Síntesis de nanopartículas anisotrópicas de oro utilizando vesículas liposomales modificadas con quitosano con potencial aplicación biomédica
Archivos
Fecha
2015-09
Autores
Soto Cruz, Jackeline
Título de la revista
ISSN de la revista
Título del volumen
Editor
Universidad Nacional (Costa Rica)
Resumen
Las nanopartículas de oro son una interesante alternativa para ser utilizadas en aplicaciones biomédicas como: terapias fototérmicas sobre células tumorales, liberación controlada de drogas y en el diseño de sensores. Sin embargo en la actualidad los métodos de síntesis utilizan reactivos que causan citoxicidad en las células y las que son sintetizadas con reactivos biocompatibles muestran un bajo rendimiento en la formación de partículas anisotrópicas. En este trabajo se desarrolló un método de síntesis de nanopartículas anisotrópicas de oro, utilizando vesículas a base de L-a-fosfatidilcolina (PC) y mezclas de PC/fosfogliceroles. Las vesículas fueron caracterizadas por medio de potencial Zeta. dispersión de luz dinámica (DLS) y microscopía electrónica de barrido-criogénico (CryoSEM). Las dispersiones mostraron potenciales Zeta negativos y tamaños de partícula entre 700 y 2600 nm, estos disminuyeron hasta alcanzar tamaños de alrededor de 100 nm según DLS, al someter las dispersiones a sonicación y extrusión, estos resultados coincidieron con los obtenidos mediante la técnica de Cryo-SEM. Las vesículas a base de PC fueron modificadas con quitosano de alto peso molecular (865 kDa) y con un grado de desacetilación de 77,8 ± 0,6 0/0, este proceso fue evaluado por medio del potencial Zeta y DLS. Las vesículas a base de PC y dimiristoilfosfatidilglicerol sal de sodio (DMPG-Na) también fueron modificadas con quitosano, este proceso fue estudiado por la técnica nanocalorímetrica de titulación isotérmica (nanoITC), potencial Zeta y DLS. De acuerdo con los resultados obtenidos se demostró que no es necesario invertir la carga inicial de la vesícula para asegurar el recubrimiento de la superficie de la misma con el quitosano. Las dispersiones preparadas se utilizaron en la síntesis de nanopartículas de oro (AuNPs). Las nanopartículas sintetizadas fueron caracterizadas por espectroscopía ultravioleta-visible (UV-Vis), microscopía electrónica de transmisión (TEM), microscopía de fuerza atómica (AFM), potencial Zeta y DLS. Con las mezclas de PC y fosfogliceroles se lograron sintetizar nanopartículas anisotrópicas, siendo la mezcla PC y DMPG-Na la que mostró un mejor rendimiento. Los máximos de absorción fueron reportados a 526 y 822 nm. Las partículas presentaron un potencial Zeta de -61 ± 16 mv y un tamaño de partícula de 132 ± 46 nm. Según las micrografías TEM se confirmó la obtención de partículas anisotrópicas, específicamente triangulares siendo la longitud de borde promedio entre los 75 y 100 nm. La síntesis de las AuNPs muestra una dependencia con la temperatura y el tiempo de reacción, siendo la síntesis a 25 0C la que genera un mejor rendimiento de partículas anisotrópicas. El efecto de la adición de sales resultó en el desplazamiento del máximo de absorción entre 800-1100 nm, distinguiéndose la completa desaparición del máximo de absorción con la adición de yoduro de sodio. Al añadir quitosano la absorción entre 7001100 nm disminuyó, obteniéndose partículas triangulares más redondeadas de acuerdo con el análisis de TEM. La centrifugación demostró ser un método de purificación efectivo según el análisis de TEM, duplicando la cantidad de partículas triangulares. Las partículas obtenidas podrían ser utilizadas en aplicaciones biomédicas debido a que se encuentran estabilizadas con fosfolípidos biocompatibles y biodegradables.
Gold nanoparticles are an interesting alternative to be used in biomedical applications such as: photothermal therapies on tumor cells, controlled drug release and sensor design. However, currently the synthesis methods use reagents that cause cytotoxicity in cells and those that are synthesized with biocompatible reagents show a low yield in the formation of anisotropic particles. In this work, a method for the synthesis of anisotropic gold nanoparticles was developed, using vesicles based on L-a-phosphatidylcholine (PC) and PC/phosphoglycerol mixtures. The vesicles were characterized by means of Zeta potential. dynamic light scattering (DLS) and cryogenic-scanning electron microscopy (CryoSEM). The dispersions showed negative Zeta potentials and particle sizes between 700 and 2600 nm, these decreased until reaching sizes of around 100 nm according to DLS, when subjecting the dispersions to sonication and extrusion, these results coincided with those obtained by the Cryo- SEM. The PC-based vesicles were modified with chitosan of high molecular weight (865 kDa) and with a degree of deacetylation of 77.8 ± 0.6 0/0, this process was evaluated by means of the Zeta potential and DLS. Vesicles based on PC and dimyristoylphosphatidylglycerol sodium salt (DMPG-Na) were also modified with chitosan, this process was studied by the isothermal titration nanocalorimetric technique (nanoITC), Zeta potential and DLS. According to the results obtained, it was shown that it is not necessary to reverse the initial charge of the vesicle to ensure the coating of its surface with chitosan. The prepared dispersions were used in the synthesis of gold nanoparticles (AuNPs). The synthesized nanoparticles were characterized by ultraviolet-visible spectroscopy (UV-Vis), transmission electron microscopy (TEM), atomic force microscopy (AFM), Zeta potential, and DLS. With the mixtures of PC and phosphoglycerols it was possible to synthesize anisotropic nanoparticles, being the mixture PC and DMPG-Na the one that showed the best performance. Absorption maxima were reported at 526 and 822 nm. The particles presented a Zeta potential of -61 ± 16 mv and a particle size of 132 ± 46 nm. According to the TEM micrographs, the obtaining of anisotropic particles was confirmed, specifically triangular, with the average edge length between 75 and 100 nm. The synthesis of the AuNPs shows a dependence on the temperature and the reaction time, being the synthesis at 25 0C the one that generates the best yield of anisotropic particles. The effect of the addition of salts resulted in the displacement of the absorption maximum between 800-1100 nm, distinguishing the complete disappearance of the absorption maximum with the addition of sodium iodide. By adding chitosan, the absorption between 700-1100 nm decreased, obtaining more rounded triangular particles according to the TEM analysis. Centrifugation proved to be an effective purification method according to TEM analysis, doubling the amount of triangular particles. The obtained particles could be used in biomedical applications because they are stabilized with biocompatible and biodegradable phospholipids.
Gold nanoparticles are an interesting alternative to be used in biomedical applications such as: photothermal therapies on tumor cells, controlled drug release and sensor design. However, currently the synthesis methods use reagents that cause cytotoxicity in cells and those that are synthesized with biocompatible reagents show a low yield in the formation of anisotropic particles. In this work, a method for the synthesis of anisotropic gold nanoparticles was developed, using vesicles based on L-a-phosphatidylcholine (PC) and PC/phosphoglycerol mixtures. The vesicles were characterized by means of Zeta potential. dynamic light scattering (DLS) and cryogenic-scanning electron microscopy (CryoSEM). The dispersions showed negative Zeta potentials and particle sizes between 700 and 2600 nm, these decreased until reaching sizes of around 100 nm according to DLS, when subjecting the dispersions to sonication and extrusion, these results coincided with those obtained by the Cryo- SEM. The PC-based vesicles were modified with chitosan of high molecular weight (865 kDa) and with a degree of deacetylation of 77.8 ± 0.6 0/0, this process was evaluated by means of the Zeta potential and DLS. Vesicles based on PC and dimyristoylphosphatidylglycerol sodium salt (DMPG-Na) were also modified with chitosan, this process was studied by the isothermal titration nanocalorimetric technique (nanoITC), Zeta potential and DLS. According to the results obtained, it was shown that it is not necessary to reverse the initial charge of the vesicle to ensure the coating of its surface with chitosan. The prepared dispersions were used in the synthesis of gold nanoparticles (AuNPs). The synthesized nanoparticles were characterized by ultraviolet-visible spectroscopy (UV-Vis), transmission electron microscopy (TEM), atomic force microscopy (AFM), Zeta potential, and DLS. With the mixtures of PC and phosphoglycerols it was possible to synthesize anisotropic nanoparticles, being the mixture PC and DMPG-Na the one that showed the best performance. Absorption maxima were reported at 526 and 822 nm. The particles presented a Zeta potential of -61 ± 16 mv and a particle size of 132 ± 46 nm. According to the TEM micrographs, the obtaining of anisotropic particles was confirmed, specifically triangular, with the average edge length between 75 and 100 nm. The synthesis of the AuNPs shows a dependence on the temperature and the reaction time, being the synthesis at 25 0C the one that generates the best yield of anisotropic particles. The effect of the addition of salts resulted in the displacement of the absorption maximum between 800-1100 nm, distinguishing the complete disappearance of the absorption maximum with the addition of sodium iodide. By adding chitosan, the absorption between 700-1100 nm decreased, obtaining more rounded triangular particles according to the TEM analysis. Centrifugation proved to be an effective purification method according to TEM analysis, doubling the amount of triangular particles. The obtained particles could be used in biomedical applications because they are stabilized with biocompatible and biodegradable phospholipids.
Descripción
Soto Cruz, J. (2015). Síntesis de nanopartículas anisotrópicas de oro utilizando vesículas liposomales modificadas con quitosano con potencial aplicación biomédica. [Tesis de Licenciatura]. Universidad Nacional, Heredia, C.R.
Palabras clave
NANOPARTICULAS, NANOPARTICLES, ORO, GOLD, CRISTALES, MEDICINA, QUITOSANO, QUIMICA