纳米金表面修饰与表面等离子体共振传感器的相互作用研究

Study of interaction of surface plasmon resonance sensor with nano-gold

为了分析纳米金表面修饰对表面等离子体共振(SPR)的放大作用,以及其对传感器本身的影响,首先,基于色散介质的吸收理论,通过建立波长型SPR生物传感器四层膜结构的数学模型,理论分析了传感器表面所吸附纳米金对传感器的影响:纳米金的表面修饰,改变了表面等离子体传感器中棱镜表面各介质层内电磁场的能量分布,削弱了金属膜在共振吸收中的作用,从而使SPR曲线的半波宽度增加,最小反射系数增大,金膜的最优膜厚度也随之改变.其次,通过不同厚度的金膜外吸附纳米金的对比试验,验证了此理论.金膜厚45nm、表面修饰10nm纳米金颗粒后,传感器的折射率灵敏度比金膜48nm未吸附纳米金SPR传感器折射率灵敏度提高了近1.5倍.

For a quantitative analysis of the detection performance of wavelength surface plasmon resonance sensor after the introduction of absorbing thin films,a mathematical model was established for the wavelength SPR biosensor. Based on absorption theory of dispersive media,the distribution of electromagnetic field in each film outside the prism is calculated. The results show that,after introducing the absorbing thin films,electromagnetic field energy distribution in each layer out of the prism surfaces was changed,the metal film contribution on the resonance absorption was reduced,which increases the half wave width of SPR curve and the minimum reflection coefficient,so the optimal film thickness of metal film was also changed. Then the effect of colloidal gold and immunogold on SPR biosensor has been theoretically and experimentally verified. The result shows that,compared with the 48 nm gold film SPR sensor,the sensitivity increases 1. 5 times when 45 nm gold film is surface-modified with 10 nm nano-gold.