SPR signals enhancement by gold nanorods for cell surface marker detection

The detection of micrometer-sized particles like cells is limited by surface plasmon resonance (SPR) biosensors because of having the depth of evanescent wave <500 nm. In this study, for the first time, we exhibited the use of streptavidin functionalized gold nanorods as intensification labels for detection of cell surface markers in SPR based biosensors. The gold nanorods (ʎ max: 735nm ) was modified with streptavidin using EDC/NHS coupling method and Human umbilical vein endothelial cells (HUVECs) was selected as cell model for detecting VE- cadherin on cell surface using real time SPR device in the 785 nm wavelength of laser source. The investigations revealed that the plasmonic field extension produced from the gold layer and gold nanorods results in multiple enhancement of SPR signals when the wavelength of laser source in SPR instrument is matched with the wavelength of maximum absorbance in gold nanorods. Also the results show that the growth of ∆RU value in specific and non-specific binding for various cell number injection are produced with increasing the cell number. The results displayed that cell detection can be performed in real- time form without any need of a time- consuming process used in conventional methods like immunocytochemistry, flow cytometry and western blotting.