Controllable Preparation Of Gold Nanoshell Materials And Surface Enhanced Raman Scattering Study

Gold nanoshells mostly consist of a silica dielectric core that is surrounded by thin goldshell. Their extinction peaks are very easily tunable over a wide range of wavelengthsparticularly in the near infrared region of the spectrum (700-1300nm) by adjusting the ratio ofthe core diameter and the thickness of the shell (referred to as core-shell ratio). And light inthis region is transmitted through tissue with relatively little attenuation. At the same time,because the single gold nanoshell particle is of large Raman scatting cross section, we can useit as substrate for SERS enhancement. The Raman scatting of the absorbed molecules can begreatly enhanced. Compared with the conventional SERS substrate, Au nanoshells can realizeSERS detection based on single particles. It is important for applying SERS techniques forbiological detection.In order to achieve individual gold nanoshells for biological detection, we developed twoaspects about the gold nanoshells in this study. On the one hand, we design the synthesis ofdifferent size and state of aggregation of gold nanoshells. Their structural and opticalproperties were discussed in the paper. Different core size and aggregation state have greateffect on SERS intensity. On the other hand，the gold nanoshells embedded dye were designedas SERS biomarkers. The SERS enhancement inside nanoshells was investigated. The SERSsignal can be enhanced by coating different Au shells. We hope that efficacy and safety of themarkers by Au nanoshells as substrate can be further improved. The concrete researchcontents are as follows:1. We prepare the silica nanoparticles by St ber process and modified them to allowsmall gold colloids to attach to the surface of silica nanoparticles. The gold shells were thengrown by the reduction of gold from the seed, gradually forming a complete shell. Bychanging the reaction conditions, we can controllably prepare the gold nanoshell materialsand research the SERS spectrum with different sizes of SiO2coated gold shell. By theresearches mentioned above, we can controllably prepare the gold nanoshells with differentplasma resonance absorption peak by adjusting the dosage of the APS and seed aging time.The wavelengths range can reach near infrared region. Further, we found that the gold shellwhich silica diameter ranging from50to80nm can produce the best SERS signals.2. We adopt surface coupling method to embed dye molecules inside SiO2nanoparticles,and then coating gold shell on them. Hence, we prepared the golden shell nanocomposite withembedding dye as biomarker. We found that the probe molecules inside the nanoshells canalso produce the SERS enhancement so that they can be used for the SERS detection.