纳米金/银修饰的空心/杂化微球的制备及其作为综合性能优异的三维拉曼增强基底的研究

Hollow Silica and PS@ Silica Microspheres with Their Respective Surfaces Being Modified with Au or Ag Nanoparticles and Their Performance as SERS Substrates

以带正电的聚苯乙烯(PS)微球为模板分别制备出表面层为二氧化硅的杂化微球(PS@Si O2)及空心二氧化硅微球(HSSi,hollow spheres of Si O2).利用巯基硅烷偶联剂的桥联作用将金或银纳米粒子修饰到二氧化硅壳层的外表面,制备出4种结构均匀、体积窄分布的复合粒子:(1)纳米金修饰在空心二氧化硅微球的外表面(HSSi-Au NPs);(2)纳米金修饰在实心的PS/二氧化硅杂化微球(PS为核、二氧化硅为壳层)的外表面(PS@Si O2-Au NPs);(3)纳米银修饰在空心二氧化硅微球的外表面(HSSi-Ag NPs)以及(4)纳米银修饰在实心的PS/二氧化硅杂化微球的外表面(PS@Si O2-Ag NPs).分别利用上述4种复合粒子作为拉曼增强(SERS)基底,并以结晶紫(CV)为探针分子对各基底的拉曼增强效果进行了研究,其CV检测限依次为10-10、10-9、10-11和10-11mol/L,均具有较高的灵敏度.结果表明,以空心二氧化硅微球作为载体的增强效果优于以实心的杂化微球作为载体的增强效果(HSSi-Au NPs对CV的检测限比PS@Si O2-Au NPs对CV的检测限低1个数量级;虽然HSSi-Ag NPs和PS@Si O2-Ag NPs对CV的检测限相同,但对于相同浓度的CV,前者所获得的信号要明显强于后者).多次随机的重复测试表明,上述4种基底均具有优良的重复性.将上述4种基底在实验室放置3个月后用于CV的检测,各个基底仍具有相近的拉曼增强效果,即上述4种SERS基底的稳定性良好.

Polystyrene @ silica hybrid microspheres（PS @ SiO2） and hollow spheres of SiO2（HSSi） were prepared using positively charged polystyrene（PS） microspheres as the template.Then,gold nanoparticles（Au-NPs） and silver nanoparticles（Ag-NPs） were modified onto the surface of PS @ SiO2 and HSSi,respectively,through the bridging coupling by mercapto silane coupling agents,which leads to the following four kinds of composite microspheres with uniform structures and narrow size distributions：（1） HSSi with the surface being modified with Au-NPs（HSSi-Au NPs）;（2） PS @ SiO2 with the surface being modified with Au NPs（PS@ SiO2-Au NPs）;（3） HSSi with the surface being modified with Ag-NPs（HSSi-Ag NPs） and（4）PS@ SiO2 with the surface being modified with Ag NPs（PS @ SiO2-Ag NPs）.These composite microspheres were used as SERS substrates,whose sensitivity,reproducibility and stability were evaluated by using crystal violet（CV） as the probe.The detection limits of CV by HSSi-Au NPs,PS@ SiO2-Au NPs,HSSi-Ag NPs and PS@ SiO2-Ag NPs are 10-10 mol / L,10-9mol / L,10-11 mol / L and 10-11 mol / L,respectively.All these substrates exhibit relatively high sensitivities;the hollow structures make positive contributions to the sensitivities.Results of repeated Raman measurements of CV on the different spots randomly selected from the substrates confirm that all the substrates have good reproducibility.Moreover,all the substrates have a good stability,because they still have good sensitivities after having been stored in ambient environment for 3 months.