Effects of nanoparticle size and cell type on high sensitivity cell detection using a localized surface plasmon resonance biosensor

A localized surface plasmon resonance (LSPR) effect was used to distinguish cell concentration on ordered arrays of Au nanoparticles (NPs) on glass substrates. Human-derived retinal pigment epithelial RPE-1 cells with flatter bodies and higher confluency were compared with breast cancer MCF-7 cells. Nanosphere lithography was used to form Au NPs with average diameters of 500 and 60nm in order to compare cell detection range, resonance peak shift, and cell concentration sensitivity. A larger cell concentration range was detected on the larger 500nm Au NPs compared to 60nm Au NPs (8.56×10³-1.09×10⁶ vs. 3.43×10⁴-2.73×10⁵cells/ml). Resonance peak shift could distinguish RPE-1 from MCF-7 cells on both Au NPs. RPE-1 cells consistently displayed larger resonance peak shifts compared to MCF-7 cells until the detection became saturated at higher concentration. For both types of cells, higher concentration sensitivity in the range of ~10⁴-10⁶cells/ml was observed on 500nm compared to 60nm Au NPs. Our results show that cells on Au NPs can be detected in a large range and at low concentration. Optimal cell sensing can be achieved by altering the dimensions of Au NPs according to different cell characteristics and concentrations.