Novel bio-nanochip based on localized surface plasmon resonance spectroscopy of rhombic nanoparticles.

A new silver (Ag) nanostructure with a rectangular distribution array composed of rhombic nanoparticles is described here. The structure has an apparent advantage of strong hot spots that have a much higher signal intensity than that of the previously reported traditional triangular structures. It generates a great enhancement of a localized surface plasmon resonance (LSPR) effect. Moreover, an antigen with longer arm length is applied to strengthen the binding signals of both the antigen and antibody. We performed experiments for the LSPR-induced extinction spectra in each step of the surface modification of the Ag nanoparticles in atmosphere environment. A spectrophotometer was used to measure the extinction spectrum of our proposed nanochip. The results obtained indicate a better sensitivity for our current nanochip than that of the other reported LSPR-based nanochips. Theoretical computational numerical simulation is also carried out with a discrete dipole approximation algorithm. Our computational results are in agreement with the corresponding experimental spectrum. This type of nanochip may have potential utility in many applications, including medical science, biological fields and biochemical analysis.