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(Micro)structural and electrochemical characterization of rGO/V2O5 composite
No full textU ovom je radu priređen papir grafenova oksida te papir grafenova oksida s dodatkom 70 % V2O5 primjenom metode vakuumske filtracije, nakon čega je provedena redukcija metodom kronoamperometrije čime je priređen rGO i kompozit rGO/V2O5. Kako je za sve primjene od iznimne važnosti povezati strukturu sa svojstvima, ovim je radom pokrivena detaljna strukturna i mikrostrukturna karakterizacija V2O5 te njegovog kompozita rGO/V2O5. Provedena su ispitivanja termičke stabilnosti strukture i ekspanzije materijala, veličine kristalita i svih strukturnih promjena i prijelaza u različite kristalne faze. Zbog izvrsnih karakteristika V2O5 i njegovih kompozita, koje su dokazane u dosadašnjoj primjeni ovog materijala u elektrokemijskim uređajima, u ovom radu su metodama cikličke voltametrije i kronopotenciomerije proučena elektrokemijska svojstva kompozita rGO/V2O5 sa stajališta primjene u baterijskim sustavima. Osim u elektrokemijskim spremnicima energije, V2O5 i njegovi kompoziti s reduciranim grafenovim oksidom poznati su i po upotrebi za fotokatalitičko dobivanje vodika, zbog čega su i u ovom radu provedena ispitivanja fotokatalitičke aktivnosti s bojilima rodamin B (RhB) i metilen plavo (MB). Rezultati su pokazali da je korišteni V2O5 materijal s vrlo malom termičkom ekspanzijom i kristalitima nanometarskih veličina te je pogodan za pripravu nanokompozita. U ovom je radu uspješno priređen kompozit rGO/V2O5 što je potvrđeno rendgenskom difrakcijom, SEM i EDS te mikroskopijom s grijaćom pločom. Priređeni kompozit je izvrstan fotokatalizator koji je razgradio 94,3 % MB bojila visoke koncentracije (25 ppm) nakon 120 min. Baterija priređena s ispitivanim kompozitom pokazala je visoke kapacitete, a detaljna ispitivanja kod različitih brzina ukazala su da je brzina reakcije kontrolirana interkalacijskim procesima.In this work, pure graphene oxide paper and one with the addition of 70 % V2O5 were prepared using the vacuum filtration method. Afterwards, the reduction was carried out using the chronoamperometry method, resulting in prepared rGO and the rGO/V2O5 composite. Structure-properties relationship is of an extreme importance for all applications, therefore this work covers the detailed structural and microstructural characterization of V2O5 and its rGO/V2O5 composite. The thermal stability of the structure and the expansion of the material, as well as the size of the crystallites and all structural changes and transitions into different crystalline phases were investigated. Due to the excellent characteristics of V2O5 and its composites, that have been proven in the previous application of this material in electrochemical devices, in this work, the electrochemical properties of rGO/V2O5 composite were studied using the methods of cyclic voltammetry and chronopotentiometry from the point of view of application in battery systems. In addition to electrochemical energy storage, V2O5 and its composites with reduced graphene oxide are also known for their use in photocatalytic production of hydrogen, and that is why in this work tests of photocatalytic activity with the dyes rhodamine B (RhB) and methylene blue (MB) were carried out. The results showed that the used V2O5 material has very low thermal expansion and nanocrystallites, therefore it is suitable for the preparation of nanocomposites. In this work, rGO/V2O5 composite was successfully prepared, which was confirmed by X-ray diffraction, SEM and EDS, and hot-stage microscopy. The prepared composite is an excellent photocatalyst that decomposed 94.3 % of high-concentration MB dyes (25 ppm) after
120 min. The battery prepared with the tested composite showed high capacities, and detailed tests at different speeds indicated that the reaction speed was controlled by intercalation processes
Determination of ecotoxicity of selected xenobiotics
No full textPrimjena brojnih vrsta ksenobiotika je neupitno doprinijela razvoju i poboljšanju kvalitete ljudskog života, ali njihov negativan utjecaj na cjelokupni ekosustav postaje sve vidljiviji. Većina ksenobiotika nakon primjene završava u otpadnim i površinskim vodama te tlu. Obzirom da ksenobiotici poput pesticida i farmaceutika već u vrlo malim dozama izazivaju određene farmakološke i fiziološke promjene, bitno je pratiti i procijeniti njihovu ekotoksičnost. Glavni cilj ovog rada je određivanje ekotoksičnosti izabaranih ksenobitika iz skupine pesticida (acetamiprid, klotianidin, tiakloprid) i antiparazitika (albendazol, febantel, mebendazol) pri pH-vrijednostima 4, 7 i 10, zatim njihovih binarnih i ternarnih smjesa te smjese svih šest izabranih ksenobiotika. Za određivanje su korišteni brzi testovi ekotoksičnosti bakterijom Vibrio fischeri na temelju standardne metode ISO 11348-3:2010 kojima je mjeren intenzitet bioluminiscencije ovih testnih organizama. Čista aktivna tvar acetamiprida je u kiselom području najviše ekotoksična te se povećanjem pH-vrijednosti ekotoksičnost smanjuje. Klotianidin je pokazao minimalnu ekotoksičnost u kiselom području, dok ostale čiste aktivne tvari nisu bile ekotoksične za Vibrio fischeri. Smjesa svih izabranih ksenobiotika je ekotoksična, najviše u lužnatom, zatim kiselom i, naposljetku, neutralnom mediju. Prisutan je sinergizam među komponentama. Najštetnija binarna smjesa je smjesa albendazola i mebendazola gdje je zamijećen sinergistički efekt kao i u ternarnim smjesama anthelmintika dok je u ternarnim smjesama neonikotinoida više izražen antagonizam. Najviše ekotoksična ternarna smjesa je smjesa albendazola, mebendazola i tiakloprida, što ne iznenađuje uzevši u obzir da je najekotoksičnija binarna smjesa albendazola i mebendazola. Iako su u okolišu najčešće prisutne smjese tvari, a manje čiste komponente, procjena rizika uglavnom je usmjerena na analizu učinka čistih tvari. Problem sa smjesama tvari je mogućnost pojave sinergizma odnosno povećanje ekotoksičnosti u odnosu na zasebne komponente zbog čega je od iznimne važnosti odrediti utječu li štetno i staviti naglasak na monitoring.The use of numerous types of xenobiotics has undoubtedly contributed to the development and improvement of the quality of human life, but their negative impact on the entire ecosystem is becoming increasingly visible. After application, most xenobiotics end up in waste water, surface water and soil. Given that xenobiotics such as pesticides and pharmaceuticals cause certain pharmacological and physiological changes even in very small doses, it is important to monitor and assess their ecotoxicity. The main goal of this work is to determine the ecotoxicity of selected xenobiotics from the group of pesticides (acetamiprid, clothianidin, thiacloprid) and antiparasitics (albendazole, febantel, mebendazole) at pH-values 4, 7 and 10, then their binary and ternary mixtures and mixtures of all six selected xenobiotics. Rapid ecotoxicity tests with the bacterium Vibrio fischeri based on the standard method ISO 11348-3:2010 were used to determine the bioluminescence intensity of these test organisms. The pure active substance acetamiprid is the most ecotoxic in the acidic range, then in the neutral and, finally, in the alkaline range. Clothianidin showed minimal ecotoxicity in the acidic area, while other pure active substances were not toxic to Vibrio fischeri. The mixture of all selected xenobiotics is ecotoxic, mostly in alkaline, then acidic and, finally, neutral. There is a synergism between the components. The most harmful binary mixture is a mixture of albendazole and mebendazole, where a synergistic effect was observed, as in ternary mixtures of anthelmintics, while antagonism is more pronounced in ternary mixtures of neonicotinoids. The most ecotoxic ternary mixture is a mixture of albendazole, mebendazole and thiacloprid, which is not surprising considering that the most ecotoxic is a binary mixture of albendazole and mebendazole. Although mixtures of substances and less pure components are present in the environment, risk assessment is mainly focused on the analysis of the effect of pure substances. The problem with mixtures is the possibility of synergism, that is, an increase in ecotoxicity compared to the individual components, which is why it is extremely important to determine whether they have a harmful effect and to emphasize monitoring
MXene application in water-based zinc-ion battery
No full textU ovom radu su pripravljeni MXene i kompozit rGO/MXene elektrode koje su okarakterizirane u dvo- i troelektrodnim sustavima te pomoću optičkog mikroskopa. Osim toga, cilj rada je bio dobiti i okarakterizirati stabilan i samostojeći materijal koji će biti pogodan kao nosač za cink u cink ionskim vodenim baterijama. Kompozitne elektrode rGO/MXene priređene su elektrokemijskom redukcijom grafenovog oksida (GO) u kompozitu GO/MXene. Utvrđeno je da stupanj redukcije GO u reducirani grafenov oksid (rGO) ovisi o tome reducira li se čisti GO ili GO u kompozitu. Kako bi se provelo ispitivanje u dvoelektrodnom sustavu priređeni su MXene i rGO/MXene papiri na koje je naknadno deponiran cink. Svojstva MXene i
rGO/MXene elektroda su ispitana metodama kronoamperometrije, cikličke voltametrije, galvanostatske polarizacije u 2 M otopini ZnSO4 te morfološkom karakterizacijom MXene i rGO/MXene slojeva pomoću optičkog mikroskopa. Cikličkom voltametrijom utvrđeno je kako sve priređene elektrode pokazuju kapacitivno ponašanje. Također je utvrđeno da elektroda koja sadrži MXene nije stabilna iznad 0,4 V. Ispitivanje različitih MXene i rGO/MXene elektroda u troelektrodnom sustavu je pokazalo kako elektroda rGO/MXene-R2 pokazuje bolja svojstva u odnosu na čisti MXene. Bolja stabilnost kompozitne rGO/MXene elektrode u odnosu na čisti MXene je potvrđena i s optičkim mikroskopom. Kompozit rGO/MXene se pokazao pogodnijim za depoziciju cinka u odnosu na MXene. Tijekom depozicije cinka u dvoelektrodnom sustavu, na MXene-a i rGO/MXene papir, kod kraćih vremena uočeni su nukleacijski maksimumi. Stoga je provedena karakterizacija nukleacije cinka na navedenim materijalima pomoću Beweick, M.Fleischman i H.R. Thirsk, i Scharifker-Hills teoretskih modela. Usporedbom rezultata kronoamperometrije i teorijskih modela za nukleacijske procese utvrđeno je da tip nukleacije najbolje odgovara trenutnoj 3D nukleaciji. Ispitivanje simetrične cinkove ćelije s MXene-Zn i rGO/MXene-Zn aktivnim materijalima pokazalo je kako priređeni aktivni materijali snižavaju prenapon otapanja i taloženja cinka.In this work, MXene and composite rGO/MXene electrodes were prepared and characterized in two- and three-electrode systems as well as by using an optical microscope. In addition, the aim of the work was to obtain and characterize a stable and free-standing material that will be suitable as a support for zinc in zinc-ion water batteries. The rGO/MXene composite electrodes were prepared by electrochemical reduction of graphene oxide (GO) in the
GO/MXene composite. It was found that the reduction degree depends on whether pure GO or GO in the composite is reduced. In order to examine the test in a two-electrode system, MXene and rGO/MXene papers were prepared, on which zinc was subsequently deposited. The properties of MXene and rGO/MXene electrodes were tested using chronoamperometry, cyclic voltammetry, galvanostatic polarization in 2 M ZnSO4 solution. The morphological characterization of MXene and rGO/MXene layers was conducted using an optical microscope. By cyclic voltammetry, it was determined that all prepared electrodes exhibit capacitive behaviour. It was also found that the electrode containing MXene is not stable above 0,4 V. Testing of different MXene and rGO/MXene electrodes in a three-electrode system indicated that the rGO/MXene-R2 electrode has better properties compared to pure MXene. The better stability of the composite rGO/MXene electrode compared to pure MXene was also confirmed with an optical microscope. The rGO/MXene composite proved to be more suitable for zinc deposition than MXene. During zinc deposition in the two-electrode system, on MXene-a and rGO/MXene paper, nucleation maxima were observed at shorter times. Therefore, the characterization of zinc nucleation on the mentioned materials was carried out by Beweick, M.Fleischman and H.R. Thirsk, and Scharifker-Hills theoretical models. By comparing the results of chronoamperometry with theoretical models for nucleation processes, 3D instantaneous nucleation was determined. Testing of a symmetrical zinc cell with MXene-Zn and rGO/MXene-Zn active materials showed that the prepared active materials lower the zinc stripping and plating overvoltage
Elektrochemical synthesis of WO3 and its application in photoelectrochemical degradation of pharmaceuticals
No full textCilj ovog rada bio je izraditi FTO/WO3 elektrode, elektrokemijskom sintezom WO3 fotokatalizatora te okarakterizirati izrađene FTO/WO3 elektrode raznim elektrokemijskim tehnikama. Elektrokemijska sinteza WO3 fotokatalizatora provedena je redukcijom peroksovolframove kiseline. Karakterizacija izrađenih FTO/WO3 elektroda provedena je praćenjem potencijala otvorenog kruga, elektrokemijskom impedancijskom spektroskopijom, Mott-Schottky analizom, linearnom polarizacijom i kronoamperometrijom. Karakterizacije izrađenih FTO/WO3 elektroda provedene su u 0,5 mol dm^-3 elektrolitnoj otopini Na2SO4. Osvjetljenje FTO/WO3 elektroda provedeno je primjenom LED lampe. Nadalje, drugi cilj ovog rada bio je odrediti djelotvornost razgradnje farmaceutika amoksicilina fotoelektrokemijskim procesom uz izrađenu FTO/WO3 elektrodu. Dobiveni rezultati karakterizacije FTO/WO3 elektroda pokazali su da je fotoaktivnost najveća kod Elektrode 2, a najmanja kod
Elektrode 1. Stoga je razgradnja farmaceutika amoksicilina fotoelektrokemijskim procesom provedena pomoću Elektrode 2. Fotoelektrokemijski proces se odvijao pri 0,8 V, tijekom
90 minuta u 0,1 mmol dm^-3 otopini amoksicilina u 0,1 mmol dm^-3 elektrolitnoj otopini Na2SO4. Djelotvornost razgradnje farmaceutika amoksicilina fotoelektrokemijskim procesom određena je HPLC analizom te je iznosila 87,41%.The aim of this study was to prepare FTO/WO3 electrodes by electrochemical synthesis of WO3 photocatalyst and to characterize the prepared FTO/WO3 electrodes using various electrochemical techniques. Electrochemical synthesis of WO3 photocatalyst was carried out by reduction of peroxotungstic acid. The characterization of prepared FTO/WO3 electrodes was performed by the open circuit potential measurement, electrochemical impedance spectroscopy, Mott-Schottky analysis, linear polarization and chronoamperometry. The characterizations of prepared FTO/WO3 electrodes were carried out in 0.5 mol dm^-3 Na2SO4 electrolyte solution. The FTO/WO3 electrodes were illuminated using an LED lamp. Furthermore, another aim of this study was to determine the degradation efficiency of amoxicillin pharmaceutical in the photoelectrochemical process using the prepared
FTO/WO3 electrode. The obtained results for characterization of the FTO/WO3 electrodes indicated that the photoactivity is highest for Electrode 2 and lowest for Electrode 1. Therefore, the degradation of the amoxicillin pharmaceutical in the photoelectrochemical process was carried out using Electrode 2. The photoelectrochemical process was carried out at 0.8 V for 90 minutes in a 0.1 mmol dm^-3 amoxicillin solution in 0.1 mmol dm^-3 Na2SO4 electrolyte solution. The degradation efficiency of amoxicillin pharmaceutical in the photoelectrochemical process was determined by HPLC analysis and amounted to 87.41%
Novel 2-substituted benzothiazole and benzimidazole derivatives – synthesis, structural characterization and antitumoral and antibacterial evaluations
No full textU ovom doktorskom radu opisana je sinteza, strukturna karakterizacija i biološka aktivnost novih derivata 2-arilbenzimidazola i 2-arilbenzotiazola, hidrazonskih derivata benzotiazola te 1,2,3-triazolnih derivata kumarina i iminokumarina. U sintezama su pored konvencionalnih metoda korištene i ekološki prihvatljive zelene metode poput sinteza potpomognutih mikrovalovima i ultrazvukom te mehanokemijske reakcije. Ultrazvukom potpomognutom reakcijom ciklokondenzacije pripravljenih O-alkiliranih benzaldehida (1‒6) ili 1,2,3-triazolnih derivata benzaldehida (10 i 11) s različito supstituiranim 1,2-diaminobenzenima uz Na2S2O5 kao oksidacijsko sredstvo, pripravljeni su novi O-alkilirani (12‒27) i 1,2,3-triazolni derivati 2-arilbenzimidazola (28‒33). Derivati 2-(4-alkoksifenil)benzotiazola (47–55) sintetizirani su konvencionalnim načinom reakcijom O-alkiliranja priređenih 2-(4-hidroksifenil)benzotiazola (40–46) s odgovarajućim aminoalkil-halogenidima uz K2CO3, dok su derivati
2-(4-alkoksifenil)-6-halobenzotiazola (56–67) pripravljeni mikrovalovima potpomognutom reakcijom O-alkiliranja 2-(4-hidroksifenil)benzotiazola (43–46). Bakrom kataliziranom Huisgenovom 1,3-dipolarnom cikloadicijom morfolinskog azida (9) i sintetiziranih derivata 2-(4-O-(propargilfenil)benzotiazola (68–74) pripravljeni su 1,2,3-triazolni derivati benzotiazola (75–81). U svrhu odabira metode sinteze derivata 2- i 3-O-(1-aril-1,2,3-triazolil)fenilbenzotiazola (88‒117) provedeno je optimiranje reakcijskih uvjeta na modelnoj klik reakciji s azidobenzenom uključujući konvencionalnu, mehanokemijsku i sintezu potpomognutu ultrazvukom. Mehanokemijskom klik reakcijom uz pomoć kapljevine su postignuta najveća iskorištenja benzotiazolnih derivata (88, 98 i 108) uz najkraće vrijeme trajanja reakcije te je mehanokemija odabrana kao metoda za pripravu 2- i 3-O-(1-aril-1,2,3-triazolil)fenilbenzotiazola (88‒117) te derivata 2-(4-O-(1-aril-1,2,3-triazolil)fenil)benzotiazola (118‒156). Hibridi benzotiazola i 4-alkilaminobenzena povezani hidrazonskom spojnicom (169–202) pripravljeni su kao E-izomeri mehanokemijskom sintezom bez otapala reakcijom kondenzacije sintetiziranih 4-alkoksibenzaldehida (1, 2, 4, 5, 161‒168) i 2-hidrazinilbenzotiazola (158–160). Mikrovalovima potpomognutom klik reakcijom kataliziranom bakrom iz odgovarajućih azida i terminalnih alkina sintetizirani su 1,2,3-triazolni iminokumarinski (207–212) i kumarinski derivati (213–223). Pripravljenim derivatima strukture su potvrđene spektroskopijom 1H- i 13C-NMR kao i dvodimenzijskim metodama NOESY, HSQC i HMBC. Antiproliferativna aktivnost in vitro pripravljenim spojevima ispitana je na nizu humanih tumorskih staničnih linija te na zdravim stanicama. Antibakterijska aktivnost in vitro je ispitana na Gram-pozitivnim i Gram-negativnim bakterijskim sojevima uključujući klinički rezistentne sojeve MRSA i VRE. Derivatima benzotiazola s 1,4-disupstituiranim
1,2,3-triazolnim prstenom (88‒97, 108‒117 i 118–156) ispitana je i antivirusna aktivnost. Kako bi se utvrdila moguća korelacija između antiproliferativne i antioksidativne aktivnosti, derivatima koji su pokazali izraženu antiproliferativnu aktivnost ispitana je antioksidativna aktivnost in vitro metodom DPPH. Od svih ispitanih spojeva najizraženiju antiproliferativnu aktivnost in vitro su pokazali: 2-(4-(2-N,N-dietiletoksi)-3-fluorfenil)-6-klorbenzimidazol (23) (K-562, Z-138, IC50 = 2.0 μM), 2-(4-(N,N-dietiletoksi)-3-metoksifenil)-6-klorbenzotiazol (59) (CFPAC, IC50 = 1.03 μM) i (E)-2-(3-(4-(N,N-dimetiletoksi)-3-fluorfenil)hidrazonil)-6-klorbenzotiazol (188) (CAPAN, IC50 = 0.6 μM, NCI-H460, IC50 = 0.9 μM). Najsnažniju selektivnu antibakterijsku aktivnost su pokazali derivati 2-(4-alkoksifenil)-6-klorbenzimidazola (15‒17) prema Enterococcus faecalis (MIC = 0.25‒1 mg/mL) te 2-(4-(N,N-dietiletoksi)fenil)-6-klorbenzotiazol (50) koji je pokazao najizraženiju aktivnost prema soju MRSA 13276
(MIC = 2 μg/mL). Najizraženiju antivirusnu aktivnost pokazao je triazolni derivat 2-klorbenzotiazola (89) prema virusu gripe H1N1 (EC50 = 6.7 μM).This doctoral thesis describes the synthesis, structural characterization and biological activity of new derivatives of 2-arylbenzimidazole and 2-arylbenzothiazole, hydrazone derivatives of benzothiazole and 1,2,3-triazole derivatives of coumarin and iminocoumarin. In addition to conventional synthetic methods, ecologically acceptable green methods were also used, such as synthesis assisted by microwaves, ultrasound and mechanochemical reactions. Ultrasound-assisted cyclocondensation reaction of prepared O-alkylated benzaldehydes (1‒6) or 1,2,3-triazole derivatives of benzaldehyde (10 and 11) with differently substituted 1,2-diaminobenzenes in the presence of Na2S2O5 as an oxidizing agent, gave new O-alkylated (12 ‒27) and 1,2,3-triazole derivatives of 2-arylbenzimidazole (28‒33).
2-(4-alkoxyphenyl)benzothiazole derivatives (47–55) were synthesized conventionally by O-alkylation reaction of prepared 2-(4-hydroxyphenyl)benzothiazole (40–46) with corresponding aminoalkyl halides in the presence of K2CO3, while 2-(4-alkoxyphenyl)-6-halobenzothiazole derivatives (56–67) were prepared by microwave-assisted O-alkylation reaction of 2-(4-hydroxyphenyl)benzothiazole (43–46). Copper-catalyzed Huisgen 1,3-dipolar cycloaddition reaction of morpholine azide (9) and 2-(4-O-(propargylphenyl)benzothiazole derivatives (68–74) gave 1,2,3-triazole derivatives of benzothiazole (75–81). In order to select the synthetic metod of target 2-arylbenzothiazole derivatives substituted at different position of the benzene ring with 1,2,3-triazole ring (88–117), optimization of the reaction conditions was conducted on a model reaction including conventional synthesis, ultrasound-assisted synthesis and mechanochemical synthesis. Since the liquid assisted mechanochemical reactions gave the highest yields of benzothiazole derivatives (88, 98 and 108) with the shortest reaction time, mechanochemistry was selected as the method for the preparation of 2- and 3-O-(1-aryl-1,2,3-triazolyl))phenylbenzothiazole (88‒117) and
2-(4-O-(1-aryl-1,2,3-triazolyl)phenyl)benzothiazole derivatives (118‒156). Hybrids of benzothiazole and 4-alkylaminobenzene bridged by a hydrazone moiety (169–202) were prepared as an E-isomers using solvent-free mechanochemical synthesis by condensation reaction of 4-alkoxybenzaldehydes (1, 2, 4, 5, 161‒168) and 2-hydrazinylbenzothiazoles (158–160). 1,2,3-triazole iminocoumarin (207–212) and coumarin derivatives (213–223) were synthesized by copper-catalyzed microwave-assisted click reaction of the corresponding azides and terminal alkynes. The structures of the prepared derivatives were confirmed by 1H- and 13C-NMR spectroscopy as well as by two-dimensional methods NOESY, HSQC and HMBC. The antiproliferative activity in vitro of the prepared compounds was evaluated against a range human tumor cell lines as well as on healthy cells. Antibacterial activity in vitro was performed on Gram-positive and Gram-negative bacterial strains including clinically resistant strains of MRSA and VRE. Benzothiazole derivatives with a 1,4-disubstituted 1,2,3-triazole ring (88‒97, 108‒117 and 118–156) were also tested for antiviral activity. In order to establish a possible correlation between antitumor and antioxidative activity, derivatives that showed pronounced antiproliferative activity were evaluated for antioxidant activity in vitro by the DPPH method. Among all the prepared derivatives the most significant antiproliferative activity in vitro showed 6-chloro-2-(4-N,N-diethyl-3-fluorophenyl)benzimidazole (23) (K-562, Z-138, IC50 = 2.0 μM), 6-chloro-2-(4-N,N-diethyl-3-methoxyphenyl)benzothiazole (59) (CFPAC, IC50 = 1.03 μM) and (E)-6-chloro-2-(3-(4-(N,N-dimethylethoxy)-3-fluorophenyl)hidrazonyl)benzothiazole (188) (CAPAN,
IC50 = 0.6 μM, NCI-H460, IC50 = 0.9 μM). The strongest selective antibacterial activity was shown by 2-(4-alkoxyphenyl)-6-chlorobenzimidazole derivatives (15‒17) on Enterococcus faecalis (MIC = 0.25–1 mg/mL) and 6-chloro-2-(4-N,N-diethylphenyl)benzothiazole (50), which showed the most pronounced activity against MRSA strain 13276 (MIC=2 μg/mL). Triazole derivative of 2-chlorobenzothiazole (89) showed the strongest antiviral activity against influenza virus H1N1 (EC50 = 6.7 μM)
Photoelectrochemical characterisation of semiconductor in the presence of perfluorinated carboxyilic acid
No full textCilj ovog rada bio je ispitati fotoelektrokemijske odzive BiVO4 elektrode i elektrode željezom (30% Fe2O3) i srebrom (6% Ag) modificiranog BiVO4 u otopinama perfluorooktanske kiseline (PFOA) i Na2SO4. Ispitivanja su provedena za osvijetljene i neosvijetljene elektrode uz LED lampu kao izvor svjetla. Pri tome je korištena metoda linearne polarizacije, elektrokemijska impedancijska spektroskopija, kronoamperometrija i praćenje potencijala otvorenog kruga u vremenu. Rezultati dobiveni ispitivanjem metodom linearne polarizacije i kronoamperometrije u 0,5 M Na2SO4 pokazuju da su obje elektrode fotoaktivne, ali modificirana elektroda pokazuje bolju fotoaktivnost odnosno veće fotostruje. Ovom metodom je također ispitana modificirana elektroda u otopini 0,01 mg/ml PFOA u 0,5 M Na2SO4. Manje vrijednosti fotostruja te značajniji porast struje iznad 1,2 V u prisustvu PFOA ukazuje na različito ponašanje elektrode u prisustvu PFOA u odnosu na čisti Na2SO4. Ispitivanjem metodom elektrokemijske impedancijske spektroskopije utvrđeno je da su veće impedancije zabilježene bez prisustva svjetla što ukazuje na dobru fotoaktivnost materijala. Također je potvrđena bolja fotoaktivnost modificiranog BiVO4. Praćenjem napon otvorenog kruga potvrđena je fotoaktivnost za obje elektrode, a budući da napon poprima negativniju vrijednost može se zaključiti da su ispitani materijali n – tip poluvodiča. Ova metoda je također pokazala da ne postoji razlika u odzivu modificiranog BiVO4 u otopini Na2SO4 i otopini PFOA u Na2SO4. što je u suprotnosti s rezultatima linearne polarizacije.The aim of this study was to investigate the photoelectrochemical responses of a BiVO₄ electrode and a BiVO₄ electrode modified with iron (30% Fe₂O₃) and silver (6% Ag) in solutions of perfluorooctanoic acid (PFOA) and Na₂SO₄. The experiments were conducted using both illuminated and non-illuminated electrodes, with an LED lamp as the light source. The methods employed included linear polarization, electrochemical impedance spectroscopy, chronoamperometry, and monitoring of open-circuit potential over time. Results obtained from linear polarization and chronoamperometry in 0.5 M Na₂SO₄ show that both electrodes exhibit photoactivity, with the modified electrode demonstrating enhanced photoactivity, as evidenced by higher photocurrents. Additionally, the modified electrode was tested in a solution of 0.01 mg/mL PFOA in 0.5 M Na₂SO₄, where the lower photocurrents and significant increase in current above 1.2 V in the presence of PFOA indicate different behavior of the electrode in the presence of PFOA compared to pure Na₂SO₄. Electrochemical impedance spectroscopy revealed higher impedances in the absence of light, indicating good photoactivity of the material, with the modified BiVO₄ showing superior photoactivity. Monitoring the open-circuit potential further confirmed the photoactivity of the electrodes, with the observed shift to more negative values suggesting that the tested materials are n-type semiconductors. However, this method also indicated different response of modified BiVO₄ in Na2SO4 and PFOA solutions, which contrasts with the results obtained from linear polarization
Synthesis of statins by immobilized enzyme in different reactor systems
No full textStatini su lijekovi s kojima se uspješno liječi hiperkolesterolemija i suzbija rizik razvoja kardiovaskularnih bolesti. Enzim 2-deoksiriboza-5-fosfat aldolaza (DERA) katalizira sintezu prekursora statina stereoselektivnom dvostrukom aldolnom adicijom. Produkti ove reakcije su 4-kloro-3-hidroksibutanal (4C-Cl) i (3R,5R)-6-kloro-3,5-dihidroksibutanal (6C-Cl) tj. laktol.
U ovom radu supstrati, acetaldehid (AA) i kloroacetaldehid (CAA), korišteni su za sintezu ovih prekursora statina, kataliziranu imobiliziranom DERA u različitim kontinuiranim reaktorima. DERA je kovalentno imobilizirana na mezoporoznu siliku i magnetske nanočestice. Cilj ovog istraživanja bio je usporediti nosioce za imobilizaciju, reaktorske sustave i varijacije procesnih parametara. Studija je također ispitala kako glutaraldehid i anhidrid jantarne kiseline djeluju kao aktivatori nosioca. Temeljito su analizirani ključni procesni pokazatelji, poput konverzije, produktivnosti i maksimalne koncentracije proizvoda. Rezultati su pokazali da je proces s enzimom imobiliziranim na mezoporoznu siliku pokazao bolje rezultate po ovim pokazateljima. Međutim, sustav koji koristi magnetske nanočestice pokazao je veću stabilnost enzima te je proces postigao stacionarne uvjete tijekom kontinuiranog rada.Statins are highly effective drugs used to treat hypercholesterolemia and reduce the risk of cardiovascular disease. The enzyme 2-deoxy-d-ribose-5-phosphate aldolase (DERA) plays a key role in synthesizing statin precursors through stereoselective double aldol addition.
This reaction yields products such as 4-chloro-3-hydroxybutanal (4C-Cl) and
(3R,5R)-6-chloro-3,5-dihydroxybutanal (6C-Cl) i.e. lactol. In this work the substrates, acetaldehyde (AA) and chloroacetaldehyde (CAA), were used for the synthesis of these statin precursors, catalyzed by immobilized DERA in different flow reactors. DERA was covalently immobilized on mesoporous silica and magnetic nanoparticles. The aim of this study was to compare carriers for immobilisation, reactor systems, and process parameter variations. The study also examined how glutaraldehyde and succinic anhydride function as carrier activators. Key process indicators, such as conversion, productivity, and maximum product concentration, were thoroughly analyzed. Results demonstrated that process with enzyme immobilised on mesoporous silica led to better performance across these indicators. However, the system using magnetic nanoparticles showed greater enzyme stability and maintained a steady state during continuous operation
Preparation and characterization of composite based on chitosan and bioceramics as drug delivery systems
No full textInženjerstvo tkiva je interdisciplinarno područje, koje primjenjuje teorijska i inženjerska znanja za razvoj biomaterijala koji obnavljaju, održavaju ili poboljšavaju funkciju tkiva. Jedan od izazova u ovom području je razvoj biomimetičkih okosnica za obnovu koštanog tkiva, u koje se također mogu ugraditi lijekovi, faktori rasta ili druge biološke komponente koje bi pospješile regenerativni učinak. Materijali koji se primjenjuju za takve slučajeve moraju biti kompatibilni s tkivom i ne smiju izazivati imunosne reakcije, stoga su u inženjerstvu koštanog tkiva popularan izbor kitozan i hidroksiapatit, koji se po sastavu podudaraju s organskim i anorganskim dijelom kosti. Kitozan je linearni polimer koji posjeduje svojstva kao što su biorazgradljivost, biokompatibilnost, hemostatična, protuupalna i antibakterijska svojstva, koja mogu potaknuti regenerativne procese u organizmu, dok dodatak hidroksiapatita omogućuje interakciju materijala s kosti. Cilj ovog rada je priprava kompozitnih okosnica na temelju kitozana i hidroksiapatita kao potencijalnih nosača antitumorskog lijeka, doksorubicina, pri liječenju koštanih defekata nastalih uklanjanjem tumorskog tkiva. Kompozitne okosnice pripravljene su metodom toplinski inducirane fazne separacije uz naknadnu liofilizaciju. Dobivene kompozitne okosnice identificirane su i karakterizirane uz pomoć infracrvene spektroskopske analize s Fourierovom transformacijom uz prigušenu totalnu refleksiju (ATR-FTIR), pretražne elektronske mikroskopije uz energijski razlučujuću rendgensku analizu (SEM-EDX) i fluorescencijske spektroskopije. Ispitan je utjecaj biokeramike na sastav, mikrostrukturu, stupanj apsorpcije vode, bioaktivnost i otpuštanje lijeka doksorubicina.Tissue engineering is an interdisciplinary field that applies scientific and engineering knowledge to develop biomaterials that regenerate, maintain or improve tissue function.
One of the challenges in this field is the development of biomimetic scaffolds for the regeneration of bone tissue which can also incorporate drugs, growth factors or other biological components that would enhance the regenerative effect. The materials used for such cases must be compatible with the tissue and must not cause immunogenic reactions, therefore chitosan and hydroxyapatite, which in composition mimic the organic and inorganic part of the bone, are popular choices in bone tissue engineering. Chitosan is a linear polymer that has properties such as biodegradability, biocompatibility, hemostatic, anti-inflammatory and antibacterial properties, which can stimulate regenerative processes in the body, while the addition of hydroxyapatite enables the material to interact with the inorganic phase of the bone. The goal of this work is the preparation of composite scaffolds based on chitosan and hydroxyapatite as carriers of the antitumor drug, doxorubicin, in the treatment of bone defects caused by the removal of tumor tissue. Composite scaffolds were prepared by the thermally induced phase separation with subsequent lyophilization. The resulting composite scaffolds were identified and characterized using Fourier transform infrared spectroscopic analysis with attenuated total reflection (ATR-FTIR), scanning electron microscopy with energy dispersive X-ray analysis (SEM-EDX) and fluorescence spectroscopy. The influence of bioceramics on the composition, microstructure, water absorption, bioactivity and drug release of doxorubicin was studied
Extraction of pharmaceutical mixture from sediment by sediment solid-phase dispersion and sulfametoxazole imprinted polymer
No full textU današnje vrijeme prisutna je široka primjena i velika potrošnja farmaceutika zbog čega farmaceutici sve više dospijevaju u okoliš i na taj način negativno utječu na cijeli ekosustav. Povećanjem koncentracije farmaceutika u vodenim tokovima dolazi i do njihovog nakupljanja u slojevima tla, ali i sedimenta. S obzirom na sve veću zabrinutost potrebno je razviti metode za detekciju farmaceutskih spojeva u okolišu kako njihova povećana koncentracija ne bi utjecaja na kvalitetu ljudskog zdravlja. U ovom završnom radu detaljno je opisana optimizacija postupka raspršenja sedimenta kroz čvrstu fazu za ekstrakciju smjese dvanaest farmaceutskih spojeva (amoksicilin, atenolol, prokain, ofloksacin, sulfametazin, sulfametoksazol, torasemid, karbamazepin, deksametazon, ß-estradiol, diazepam i diklofenak). Učinkovitost metode određena je tekućinskom kromatografijom visoke učinkovitosti vezanom na detektor s nizom dioda. Ekstrakcija je provedena uz pomoć različitih otapala i njihovih kombinacija kako bi se postigli optimalni uvjeti, a kao najbolja kombinacija pokazala se smjesa natrijevog hidroksida i metanola. Za optimalne uvjete ekstrakcije farmaceutika odabrana je kombinacija 0,1 M natrijevog hidroksida i metanola u omjeru 2:8, volumena 5 mL na sorbensu C18. Nakon optimizacije parametara, isti su primijenjeni i za ekstrakciju raspršenja sedimenta kroz čvrstu fazu uz polimer s otiskom molekule sulfametoksazola. Obje spomenute metode su validirane te primijenjene na realne uzorke sedimenta, pokazujući svoju učinkovitost u identifikaciji i kvantifikaciji farmaceutika. Primjena polimera s otiskom sulfametoksazola znatno je poboljšala učinkovitost metode, posebice u slučaju sulfametoksazola.Nowadays, the use and consumption of pharmaceuticals widespread, which leads to their increasing presence in the environment and thus has a negative impact on the entire ecosystem. The increasing concentration of pharmaceuticals rising in water bodies leads to their accumulation in soil layers and sediments. Due to the growing concern, it is crucial to develop methods to detect pharmaceutical compounds in the environment in order to prevent their increased concentration from affecting human health. This thesis comprehensively describes the optimization of a solid-phase dispersion method for extracting a mixture of twelve pharmaceutical compounds (amoxicillin, atenolol, procaine, ofloxacin, sulfamethazine, sulfamethoxazole, torasemide, carbamazepine, dexamethasone, ß-estradiol, diazepam, and diclofenac). The method's efficacy was determined using high-performance liquid chromatography coupled with a diode array detector. The extraction was carried out with different solvents and their combinations in order to achieve optimal conditions, with the mixture of sodium hydroxide and methanol proving to be the best combination. For optimal extraction conditions, a solvent combination of 0.1 M sodium hydroxide and methanol in a ratio of 2:8, with a volume of 5 mL on a C18 sorbent was chosen. After parameter optimization, these were also applied for the extraction by sediment solid-phase dispersion with the sulfametoxazole imprinted polymer. Both method were validated and applied to real sediment samples, demonstrating their effictiveness in pharmaceutical identification and quantification. In order to achieve optimal utilization of all pharmaceuticals, the application of the sulfametoxazole imprinted polymer of considarable importance, especially in the case of sulfametoxazole
Synthesis of novel benzothiazole derivatives with antitumoral potential
No full textU ovom radu je opisana sinteza novih 1,2,3-triazolnih derivata benzotiazola te njihova strukturna karakterizacija 1H- i 13C-NMR spektroskopijom. Mikrovalovima potpomognutom SN2 reakcijom 2-hidroksibenzaldehida i propargil-bromida uz K2CO3 kao bazu pripravljen je 2-(prop-2-in-1-iloksi)benzaldehid (1). Propargilirani derivat benzotiazola (2) priređen je ciklizacijom 2-O-propargilbenzaldehida (1) i ortho-aminotiofenola u dimetilformamidu uz oksidacijsko sredstvo Na2S2O5. Ciljani 1,2,3-triazolni derivati benzotiazola (3 – 14) sintetizirani su mehanokemijskim reakcijama Huisgenovom 1,3-dipolarnom cikloadicijom 2-(2-(prop-2-in-1-iloksi)fenil)benzo[d]tiazola (2) i odgovarajućih aromatskih azida uz bakrov(II) acetat kao katalizator. Strukture svih novopriređenih spojeva potvrđene su
1H- i 13C-NMR spektroskopijom.This paper describes the synthesis of new 1,2,3-triazolyl benzothiazole derivatives and their structural characterization by 1H- and 13C-NMR spectroscopy. Microwave-assisted SN2 reaction of 2-hydroxybenzaldehyde and propargyl bromide with K2CO3 as a base
2-(prop-2-yn-1-yloxy)benzaldehyde (1) was prepared. A propargylated benzothiazole derivative (2) was prepared by cyclization of 2-O-propargylbenzaldehyde (1) and
ortho-aminothiophenol in dimethylformamide using Na2S2O5 as oxidizing agent. Target 1,2,3-triazolyl benzothiazole derivatives (3 - 14) were synthesized by mechanochemical reactions by Huisgen 1,3-dipolar cycloaddition of
2-(2-(prop-2-yn-1-yloxy)phenyl)benzo[d]thiazole (2) and the corresponding aromatic azides with copper (II) acetate as catalyst. The structures of all newly prepared compounds were confirmed by 1H- and 13C-NMR spectroscopy