Development of a Refractive Index Sensor Based on the Deposition of Gold and Silver Nanowires on ITO Glass for CA15-3 Detection

As a step towards the development of highly sensitive and accurate biosensors for the early detection and monitoring of breast cancer, we have developed a refractive index sensor for the detection of CA15-3 breast cancer biomarker based on the deposition of gold and silver nanowires on ITO glass. 1 cm × 1 cm ITO glass was washed and vacuum dried. Gold films were sputtered on the clean dried ITO glass using an ion sputtering machine and labelled ITO/ Au electrode. Silver nanowires solution were deposited on the ITO/Au electrode and labelled ITO/AU/AgNWs electrode. The ITO/Au/AgNWs electrode was then embedded in a 12 well-plate containing CA15-3 antibody and labelled ITO/Au/ AgNWS/CA15-3 antibody electrode, which was used to detect CA15-3 antigen. The UV absorption wavelength of the sensor was found to be within the range of 320 nm to 350 nm. The sensor has a linear response to CA 15-3 antigen at concentrations ranging from 3 IU/mL to 32 IU/mL, and showed good CA15-3 detection properties with significant linear relationships between the wavelength change and the CA15-3 antigen concentration, the wavelength change and the refractive index, and the CA15-3 antigen concentration and refractive index. Our study provides a new and sure way towards the development of highly sensitive, accurate and efficient biosensors for the early detection and monitoring of breast cancer during therapy because Localized Surface Plasmon Resonance (LSPR) based detection techniques has an advantage over other detection techniques. Moreover, LSPR is superior to conventional methods when it comes to long term monitoring applications since LSPR of metallic nanoparticles do not bleach or blink. Also, the binding of nanoparticles to organic molecules increases the local refractive index since the index of refraction of typical buffer solutions are smaller than that of organic molecules.