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复合SERS活性和超顺磁性的磁核金壳纳米颗粒在SERS传感、样品分离与富集、定向输运等方面已有广泛应用.已报道的基于磁核制备的金纳米壳大多为平滑的金壳,基于磁核生长枝杈状金壳可以提升颗粒的SERS增强性能,但相关报道甚少.本文基于种子生长法并引入定向生长控制剂AgNO_3,合成了一种新型的磁核枝杈状金壳纳米颗粒,系统地研究了金壳的生长过程与机制、表面形貌的控制生长以及对SERS性能的影响.此外,设计并构建了具有良好的结构刚性、稳定性和空间定位能力的四面体DNA探针,并将其修饰到磁核枝杈状金壳纳米颗粒表面构建得到检测基底.通过在金纳米颗粒表面修饰单链DNA构建SERS探针,利用碱基互补配对形成“检测基底-目标核酸-SERS探针”三明治结构复合物,借助外加磁场分离检测液中的复合物并富集后进行SERS检测,实现了对于血清中肿瘤核酸标志物miRNA-21的高灵敏、特异性检测,检测限达到623 amol L~(-1).
Composite SERS activity and superparamagnetic magnetic core-shell nanoparticles have been widely used in SERS sensing, sample separation and enrichment, directional transport, etc. The reported gold nanoshells based on magnetic cores are mostly smooth Gold shell, based on the growth of the magnetic core of the twig-like gold shell can enhance the particle SERS enhancement performance, but little has been reported.In this paper, based on the seed growth method and the introduction of directional growth control agent AgNO_3, a new type of magnetic core twig- Nano-particles, systematically studied the growth process and mechanism of the gold shell, the controlled growth of the surface morphology and the effect on the performance of SERS.In addition, tetrahedron DNA with good structural rigidity, stability and spatial orientation was designed and constructed Probe and modified to the surface of the magnetic core twig-like gold shell nanoparticles to obtain a detection substrate by constructing single-stranded DNA on the surface of the gold nanoparticle to construct a SERS probe, using complementary base pairing to form a “detection substrate-target nucleic acid -SERS probe ”sandwich structure complex, with the help of an external magnetic field separation of detection complexes in the solution and enrichment for SERS detection, to achieve the serum tumor nucleic acid marker mi The detection limit of RNA-21 was 623 amol L -1 with high sensitivity and specificity.