cu(II) complexes, metal complexes
Published in RUNG: 10.11.2023; Views: 237; Downloads: 2
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Crystallizing covalent organic frameworks from metal organic framework through chemical induced‑phase engineering
Abdul Khayum Mohammed, Safa Gaber, Jesus Raya, Tina Skorjanc, Nada Elmerhi, Sasi Stephen, Pilar Pena Sanchez, Felipe Gandara, Steven J. Hinder, Mark A. Baker, Kyriaki Polychronopoulou, Dinesh Shetty, 2023, original scientific article

Abstract: The ordered porous frameworks like MOFs and COFs are generally constructed using the monomers through distinctive metal-coordinated and covalent linkages. Meanwhile, the inter-structural transition between each class of these porous materials is an under-explored research area. However, such altered frameworks are expected to have exciting features compared to their pristine versions. Herein, we have demonstrated a chemical-induction phase-engineering strategy to transform a two dimensional conjugated Cu-based SA-MOF (Cu-Tp) into 2D-COFs (Cu-TpCOFs). The structural phase transition offered in-situ pore size engineering from 1.1 nm to 1.5–2.0 nm. Moreover, the Cu-TpCOFs showed uniform and low percentage-doped (~ 1–1.5%) metal distribution and improved crystallinity, porosity, and stability compared to the parent Cu-Tp MOF. The construction of a framework from another framework with new linkages opens interesting opportunities for phase-engineering.
Keywords: Metal organic framework, covalent organic framework, phase engineering, chemical transformation, porous materials
Published in RUNG: 10.11.2023; Views: 253; Downloads: 3
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In vitro tumor hypoxia imaging with fluorescent covalent organic frameworks
Tina Skorjanc, Dinesh Shetty, Damjan Makuc, Gregor Mali, Martina Bergant Marušič, Matjaz 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: 362; Downloads: 3
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A Rational Design of Isoindigo-Based Conjugated Microporous n-Type Semiconductors for High Electron Mobility and Conductivity
Kayaramkodath Chandran Ranjeesh, Ayman Rezk, Jose Ignacio Martinez, Safa Gaber, Areej Merhi, Tina Skorjanc, Matjaz Finsgar, Gisha Elizabeth Luckachan, Ali Trabolsi, Bilal R. Kaafarani, Ammar Nayfeh, Dinesh Shetty, 2023, original scientific article

Abstract: The development of n-type organic semiconductors has evolved significantly slower in comparison to that of p-type organic semiconductors mainly due to the lack of electron-deficient building blocks with stability and processability. However, to realize a variety of organic optoelectronic devices, high-performance n-type polymer semiconductors are essential. Herein, conjugated microporous polymers (CMPs) comprising isoindigo acceptor units linked to benzene or pyrene donor units (BI and PI) showing n-type semiconducting behavior are reported. In addition, considering the challenges of deposition of a continuous and homogeneous thin film of CMPs for accurate Hall measurements, a plasma-assisted fabrication technique is developed to yield uniform thin films. The fully conjugated 2D networks in PI- and BI-CMP films display high electron mobility of 6.6 and 3.5 cm2 V−1 s−1, respectively. The higher carrier concentration in PI results in high conductivity (5.3 mS cm−1). Both experimental and computational studies are adequately combined to investigate structure–property relations for this intriguing class of materials in the context of organic electronics.
Keywords: conjugated microporous polymers, isoindigo, semiconductors, conductivity, electron mobility
Published in RUNG: 18.08.2023; Views: 396; Downloads: 2
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Enzyme-immobilized Hierarchically Porous Covalent Organic Framework Biocomposite for Catalytic Degradation of Broad-range Emerging Pollutants in Water
Nada Elmerhi, Khadega Al-Maqdi, Khawlah Athamneh, Abdul Khayum Mohammed, Tina Skorjanc, Felipe Gandara, Jesus Raya, Simon Pascal, Olivier Siri, Ali Trabolsi, Iltaf Shah, Dinesh Shetty, Syed Salman Ashraf, 2023, original scientific article

Abstract: 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.
Keywords: covalent organic frameworks, enzymes, emerging pollutants, water purification, biocomposite
Published in RUNG: 11.08.2023; Views: 442; Downloads: 2
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Separation of mercuric ions using 2-thienylbenzimidazole/cucurbit[7]uril/iron-oxide nanoparticles by pH control
Falguni Chandra, Paltan Laha, Farah Benyettou, Tina Skorjanc, Na'il Saleh, 2023, original scientific article

Abstract: 2-Thienylbenzimidazole (TBI)/cucurbit[7]uril (CB7) host–guest complex was used as a motif to significantly improve the turnover of γ-Fe3O4 magnetic nanoparticles for potential application in the separation of toxic mercuric ions in polluted water samples. The mechanism of restoring the original solid materials is based on applying the pH-controlled preferential binding of the CB7 host to the TBI guest. The analytical application of this concept has not been realized in the literature. The pH-controlled stimuli-responsive abilities were confirmed in aqueous solution by the three-order of magnitudes higher stability constant of the protonated TBIH+/CB7 complex (e.g., K = 4.8 × 108 M−1) when compared to neutral TBI/CB7 complex (e.g., K = 2.4 × 105 M−1), also manifested in an increase in pKa values by ~ 3.3 units in the ground state. The supramolecular interaction and adsorption on iron oxide nanoparticles (NPs) were also spectroscopically confirmed in the solid state. The excited-state lifetime values of TBI/CB7NPs increased upon lowering the pH values (e.g., from 0.6 to 1.3 ns) with a concomitant blue shift of ~ 25 nm because of polarity effects. The time-resolved photoluminescent behaviors of the final solids in the presence of CB7 ensured pH-driven reusable systems for capturing toxic mercuric ions. The study offers a unique approach for the controllable separation of mercury ions using an external magnet and in response to pH through preferential binding of the host to guest molecules on the top of magnetic surfaces.
Keywords: iron oxide nanoparticles (IONPs), mercury, thienylbenzimidazole, cucurbit[n]uril
Published in RUNG: 13.07.2023; Views: 555; Downloads: 0
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Covalent organic frameworks for fluorescent imaging of hypoxia
Tina Skorjanc, Dinesh Shetty, Gregor Mali, Damjan Makuc, Martina Bergan Marušič, Matjaz Valant, 2023, published scientific conference contribution abstract

Keywords: hypoxia, covalent organic frameworks, imaging, fluorescence, post-synthetic modification
Published in RUNG: 06.06.2023; Views: 653; Downloads: 0
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Cationic polymer thin films for electrochemical detection of bacteria
Tina Škorjanc, 2022, published scientific conference contribution abstract

Keywords: sensors, electrochemical impedance spectroscopy, porous materials, E. coli
Published in RUNG: 06.12.2022; Views: 901; Downloads: 5
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