1. Impregnacija biokompozitnih aerogelov za biomedicinske aplikacije : magistrsko deloLara Plohl, 2024, magistrsko delo Opis: V magistrskem delu bomo predstavili pripravo biokompozitnih aerogelov iz pektina, naravnega polisaharida, ter polimera polikaprolaktona (PCL). S pomočjo postopka sol gel smo pripravili hidrogelne materiale z različnimi masnimi in volumskimi razmerji pektina raztopljenega v vodi ter PCL raztopljenega v etil-laktatu (EL). Tako pripravljene hidrogele in kasneje alkogele smo z uporabo superkritičnega sušenja pretvorili v aerogele. Karakterizacija aerogelov je vključevala določitev specifične površine z Brunauer, Emmett in Teller (BET) metodo, pri čemer je bila največja izmerjena specifična površina 309 m2/g. Z metodo Barrett, Joyner in Helenda (BJH) smo določili velikost in porazdelitev por biokompozitnih aerogelov. Ugotovili smo, da pripravljeni aerogeli sodijo v mezoporozne materiale. Aerogeli, ki so se po izvedeni plinski adsorpciji izkazali za najobetavnejše so bili izbrani za nadaljnja testiranja. Morfologijo aerogelov smo preučili z vrstičnim elektronskim mikroskopom (SEM), medtem ko smo termično analizo izvedli z uporabo termogravimetrične analize (TGA) in diferencialno skenirne kalorimetrije (DSC). Testirali smo nabrekanje aerogelov ter ugotovili, da vsi vzorci nabreknejo v manj kot eni uri, kar kaže na njihovo potencialno uporabo pri dostavi zdravil. S testom sproščanja natrijevega diklofenaka (DCF) v raztopini fosfatnega pufra (PBS) smo ugotavljali hitrost sproščanja te aktivne učinkovine. Ugotovili smo, da vzorec z najmanjšim deležem PCL doseže 100 % sproščanje DCF v eni uri, kar je bolj primerno za aplikacije kjer je zaželeno hitro sproščanje zdravila. Vzorec z največjim deležem PCL kaže počasnejše in bolj nadzorovano sproščanje aktivne učinkovine, ki doseže 100 % sproščanje po šestih dneh. Vsi izbrani vzorci so pokazali uspešno impregnacijo z DCF in potencial kot sistemi za dostavo zdravil.
Ključne besede: biokompozitni aerogeli, pektin, polikaprolakton, biomedicinske aplikacije, dostava zdravil, natrijev diklofenak
Objavljeno v DKUM: 04.09.2024; Ogledov: 60; Prenosov: 17
 Celotno besedilo (4,26 MB) |
2. Reinforcing ethyl cellulose aerogels with poly(lactic acid) for enhanced bone regenerationGabrijela Horvat, Jan Rožanc, Uroš Maver, Matjaž Finšgar, Željko Knez, Zoran Novak, 2024, izvirni znanstveni članek Opis: Developing double porous biodegradable and biocompatible scafolds that can incorporate and release drugs in a controlled manner holds immense potential in regenerative medicine. This study presents a synthesis method for preparing a macro-mesoporous scafold, where poly(lactic acid) adds to the macroporous region and mechanical properties, and ethyl cellulose adds to the surface area (182 m2 /g). High surface area enables the incorporation of model drug indomethacin with an entrapment efciency of 17.0% and its later controlled release profle. The resulting scafold has desirable mechanical properties in the range of a natural trabecular bone with a compressive modulus of 22.4 MPa. The material is stable in the simulated body fuids for 120 days before the slow degradation starts. In vitro studies demonstrate the material’s ability to support bone cell adhesion, proliferation, and diferentiation, promoting osteogenic activity. Overall, the unique combination of poly(lactic acid) and ethyl cellulose produces advanced materials with tailored macro and mesopore properties, remarkable mechanical properties, optimal degradation rate, and drug delivery potential, making it a promising candidate for bone scafolds in regenerative medicine and tissue engineering
Ključne besede: bio composite, polymer-matrix composites (PMCs), polymers, porosity/voids, secondary ion mass spectrometry
Objavljeno v DKUM: 23.08.2024; Ogledov: 130; Prenosov: 6
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3. Hybrid polylactic-acid–pectin aerogels : synthesis, structural properties, and drug releaseGabrijela Horvat, Klara Žvab, Željko Knez, Zoran Novak, 2023, izvirni znanstveni članek Opis: Wound-dressing materials often include other materials stimulating wound healing. This research describes the first formulation of biodegradable hybrid aerogels composed of polylactic acid and pectin. The prepared hybrid material showed a highly porous structure with a surface area of 166 +/- 22.6 m(2)center dot g(-1). The addition of polylactic acid may have decreased the surface area of the pure pectin aerogel, but it improved the stability of the material in simulated body fluid (SBF). The pure pectin aerogel showed a high swelling and degradation ratio after 3 h. The addition of the polylactic acid prolonged its stability in the simulated body fluid from 24 h to more than one week, depending on the amount of polylactic acid. Biodegradable aerogels were loaded with indomethacin and diclofenac sodium as model drugs. The entrapment efficiencies were 63.4% and 62.6% for indomethacin and diclofenac sodium, respectively. Dissolution of both drugs was prolonged up to 2 days. Finally, sodium percarbonate and calcium peroxide were incorporated into the bioaerogels as chemical oxygen sources, to evaluate oxygen generation for potential wound healing applications.
Ključne besede: hybrid aerogels, bioaerogel, pectin, polylactic acid, wound healing
Objavljeno v DKUM: 20.02.2024; Ogledov: 357; Prenosov: 24
Celotno besedilo (2,62 MB)
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4. Green Processing of Neat Poly(lactic acid) Using Carbon Dioxide under Elevated Pressure for Preparation of Advanced Materials : A Review (2012–2022)Stoja L. Milovanović, Ivana Lukic, Gabrijela Horvat, Zoran Novak, Sulamith Frerich, Marcus Petermann, Carlos A. García-González, 2023, pregledni znanstveni članek Opis: This review provides a concise overview of up-to-date developments in the processing of neat poly(lactic acid) (PLA), improvement in its properties, and preparation of advanced materials using a green medium (CO2 under elevated pressure). Pressurized CO2 in the dense and supercritical state is a superior alternative medium to organic solvents, as it is easily available, fully recyclable, has easily tunable properties, and can be completely removed from the final material without post-processing steps. This review summarizes the state of the art on PLA drying, impregnation, foaming, and particle generation by the employment of dense and supercritical CO2 for the development of new materials. An analysis of the effect of processing methods on the final material properties was focused on neat PLA and PLA with an addition of natural bioactive components. It was demonstrated that CO2-assisted processes enable the control of PLA properties, reduce operating times, and require less energy compared to conventional ones. The described environmentally friendly processing techniques and the versatility of PLA were employed for the preparation of foams, aerogels, scaffolds, microparticles, and nanoparticles, as well as bioactive materials. These PLA-based materials can find application in tissue engineering, drug delivery, active food packaging, compostable packaging, wastewater treatment, or thermal insulation, among others.
Ključne besede: aerogels, drying, foaming, impregnation, particle generation, PLA
Objavljeno v DKUM: 06.02.2024; Ogledov: 395; Prenosov: 23
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5. Razvoj materialov z aktivnim kisikom za hitrejše celjenje ran : magistrsko deloNika Atelšek Hozjan, 2023, magistrsko delo Opis: Magistrsko delo predstavlja sintezo, razvoj in karakterizacijo do sedaj še neobstoječih biorazgradljivih materialov - aerogelov z aktivnim kisikom za namene hitrejšega celjenja ran. Kot vhodna materiala smo uporabili polisaharid ksantan in biopolimer polilaktično kislino (PLA), ki sta biokompatibilna in cenovno dostopna. Ksantan služi kot osnovni material, ki enkapsulira aktivne učinkovine za namene kontroliranega sproščanja, medtem ko PLA izboljša mehanske lastnosti našega materiala.
V sklopu našega raziskovalnega dela smo po sol-gel postopku s kombiniranjem PLA v etil laktatu ter ksantana v vodi pripravili kompozitne hidrogele. S superkritičnim sušenjem smo jih pretvorili v aerogele in okarakterizirali s plinsko adsorpcijo. S tem smo določili velikost specifičnih površin (BET), ki so dosegle vrednosti do 396 m2/g, ter povprečno velikosto in prostornino por v mezoporoznem območju. Izvedli smo tudi termično analizo z DSC/TGA, test nabrekanja in stabilnosti ter z njimi ocenili termično stabilnost in lastnosti razpada materialov. Rezultati so pokazali, da je kombinacija ksantana in PLA podaljšala stabilnost materiala v simulirani telesni tekočini (SBF) tudi do 72 ur. Materiali z večjo vsebnostjo PLA so absorbirali SBF do 67 kratnika svoje mase, kar je najverjetneje posledica boljše stabilnosti v SBF. Sestavo aerogelov in s tem prisotnost posameznih komponent smo potrdili z analizo FT IR. Glede na rezultate karakterizacije smo izbrali dva materiala z najobetavnejšimi lastnostmi, ter v njiju vključili učinkovini, ki ob stiku z rano generirata kisik, ter zdravilno učinkovino deksametazon. Sproščanje kisika iz materiala smo določili s standardno metodo izpodrivanja vode, pri kateri je bila količina izpodrinjene vode neposredno sorazmerna količini nastalega kisika. Meritve smo izvajali 48 ur, rezultati pa so pokazali, da je material sproščal kisik v celotnem časovnem intervalu. Testirali smo tudi sproščanje deksametazona v SBF, ki je bilo uspešno v primeru obeh impregniranih aerogelov. Nazadnje smo preverili antimikrobno delovanje materialov proti bakterijam Escherichia coli in Staphylococcus aureus. Oba aerogela sta inhibirala rast bakterij in s tem izkazala antimikrobno učinkovitost.
Ključne besede: aerogel, aktivni kisik, biomaterial, celjenje kroničnih ran, kontrolirano sproščanje
Objavljeno v DKUM: 18.09.2023; Ogledov: 487; Prenosov: 177
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6. 3rd International Conference on Aerogels for Biomedical and Environmental Applications : book of abstracts2023 Opis: The 3rd lnternational Conference on Aerogels for Biomedical and Environmental Applications, organized by the Faculty of Chemistry and Chemical Engineering University of Maribor and the AERoGELS COST Action, presented the latest research results and applications of aerogels. This publication compiles the abstracts of the conference and highlights the main results and innovations. The abstracts address the use of aerogels in medical, pharmaceutical, and food applications, including drug delivery systems, scaffolds tor tissue engineering, and bioactive coatings. They also explore aerogels as catalysts, insulators, and environmental solutions and investigate improved catalytic activity and thermal insulation properties. The abstracts emphasize interdisciplinary collaboration and provide ideas tor future research directions. This publication provides valuable insights tor researchers and industry professionals interested in harnessing the remarkable properties of aerogels for biomedical and environmental purposes.
Ključne besede: aerogels, advanced materials, environmental applications, biomedical applications, research and development
Objavljeno v DKUM: 11.08.2023; Ogledov: 507; Prenosov: 74
Celotno besedilo (12,27 MB)
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7. Migracija vode v zmesi farmacevtske učinkovine in pomožnih snovi : diplomsko delo visokošolskega strokovnega študijskega programa I. stopnjeMaša Krakar, 2023, diplomsko delo Opis: V diplomski nalogi smo raziskovali migracijo vode v zmeseh farmacevtske učinkovine (XN) in pomožnih snovi (PS). Uporabili smo XN in pet pomožnih snovi (škrob koruzni sušen, mikrokristalinično celulozo, brezvodno laktozo, laktozo monohidrat in manitol), katere smo izbrali po principu higroskopnih lastnosti in različnih energij vezave vode. Da bi razumeli vpliv vsebnosti vode in vodne aktivnosti na strukturo snovi, smo na začetku posamezne pomožne snovi in zmesi analizirali s tehnikami DSC, TGA, vodna aktivnost (aw) in dinamična sorpcija vode (DVS).
Razen XN, ki je kazala fizikalno nestabilnost pri visokih stopnjah relativne vlažnosti (RV) in je prešla v novo kristalno (hidratno) obliko, so bile ostale snovi fizikalno stabilne. Potem smo pripravili fizikalne zmesi 1:1, XN : pomožna snov, jih za dva tedna zaprli v neprodušno zaprto vialo, da je potekal prenos vode med snovmi do ravnotežnih vrednosti in nato zmesi analizirali z aw, DSC in TGA.
Pri zmeseh, kjer smo detektirali strukturno spremembo, smo posneli še Raman in Rentgensko praškovno analizo. Tekom eksperimenta smo oblikovali komoro za izmenjavo vode preko parne faze med fizično ločenimi komponentami. Uporabili smo velike steklene tehtiče, v katere smo vstavili dve aluminijasti ladjici, v prvo smo zatehtali XN in v drugo pomožno snov (1:1 w/w). Steklene tehtiče smo nato zaprli s steklenim pokrovom, katerim smo obrus dodatno zatesnili s silikonsko mastjo. Tak zaprt sistem je pri sobnih pogojih omogočal prehajanje vode le med obema vzorcema v tehtiču preko parne faze, na nekontakten način.
Po 2 tednih smo analizirali vsebnost vode in vodno aktivnost v obeh eksperimentih. Z meritvijo vodne aktivnosti smo pri 1:1 in 1:3 (W/W) kontaktnih in nekontaktnih zmeseh preučili smer in obseg migracije vode. Pri kontaktnih zmeseh smo dokazali eno od hipotez naloge, in sicer da voda migrira iz snovi z višjo vodno aktivnostjo v snov z nižjo vodno aktivnostjo. V primeru mešanic navlaženih PS (škrob, MCC in XN), ki so vsebovale povečano vsebnost nevezane in šibko vezane vode, smo ugotovili, da je bila količina izmenjane vode med PS in XN v smeri XN tako velika, da je prišlo do vgradnje vode v kristalno strukturo XN in nastanka nove pojavne oblike XN, hidratne oblike, natančneje hemihidrata, kar smo potrdili z naborom komplementarnih analiznih tehnik (DSC, TGA, XRPD, Raman). Skupaj s posnetimi sorpcijskimi izotermami smo lahko napovedali smer migracije in količino migrirane vode za vsako posamezno komponento.
Na podlagi ugotovljenih rezultatov smo tako lahko razvili delni protokol za izbor PS, ki jih dodamo farmacevtski učinkovini, ki kaže tendenco prehajanja v hidratne oblike ob prisotnosti povečane vsebnosti nevezane ali šibko vezane vode. Protokola se bomo posluževali pri razvoju novih izdelkov, v katere bomo vgrajevali učinkovine, ki imajo podobne lastnosti kot XN.
Ključne besede: farmacevtska učinkovina, sorpcija, migracija vode, vsebnost vode, vodna aktivnost, fizikalna stabilnost, hidrati
Objavljeno v DKUM: 29.03.2023; Ogledov: 664; Prenosov: 38
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8. Formation, characterization and application of polysaccharide aerogelsGabrijela Horvat, 2018, doktorska disertacija Opis: The aim of this PhD dissertation was to describe and analyze the preparation and characterization of polysaccharide aerogels and their future pharmaceutical and medical application. For the research, we used four types of polysaccharides: pectin, alginate, xanthan and guar. We used two types of pectin, high-methoxyl and low-methoxyl pectin, because of their different gelation mechanisms. The first part of the dissertation describes the preparation and characterization of pure polysaccharide aerogels. First, we prepared pectin spherical aerogels, cross-linked with three different ions, and we investigated their final properties. Later, we developed a new method for the preparation of alginate, pectin, xanthan and guar aerogels. We used only ethanol and no other cross-linkers. Ethanol was removed in the later processes of supercritical drying, and the remaining final material was thus only porous polysaccharide. By this method, we were able to prepare pure xanthan and guar aerogels. Prior to this study, xanthan and guar aerogels were prepared only as composites. Pectin aerogels prepared by the new method have amazing properties. On the other hand, alginate aerogels show poor characteristics, and thus the methods need to be optimised. We tried different alginate viscosities, different alcohols (methanol, ethanol, 1-propanol and 1-butanol), and we investigated longer (24h) and shorter (1h) gel setting times.
The second part of this dissertation describes the pharmaceutical and medical applications of prepared aerogels. The release of diclofenac sodium from spherical pectin aerogels was investigated in vitro. Calcium cross-linked aerogels were not able to retain the drug, and its release was immediate. In order to achieve controlled release of diclofenac sodium, zinc ions had to be used as cross-linkers. Later, a low water-soluble drug, nifedipine, was used as a model drug for the monolithic aerogels prepared by the new method. The release of nifedipine from pectin and alginate aerogels was highly increased, compared to the crystalline drug. This result is promising for future evaluation of these materials for increasing the bioavailability of poorly water-soluble drugs. Nifedipine release from xanthan and guar aerogels was prolonged up to two weeks. This result reveals a new perspective on such materials for their potential use in medicine as implants and local drug delivery. According to these results, we then developed a new coating material for medical-grade stainless steel from xanthan and pectin. An aerogel coating was loaded with diclofenac sodium and indomethacin, and their release profiles were investigated in vitro. Electrochemical analysis and cell tests proved the safety of such materials for use in medicine. Using aerogel coatings, the drug can be introduced locally into the body; therefore, the need for intravenous, post-operational treatment is greatly reduced.
Ključne besede: polysaccharides, aerogels, supercritical drying, drug carriers
Objavljeno v DKUM: 09.04.2018; Ogledov: 2097; Prenosov: 294
Celotno besedilo (5,84 MB) |
