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

• Au nanoparticles (NP) with 500 and 60 nm diameters for cell concentration sensing.
• Detection range and sensitivity depend on NP size and cell types.
• Larger cell concentration range is detected on 500 than 60 nm Au NPs.
• RPE-1 from MCF-7 cells could be distinguished by optical sensing.
• Resonance peak shift provided large range cell detection at low concentration.

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 60 nm in order to compare cell detection range, resonance peak shift, and cell concentration sensitivity. A larger cell concentration range was detected on the larger 500 nm Au NPs compared to 60 nm Au NPs (8.56×103–1.09×106 vs. 3.43×104–2.73×105 cells/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 ~104–106 cells/ml was observed on 500 nm compared to 60 nm 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.