Enzyme-polymer hybrid layers for self-cleaning surfaces

This work focused on the generation and characterization of ultrathin coatings with a self-cleaning ability. The general idea was to immobilize a typical detergent enzyme on model surfaces in a way that retains the activity of the enzyme. The specific system under investigation was a hydrogel coatin...

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Autor principal:	Shah, Urmil
Otros Autores:	Galleano, Mónica
Formato:	Tesis de maestría acceptedVersion
Lenguaje:	Inglés
Publicado:	Facultad de Farmacia y Bioquímica 2015
Materias:	Enzimas Radiación UV Polietilenglicol Hidrogel Autolimpieza Enzyme UV Radiation Hydrogel Self-cleaning surfaces Ciencia de la vida
Acceso en línea:	http://repositoriouba.sisbi.uba.ar/gsdl/cgi-bin/library.cgi?a=d&c=afamaster&cl=CL1&d=HWA_831 http://repositoriouba.sisbi.uba.ar/gsdl/collect/afamaster/index/assoc/HWA_831.dir/831.PDF
Aporte de:	Repositorio Digital de la Universidad de Buenos Aires (UBA) de Universidad de Buenos Aires

id	I28-R145-HWA_831
record_format	dspace
institution	Universidad de Buenos Aires
institution_str	I-28
repository_str	R-145
collection	Repositorio Digital de la Universidad de Buenos Aires (UBA)
language	Inglés
orig_language_str_mv	eng
topic	Enzimas Radiación UV Polietilenglicol Hidrogel Autolimpieza Enzyme UV Radiation Hydrogel Self-cleaning surfaces Ciencia de la vida
spellingShingle	Enzimas Radiación UV Polietilenglicol Hidrogel Autolimpieza Enzyme UV Radiation Hydrogel Self-cleaning surfaces Ciencia de la vida Shah, Urmil Enzyme-polymer hybrid layers for self-cleaning surfaces
topic_facet	Enzimas Radiación UV Polietilenglicol Hidrogel Autolimpieza Enzyme UV Radiation Hydrogel Self-cleaning surfaces Ciencia de la vida
description	This work focused on the generation and characterization of ultrathin coatings with a self-cleaning ability. The general idea was to immobilize a typical detergent enzyme on model surfaces in a way that retains the activity of the enzyme. The specific system under investigation was a hydrogel coating which was chemically anchored on the surface and which also served as a carrier for the enzyme. The hydrogel coating was prepared from water-soluble polymers that carry a small percentage of photo-reactivegroups suitable for reaction with neighbouring chains in a way that leads to crosslinking. Similar groups on the surface provide a surface anchoring of the layers by theestablishment of covalent bonds between the two components. Amylase was chosen as the enzyme because it is readily available and it cleaves carbohydrates which are typically present in many surface stains. The resulting molecules are smaller and typicallymore soluble in water such that a stain containing such components is more easily rinsed off the surface.\nThis enzyme was to be incorporated into the hydrogel carrier coating by means of co-deposition via dip coating. Thesubsequent UV crosslinking whichlead to a surface anchoring not only of the film but also of the enzyme by means of either physical entrapment or chemical anchoring through the surface reaction.\nPrevious finding suggested an insufficient anchoring of enzymes via this route as the enzyme needs to be deposited from buffer solutions which contain high amounts of salt. This is also deposited and keeps much of the enzyme from being incorporated into the hydrogel coating. For this reason the enzyme was modified with another hydrophilic polymer, Polyethylene glycol chains were chemically attached to the amylase via an active ester. Using this procedure the amylase was rendered soluble in ethanol without losing anyactivity and overall increased in enzymatic activity as compared to the native enzyme.\nAn investigation of the coating procedure by various techniques revealed indeed that the route via PEGylated amylase and deposition from ethanol in the absence of any salt yielded much smoother layers in which the enzyme was rather homogenously distributed. Control coatings generated from native amylase and deposited from PBS buffer gave very rough coatings that were covered with salt crystals.\nA comparison of the enzymatic activity via colorimetric measurements first demonstrated that enzymaticallycoatings could be generated via both routes. The coatings prepared from PEG-conjugated amylase however were always more active than those prepared from native amylase and they also retained this active character better if exposed to UV light or heat.\nA simple self-cleaning test also showed that coatings prepared from native amylase lost their initially good self-cleaning character after a first rinse. Repeated use of such samples was not possible. The coatings carrying PEGylated enzyme also lost much of their initial activity after the first test but repeated use was possible and clear degradation of starch in a test involving mayonnaise was clearly visible.\nThe general concept of enzyme carrying coatings based on surface-attached hydrogels was successfully demonstrated. Further investigations should concentrate on the analysis of the influence of the deposition conditions on the enzyme activity. Such investigations should include a more thorough characterization of the resulting layers. Such research may eventually lead to self-cleaning surfaces that are stable on a time scale which is suitable at least for delicate applications e.g. in a biomedical environment.\n
author2	Galleano, Mónica
author_facet	Galleano, Mónica Shah, Urmil
format	Tesis de maestría Tesis de maestría acceptedVersion
author	Shah, Urmil
author_sort	Shah, Urmil
title	Enzyme-polymer hybrid layers for self-cleaning surfaces
title_short	Enzyme-polymer hybrid layers for self-cleaning surfaces
title_full	Enzyme-polymer hybrid layers for self-cleaning surfaces
title_fullStr	Enzyme-polymer hybrid layers for self-cleaning surfaces
title_full_unstemmed	Enzyme-polymer hybrid layers for self-cleaning surfaces
title_sort	enzyme-polymer hybrid layers for self-cleaning surfaces
publisher	Facultad de Farmacia y Bioquímica
publishDate	2015
url	http://repositoriouba.sisbi.uba.ar/gsdl/cgi-bin/library.cgi?a=d&c=afamaster&cl=CL1&d=HWA_831 http://repositoriouba.sisbi.uba.ar/gsdl/collect/afamaster/index/assoc/HWA_831.dir/831.PDF
work_keys_str_mv	AT shahurmil enzymepolymerhybridlayersforselfcleaningsurfaces
_version_	1766017575933706240
spelling	I28-R145-HWA_8312019-09-27 This work focused on the generation and characterization of ultrathin coatings with a self-cleaning ability. The general idea was to immobilize a typical detergent enzyme on model surfaces in a way that retains the activity of the enzyme. The specific system under investigation was a hydrogel coating which was chemically anchored on the surface and which also served as a carrier for the enzyme. The hydrogel coating was prepared from water-soluble polymers that carry a small percentage of photo-reactivegroups suitable for reaction with neighbouring chains in a way that leads to crosslinking. Similar groups on the surface provide a surface anchoring of the layers by theestablishment of covalent bonds between the two components. Amylase was chosen as the enzyme because it is readily available and it cleaves carbohydrates which are typically present in many surface stains. The resulting molecules are smaller and typicallymore soluble in water such that a stain containing such components is more easily rinsed off the surface.\nThis enzyme was to be incorporated into the hydrogel carrier coating by means of co-deposition via dip coating. Thesubsequent UV crosslinking whichlead to a surface anchoring not only of the film but also of the enzyme by means of either physical entrapment or chemical anchoring through the surface reaction.\nPrevious finding suggested an insufficient anchoring of enzymes via this route as the enzyme needs to be deposited from buffer solutions which contain high amounts of salt. This is also deposited and keeps much of the enzyme from being incorporated into the hydrogel coating. For this reason the enzyme was modified with another hydrophilic polymer, Polyethylene glycol chains were chemically attached to the amylase via an active ester. Using this procedure the amylase was rendered soluble in ethanol without losing anyactivity and overall increased in enzymatic activity as compared to the native enzyme.\nAn investigation of the coating procedure by various techniques revealed indeed that the route via PEGylated amylase and deposition from ethanol in the absence of any salt yielded much smoother layers in which the enzyme was rather homogenously distributed. Control coatings generated from native amylase and deposited from PBS buffer gave very rough coatings that were covered with salt crystals.\nA comparison of the enzymatic activity via colorimetric measurements first demonstrated that enzymaticallycoatings could be generated via both routes. The coatings prepared from PEG-conjugated amylase however were always more active than those prepared from native amylase and they also retained this active character better if exposed to UV light or heat.\nA simple self-cleaning test also showed that coatings prepared from native amylase lost their initially good self-cleaning character after a first rinse. Repeated use of such samples was not possible. The coatings carrying PEGylated enzyme also lost much of their initial activity after the first test but repeated use was possible and clear degradation of starch in a test involving mayonnaise was clearly visible.\nThe general concept of enzyme carrying coatings based on surface-attached hydrogels was successfully demonstrated. Further investigations should concentrate on the analysis of the influence of the deposition conditions on the enzyme activity. Such investigations should include a more thorough characterization of the resulting layers. Such research may eventually lead to self-cleaning surfaces that are stable on a time scale which is suitable at least for delicate applications e.g. in a biomedical environment.\n Fil: Shah, Urmil. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica; Argentina Galleano, Mónica Facultad de Farmacia y Bioquímica Rühe, Jürgen Shah, Urmil 2015-06-01 Este trabajo se centró en la generación y caracterización de recubrimientos ultrafinos con capacidad autolimpiante. El objetivo general fue inmovilizar una enzima detergente típica en superficies modelo a través de un procedimiento que permitiera conservar la actividad enzimática. El sistema específico bajo investigación fue un recubrimiento de hidrogel capaz de unirse químicamente a la superficie y simultáneamente servir como vehículo para la enzima. El recubrimiento de hidrogel se preparó a partir de polímeros solubles en agua con un pequeño porcentaje de grupos fotorreactivos adecuados para reacciones de entrecruzamiento entre cadenas vecinas. Grupos similares en el recubrimiento proporcionan un anclaje para el establecimiento de enlaces covalentes con la enzima. La enzima amilasa fue elegida por su amplia disponibilidad y su capacidad de degradar hidratos de carbono. Los hidratos de carbono son moléculas típicamente presentes en muchas manchas de superficie y como resultado de la acción de la amilasa se producen moléculas más pequeñas y generalmente más solubles, de manera que una mancha que contiene estos componentes se elimina más fácilmente.\nLa enzima fue incorporada en el recubrimiento de hidrogel por co-deposición mediante inmersión. Posteriormente, a través de la exposición a radiación UV se generó un entrecruzamiento que condujo al anclaje, no solo de la película a la superficie, sino también de la enzima a la película, a través de atrapamiento físico o anclaje químico.\nEstudios previos indicaron un anclaje insuficiente de las enzimas cuando el proceso se realizaba a través de esta técnica de co-deposición con inmersión, dado que la enzima era depositada a partir de soluciones buffer con altas cantidades de sal, que también se depositaba sobre la superficie. Este fenómeno impedía la incorporación de gran parte de la enzima al recubrimiento de hidrogel. Por esta razón la enzima se modificó con otro polímero hidrófilo, el polietilenglicol (PEG). Se unieron químicamente cadenas de PEG a la amilasa a través de un éster activo. Utilizando este procedimiento, la amilasa se solubilizó en etanol sin perder actividad.\nSe investigaron diversas técnicas de recubrimiento y se demostró que la utilización de la amilasa conjugada con PEG y la deposición a partir de etanol en ausencia de cualquier sal produjo recubrimientos con una distribución homogénea de la enzima y de características muy lisas, mientras que los recubrimientos generados con amilasa nativa depositada a partir de solución buffer salina dieron origen a recubrimientos muy ásperos y cubiertos con cristales de sal.\nUn análisis comparativo de la actividad enzimática, a través de mediciones colorimétricas, demostró que los recubrimientos tenían actividad enzimática, cualquiera fuera el procedimiento utilizado para su generación. Los recubrimientos preparados a partir de amilasa conjugada con PEG mostraron siempre mayor actividad que los preparados a partir de amilasa nativa y retuvieron mejor la actividad enzimática después de la exposición a radiación UV o calor.\nA través de una prueba de autolimpieza sencilla se demostró que los recubrimientos preparados a partir de amilasa nativa perdieron su propiedad autolimpiante, inicialmente buena, después de un primer enjuague. El uso repetido de dichos recubrimientos no fue posible. Los recubrimientos producidos con la amilasa conjugada con PEG también perdieron gran parte de su actividad autolimpiante inicial después del primer enjuague, pero fueron reutilizables. Se utilizó un ensayo de degradación del almidón en una muestra de mayonesa para estos estudios.\nEl objetivo general del recubrimiento de hidrogel con enzimas unidas a superficie se cumplió exitosamente en este trabajo. Investigaciones futuras se deberán enfocar en el análisis de la influencia de las condiciones de deposición sobre la actividad de la enzima. Esas investigaciones deberían incluir una caracterización más profunda de la estructura del recubrimiento resultante. Este tipo de investigación podría conducir eventualmente a desarrollar superficies autolimpiantes estables en escalas de tiempo adecuadas para aplicaciones específicas, por ejemplo, en el entorno biomédico. application/pdf Fraga, César Hermida, Laura Mertelsmann, Roland Enzimas Radiación UV Polietilenglicol Hidrogel Autolimpieza Enzyme UV Radiation Hydrogel Self-cleaning surfaces eng Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by-nc-nd/2.5/ar/ Ciencia de la vida Enzyme-polymer hybrid layers for self-cleaning surfaces info:eu-repo/semantics/masterThesis info:ar-repo/semantics/tesis de maestría info:eu-repo/semantics/acceptedVersion http://repositoriouba.sisbi.uba.ar/gsdl/cgi-bin/library.cgi?a=d&c=afamaster&cl=CL1&d=HWA_831 http://repositoriouba.sisbi.uba.ar/gsdl/collect/afamaster/index/assoc/HWA_831.dir/831.PDF

Enzyme-polymer hybrid layers for self-cleaning surfaces

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