1. 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, prispevek na konferenci brez natisa Opis: 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.
Ključne besede: covalent organic frameworks, imaging, delivery, nanoendoscopy, nanowire
Objavljeno v RUNG: 22.07.2024; Ogledov: 172; Prenosov: 1
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2. A porous organic polymer for synergistic light-triggered NO release and anticancer drug delivery : lecture at the iCeMS Retreat 2024, Kobe, Japan, 4. 7. 2024Tina Škorjanc, 2024, prispevek na konferenci brez natisa Opis: Treatment of biologically complex diseases, such as cancer, can significantly benefit from combination therapies. These powerful therapies are able to simultaneously target different biological targets, thereby overcoming or reducing drug resistance, decreasing dose-related toxicity, and potentially exhibiting synergistic effects. Herein, we combine the effects of nitric oxide (NO) gas therapy and an anticancer drug Doxorubicin (Dox) using a porous organic polymer (POP) as a delivery vehicle for both. SH-POP, synthesized by a facile, room-temperature method, is rich in both thiol (-SH) and secondary amine (R-NH-R’) functional groups, which can be post-synthetically nitrosylated in a room-temperature reaction that uses water as a solvent, yielding SNO-POP. Fourier-transform infrared (FT-IR) and Raman spectroscopy confirm that both types of functional groups are nitrosylated. Upon white light irradiation, SNO-POP releases up to ~60 µmol of NO per g, and exhibits reversible switch on – switch off NO release behavior triggered by simple light irradiation for at least 20 cycles. Unlike many conventional systems, where a known small-molecule NO donor is incorporated into the pores, here, the porous polymer itself serves as a NO donor, so the pores remain available for the encapsulation of another therapeutic, i.e. Dox. The release of Dox from the Dox@SNO-POP system is pH-sensitive and occurs preferentially in a slightly acidic environment (pH = 5.4). HeLa cancer cell viability studies confirm an enhancement in toxicity that can be ascribed to the synergistic effects of light-triggered NO release and pH-triggered Dox release. Confocal microscopy imaging reveals the presence of both species inside cells. This study is expected to stimulate the development of porous polymers as potent vehicles for combination therapies in cancer treatment and beyond.
Ključne besede: porous organic polymer, nitric oxide, combination therapy, synergistic therapy, chemotherapy
Objavljeno v RUNG: 05.07.2024; Ogledov: 224; Prenosov: 1
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3. Covalent-organic frameworks for luminescent sensorsTina Škorjanc, Matjaž Valant, 2024, samostojni znanstveni sestavek ali poglavje v monografski publikaciji Opis: 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.
Ključne besede: ensors, covalent organic frameworks, fluorescence, biosensor, explosives
Objavljeno v RUNG: 01.07.2024; Ogledov: 220; Prenosov: 1
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4. Fluorescent covalent organic frameworks : promising bioimaging materialsChimatahalli Santhakumar Karthik, Tina Škorjanc, Dinesh Shetty, 2024, izvirni znanstveni članek Opis: 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.
Ključne besede: covalent organic frameworks, fluorescent materials, imaging, bioimaging, biosensors
Objavljeno v RUNG: 05.03.2024; Ogledov: 805; Prenosov: 3
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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, 2023, izvirni znanstveni članek Opis: 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.
Ključne besede: covalent organic frameworks, ammonia, electrochemical synthesis, electrochemistry, nitrogen reduction reaction, ruthenium
Objavljeno v RUNG: 11.12.2023; Ogledov: 948; Prenosov: 6
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6. Sustained delivery of Cu(II)-based DNA intercalators by nanometer-sized cyclodextrin-based porous polymersTina Škorjanc, Julian Heinrich, Damjan Makuc, Nora Kulak, Matjaž Valant, 2023, izvirni znanstveni članek 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: 1241; Prenosov: 4
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7. Crystallizing covalent organic frameworks from metal organic framework through chemical induced-phase engineeringAbdul Khayum Mohammed, Safa Gaber, Jesus Raya, Tina Škorjanc, Nada Elmerhi, Sasi Stephen, Pilar Pena-Sánchez, Felipe Gándara, Steven Hinder, Mark A. Baker, Kyriaki Polychronopoulou, Dinesh Shetty, 2023, izvirni znanstveni članek Opis: 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.
Ključne besede: metal organic framework, covalent organic framework, phase engineering, chemical transformation, porous materials
Objavljeno v RUNG: 10.11.2023; Ogledov: 1317; Prenosov: 5
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8. In vitro tumor hypoxia imaging with fluorescent covalent organic frameworksTina Skorjanc, Dinesh Shetty, Damjan Makuc, Gregor Mali, Martina Bergant Marušič, Matjaž Valant, 2023, objavljeni povzetek znanstvenega prispevka na konferenci 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: 1187; Prenosov: 4
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9. Štipendije za študij v tujiniTina Škorjanc, druga izvedena dela Opis: Financiranje celotnega dodiplomskega študija je v veliko državah sveta mogoče s pomočjo vladnih oz. državnih štipendij ciljne države ali s pomočjo financiranja, ki ga ponujajo univerze. Dr. Tina Škorjanc se bo v predavanju osredotočila na oba aspekta.
Predstavila bo možnosti na Japonskem, v Južni Koreji, Rusiji, Nemčiji, Singapurju, Kanadi, Italiji in Franciji ter v ZDA in Združenih arabskih emiratih, kjer je študirala tudi sama. Možnosti financiranja dodiplomskega študija v tujini obstajajo tudi v Sloveniji, zato bo opisala nekaj tovrstnih opcij.
Predstavila bo tudi program Vulcanus iz Japonske, program Erasmus, ki je Slovencem večinoma dobro poznan, in različne poletne šole. Delila bo svoje izkušnje iz poletne šole na Nizozemskem in z delavnice v Savdski Arabiji.
Za konec predavanja bo povedala še nekaj o sistemu prijav, vpisnih pogojih in morebitnih dodatnih zahtevah, denimo certifikatih o znanju tujega jezika. Za sodelujoče bo zagotovo zelo koristna tudi možnost postavljanja vprašanj, na katera bo z veseljem odgovorila.
Ključne besede: študij v tujini, štipendije, Erasmus, Vulcanus, DAAD, vladna štipendija
Objavljeno v RUNG: 01.09.2023; Ogledov: 880; Prenosov: 3
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10. Povratna vozovnica – Združeni arabski emiratiTina Škorjanc, druga izvedena dela Opis: Tina je 26. avgusta 2011 polna pričakovanj pristala v Združenih arabskih emiratih in ti so postali njen dom za skoraj desetletje. Na potopisnem predavanju bo spregovorila o tem, kako se je v pretežno muslimanski državi počutila kot študentka naravoslovja, kako ZAE spodbujajo razvoj kulturnih dejavnosti in zakaj je kar 80 % prebivalcev tujcev. In o znamenitostih: steklenih stolpnicah in blišču Dubaja, neskončnih puščavah Abu Dabija, konjih in kamelah za lepotna tekmovanja v Adžmanu, skalnih gorovjih v Ras Al Khaimah in Umm Al Quwainu ter lepotah Indijskega oceana v Fudžeiri.
Ključne besede: Abu Dabi, Dubaj, Sharjah, Fujairah, Ras al Khaimah, Umm al Quwain, Ajman
Objavljeno v RUNG: 01.09.2023; Ogledov: 872; Prenosov: 3
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