Optical Response of a Golden Plasmonic Device with Nanoholes to Asses Biological Cells

Abstract

ABSTRACT: We have studied the optical response of a 60-nm-thick gold film with circular apertures of radius 90 nm, perforated periodically every 500 nm. Special attention was paid to the wavelength and transmittance changes at the extraordinary optical transmission peak for biological cells with different properties, which were immersed in a water solution on top of the sensor. The problem was computationally solved using two geometrical models in COMSOL. Particularly, we have studied the inuence of the cell membrane and size, its cytoplasmic index, the contact length between cell and sensor, and some nuclear properties such as its refractive index, size and location. Finally, the overall behaviour of the device is reported for two samples of 50 lymphocytes and circulating tumour cells coming from a colorectal primary tumour. We have demonstrated that the sensor can discern these two cell types with an accuracy greater than 66%.

RESUMEN: Se ha estudiado la respuesta óptica de una placa de oro de 60 nm de anchura con aperturas circulares de radio 90 nm y perforadas con una periodicidad de 500 nm. Se ha observado el cambio de longitud de onda y transmitancia en el pico de transmisión óptica extraordinaria para células biológicas de diferentes características inmersas en una solución acuosa ubicada sobre el sensor. Mediante dos modelos geométricos bidimensionales se ha resuelto computacionalmente el problema en COMSOL. En particular, se ha observado la influencia de la membrana y el tamaño celulares, el índice citoplasmático, la longitud de contacto célula-placa y las propiedades del núcleo (índice de refracción, tamaño y posición). Finalmente, se ha comparado globalmente el comportamiento del sensor para dos muestras de 50 linfocitos y células tumorales circulantes procedentes de un cáncer colorrectal como tumor primario. Se ha demostrado una eficiencia del sensor en la discriminación linfocito-célula tumoral superior al 66%.