分别利用射频溅射法和溶胶-凝胶模板法,在玻璃基板上制备45nm厚的金膜和45 nm厚的SiO2介孔薄膜,用作表面等离子体共振(SPR)芯片,然后基于Kretschmann结构和共振波长测量模式构建了近红外SPR传感器.实验表明,在宽带平行光入射条件下,随着入射角度(θ)的减小,共振波长(λR)红移,折射率灵敏度(S=ΔλR/n)迅速提高.在θ=8°时测得的折射率灵敏度为24241 nm/RIU,是θ=15°所对应的灵敏度(2524.2 nm/RIU)的9.6倍.与常规的裸金SPR传感器相比,在相同的共振波长下,SiO2介孔薄膜修饰层使得SPR共振吸收峰明显变窄,光谱分辨率升高.低浓度溶菌酶水溶液在θ=10°时测得的SPR近红外共振波长随溶菌酶浓度增大而线性红移,其斜率为ΔλR/C=1.5×107nm· L/mol,即溶菌酶浓度增加6.67×10-8 mol/L能够导致共振波长红移1nm.1×10-7 mol/L Cu2+溶液可使SPR共振波长红移3nm.%An infrared surface plasmon resonance (SPR) sensor with wavelength interrogation was prepared based on Kretschmann configuration. The SPR chips were fabricated by sputtering a 45-nm gold layer on the glass substrate followed by sol-gel template synthesis of a 45-nm-thick mesoporoussilica film. The experimental results indicate that with a broadband collimated incident beam both the resonance wavelength (λr) and the refractive-index sensitivity (S) increase with decreasing the incident angle (θ). The refractive-index sensitivity was measured as S = 24241 nm/RIU at θ=8% being 9. 6 times as high as S = 2524. 2 nm/RIU obtained at 8= 15°. Compared with a conventional SPR sensor with a naked gold film, the modification of SPR chips with mesoporous silica thin films makes the resonance absorption band narrower and consequently offers a higher SPR spectrum resolution. The results measured at θ=10° using low concentrations of aqueous lysozyme solutions indicate a linear dependence of the resonance wavelength on the protein concentration with a slope of △λr/C=1. 5× 107 nm · L/mol, implying that an increase of 6. 67 × 10-8 mol/L in protein concentration can causes a redshift of △λr = 1 nm. For the detection of Cu2+ions, the results indicated that adsorption of Cu2+ ions from the 1×10-7 mol/L aqueous solution can make the resonance wavelength redshift 3 nm.
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