1. Hydrazone-linked covalent organic framework catalyst via efficient Pd recovery from wastewaterMahira Bashri, Sushil Kumar, Pallab Bhandari, Sasi Stephen, Matthew J. O'Connor, Safa Gaber, Tina Škorjanc, Matjaž Finšgar, Gisha Elizabeth Luckachan, Blaž Belec, 2024, original scientific article Abstract: Global consumption and discharge of palladium (Pd) have raised environmental concerns but also present an opportunity for the sustainable recovery and reuse of this precious metal. Adsorption has proven to be an efficient method for the selective recovery of Pd from industrial wastewater. This study investigated a hydrazone-linked covalent organic framework (Tfpa-Od COF) as a potential material for the high-affinity adsorption of Pd2+ ions from wastewater, achieving a Kd value of 3.62 × 106 mL g–1. The electron-rich backbone of the COF contributes to its excellent selective removal efficiency (up to 100%) and adsorption capacity of 372.59 mg g–1. Furthermore, the Pd-adsorbed COF was evaluated as a sustainable catalyst for the Suzuki–Miyaura coupling reaction, demonstrating good catalytic conversion and recyclability. This work attempts to showcase a protocol for reusing waste palladium generated in water to fabricate heterogeneous catalysts and, thereby, promote the circular economy concept. Keywords: covalent organic frameworks, sustainability, catalysis, palladium adsorption, water purification Published in RUNG: 22.08.2024; Views: 744; Downloads: 6 Full text (4,04 MB) This document has many files! More... |
2. Strategies to overcome particle size limitations in covalent organic frameworks for bioimaging and delivery : lecture at the 9th International Conference on Metal-Organic Frameworks and Open Framework Compounds (MOF2024), Singapore, 15th-19th July 2024Tina Škorjanc, 2024, unpublished conference contribution Abstract: Particle size is an important physical parameter in any nanomaterial designed for biomedical applications. It critically influences the biological fate of nanoparticles. It is generally believed that a range between 10 and 200 nm is most relevant to physical and biochemical targeting through both intravascular and site-specific deliveries.1
High porosity, purely organic nature, structural tunability and the ability to gradually release therapeutically-relevant cargo have rendered covalent organic frameworks (COFs) promising materials in biomedical research. While several COF-based drug delivery systems have been reported, particle aggregation and the associated particle size pose a significant barrier to real-life implementation of these systems.2 In the current talk, two strategies to address these issues will be presented as they have been applied to biosensing and delivery applications.
Firstly, prolonged ultrasonication has proven an effective method of reducing the COF particle size while maintaining the material’s chemical properties.3 A fluorescent COF, that was post-synthetically modified to incorporate a hypoxia-targeting nitroimidazole moiety, was exposed to prolonged ultrasonication which effectively reduced the particle size from several µm to <170 nm.4 The ultrasonication treatment did not significantly hamper the material’s physical or chemical properties, such as crystallinity, and it even enhanced its fluorescence signal by overcoming aggregation-caused quenching (ACQ). The material and its constituent building blocks were shown to have minimal or no cytotoxicity. The COF’s internalization was monitored by fluorescence spectroscopy, and it preferentially accumulated in cells exposed to hypoxic environment, thus serving as a fluorescent biosensor for hypoxia.
Another strategy of limiting the COF particle size is to grow the material on nano-sized substrates. Silver nanowires (AgNWs) have been shown as effective intracellular sensors5 and single-cell endoscopic tools.6 We have prepared AgNWs with diameters below 200 nm and have employed various synthetic methods to coat them with thiol-functionalized COFs. Favorable coordination bonds that form between Ag and the thiol functional group in the COF linkers drive the assembly process. Both bottom-up synthetic approaches, where the COF is grown on the surface of AgNWs, and top-down strategies, where pre-synthesized COF particles are attached onto AgNWs surface have been successful. The inorganic-organic hybrid materials were characterized by various techniques, including electron microscopy, Fourier-transform infrared spectroscopy, thermogravimetric analysis, and powder X-ray diffraction. All characterizations combined suggest that the diameter of the COF-coated AgNWs remains well in the nanometer-size regime.
References:
(1) Hickey, J. W.; Santos, J. L.; Williford, J.-M.; Mao, H.-Q. Control of Polymeric Nanoparticle Size to Improve Therapeutic Delivery. J. Control. Release 2015, 219, 536–547.
(2) Esrafili, A.; Wagner, A.; Inamdar, S.; Acharya, A. P. Covalent Organic Frameworks for Biomedical Applications. Adv. Healthc. Mater. 2021, 10 (6), 2002090.
(3) Skorjanc, T.; Heinrich, J.; Makuc, D.; Kulak, N.; Valant, M. Sustained Delivery of Cu(II)-Based DNA Intercalators by Nanometer-Sized Cyclodextrin-Based Porous Polymers. ACS Appl. Nano Mater. 2023, 6 (22), 21162–21168.
(4) Skorjanc, T.; Shetty, D.; Kumar, S.; Makuc, D.; Mali, G.; Volavšek, J.; Bergant Marušič, M.; Valant, M. Nitroreductase-Sensitive Fluorescent Covalent Organic Framework for Tumor Hypoxia Imaging in Cells. Chem. Commun. 2023, 59 (38), 5753–5756.
(5) Zhang, Q.; Inose, T.; Ricci, M.; Li, J.; Tian, Y.; Wen, H.; Toyouchi, S.; Fron, E.; Ngoc Dao, A. T.; Kasai, H.; Rocha, S.; Hirai, K.; Fortuni, B.; Uji-i, H. Gold-Photodeposited Silver Nanowire Endoscopy for Cytosolic and Nuclear PH Sensing. ACS Appl. Nano Mater. 2021, 4 (9), 9886–9894.
(6) Ricci, M.; Fortuni, B.; Vitale, R.; Zhang, Q.; Fujita, Y.; Toyouchi, S.; Lu, G.; Rocha, S.; Inose, T.; Uji-I, H. Gold-Etched Silver Nanowire Endoscopy: Toward a Widely Accessible Platform for Surface-Enhanced Raman Scattering-Based Analysis in Living Cells. Anal. Chem. 2021, 93 (12), 5037–5045. Keywords: covalent organic frameworks, imaging, delivery, nanoendoscopy, nanowire Published in RUNG: 22.07.2024; Views: 955; Downloads: 2 Link to file This document has many files! More... |
3. Covalent-organic frameworks for luminescent sensorsTina Škorjanc, Matjaž Valant, 2024, independent scientific component part or a chapter in a monograph Abstract: In summary, this chapter discussed the richness of COFs that have been utilized in luminescence-based sensing of various analytes. Literature reports were classified based on the analyte type and a section was dedicated to each explosive compounds, metal cations, biological molecules, pH, VOCs, amines and water, anions, and enantiomers. Different design strategies implemented to develop sensors for each analyte were highlighted as were the detection mechanisms and key parameters of the performance, such as
LODs. In comparison to the state-of-the-art prior to 2020, we note several changes in the most recent developments of luminescent COF sensors. Keywords: ensors, covalent organic frameworks, fluorescence, biosensor, explosives Published in RUNG: 01.07.2024; Views: 895; Downloads: 2 Link to file This document has many files! More... |
4. Fluorescent covalent organic frameworks : promising bioimaging materialsChimatahalli Santhakumar Karthik, Tina Škorjanc, Dinesh Shetty, 2024, original scientific article Abstract: Fluorescent covalent organic frameworks (COFs) have emerged as promising candidates for imaging living cells due to their unique properties and adjustable fluorescence. In this mini-review, we provide an overview of recent advancements in fluorescent COFs for bioimaging applications. We discuss the strategies used to design COFs with desirable properties such as high photostability, excellent biocompatibility, and pH sensitivity. Additionally, we explore the various ways in which fluorescent COFs are utilized in bioimaging, including cellular imaging, targeting specific organelles, and tracking biomolecules. We delve into their applications in sensing intracellular pH, reactive oxygen species (ROS), and specific biomarkers. Furthermore, we examine how functionalization techniques enhance the targeting and imaging capabilities of fluorescent COFs. Finally, we discuss the challenges and prospects in the field of fluorescent COFs for bioimaging in living cells, urging further research in this exciting area. Keywords: covalent organic frameworks, fluorescent materials, imaging, bioimaging, biosensors Published in RUNG: 05.03.2024; Views: 1570; Downloads: 8 Full text (5,40 MB) This document has many files! More... |
5. An in situ proton filter covalent organic framework catalyst for highly efficient aqueous electrochemical ammonia productionKayaramkodath C. Ranjeesh, Sukhjot Kaur, Abdul K. Mohammed, Safa Gaber, Divyani Gupta, Khaled Badawy, Mohamed Aslam, Nirpendra Singh, Tina Škorjanc, Matjaž Finšgar, 2024, original scientific article Abstract: The electrocatalytic nitrogen reduction reaction (NRR) driven by renewable electricity provides a green synthesis route for ammonia (NH3) production under ambient conditions but suffers from a low conversion yield and poor Faradaic efficiency (F.E.) because of strong competition from hydrogen evolution reaction (HER) and the poor solubility of N2 in aqueous systems. Herein, an in situ proton filter covalent organic framework catalyst (Ru-Tta-Dfp) is reported with inherent Ruthenium (Ru) sites where the framework controls reactant diffusion by suppressing proton supply and enhancing N2 flux, causing highly selective and efficient catalysis. The smart catalyst design results in a remarkable ammonia production yield rate of 2.03 mg h−1 mgcat−1 with an excellent F.E. of ≈52.9%. The findings are further endorsed with the help of molecular dynamics simulations and control COF systems without in situ proton filter feasibility. The results point to a paradigm shift in engineering high-performance NRR electrocatalysts for more feasible green NH3 production. Keywords: covalent organic frameworks, ammonia, electrochemical synthesis, electrochemistry, nitrogen reduction reaction, ruthenium Published in RUNG: 11.12.2023; Views: 1470; Downloads: 8 Full text (2,77 MB) This document has many files! More... |
6. 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: 1727; Downloads: 7 Link to file This document has many files! More... |
7. Enzyme-immobilized hierarchically porous covalent organic framework biocomposite for catalytic degradation of broad-range emerging pollutants in waterNada Elmerhi, Khadega Al-Maqdi, Khawlah Athamneh, Abdul Khayum Mohammed, Tina Škorjanc, Felipe Gándara, Jesus Raya, Pascal Simon, Olivier Siri, Ali Trabolsi, 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: 2064; Downloads: 11 Full text (1,45 MB) This document has many files! More... |
8. Biological applications of porous polymers and covalent organic frameworks : lecture at the Otto-von-Guericke Universität Magdeburg, Tuesday, 27th June 2023, Magdeburg, GermanyTina Škorjanc, 2023, unpublished conference contribution Abstract: 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. Keywords: Porous organic polymers, covalent organic frameworks, biosensors, hypoxia Published in RUNG: 13.07.2023; Views: 1678; Downloads: 0 This document has many files! More... |
9. 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: 2078; Downloads: 3 Link to file This document has many files! More... |
10. 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: 2014; Downloads: 19 Full text (1,55 MB) This document has many files! More... |