Electrogenerated chemiluminescence: from mechanistic insights to bioanalytical applications

U okviru ove doktorske disertacije ispitana je elektrogenerisana hemiluminiscencija (eng.Electrogenerated chemiluminiscence - ECL) kao i razvoj novih ECL sistema za bioanalitičkuprimenu. ECL je metoda u kojoj se analitički signal u vidu luminiscentnog zračenja, dobijaputem elektrohemijske reakcije indukovane na površini elektorde. ECL omogućava veomapreciznu detekciju u subpikomolarnim opsegu koncentracija sa gotovo nultim pozadinskimsignalom. Direktno optičko očitavanje može se izvršiti veoma jednostavno pomoćufotomultiplikatorskih cevi (eng. photomultiplier tube - PMT) ili jeftinih CCD (eng. chargecoupled device - CCD) kamera. Zbog toga se ECL može lako kombinovati sa drugimtehnologijama kao što su mikrofluidni sistemi i kapilarna elektroforeza u cilju dobijanjakompletnog sistema za detekciju. ECL detekcija se široko koristi u komercijalizovanimsistemima. Ova teza ima za cilj proučavanje osnovnih ECL procesa kao i razvoj inovativnihECL sistema za bioanalitičku primenu.Prvo poglavlje je posvećeno opštim principima ECL–a. Dva različita mehanizma za generisanjeECL-a (anihilacija i ECL pomoću koreaktanata (eng. co-reactant)) su objašnjeni do detalja.Najčešće korišćene ECL luminofore, bazirane na kompleksima rutenijuma, kao i sve vrstekorektanata, su takođe opisane. Na kraju, glavne primene elektrohemijske luminiscencije suukratko prikazane.U drugom poglavlju, proučavani su ECL mehanizmi zastupljeni u imunotestovima u kojima suplatforme za ECL detekciju bazirane na česticama mikrometarskih dimenzija. Ispitan je učinakrazličitih ECL mehanizama na ukupan intenzitet emitovanog ECL signala.Spektroelektrohemija i ECL snimanje su kombinovani za posmatranje generisanja ECL nanivou jedne mikrosfere, funkcionalizovane kompleksom rutenijuma sa dva koreaktanta,pomoću prostornog mapiranja ECL reaktivnosti. Ovaj novi pristup snimanja ECL signala pružauvid u ECL mehanističke rute koji omogućavaju izuzetno visoku osetljivost komercializovanimbiotestovima baziranim na korisćenju mikrosfera/mikroperli.Treće poglavlje govori o elektrohemijskim osobinama nanoelektroda (eng. nanoelectrodeensembles - NEEs), i najnovijem napretku na polju njihove pirmene u bioelektroanalitičkojhemiji. Elektrohemijske osobine koje čine NEEs veoma korisnim u razvoju hemijskih...Electrogenerated chemiluminiscence (ECL) is a process which emits luminiscent signals byconverting electrochemical energy into radiative energy. It offers very sensitive detection ofsub-picomolar concentrations with an extremely large dynamic range, greater than six ordersof magnitude and almost zero background signal. The direct optical readout can be performedjust with a photomultiplier tube (PMT) or inexpensive CCD cameras and therefore, easilycombined with other technologies such as microfluidics and capillary electrophoresis to obtaincomplete detection systems. ECL detection is widely used in commercialized systems with anincreasing trend. The present thesis is aimed at studying the fundamental ECL process and atdeveloping new ECL systems for original bioanalytical applications.Chapter one is dedicated to the general principles of ECL. Two different pathways to generateECL, annihilation and co-reactant ECL, are explained in details. The most used ECLluminophores, based on ruthenium complexes, and co-reactants are also presented. In the lastpart of this chapter, the principal applications of ECL are briefly described.In the second chapter, the study of ECL mechanisms used in bead-based immunoassays andtheir influence on ECL emission were investigated. Spectroelectrochemistry and ECL imagingwas combined to observe the ECL generation from a single micro-bead, functionalized withruthenium complex with two efficient co-reactants, by mapping the ECL reactivity in space.This new imaging approach provides insights into the ECL mechanistic route operating in sucha commercialized bead-based bioassays and its extremely high sensitivity.Chapter 3 addresses the electrochemical properties of nanoelectrode ensembles and arrays(NEEs) with recent advances in bioelectroanalytical applications. The electrochemicalcharacteristic that makes the NEEs very useful in the development of chemical nanosensors isthe dramatic lowering of capacitive currents (that are the largest component of the noise, ormore properly the background signal of voltammetric measurements) allowing very sensitivedetection of analytes of interest. Exploiting both gold NEEs as a sensor platform and generationof ECL at low oxidation potentials, a new sensitive and specific ECL immunosensor fordiagnosis of celiac disease (CD) will be presented.In the last chapter, principles of bipolar electrochemistry (BE) will be presented. This concepthas been recently used to control the motion of autonomous microswimmers, breaking thesymmetry on the surface of this conductive objects in a wireless manner. The strategy to triggerthe motion relies on the generation and release of bubbles and was used for translation, rotationand levitation and it will be described in details. We will present the integration of ECL light..

Innovative aproach for wireless electrochemical remediation of cyanotoxins based on bipolar electrochemistry

Bipolar electrochemistry (BPE) is an unconventional method to address conducting and semiconducting particles in a wireless manner. Unique features of BPE when compared to conventional electrochemical setup where electrochemical reactions take place at the surface of two different electrodes both connected to a potentiostat, allow us to address bipolar electrode electrochemically in a wireless fashion because there is no direct connection with the power supply (see Figure 1.). Herein, we used the concept of BPE as a straightforward way for the site selective deposition of materials on bipolar electrodes. Furthermore, we use these materials for the electrochemical remediation of cyanotoxins, a potential global health problem, exploiting the versatility of bipolar electrochemistry. Due to the high toxicity of cyanotoxins, highly efficient remediation methods have been under development in recent years, with advanced oxidation processes focused on mineralization as major target. Electrochemical remediation arose as an interesting alternative with few reported protocols to date

Evaluation of commercial bottled water quality from the health aspect

The term bottled water means water packed in a health-correct packaging and available in the market for human consumption. Consumers still have insufficient knowledge of importance of the certain ingredients and their harmful or beneficial effect on the human organism. There is not enough expert information about the harmfulness of certain ingredients in the water, but many countries in the world have adopted legal regulations in which quality parameters of bottled water are standardized (EEC, WHO1, EPA, IBWA, FDA). The race for profit and the lack of necessary quantities of bottled waters moved declarations in to the second plan. The declaration on bottled waters should describe also the physiological characteristics, since the consumption of high-mineral water may lead to adverse effects on the health of consumers, primarily children. In such declared water, missing physiological characteristics of water, redox statuses, and possible consequences on the health, are neglected due to excessive consumption of waters with high mineral content. Due to the increased content of mineral substances and high sodium intake, the allowed daily intake should be declared for water loaded with mineral substances. Redox status of water represents a health factor and it is completely defined by the pH value, redox potential and rH2 factor, parameters which were the subject of this study in this work. The oxide-reduction potential of water, EROX, represents the mixed potential of all present redox pairs and directly affects the behavior of water relative to the agents to which comes into contact2. The results pointed to the necessity of a fuller declaration of bottled water, because in that case bottled water gained in importance and would decrease the consequences of the possible bad effects on health due to excessive consumption of water rich with minerals. Test results demonstrated that our market has a wide range of bottled waters, and that the health aspect can be estimated through the oxidation-reduction properties

Hidrogeohemijska istraživanja u jugoistočnom Banatu na teritoriji Republike Srbije

In the research phase of the geological status of the area of southeastern Banat, samples were collected from surface waters, wells, and lakes. The content of U, Ra, Rn is determined in water. The sampling network was adjusted to the hydrographic characteristics of the terrain, and a hydrogeochemical map has been made at a scale of 1:50 000. In addition to hydrogeochemical prospecting, samples of the soil river sediments were taken to determine the profile of the coast of the following lakes: Vračarevo, Šaransko, Bagersko and Veliko lake. The regional hydrogeochemical prospecting included the area of the Bela Crkva, which drained the sediments of Negotin and Kvartara. In this area and wider, in accordance with the results of regional investigation, semi-geological and semi-geochemical research was carried out to identify resources of mineral deposits as well as the sources for water supply of rural settlements. During research, samples of water from surface streams, sources, wells, lakes, water reservoirs, creek sediments and wall samples were collected and examined.U fazi istraživanja geološkog statusa područja jugoistočnog Banata, prikupljeni su uzorci sa površinskih akvatorija, bunara i jezera. U vodi je determinisan sadržaj U, Ra, Rn. Mreža uzorkovanja je prilagođena hidrografskim karakteristikama terena, i napravljena je hidrogeohemijska mapa 1:50 000. Pored hidrogeohemijske prospekcije, uzeti su uzorci rečnih sedimenata zemljišta kako bi se odredio profil obale sledećih jezera: Vračarevo, Šaransko, Bagersko i Veliko jezero. Regionalna hidrogeohemijska prospekcija obuhvatila je područje Bele Crkve, koje dreniraju sedimente Neogena i Kvartara. U ovom području i šire, u skladu sa rezultatima regionalnih ispitivanja, obavljena su i poludetaljna geološka-geohemijska istraživanja u cilju identifikacije ležišta mineralnih sirovina, kao i izvorišta za vodosnabdevanje ruralnih naselja. U toku prospekcije, prikupljeni i ispitani su uzorci voda iz površinskih tokova, izvora, bunara, jezera, vodenih akumulacija, potočnih sedimenata i uzorci stena

Mikrobne gorive ćelije: održiva tehnologija za proizvodnju energije i prečišćavanje otpadnih voda

Energy is the main driver of economic growth and it is of vital significance for the modern socieity survival. Future economic growth is dependent of the long-term availability of energy from the sustainable and ecologicaly accepted sources. Microbial fuel cell (MFC) is a new approach to the wastewater treatment with the simulntanious energy production. MFC is an electrochemical device that uses bacteria to generate electricity from biodegradation of organic substrates. Bacteria obtain the energy required for metabolism by electron transfer from an electron donor, such as glucose or acetate, to an electron acceptor, such as oxygen. The application of a microbial fuel cell for the treatment of wastewater has many advantages: the process is clean, safe noise-free, the emissions are low, and the efficiency is high with direct energy production. The subject of this review paper is a detailed development of microbial fuel cells, working principle, types of used microorganisms, as well as potential application.Energija je osnovni pokretat ekonomskog rasta i od vitalnog je značaja za opstanak modernog društva. Budući ekonomski rast zavisi od dugoročne dostupnosti energije iz izvora koji su pristupatni i ekološki prihvatljivi. Mikrobne gorivne ćelije (MFC - microbial fuel cell) mogu predstavljati potpuno novi pristup u prečišćavanju otpadnih voda uz proizvodnju održive čiste energije. MFC je elektrohemijski uredaj koji koristi bakterije za proizvodnju električne energije iz biorazgradljivih organskih supstrata. Bakterije dobijaju energiju potrebnu za metabolizam prenosorn elektrona sa donora elektrona, kao što su glukoza ili acetat, do akceptor elektrona, kao što je kiseonik. Prednosti korišćenja mikrobne gorinve ćelije u prečišćavanju otpadnih voda su sledeće: čist postupak, bezbedan i bez buke, niske emisije i visoka efikasnost uz direktnu proizvodnju energije. Predmet ovog rada je detaljni pristup u pregledu mikrobnih gorivnih ćelija, principa rada, vrste mikroorganizama kao i njihova potencijalna primena

Applied geochemistry in spatial planning of the vranje region, (Southern) Serbia

In terms of development of agriculture, industry and tourism, in the spatial planning the level of exploration of mineral resources and environmental protection in rural areas is of great importance. The area of Vranje tertiary basin, located in the western part of the Serbian-Macedonian massif was selected. It spreads on both sides of the South Morava river, from Vladicin Han at the North, via Vranje and Ristovac to Bujanovac at the South. The total length of the basin is about 30 km and the width varies from 10 to 17 km. The area located west of the Vranje basin belongs to the granodiorite massif of Bujanovac and on the east to grandiorite and quartz diorite massif of Surdulica, in which the wolfram ore, occurrences and deposits of lead zinc, copper, iron, phosphorites and in the basin radioactive anomalies are registered. Geological and structural characteristics of the terrain are of the important for the planning of industrial facilities, further geochemical composition is essential for the planning and agriculture development. For the tourism development, from the point of use for therapeutic purposes, balneological characteristics of the hot water are of the important. The research results will be presented on geochemical maps, tables and charts, with special emphasis on Vranjska spa and its importance in the development of health tourism in the region

Evaluation of bottled water quality from the market of the republic of serbia

The term bottled water applies for water packaged in a health-correct packaging available in the market for human consumption. Consumers still have insufficient knowledge of the importance of certain water ingredients and their harmful or beneficial effect on the human organism. There is not enough expert information about the harmfulness of certain ingredients in the water, even if many countries of the world have adopted legal acts in which quality parameters of bottled water are standardized1. In such declared water, physiological characteristics of water, redox status and the consequences of bad health effects are neglected due to excessive consumption of waters with high mineral content. Due to the increased content of mineral substances and high sodium intake, the allowed daily intake should be declared for water loaded with mineral substances. The oxide-reduction potential of water, EROX, represents the mixed potential of all present redox pairs and directly affects the behavior of water relative to the agents with it comes into contact. In this research, we measured all parameters that define redox status: pH value, redox potential and rH2 factor in a wide range of bottled waters available on the market of the Republic of Serbia. The substances that are declared as potentially toxics2 were detected by HPLC-MS/MS. The results pointed to the necessity of a detailed declaration of bottled water to decrease the possible consequences of bad effects on health due to excessive consumption of water rich with minerals

Hidrogeohemijska istraživanja u jugoistočnom Banatu na teritoriji Republike Srbije

In the research phase of the geological status of the area of southeastern Banat, samples were collected from surface waters, wells, and lakes. The content of U, Ra, Rn is determined in water. The sampling network was adjusted to the hydrographic characteristics of the terrain, and a hydrogeochemical map has been made at a scale of 1:50 000. In addition to hydrogeochemical prospecting, samples of the soil river sediments were taken to determine the profile of the coast of the following lakes: Vračarevo, Šaransko, Bagersko and Veliko lake. The regional hydrogeochemical prospecting included the area of the Bela Crkva, which drained the sediments of Negotin and Kvartara. In this area and wider, in accordance with the results of regional investigation, semi-geological and semi-geochemical research was carried out to identify resources of mineral deposits as well as the sources for water supply of rural settlements. During research, samples of water from surface streams, sources, wells, lakes, water reservoirs, creek sediments and wall samples were collected and examined.U fazi istraživanja geološkog statusa područja jugoistočnog Banata, prikupljeni su uzorci sa površinskih akvatorija, bunara i jezera. U vodi je determinisan sadržaj U, Ra, Rn. Mreža uzorkovanja je prilagođena hidrografskim karakteristikama terena, i napravljena je hidrogeohemijska mapa 1:50 000. Pored hidrogeohemijske prospekcije, uzeti su uzorci rečnih sedimenata zemljišta kako bi se odredio profil obale sledećih jezera: Vračarevo, Šaransko, Bagersko i Veliko jezero. Regionalna hidrogeohemijska prospekcija obuhvatila je područje Bele Crkve, koje dreniraju sedimente Neogena i Kvartara. U ovom području i šire, u skladu sa rezultatima regionalnih ispitivanja, obavljena su i poludetaljna geološka-geohemijska istraživanja u cilju identifikacije ležišta mineralnih sirovina, kao i izvorišta za vodosnabdevanje ruralnih naselja. U toku prospekcije, prikupljeni i ispitani su uzorci voda iz površinskih tokova, izvora, bunara, jezera, vodenih akumulacija, potočnih sedimenata i uzorci stena

The influence of water and packaging quality on bottled water health safety

The term bottled water refers to the water that is packaged in a health-correct packaging and that is available on the market for human consumption. Consumers still have insufficient knowledge of the importance of certain ingredients and their harmful or beneficial effects on the human body. Nowdays there are many legal acts in the world that regulate the quality of bottled water. In order to assess the impact of packaging quality on the quality of bottled water, it is necessary to look at the regulation, both in the field of water and in the field of packaging polymer. The information provided on the declaration is insufficient to see the quality of the bottled water itself, and there is no indication of the potential toxic elements that can migrate from the packaging into the water. Although PET is considered as inert material according certain components that are added to PET production can migrate in the water, that must be regurarly controlled. Declarations of such products must follow the updating and monitoring of potentially toxic parameters in accordance with European and world regulations. The impact of packaging, transport and storage on the change of bottled water quality from the aspect of potentially toxic substances has been shown in many studies in the world, however, studies of this type are rare in our country.Pod pojmom flaširane vode podrazumeva se voda koja se pakuje u zdravstveno ispravnu ambalažu i koja je na tržištu dostupna za ljudsku upotrebu. Kod potrošača postoji još uvek nedovoljna upućenost u značaj pojedinih sastojaka i njihovo štetno ili korisno dejstvo na ljudski organizam a u svetu postoji mnogo zakonskih akata u kojima su normirani parametri kvaliteta flaširane vode. Da bi se ocenio uticaj kvaliteta ambalaže na kvalitet flaširane vode neophodno je istovremeno sagledati regulativu iz obe oblasti. Podaci koji se navode na deklaraciji nedovoljni su za sagledavanje kvaliteta same vode koja se flašira, a nema ni ukazatelja na potencijalno toksične elemente koji mogu migrirati iz ambalaže u vodu. Iako se voda pakuje u PET koji se smatra inertnim materijalom, određene komponente koje se dodaju pri proizvodnji PET materijala mogu da migriraju u vodu koja se prema tome mora redovno kontrolsati. Deklarisanje ovakvih proizvoda mora pratiti ažuriranje i praćenje potencijalno toksičnih parametara u skladu sa evropskom i svetskom regulativom. Uticaj ambalažiranja, transporta i skladištenja na promenu kvaliteta flaširanih voda sa aspekta potencijalno toksičnih supstanci, do sada je već pokazan u mnogim studijama u svetu, ali su retke studije iz ove oblasti u našoj zemlji

Innovative approach for wireless electrochemical remediation of cyanotoxins based on bipolar electrochemistry

Bipolar electrochemistry (BPE) is an unconventional method to address conducting and semiconducting particles in a wireless manner1. Unique features of BPE when compared to conventional electrochemical setup where electrochemical reactions take place at the surface of two different electrodes both connected to a potentiostat, allow us to address bipolar electrode electrochemically in a wireless fashion because there is no direct connection with the power supply (see Figure 1.). Herein, we used the concept of BPE for the electrochemical remediation of cyanotoxins following the formed products by HPLC-MS/MS. Due to the high toxicity of cyanotoxins presenting potential global health problem, highly efficient remediation methods have been under development in recent years, with advanced oxidation processes focused on mineralization as major target. Electrochemical remediation arose as an interesting alternative with few reported protocols to date