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Metal-organic frameworks for efficient drug adsorption and delivery

Hyjek Kornelia, Jodłowski Przemysław

Scientiae Radices

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2023

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Vol. 2, Iss. 2

115-189

EN

In recent years, the number of materials used as drug delivery systems (DDS) has increased dramatically. The widespread use of DDSs has improved both the safety and efficacy of therapy. The systems currently in use pose numerous drawbacks and require proper improvements. Although many modern materials are being developed, metal-organic frameworks (MOFs) deserve special attention. Thermal and chemical stability, high specific surface area, low toxicity, high biocompatibility, and great potential for modification are the main features enabling MOFs to be used as DDS. In this review, we describe MOFs, their structure, synthesis, and characterization, as well as drug loading, drug release kinetics, and bioassays. A critical approach is to outline the disadvantages as well as the limitations of MOFs and to identify areas that need to be studied more thoroughly. Nonetheless, the prospective nature of MOFs as DDS and potential adsorbents in overdose or poisoning is presented and highlighted.

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Sieci metalo-organiczne jako multifunkcjonalne materiały przyszłości : mechanochemiczne podejście do syntezy

Jędrzejowski D.

Wiadomości Chemiczne

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2018

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[Z] 72, 9-10

645--666

EN

Metal-organic frameworks (MOFs) are a relatively new class of advanced inorganic-organic materials. Due to their modular structures and possible incorporation of various properties, that materials find more and more applications in many fields of science and industry. MOFs are coordination polymers, i.e. compounds with coordination bonds propagating infinitely in at least one dimension. Their characteristic feature is the presence of potential free spaces, i.e. pores. The free spaces often appear after proper activation, e.g. thermal activation. Other common properties of MOFs include for instance large specific surface areas and pore volumes, modifiable size and chemical environment of the pores, and network flexibility. All these properties result in the use of MOFs in e.g. selective sorption, separation or storage of gases, heterogeneous catalysis, design and fabrication of sensors, etc. During more than twenty years of the history of MOFs, many methods of their synthesis have been developed, including the most popular in solution at elevated temperatures (e.g. solvothermal method). Nevertheless, the activity of pro-ecological environments and the requirements set by international organizations encourage scientists to create new methods of synthesis, which, according to the guidelines presented by the 12 principles of green chemistry, will be safer, less aggressive, less toxic and less energy-consuming. One of the answers to meet these requirements is the use of mechanosynthesis. Mechanochemical synthesis relies on the supply of energy to a system by mechanical force, by grinding or milling. By combining or transforming solids in this way, the presence of a solvent, which is most often the main source of contamination and waste, can be minimised or completely excluded. Mechanical force is typically used for purposes other than MOF synthesis, e. g. catalyst grinding. Nevertheless, the use of mechanical force in synthesis is becoming more and more popular. The most important advantages of this approach, apart from its environmental impact, are very high efficiency (usually close to 100%) and drastically reduced reaction time. Of course, there are examples where these advantages are not observed. In such cases, mechanosynthetic modifications are introduced, such as e.g. addition of small amount of liquid (Liquid-Assisted Grinding) and/or a small addition of simple inorganic salt (Ion- and Liquid-Assisted Grinding). Furthermore, new instrument setups are being developed to monitor reaction mixtures in situ during mechanosynthesis, e.g. by use of such techniques as powder X-ray diffraction and Raman spectroscopy. This enables valuable insights into mechanisms and allows for mechanosynthesis optimization.

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Przewodnictwo protonowe w sieciach metalo-organicznych : nowe możliwości w technologii ogniw paliwowych

Szufla M.

Wiadomości Chemiczne

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2018

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[Z] 72, 3-4

147--163

EN

Nowadays energy demands are huge and still increasing. This fact drives the search for modern technologies which are economically advantageous and environmentally friendly. A fuel cell technology is one of many solutions and hydrogen fuel cells are especially important. The essential element of such a cell is the electrolytic membrane which makes proton transfer possible. In this article, selected examples of metal-organic frameworks (MOFs) that can be used as proton-conducting membranes are described. Porous structure of such materials as well as the existence of proton-donating and accepting groups on their pore walls allow for creation of hydrogen bonding network enabling the proton hopping (Grotthuss’s conduction mechanism). The conduction can also occur on the way of diffusion of bigger ions, e.g. H3O+ (vehicular conduction mechanism) Proton conducting MOFs can be divided according to temperature in which these materials can operate. There are two regimes – below 100°C – conductivity in MOFs is aided by the presence of water molecules, and above 100°C – conductivity does not depend on humidity. Important group among MOFs conductive under low-temperature conditions are oxalate-based frameworks. Taking into account synthetic methods, interesting case is the MOF reported by Matoga and co-workers, which was obtained on the way of economically and environmentally friendly mechanosynthesis. High proton conductivity in metal-organic frameworks can be achieved not only when channels are filled with water molecules but also by introduction of non- -volatile organic compounds to framework voids or by incorporating them into the framework. Imidazole, 1,2,4-triazole, pyrazoline or histamine may play the role of such compounds. Remarkable examples of this strategy include the MOF reported by Kitagawa and co-workers, where 1,2,4-triazole molecules are incorporated into the framework as well as the material in which proton conduction occurs owing to the presence of imidazole guest molecules.