Fabrication of gold nanoparticles array for optical analysis

Abstract

Gold nanoparticles have received increasing attention due to their unique properties such as localized surface plasmon resonance (LSPR), chemical stability, and biocompatibility. LSPR of gold nanoparticles is strong and sensitive to change of surrounding environment, and thus it is widely used in the form of arrayed substrate using photo reduction, assembly bias capillary assisted method and others to detect various types of chemicals. However, previous researches have problems in low reproducibility because the shape and size of nanoparticles are irregular. And the shape and size of nanoparticles give effect on optical property for nanoparticles. In this study, the shape and size controlled gold rhombic dodecahedron; truncated rhombic dodecahedron and octahedron were synthesized and applied as optical analysis to control the optical property. PDMS molds with uniform morphology were prepared in various size and large area using self-assembled polystyrene spheres and Au nanoparticles arrays were fabricated by drop casting the synthesized gold nanoparticles solution on the PDMS molds. Regular arrays of gold nanoparticles fabricated by this cheap and easy process have high reproducibility, statistical reliability and usability as equipment. Raman signals of 4-nitrobenzenthiol absorbed on fabricated gold nanoparticles array were measured to confirm optical applicability. All the gold nanoparticles arrays show strong Raman signal enhancement, and thus they are suitable for surface enhanced Raman scattering substrates. Rhombic dodecahedral gold nanoparticles display enormously strong enhancement compared to other nanoparticles. Because of the effect of decrease in surface area in the confocal area, enhancement factor decrease as the size of pattern increases.