Fluorescence Enhancement of IgG-FITC Based on Surface Plasmon Resonance of Ag@SiO2 Nanoparticles as Application of Biomarker

• Published in: Analytical letters Vol. 46; no. 5; pp. 844 - 855
• Main Authors: Hu, Zi-Yang, Tang, Jian-Hua, Ge, Zhi-Li, Song, Tian-Mei, Qiu, Ting, Xie, Hong-Ping, Guo, Li-Ping
• Format: Journal Article
• Language: English
• Published: Taylor & Francis Group 24.03.2013
• Subjects: Fluorescence enhancement; IgG-FITC; Nanoparticles; Surface plasmon resonance
• ISSN: 0003-2719; 1532-236X
• DOI: 10.1080/00032719.2012.738342

Ag@SiO 2 nanoparticles with the core-shell structure have been prepared, of which the silver core was about 50 nm and the thickness of silica shell was approximately 10 nm. In slightly alkaline aqueous solution (pH = 8), through electrostatic force between cationic polymer PDDA (i.e., poly-diallyldimethylammonium chloride) and the obtained Ag@SiO 2 nanoparticles, PDDA molecules were fixed on the surface of Ag@SiO 2 nanoparticles. The prepared Ag@SiO 2 /PDDA nanoparticles have both rich positive surface charges and rich micro-holes of silica shell. Based on micro-hole adsorption, the small molecule FITC (i.e., fluorescein isothiocyanate) marking on IgG (i.e., immunoglobulin) was adsorbed into the rich microholes of silica shell; at the same time, the negatively charge macromolecule IgG marked by FITC was firmly fixed on the rich positive charges surface of Ag@SiO 2 /PDDA nanoparticles by electrostatic interaction. And then, Ag@SiO 2 /PDDA/IgG-FITC fluorescent nanoparticles with the SPR fluorescence enhancement were prepared. The shell-type SiO 2 /PDDA/IgG-FITC nanoparticles were obtained by dissolving the silver core in the prepared core-shell Ag@SiO 2 /PDDA/IgG-FITC nanoparticles by using H 2 O 2 . Compared with the shell-type nanoparticles, the fluorescence intensity of Ag@SiO 2 /PDDA/IgG-FITC was enhanced 1.7 times. The prepared Ag@SiO 2 /PDDA/IgG-FITC nanoparticles have both SPR-based fluorescence enhancement ability and the surface distributing IgG-based obvious advantages including good biocompatibility and easy marking with other biomolecules.