Electron transfer processes in biomimetic membranes incorporating prenylquinones
The photosynthesis is the process used by the plants and bacteria cells to convert the inorganic matter in organic thanks to the light energy. This process consist on several steps, being one of them the plastoquinone-9 (PQ) electronic transport from the Photosystem II to the cytochrome. In this Ph....
| Autor: | |
|---|---|
| Formato: | tesis doctoral |
| Estado: | Versión publicada |
| Fecha de publicación: | 2014 |
| País: | España |
| Recursos: | CBUC, CESCA |
| Repositorio: | TDR. Tesis Doctorales en Red |
| OAI Identifier: | oai:www.tdx.cat:10803/285294 |
| Acesso em linha: | http://hdl.handle.net/10803/285294 https://dx.doi.org/10.5821/dissertation-2117-95597 |
| Access Level: | acceso abierto |
| Palavra-chave: | 537 54 66 |
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Electron transfer processes in biomimetic membranes incorporating prenylquinones |
| title |
Electron transfer processes in biomimetic membranes incorporating prenylquinones |
| spellingShingle |
Electron transfer processes in biomimetic membranes incorporating prenylquinones Hoyo Pérez, Javier 537 54 66 |
| title_short |
Electron transfer processes in biomimetic membranes incorporating prenylquinones |
| title_full |
Electron transfer processes in biomimetic membranes incorporating prenylquinones |
| title_fullStr |
Electron transfer processes in biomimetic membranes incorporating prenylquinones |
| title_full_unstemmed |
Electron transfer processes in biomimetic membranes incorporating prenylquinones |
| title_sort |
Electron transfer processes in biomimetic membranes incorporating prenylquinones |
| dc.creator.none.fl_str_mv |
Hoyo Pérez, Javier |
| author |
Hoyo Pérez, Javier |
| author_facet |
Hoyo Pérez, Javier |
| author_role |
author |
| dc.contributor.none.fl_str_mv |
Torrent Burgués, Joan Guaus Guerrero, Esther Universitat Politècnica de Catalunya. Departament d'Enginyeria Química |
| dc.subject.none.fl_str_mv |
537 54 66 |
| topic |
537 54 66 |
| description |
The photosynthesis is the process used by the plants and bacteria cells to convert the inorganic matter in organic thanks to the light energy. This process consist on several steps, being one of them the plastoquinone-9 (PQ) electronic transport from the Photosystem II to the cytochrome. In this Ph. D. Thesis we prepare membranes that mimic the characteristics of the natural cell membranes and we characterize them using several techniques in order to obtain the PQ molecules position in the membranes and to study its electrochemical behaviour. These membranes are prepared using several lipids and their mixtures with PQ and ubiquinone-10 (UQ). Both the pure components and the lipid:quinone mixtures have been studied using surface pressure-area per molecule isotherms. These isotherms give information about the film stability (Langmuir film) at the air/water interface and the mathematical treatment of their results indicates the thermodynamic behaviour of the mixture and their physical state. Moreover, the Brewster Angle Microscopy technique has been used to study in situ the possibility of microscopic aggregation. On the other hand, the Langmuir-Blodgett (LB) film has been transferred onto mica forming a monolayer that mimics the bottom layer of the biological membranes. This monolayer has been topographically characterized using AFM and both the height and the physical state that they present have been obtained. In addition, these monolayers have been transferred onto ITO that is a hydrophilic substrate with good optical and electrical features, so that, being a good candidate for studying the electrochemical behaviour of these systems. On the other hand, the DPPC:UQ system has been also studied preparing SPBs using liposomes. These SPBs have been characterized using force spectroscopy and the other techniques that have been pointed previously and are suitable to working with SPBs. The obtained results for the pure quinones indicate that they form Langmuir monolayers in the liquid expanded (LE) state at surface pressures below the collapse. The cyclic voltammograms (CV) of the LB films transferred on ITO shows one (process I) or two processes (process I and II), depending on the surface pressure at which the monolayer has been transferred. The processes present the same formal potentials for both quinones at biological pH. On the other hand, the pure lipids, in general, form more compact states than the corresponding lipid:quinone mixture. The galactolipid:quinone systems indicate that, at low surface pressures, non-ideal mixtures are obtained being favoured the interactions between molecules of the same kind. Increasing the surface pressure, the system changes from LE to liquid-condensed (LC), which implies the quinone rejection from the lipids head zone. The electrochemical results indicate that this rejection can be vertically or horizontally. Vertically, achieving a position above the lipid head region but still in the lipid matrix, or out of the lipìd matrix, placed parallel to the matrix over it. The horizontal rejection (from the LC zones) implies that the quinone molecules are placed in the LE zones enriching them and forming pools of quinone. The positions described for the quinone in a lipid: quinone system can be classified in "diving", with the quinone molecules in the matrix with or without ITO-quinone contact, and "swimming", which is correlated with the quinones placed over the matrix. The "diving" and "swimming" positions induce different redox processes and the charge involved at each process indicates which position is predominant. Both redox processes are irreversible due to the slow charge transfer rate at the ITO-monolayer/electrolyte interface. Moreover, this electron transfer is produced by direct transfer or electron hopping. |
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2014 |
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2014 2015 2016 |
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info:eu-repo/semantics/doctoralThesis info:eu-repo/semantics/publishedVersion |
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doctoralThesis |
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publishedVersion |
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http://hdl.handle.net/10803/285294 https://dx.doi.org/10.5821/dissertation-2117-95597 |
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http://hdl.handle.net/10803/285294 https://dx.doi.org/10.5821/dissertation-2117-95597 |
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Inglés |
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Inglés |
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http://creativecommons.org/licenses/by-nc/3.0/es/ info:eu-repo/semantics/openAccess |
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http://creativecommons.org/licenses/by-nc/3.0/es/ |
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openAccess |
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382 p. application/pdf application/pdf |
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Universitat Politècnica de Catalunya |
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Universitat Politècnica de Catalunya |
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TDX (Tesis Doctorals en Xarxa) reponame:TDR. Tesis Doctorales en Red instname:CBUC, CESCA |
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CBUC, CESCA |
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TDR. Tesis Doctorales en Red |
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1869421975803265024 |
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Electron transfer processes in biomimetic membranes incorporating prenylquinonesHoyo Pérez, Javier5375466The photosynthesis is the process used by the plants and bacteria cells to convert the inorganic matter in organic thanks to the light energy. This process consist on several steps, being one of them the plastoquinone-9 (PQ) electronic transport from the Photosystem II to the cytochrome. In this Ph. D. Thesis we prepare membranes that mimic the characteristics of the natural cell membranes and we characterize them using several techniques in order to obtain the PQ molecules position in the membranes and to study its electrochemical behaviour. These membranes are prepared using several lipids and their mixtures with PQ and ubiquinone-10 (UQ). Both the pure components and the lipid:quinone mixtures have been studied using surface pressure-area per molecule isotherms. These isotherms give information about the film stability (Langmuir film) at the air/water interface and the mathematical treatment of their results indicates the thermodynamic behaviour of the mixture and their physical state. Moreover, the Brewster Angle Microscopy technique has been used to study in situ the possibility of microscopic aggregation. On the other hand, the Langmuir-Blodgett (LB) film has been transferred onto mica forming a monolayer that mimics the bottom layer of the biological membranes. This monolayer has been topographically characterized using AFM and both the height and the physical state that they present have been obtained. In addition, these monolayers have been transferred onto ITO that is a hydrophilic substrate with good optical and electrical features, so that, being a good candidate for studying the electrochemical behaviour of these systems. On the other hand, the DPPC:UQ system has been also studied preparing SPBs using liposomes. These SPBs have been characterized using force spectroscopy and the other techniques that have been pointed previously and are suitable to working with SPBs. The obtained results for the pure quinones indicate that they form Langmuir monolayers in the liquid expanded (LE) state at surface pressures below the collapse. The cyclic voltammograms (CV) of the LB films transferred on ITO shows one (process I) or two processes (process I and II), depending on the surface pressure at which the monolayer has been transferred. The processes present the same formal potentials for both quinones at biological pH. On the other hand, the pure lipids, in general, form more compact states than the corresponding lipid:quinone mixture. The galactolipid:quinone systems indicate that, at low surface pressures, non-ideal mixtures are obtained being favoured the interactions between molecules of the same kind. Increasing the surface pressure, the system changes from LE to liquid-condensed (LC), which implies the quinone rejection from the lipids head zone. The electrochemical results indicate that this rejection can be vertically or horizontally. Vertically, achieving a position above the lipid head region but still in the lipid matrix, or out of the lipìd matrix, placed parallel to the matrix over it. The horizontal rejection (from the LC zones) implies that the quinone molecules are placed in the LE zones enriching them and forming pools of quinone. The positions described for the quinone in a lipid: quinone system can be classified in "diving", with the quinone molecules in the matrix with or without ITO-quinone contact, and "swimming", which is correlated with the quinones placed over the matrix. The "diving" and "swimming" positions induce different redox processes and the charge involved at each process indicates which position is predominant. Both redox processes are irreversible due to the slow charge transfer rate at the ITO-monolayer/electrolyte interface. Moreover, this electron transfer is produced by direct transfer or electron hopping.La fotosíntesi és el procés mitjançant el qual les cèl·lules de les plantes i bactèries converteixen la matèria inorgànica en orgànica gràcies a la llum. Aquest procés consta de diferents etapes i una d'elles és el transport electrònic per part de la plastoquinona-9 (PQ) des del Fotosistema II fins al citocrom. En aquesta tesi preparem membranes que emulen les característiques de les membranes de les cèl·lules naturals i les caracteritzem amb diverses tècniques per tal d'obtenir la posició de les molècules de PQ en la membrana i estudiar el seu comportament electroquímic. Aquestes membranes es preparen utilitzant diferents lípids i les seves mescles amb PQ i ubiquinona-10 (UQ). Tant els components purs com les mescles s'han estudiat fent servir isotermes pressió superficial-àrea per molècula, ja que dóna informació de l'estabilitat de la pel·lícula de molècules (pel·lícula Langmuir) a la interfase aire|aigua. El tractament matemàtic dels resultats d'aquestes isotermes permet obtenir el comportament termodinàmic de la mescla i el seu estat físic. A més, s'han estudiat els sistemes in situ fent servir la tècnica de Brewster Angle Microscopy per observar la possibilitat de segregació microscòpica. Per altra banda, la pel·lícula Langmuir-Blodgett (LB) ha estat transferida sobre mica formant una monocapa que simula la capa inferior de les membranes naturals. Aquesta capa s'ha caracteritzat topogràficament utilitzant AFM, s'ha mesurat l'alçada i s'ha estudiat l'estat físic que presenta. A més, aquestes pel·lícules s'han transferit sobre ITO que és un substrat hidrofílic que té unes bones característiques òptiques i elèctriques i per tant permet obtenir el comportament electroquímic d'aquests sistemes. En afegit, el sistema DPPC:UQ s'ha estudiat preparant SPBs utilitzant liposomes. Aquestes SPBs s'han caracteritzat per espectroscòpia de força, a més de les tècniques prèviament exposades que li són aplicables. Els resultats obtinguts per les quinones pures indiquen que formen monocapes de Langmuir en fase líquid expandit (LE) a pressions superficials inferiors al col·lapse. L'estudi per voltametria cíclica (CV) de LB de quinones transferides sobre ITO mostra, en funció de la pressió superficial de transferència, un (I) o dos processos redox (processos I i II) amb els mateixos potencials formals per les dues quinones a pH biològic. Per altra banda, els lípids purs, en general, formen fases més compactes que els sistemes galactolípid:quinona. Els sistemes galactolípid:quinona indiquen que, a pressions baixes, es formen mescles no ideals, on estan afavorides les interaccions entre molècules iguals. A l'augmentar la pressió, el sistema pateix una transició de fase de LE a líquid compacte (LC) que provoca l'expulsió de la quinona de la zona dels caps dels lípids. L'estudi per CV indica que aquesta expulsió pot ser vertical o horitzontal. Vertical, posicionant-se la quinona per sobre dels caps dels lípids, però encara dintre de la matriu lipídica, o fora de la matriu, posicionant-se perpendicularment a les cadenes lipídiques. L'expulsió horitzontal (de les zones LC) implica que la quinona va a parar a les zones LE, enriquint aquestes en quinona i formant-se "pools" de quinona. Les posicions descrites per la quinona en un sistema lípid:quinona es poden classificar en "diving" amb les quinones dintre de la matriu, ja sigui amb o sense contacte ITO-quinona, i la "swimming", que són quinones que estan a sobre de la matriu. Les posicions "diving" and "swimming" donen lloc a processos redox diferents i la càrrega que presenta cada procés, permet saber quina posició és dominant. Els dos processos redox són irreversibles donada la lenta transferència de càrrega en les interfases ITO-monocapa/electrolit. A més, aquest intercanvi d'electrons té lloc per transferència directa o per electron hopping.DOCTORAT EN ENGINYERIA DE PROCESSOS QUÍMICS (Pla 2007)Universitat Politècnica de CatalunyaTorrent Burgués, JoanGuaus Guerrero, EstherUniversitat Politècnica de Catalunya. Departament d'Enginyeria Química201520162014info:eu-repo/semantics/doctoralThesisinfo:eu-repo/semantics/publishedVersion382 p.application/pdfapplication/pdfhttp://hdl.handle.net/10803/285294https://dx.doi.org/10.5821/dissertation-2117-95597TDX (Tesis Doctorals en Xarxa)reponame:TDR. Tesis Doctorales en Redinstname:CBUC, CESCAInglésL'accés als continguts d'aquesta tesi queda condicionat a l'acceptació de les condicions d'ús establertes per la següent llicència Creative Commons: http://creativecommons.org/licenses/by-nc/3.0/es/http://creativecommons.org/licenses/by-nc/3.0/es/info:eu-repo/semantics/openAccessoai:www.tdx.cat:10803/2852942026-06-14T12:46:07Z |
| score |
15,300719 |