- 8 - ABSTRACT (EN) The thesis is submitted as a commented set of reviewed publications documenting and depicting the possibilities of mass spectrometry in the field of chemical, biological and pharmaceutical research; namely for the purposes of structure elucidation of selected organometallic complexes, analyses of drugs and their metabolites, monitoring of important biological markers. In course of experimental work, the following objectives were studied and solved:  Proposal and realization of micro-scale preparation of selected rhenium complexes with aromatic ligands, utilizing tetrabutyammonium tetrachlorooxorhenate as a starting material; preparation and structure characterization of oxorhenium(V) complexes with 1,2-dihydroxybenzene, 1,2,3-trihydroxybenzene, and 2,3- dihydroxynaphtalene as ligands by means of ESI/MS, APPI/MS and LDI-MS; ESI/MS and UV/Vis study of kinetic behavior of complexes arising from the reaction of tetrabutylamonnium tetrachlooxorhenate with pyrogallol and catechol as ligands. Special aim was devoted to the study of subsequent chemical transformation of primarily formed Re(V) complexes; structure characterization of selected ferrocene complexes with copper, gold and silver by means of ESI/MS.  Proposal of methodology of structure characterization and quantification of the...

Karzinome der Gallenwege sind mit einer schlechten Prognose assoziiert. Eine potentiell kurative chirurgische Resektion ist bei der Mehrzahl der Patienten aufgrund des späten Zeitpunkts der Diagnosestellung nicht möglich, so dass derzeit vorrangig palliative Therapieansätze Anwendung finden. Das nur geringe Ansprechen auf konventionelle Radio- oder Zytostatikatherapie begründet die Notwendigkeit neuer Therapieansätze. Einen möglichen Angriffspunkt stellt hierbei die Polo-like-Kinase 1 (Plk1) dar, da ihre zentrale Rolle in der Regulation des Zellzyklus zunehmend erkannt und eine vermehrte Expression in malignem Tumorgewebe verglichen mit gesundem Gewebe nachgewiesen wurde. Das Dihydropteridinon BI 2536 ist ein poten-ter, niedermolekularer und selektiver Hemmstoff der Plk1 und sollte daher auf seine Wirksamkeit an Gallenwegskarzinomen untersucht werden. In der vorliegenden Arbeit konnte gezeigt werden, dass BI 2536 die untersuchten 14 Zelllinien von Gallenblasen- und Gallengangskarzinomen wirkungsvoll hemmt. Das Ansprechen unterschied sich zwischen den Zelllinien und ordnet sich vergleichbar zu Veröffentlichungen an anderen malignen Tumoren ein. Die Expression von Plk1 und dessen assoziierten Transkriptionsfaktor FoxM1 konnte bei Westernblot-Versuchen bei allen Zelllinien nachgewiesen werden, was eine Bedeutung in der Onkogenese vermuten lässt. Die Behandlung mit BI 2536 beeinflusste jedoch die Proteinmenge beider nicht. An für die folgenden Versuche ausgewählten drei Zelllinien zeigten sich in der reversen Transkription mit anschließender Echtzeit-Polymerase-Kettenreaktion (qRT PCR) ähnliche Ergebnisse in Bezug auf die exprimierte mRNA von Plk1. Westernblot-Analysen ermittelten keine signifikanten Veränderungen der an wichtigen intrazellulären Kaskaden beteiligten Proteine p42/44 und Akt sowie deren phosphorylierten Formen. Obwohl die Proteinmenge des Mitosemarkers Phospho-Histon H3 ebenso unverändert blieb, führte die Behandlung mit BI 2536 – dies zeigen Ergebnisse der Durchflusszytometrie – zu einer signifikanten, dosisabhängigen Zunahme der G2/M Fraktion des Zellzyklus und Zunahme der Apoptose-rate. Der maximale Hemmeffekt in der Behandlung von BI 2536 lag bei einer Inkubations-dauer von vier Tagen. Die Empfehlungen aus den klinischen Studien der Phase II von BI 2536 sowie dem Ziel der Vermeidung von Resistenzen ergibt sich die Notwendigkeit von Kombinationsversuchen mit Zytostatika, die in einer anderen Phase des Zellzyklus angreifen. Die in der Behandlung von Gallenwegskarzinomen etablierten Antimetaboliten 5-Fluorouracil und Gemcitabin wurden hierzu ausgewählt und es zeigten sich für 5 Fluorouracil synergistische, für Gemcitabin hingegen additive Kombinationseffekte. Zusätzlich wurde die Wechselwirkung mit dem IGF 1-Rezeptor-Inhibitor NVP-AEW541 untersucht, der ebenfalls einen neuen Behand-lungsansatz in der Krebstherapie darstellt und bei Gallenwegskarzinomen in vitro wirksam ist. Auch hier zeigen sich synergistische Effekte, die jedoch erst in höheren Behandlungs-dosen auftraten. Die Ergebnisse dieser Arbeit zeigen, dass die Hemmung der Plk1 bei Gallenblasen- und Gallengangskarzinomen einen wirksamen Behandlungsansatz darstellt. Auf der Grundlage der in dieser Arbeit beschriebenen Ergebnisse wird eine weitere präklinische und klinische Testung von selektiven Plk1-Hemmstoffen wie BI 2536 an Gallenwegskarzinomen empfohlen.:Vorbemerkung 1 Inhaltsverzeichnis 2 Abkürzungsverzeichnis 3 Bibliographische Beschreibung 4 1 Einleitung 5 1.1 Gallenwegskarzinome 5 1.1.1 Epidemiologie, Einteilung und Histologie 5 1.1.2 Klinische Symptomatik und Diagnostik 6 1.1.3 Therapie und Prognose 7 1.2 Polo like-Kinase 1 9 1.2.1 Entdeckung und Aufbau der Polo like-Kinasen 9 1.2.2 Funktionen 9 1.2.3 Regulation 11 1.2.4 Bedeutung in der Onkologie 12 1.2.5 Hemmung 12 1.3 BI 2536 14 1.4 Zielstellung der Arbeit 15 2 Publikation 17 3 Zusammenfassung 29 4 Summary 31 5 Literaturverzeichnis 32 6 Erklärung über die eigenständige Abfassung der Arbeit 45 7 Lebenslauf 46 8 Publikationen im Rahmen dieser Arbeit 48 9 Danksagung 49

P-glycoprotein (P-gp) protects the mammalian intestinal epithelium by effluxing toxins from the epithelial cells as well as release of human endocannabinoids that inhibit neutrophil infiltration. Diminished or dysfunctional P-gp is associated with intestinal inflammation including ulcerative colitis (UC). Due to the microbiome dysbiosis associated with UC, we hypothesize that the healthy microbiota promote colonic P-gp expression. Utilizing mouse models of antibiotic treatment, microbiota reconstitution, and metabolite perturbation, we have shown butyrate and secondary bile acids, dependent on vancomycin-sensitive bacteria, induce P-gp expression in vivo. We have shown these metabolites together potentiate induction of P-gp in intestinal epithelial cell lines in vitro, which is sufficient to inhibit primary human neutrophil transmigration. Furthermore, in UC patients we find diminished P-gp expression is coupled to reduction of anti-inflammatory endocannabinoids and luminal content with reduced capability to induce P-gp expression. Additionally, we have found butyrate contributes to P-gp expression via histone deacetylase inhibition, and secondary bile acids regulate P-gp expression via nuclear receptors pregnane X receptor and vitamin D receptor. Employing RNA sequencing (RNAseq) in IECs uncovered signaling networks that are uniquely triggered with the combination of butyrate and secondary bile acids, suggesting additional pathways required for maximal P-gp expression in the colon. Together we identify a mechanistic link between cooperative functional outputs of the complex microbial community and suppression of intestinal inflammation. These data emphasize the importance of the intestinal microbiome in driving the P-gp axis to suppress aberrant neutrophil infiltration and identify potential therapeutic targets for promoting P-gp expression in an inflamed colon to reset homeostasis.

<p>The main goal of this thesis research is to expand the range of unique properties of phase transforming cellular materials (PXCMs), a new class of architected materials, and to extend their applicability both in the engineering disciplines and in the medical field. A novel aspect of PXCMs is their unique energy dissipation during loading via a snapping mechanism associated with a geometric transition between one stable configuration to another stable configuration at the unit cell level. Phase transformation is analogous to displacive transformations, such as martensitic transformations in shape memory alloys, with no change in configurational entropy. To accomplish this goal, three problem areas are addressed with the first exploring the effects of length scale as added structural hierarchy on material properties and energy dissipation, the second providing an analysis of the durability of architected materials via a novel additive manufacturing method, and the third, an extension into the medical field. Two examples are provided that demonstrate the effects of length scale as added structural hierarchy on material properties, and a machine learning approach for the feasible design of materials with additional levels of structural hierarchy is presented. A simple design approach coupled with a novel additive manufacturing method is discussed for the design of architected materials with high durability. Lastly, a concept for de-clogging bile stents via a temperature driven, shape-memory mechanism inspired by peristaltic locomotion in the human esophagus is presented.</p>

Koffein (1,3,7-Trimethylxanthin) und Coprostanol (5beta-cholestan-3beta-ol) wurden im Berliner Oberflächenwasser nachgewiesen. Ihre Konzentrationen korrelierten mit dem Verunreinigungsgrad der Proben, was nahelegt, dass sie sich als Marker für menschliche Aktivität eignen. Bemerkenswerterweise wurde Koffein in jeder einzelnen Oberflächenwasserprobe oberhalb der Bestimmungsgrenze von 0,025 µg/L gefunden. Um Oberflächenwasserproben in größeren Serien zu untersuchen, war die Entwicklung zweier neuer Methoden erforderlich: ein Immunoassay, basierend auf einem monoklonalen Antikörper für Koffein und eine dispersive flüssig-flüssig Mikroextraktionsmethode (DLLME), gefolgt von Flüssigkeitschromatographie gekoppelt mit Tandem-Massenspektrometrie (LC-MS/MS) für Coprostanol. Der entwickelte Koffein-Immunoassay zeigt die beste je erhaltene Nachweisgrenze für Koffein (0,001 µg/L), erlaubt Hochdurchsatz-Analysen und erfordert keine Probenvorbereitung. Der Assay wurde auch erfolgreich für die Messung von Koffein in Getränken, Haarwaschmitteln, Koffeintabletten und menschlichem Speichel angewendet. Antikörper gegen Coprostanol sind nicht kommerziell erhältlich. Eine neue Strategie Anti-Coprostanol-Antikörper zu generieren wurde erarbeitet, die eine analoge Verbindung – Isolithocholsäure (ILA) – als Hapten verwendet, mit der eine Gruppe von Mäusen immunisiert wurde. Ein polyklonales Anti-ILA-Serum wurde produziert, welches Coprostanol bindet, aber die niedrige Affinität erlaubte nicht den Aufbau eines Immunoassays, der die Messung von Umweltkonzentrationen des Anayten (im Bereich ng/L) zulässt. Spezifische Anti-ILA-Immunglobuline G wurden auch in den Faeces der Mäuse gefunden. Coprostanol wurde in den Wasserproben durch die Verwendung einer neuentwickelten LC-MS/MS-Methode unter APCI-Ionisation (atmospheric pressure chemical ionisation) gemessen. Konzentrationen oberhalb von 0,1 µg/L wurden nach Voranreicherung der Probe mittels DLLME bestimmt. / Caffeine (1,3,7-trimethylxanthine) and coprostanol (5beta-cholestan-3beta-ol) were detected in samples of Berlin’s surface water. Their concentrations correlated with the contamination status of the samples, suggesting their usefulness as markers of human activity. Remarkably, caffeine concentrations were always well above the limit of quantitation of 0.025 µg/L. In order to screen surface water samples in larger series, the development of two novel methods was required: a monoclonal antibody-based immunoassay for caffeine and a dispersive liquid-liquid microextraction (DLLME) method, followed by liquid chromatography tandem mass spectrometry (LC-MS/MS) for coprostanol. The caffeine immunoassay developed shows the best analytical limit of detection (LOD) obtained so far for caffeine (0.001 µg/L), allows high-throughput analysis, and does not require sample pre-treatment. The assay was also successfully employed to measure caffeine in beverages, shampoos, caffeine tab-lets, and human saliva. Antibodies to coprostanol are not commercially available. A new strategy to generate anti-coprostanol antibodies was elaborated using an analogous com-pound as hapten – isolithocholic acid (ILA) – and immunizing a group of mice. A polyclonal anti-ILA serum was produced, which binds coprostanol but the low affinity did not permit setting up an immunoassay to measure environmental concentrations of the analyte (in the range of ng/L). Specific anti-ILA immunoglobulin G were also found in the faeces of the immunized mice. Coprostanol was quantified in the water samples using a newly developed LC-MS/MS method using atmospheric pressure chemical ionisation (APCI). Concentrations above 0.1 µg/L were determined after sample preconcentration using DLLME. This extraction method also proved to be successful for enrichment of coprostanol-related compounds such as cholesterol, cholestanol, cholestanone, ergosterol, and stigmasterol.

<p>Danas, u raznim analitičkim laboratorijama postoji veći broj analitičkih protokola,<br />zasnovanih bilo na izuzetno sofisticiranim ili jednostavnijim tehnikama, koji služe za<br />određivanje različitih ciljnih analita od farmakolo&scaron;kog značaja. Među tim grupama ciljnih analita pripadaju i antibiotici koji predstavljaju veliko otkriće u oblasti medicine i zahvaljujući njima spa&scaron;eno je vi&scaron;e od sedam miliona života, ali pored navedenih koristi, antibiotici mogu da izazovu&nbsp; veliki broj neželjenih efekata i žučne kiseline zajedno sa svojim derivatima, koji su fiziolo&scaron;ki deterdženti, mogu biti citotoksične za organizam ako se njihova koncentracija ne kontroli&scaron;e. U ovoj doktorskoj disertaciji prikazan je razvoj analitičkih metoda pre svega voltametrijskihmetoda u kombinaciji sa jednostavnim i savremenim elektrodama/senzorima za određivanje&nbsp; odabranih analita kao &scaron;to je antraciklični antibiotik doksorubicin (DOX), makrolidni antibiotici<br />eritromicin-etilsukcinata (EES), azitromicina (AZI), klaritromicina (CLA) i roksitromicina&nbsp; (ROX) i 3-dehidro-deoksiholne kiseline.</p><p>Voltametrijska karakterizacija i određivanje gore navedenih antibiotika primenom obnovljive srebro-amalgam film elektrode (Hg(Ag)FE)rađena je direktnom katodnom&nbsp; voltametrijom sa pravougaonim talasima (SWV) i visoko osetljivom adsorptivnom voltametrijom sa pravougaonim talasima (SW-AdSV) u Briton-Robinson puferu, kao pomoćnom elektrolitu, obuhvatajući &scaron;irok opseg pH vrednosti. Odgovor DOX-a primenom&nbsp; Hg(Ag)FE&nbsp;praćen je u intervalu potencijala od -0,20 do -0,80 V.&nbsp; Za analizu tragova, optimizacija metode ukazuje da su optimalni parametri za analitički pik na potencijalu (Ep ) -0,57 V u odnosu na zasićenu kalomelovu elektrodu (ZKE): pH 6,0, potencijal&nbsp; akumulacije -0,20 V i vreme&nbsp; akumulacije 140 s. U model rastvoru, DOX je određivan u koncentracionom opsegu 4,99-59,64&nbsp; ng mL^-1. Razvijena SW-AdSV metoda je primenjena za određivanje DOX-a u obogaćenom uzorku humanog urina. Niža koncentracija DOX-a 9,89ng mL^-1&nbsp;u voltametrijskoj&nbsp; ćeliji je određivana sa relativnom standardnom devijacijom (RSD) manjom od 6,0%. &Scaron;to se ispitivanih makrolida tiče oni su pokazali redukcione signale u dalekoj negativnoj oblasti potencijala. Ispitivanja direktnom katodnom SWV rađena su u opsegu potencijala od -0,75 V do -2,00 V u odnosu na ZKE, pri čemu su dobijena jedan ili dva redukciona pika u opsegu potencijala od -1,5 V do -1,9 V. Oblik i intenzitet signala zavisi od primenjene pH vrednosti u &scaron;irokoj pH oblasti. Za analitičke svrhe, radi razvoja direktne katodne SWV i adsorptivne inverzne/striping SWV metode, pogodnim su se pokazale neutralna i slabo alkalna sredina tj. pH 7,0 sa&nbsp; E_p na -1,67 V u odnosu na ZKE za ROX i EES i pH 7,2 sa E_p na -1,85 V u odnosu na ZKE za AZI i pH 7,4 sa E_p na -1,64 V u odnosu na ZKE za CLA. Na osnovu snimljenih cikličnih voltamograma na&nbsp; optimalnim pH vrednostima, može se predložiti adsorptivno-kontrolisan kinetički proces na elektrodi u slučaju sva&nbsp; četiri ispitivana jedinjenja. Takođe,&nbsp; ¹H NMR merenja uz potiskivanje&nbsp; signala vode u pH oblasti između pH 6,0 i 10,5 ukazuju na to da su makrolidni molekuli pri optimalnim analitičkim uslovima predominantno u protonovanoj formi preko tercijerne amino grupe &scaron;to potpomaže, u sva&nbsp; četiri slučaja, njihovu adsorpciju na odgovarajuće polarizovanoj Hg(Ag)FE. Optimizovane direktne katodne SWV metode&nbsp; pokazuju dobru linearnost u koncentracionom opsegu 4,81-23,3&nbsp; &micro;g mL^-1 , 4,53-29,8&nbsp; &micro;g mL^-1 , 1,96-28,6&nbsp; &micro;g mL^-1 i 1,48-25,9 &micro;g mL^-1 za AZI, EES, CLA odnosno ROX. Razvijene SW-AdSV metode rezultiraju u linearnom odgovoru pri nižim koncentracionim intervalima 1,0-2,46 &micro;g mL^-1 ,&nbsp; 0,69-2,44&nbsp; &micro;g mL^-1, 0,05-0,99 &micro;g mL^-1 i 0,10-0,99&nbsp; &micro;g mL^-1 , za AZI, EES, CLA i ROX. RSD za sve razvijene metode nije veća od 1,5% izuzev SWV metode u slučaju AZI-a gde je 4,5%. Direktna katodna SWV metoda&nbsp; je uspe&scaron;no primenjena za određivanje EES-a u farmaceutskom proizvodu Eritromicin^&reg; dok SW-AdSV metoda je primenjena u slučaju određivanja EES-a u obogaćenom uzorku humanog urina i&nbsp;za određivanje ROX-a u farmaceutskom proizvodu Runac^&reg; . U svim pomenutim slučajevima, primenjena je metoda standardnog dodatka. Pouzdanost i tačnost elaboriranih procedura u slučaju određivanja EES-a u model sistemu i&nbsp; farmaceutskom proizvodu Eritromicin^&reg; su potvrđena poređenjem sa rezultatima dobijenim primenom HPLC-DAD metode.</p><p>Nakon preliminarnih studija 3-dehidro-deoksiholne&nbsp; kiseline/3-dehidro-deoksiholata primenom elektrode od staklastog ugljenika (GCE), gde je uočeno da ne dolazi do formiranja redukcionog signala u Briton-Robinson puferu između pH 5,0 i 11,8 primenom direktne katodne SWV, bizmut-film je izdvojen&nbsp; <em>ex situ</em> na povr&scaron;ini iste elektrode od staklastog ugljenika (BiF-GCE) iz uobičajeno kori&scaron;ćenog rastvora za elektrodepoziciju (0,02 mol L^-1 Bi(NO₃)₃, 1,0 mol L^-1 HCl i 0,5 mol L^-1 KBr) i tako pripremljena elektroda je primenjena za karakterizaciju i određivanje pomenutog jedinjenja u alkalnoj sredini. Redukcioni signal ispitivanog analita od analitičkog značaja je uočen jedino primenom BiF-GCE u Briton-Robinson puferusa pH vrednostima između 9,5 i 11,8 u režimu adsorptivne inverzne/stripingvoltametrije sa pravougaonim talasima, dok u slučaju direktnih katodnih SWV eksperimentalnih uslova uočen je slab redukcioni pik sa niskom strujom maksimuma pika. Optimizovani eksperimentalni uslovi za određivanje 3-dehidro-deoksiholata obuhvataju odgovarajuće kondicioniranje elektrode uključujući kondicioniranje&nbsp; <em>ex situ</em> pripremljene BiF-GCE u Briton-Robinson pomoćnom elektrolitu pH 11,8 do stabilizacije struje bazne linije elektrohemijskim cikliranjem potencijala radne elektrode u potencijalskom opsegu između -1,00 i -2,00 V u odnosu na ZKE (blizu 15 puta) i primenu dva ključna parametara adsorptivne voltametrije sa pravougaonim talasima: vreme akumulacije od 30 s i potencijal akumulacije&nbsp; -1,00 V u odnosu na ZKE. Zbog relativne asimetričnosti dobijenih redukcionih signala ispitivanog analita sa&nbsp; E_p na -1,35 V u odnosu na ZKE, &scaron;to je takođe prisutno i u slučaju primene SW-AdSV, određivanje ispitivanog analita je zasnovano na linearnoj zavisnosti između povr&scaron;ine pika redukcionog signala&nbsp; spitivanog analita i njegove odgovarajuće koncentracije i postignuta granica detekcije je 1,43 &micro;g mL^-1 sa dva linearna opsega kalibracione krive od 4,76 &micro;g mL^-1 do 13,0 &micro;g mL^-1 i od 13,0 &micro;g mL^-1 do 23,1 &micro;g mL^-1 za razvoj analitičke metode. RSD metode je 3,22%. Dodatni eksperimenti, elektroliza ispitivanog analita na potencijalu -1,55 V (blizu maksimuma pika ciljnog analita) u odnosu na ZKE su rađeni primenom GCE u obliku ploče (povr&scaron;ina 33,52 cm 2 ) modifikovane sa&nbsp; <em>ex situ&nbsp;</em>pripremljenim bizmut-filmom. Rastvor od interesa uzorkovan je na početku eksperimenta, nakon 2,5 h i nakon 4,5 h tretmana. Ovakvi uzorci su analizirani primenom ¹H NMR merenja uz potiskivanje signala vode u puferskom rastvoru pH 11,8. Može se pretpostaviti da tokom elektrolize 3-dehidro-deoksiholata dolazi do redukcije keto grupe prisutne u strukturi ispitivanog analita.</p><p>Na osnovu literaturnih podataka da neki od ciljnihmakrolidnih antibiotika kao &scaron;to je npr. azitromicin pokazuju oksidativno pona&scaron;anje na elektrodi od ugljenične paste i elektrodi od zlata deteljna karakterizacija i određivanje&nbsp; četiri makrolidna antibiotika rađena je primenom&nbsp; asične&nbsp;elektrode od ugljenične paste (CPE) koja se sastoji samo od grafitnog praha i parafinskog ulja sa optimizovanih direktnih anodnih SWV metoda. U slučaju EES-a i AZI-a diferencijalna pulsna voltametrija (DPV) je testirana za iste svrhe. Ključni&nbsp; parametar u slučaju razvoja analitičkih voltametrijskih metoda je odabir pH vrednosti pomoćnog elektrolita gde je oblik/simetričnost i intenzitet oskidacionog pika glavni kriterijum prilikom odabira. Kao odgovarajuće pH vrednosti za voltametrijsko određivanje EES-a primenom SWV metode odabrana je pH 8,0 sa E_p na 0,83<br />V u odnosu na ZKE, dok u slučaju DPV metode pH 12,0 sa&nbsp; E_p na 0,55 V u odnosu na ZKE je bila najpogodnija za analitičke svrhe. Za određivanje AZI-a, u slučaju obe SWV i DPV metode pH 7,0 se pokazala najpogodnijom sa E_p analitičkog signala na 0,85 V odnosno 0,80 V u odnosu na ZKE, dok u slučaju CLA i ROX koji su ispitivani samo primenom SWV metode za analitičke svrhe pH 12,0 je bila najpogodnija sredina sa E_p analitičkog signala na 0,65 V odnosno na 0,63 V&nbsp;u odnosu na ZKE. Postignute granice detkcije primenom nemodifikovane CPE i direktne anodne SWV su uglavnom u submikrogramskom koncentracionom opsegu 0,17 &micro;g mL^-1 , 0,32&nbsp; &micro;g mL^-1 i 0,30&nbsp; &micro;g mL^-1, u slučaju EES-a, AZI-a i ROX-a i u niskom mikrogramskom koncentracionom opsegu 1,43&nbsp; &micro;g mL^-1 za CLA. Razvijena SWV metoda sa jednostavnom CPE pokazala se pogodnom za određivanje ROX-a u komercijalnom proizvodu Runac^&reg; tableti. U slučaju optimizovanih DPV metoda postignute granice detekcije za EES i AZI su u niskom mikrogramskom&nbsp; koncentracionom opsegu 1,03&nbsp; &micro;g mL^-1 odnosno 1,53&nbsp; &micro;g&nbsp; mL^-1 . U želji da se&nbsp;postigne niža granica detekcije za AZI, DPV metoda&nbsp; je testirana u kombinaciji sa&nbsp; CPE radnom elektrodom povr&scaron;inski modifikovanom sa zlatnim nanočesticama&nbsp; prečnika 10 nm (Au-CPE) i&nbsp; postignuta granica detekcije je 0,95&nbsp; &micro;g mL^-1 sa&nbsp; E_p analitičkog signala na 0,80 V u odnosu na&nbsp; ZKE. RSD metode u slučaju Au-CPE je 3,5%, dok je u slučaju nemodifikovane CPE 6,0%.&nbsp; Linearnost analitičke metode zasnovane na primeni Au-CPE je dva puta &scaron;ira nego u slučaju&nbsp; primene nemodifikovane CPE.</p><p>Na osnovu dobijenih rezultata može se zaključiti da&nbsp; odgovarajuće kombinacije&nbsp; optimizovanih voltametrijskih tehnika sa ekolo&scaron;ki prihvatljivim i lako primenljivim radnim&nbsp; elektrodama, kao &scaron;to su Hg(Ag)FE, BiF-GCE i CPE zajedno sa Au-CPE, rezultuju razvojem&nbsp; pouzdanih analitičkih metoda, kako u oksidacionim tako i u redukcionim proučavanjima, koje&nbsp; često omogućuju&nbsp; određivanje tragova analita od farmakolo&scaron;kog značaja u jednostavnim, a u&nbsp;nekim slučajevima i u složenim sistemima.&nbsp;</p> / <p>Nowadays in different analytical laboratories there is the increasing number of analytical protocols, either based on highly sophisticated or simpler measurements techniques, which serving for determination of different target analytes of pharmacological importance. Among such target groups of the analyte belongs the antibiotics which present a great discovery in the field of medicine and thanks to them were saved more than seven million people but beside to the mentioned great benefits, antibiotics can cause a large number of side effects and bile acids together with their derivatives which are physiological detergents but if their concentration is not<br />controlled they can be cytotoxic to the body. In the present doctoral dissertation the development of analytical methods, primarily analytical voltammetric methods in combination with simple and contemporary electrodes/sensors, for the determination of selected analytes as antracycline antibiotic doxorubicin (DOX), macrolide antibiotics erythromycin ethylsuccinate (EES), azithromycin (AZI), clarithromycin (CLA) and roxithromycin (ROX) and 3-dehydrodeoxycholic acid were performed.</p><p>Voltammetric characterization and determination of the above mentioned antibiotics using a renewable silver-amalgam film electrode (Hg(Ag)FE) was performed by direct cathodic square-wave voltammetry (SWV) and by highly sensitive adsorptive square-wave voltammetry (SW-AdSV) in aqueous Britton-Robinson buffer solutions as supporting electrolyte covering the wider pH range. The Hg(Ag)FE response of DOX was monitored in the potential range between -0.20 and -0.80 V. For the trace level analysis the method optimization showed that the optimal conditions for the analytical peak with peak potential (E_p) at -0.57 V vs. SCE were: the pH 6.0, the accumulation potential -0.20 V, and the accumulation time 140 s. In the model solutions, DOX was determined in the concentration range of 4.99-59.64 ng mL^-1. The developed SWAdSV method was applied for the determination of DOX in spiked human urine sample. The lowest concentration of DOX of 9.89 ng mL^-1 in voltammetric vessel was determined with the relative standard deviation (RSD) less than 6%. As for the investigated macrolides, they showed reduction signals in fairly negative potential range. During direct cathodic SWV investigations conducted over the potential range from -0.75 V to -2.00 V vs. SCE, either one or two reduction peaks were obtained in the&nbsp; potential range from -1.5 to -1.9 V. For analytical purposes concerning the development of direct cathodic SWV and adsorptive stripping SWV methods the neutral&nbsp; and slightly alkaline media were suitable as pH 7.0 with E_p at -1.67 V vs.&nbsp; SCE for ROX and EES and pH 7.2 and pH 7.4 with E_p at -1.85 V and -1.64 V vs. SCE for AZI and CLA, respectively. Based on the cyclic voltammograms recorded at these pH values, adsorptioncontrolled electrode kinetics process can be proposed for all four investigated compounds. The water suppressed ¹H NMR measurements in the pH range between 6.0 and 10.5 indicated that the macrolide molecules at the optimal analytical conditions are predominantly in protonated form via their tertiary amino groups which supported in all four cases their adsorption on the appropriately polarized Hg(Ag)FE electrode. The optimized direct cathodic SWV methods showed good linearity in concentration ranges 4.81-23.3 &mu;g mL^-1, 4.53-29.8 &mu;g mL^-1, 1.96-28.6&nbsp; &mu;g mL^-1, and 1.48-25.9 &mu;g mL^-1 for AZI, EES, CLA and ROX, respectively. The SW-AdSV methods resulted in the linear responses at lower concentration ranges as 1.0-2.46 &mu;g mL^-1, 0.69- 2.44 &mu;g mL^-1, 0.05-0.99 &mu;g mL^-1 and 0.10-0.99 &mu;g mL^-1, for AZI, EES, CLA and ROX, respectively. The RSD for all developed methods was not higher than 1.5% except the SWV method for AZI with 4.7%. The direct cathodic SWV method was successfully applied for the determination of EES in the pharmaceutical preparation Eritromicin^&reg;, while SW-AdSV was tested in the case of the spiked urine sample and for determination of ROX in pharmaceutical preparation Runac^&reg;. In all above cases, the standard addition method was used. The reliability and accuracy of the above procedures in the case of EES determination in model system and pharmaceutical preparation Eritromicin^&reg; were validated by comparing them with those obtained by means of HPLC-DAD measurements.</p><p>After initial study of 3-dehydro-deoxycholic acid/3-dehydro-deoxycholate by glassy carbon electrode, where the absence of any reduction peak was observed in the Britton-Robinson buffer solutions between pH 5.0 and 11.8 by direct cathodic SWV, a bismuth-film was electrodeposited ex situ on the same glassy carbon electrode surface (BiF-GCE) from the usually used plating solution (0.02 mol L^-1 Bi(NO₃)₃, 1.0 mol L^-1 HCl and 0.5 mol L^-1 KBr) and such prepared film-electrode was applied for the characterization and determination of the the target analyte in alkaline media. The reduction signal of analytical importance was observed only by BiF-GCE in Britton-Robinson buffer solutions with pH values between 9.5 and 11.8 in adsorptive stripping square-wave voltammetry working regime, while in the case of the direct cathodic SWV experimental protocol only a very poor reduction peak was obtained. The optimized experimental conditions for the 3-dehydro-deoxycholate determination consist of the optimized electrode conditioning including the electrochemical cycling of the <em>ex situ </em>prepared BiF-GCE potentials in the potential span between -1.0 and -2.0 V vs. SCE (nearly 15 times) in the Britton-Robinson supporting electrolyte pH 11.8 till the stabilization of the baseline current, and the application of two key parameters of the adsorptive square-wave voltammetric protocol: the accumulation time as 30 s and accumulation potential as -1.0 V vs. SCE. Because of the relative asymmetry of the obtained reduction signals of the target analyte with peak E_p at -1.35 V vs. SCE, which is still present in the case of the SW-AdSV, the quantification of the target analyte was based on the linear correlation between peak area of the reduction signal and its appropriate concentrations, and reached limit of detection is 1.43 &mu;g mL^-1 and with two linear ranges of calibration curve from 4,76 &mu;g mL^-1 to 13.0 &mu;g mL^-1 and from 13,0 &mu;g mL^-1 to 23,1 &mu;g mL^-1 for the development of analytical method. The RSD of the method&nbsp; was 3.22%. Additional experiments were performed applying GCE with rectangular form (area 35.32 cm²) modified with ex situ prepared bismuth-film for the electrolysis of the target analyte which was performed at the potential -1.55 V (nearly the peak maxima of the target analyte) vs. SCE. The solution of interest was sampled at the beginning of the experiment, after 2.5 h and after 4.5 h of treatment. Such samples were analysed by simply water suppressing ¹H NMR measurements in the buffered solution at pH 11.8. It can be assumed that during electrolysis of 3-dehydrodeoxycholate the reduction of the keto group present in the structure of the target analyte can be occurred.</p><p>Driven by earlier literature data about the fact that some of the target macrolide antibiotics as e.g. azithromycin showed oxidation behavior at a carbon paste and gold working electrodes detailed characterization and determination of four target macrolide antibiotics were performed on classical carbon paste electrode (CPE) constituted only from graphite powder and paraffin oil with optimized direct anodic SWV methods. In the cases of EES and AZI differential pulse voltammetric (DPV) methods were tested for the same purpose as well. The key parameter in the case of the development of the analytical voltammetric methods is the selection of the pH value of the supporting electrolyte where the shape/simmetry and intensity of the oxidation peak were the criteria. As the appropriate pH value for determination of EES by SWV method the pH 8.0 was selected with E_p at 0.83 V vs. SCE while in the case of the DPV method the pH 12.0 with E_p at 0.55 V vs. SCE was the most suitable for analytical&nbsp; purpose. As for AZI determination, in the case of both SWV and DPV methods the pH 7.0 was the most appropriate supporting electrolyte with the Ep of analytical signal at 0.85 V and 0.80 V vs. SCE, respectively, while in the case of CLA and ROX which were investigated only with SWV method for the analytical purposes the pH 12.0 was the most suitable with E_p at 0.65 V and at 0.63 V vs. SCE. The obtained detection limits applying the bare CPE and the direct anodic SWV are mainly&nbsp; in submicrogram concentration range as 0.17 &mu;g mL^-1; 0.32 &mu;g mL^-1 and 0.30 &mu;g mL^-1 for EES, AZI, and ROX and in the low microgram concentration range as 1.43 &mu;g mL^-1 for the CLA, respectively. The developed method succesfully tested for the determination of ROX in the commercial formulation, Runac^&reg; tablet. In the case of the optimized DPV methods the obtained detection limits for EES and AZI are in the low microgram concentration range 1.03 &mu;g mL^-1 and 1.53 &mu;g mL^-1, respectively. For the improvement of the sensitivity for AZI the DPV method was tested in combination with a&nbsp; CPE working electrode surface modified with gold nanoparticles with diameter of 10 nm (Au-CPE) and reached the limit of detection was 0.95 &mu;g mL^-1 at E_p of 0.80 V vs. SCE. The RSD of the method in the case of the Au-CPE is 3.5% while in the case of the native CPE 6.0%. The linearity of the Au-CPE based analytical method is twice wider then it is case with the bare CPE applying protocol.</p><p>Based on the obtained results it can be conclude that the appropriate combination of the optimized voltammetric pulse techniques and the environmentally friendly and easy to use working electrodes as Hg(Ag)FE, BiF-GCE and CPE together with Au-CPE resulted in the development of reliable analytical method either in the oxidation or reduction studies, often allowing trace level determination of pharmacological importance target analytes in simpler and in some case complexes systems.</p>

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